[123doc.vn] luan van cong nghe hoa nghien cuu tong hop dau diesel sinh hoc tu ba ca phe phe thai
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BGIO DC V O TO
TRNG I HC CN TH
KHOA KHOA HC TNHIN
LUN VN TT NGHIP I HC
NGHIN CU TNG HP DU DIESELSINH HC TB C PH PHTHI
CN BHNG DN SINH VIN THC HINTS. Bi ThBu Hu Bi Lin Khoa
MSSV: 3077158Ngnh: Ha Hc K33
Thng 5 - 2011
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TRNG I HC CN TH CNG HA X HI CHNGHA VIT NAM
KHOA KHOA HC TNHIN c lp-Tdo-Hnh phc
BMN HA HC
Cn Th, ngy thng nm 2011
PHIU NGHTI TT NGHIP CHO SINH VIN
NM HC 20102011
1.Cn bhng dn: Ts. Bi ThBu Hu.
2.Tn ti: NGHIN CU TNG HP DU DIESEL SINH HC TB CPH
3.a im thc hin: phng th nghim hu c chuyn su Khoa Khoa Hc TNhinTrng i Hc Cn Th.
4.
Slng sinh vin thc hin: 1
5.Hv tn sinh vin thc hin: Bi Lin Khoa (MSSV: 3077158).
6.Mc ch yu cu: Nghiu cu qui trnh tng hp biodiesel tb c ph quy mphng th nghim.
7.Ni dung chnh v gii hn ca ti: ti gm 4 phn:
Chng 1: TNG QUAN
Chng 2: PHNGTIN V PHNG PHP NGHIN CU
Chng 3: THC NGHIMChng 4: KT QUV THO LUN
Chng 5: KT LUN V KIN NGH
8.Cc yu cu htr: Trang thit b, dng cth nghim v kinh ph thc hin ti.
9.Kinh ph dtr cho vic thc hin ti: 800.000 ng.
Sinh vin ngh
(K tn v ghi r htn)
Bi Lin Khoa
kin ca bmn kin ca cn bhng dn
Ts. Bi ThBu Hu
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Trng i Hc Cn Th Cng Ha X Hi ChNgha Vit Nam
Khoa Khoa Hc TNhin c lpTDoHnh Phc
BMn Ha Hc
Cn Th, ngy thng nm 2011
NHN XT V NH GI CA CN BHNG DN1.Cn bhng dn: Ts. Bi ThBu Hu
2.Tn ti: NGHIN CU TNG HP DU DIESEL SINH HC TB CPH PHTHI
3.Sinh vin thc hin: Bi Lin Khoa (MSSV: 3077158).
4.Lp: CNhn Ha Hc K33.
5.Ni dung nhn xt:
a.Nhn xt vhnh thc ca lun vn tt nghip: .....................................................
...........................................................................................................................................
...........................................................................................................................................
b.Nhn xt vni dung ca lun vn tt nghip (nghghi chi tit v y ): ......
...........................................................................................................................................
...........................................................................................................................................
Nhng vn cn hn ch: ..................................................................................
...........................................................................................................................................
...........................................................................................................................................
c.Nhn xt i vi sinh vin thc hin ti: .............................................................
...........................................................................................................................................
...........................................................................................................................................
d.Kt lun nghv im: .........................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................Cn Th, ngy thng nm 2011
Cn bchm hng dn
Ts. Bi ThBu Hu
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Trng i Hc Cn Th Cng Ha X Hi ChNgha Vit Nam
Khoa Khoa Hc TNhin c lpTDoHnh Phc
BMn Ha Hc
Cn Th, ngy thng nm 2011
NHN XT V NH GI CA CN BPHN BIN
1.Cn bhng dn: Ts. Bi ThBu Hu
2.Tn ti: NGHIN CU TNG HP DU DIESEL SINH HC TB CPH PHTHI
3.Sinh vin thc hin: Bi Lin Khoa (MSSV: 3077158).
4.Lp: CNhn Ha Hc K33.
5.Ni dung nhn xt:
a.
Nhn xt vhnh thc ca lun vn tt nghip: .....................................................
...........................................................................................................................................
...........................................................................................................................................
b.Nhn xt vni dung ca lun vn tt nghip (nghghi chi tit v y ): ......
...........................................................................................................................................
...........................................................................................................................................
Nhng vn cn hn ch: ..................................................................................
...........................................................................................................................................
...........................................................................................................................................
c.Nhn xt i vi sinh vin thc hin ti: .............................................................
...........................................................................................................................................
...........................................................................................................................................
d.Kt lun nghv im: .........................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
Cn Th, ngy thng nm 2011
Cn bchm phn bin
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LI CAM OAN
Tt c nhng d liu v s liu s dng trong ni dung bi lun vn c ti
tham kho nhiu ngun khc nhau v c ghi nhn tnhng kt quth nghim m
ti tin hnh. Ti xin cam oan vstn ti v tnh trung thc khi sdng nhng d
liu v sliu ny.
Bi Lin Khoa
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LI CM N
Sau hn ba thng thc hin lun vn tt nghip, em hc hi c nhiu kinthc qu bu v lnh vc m em nghin cu. hon thnh lun vn chnh l nh
nhng iu bch m Thy C truyn t cho em trong sut nhng nm thng i
hc v l nn tng tri thc em ttin bc vo i.
Em xin chn thnh cm n qu Thy C ca Trng i Hc Cn Th ni chung
v Thy C Khoa Khoa Hc TNhin ni ring. c bit em xin gi li bit n su
sc n C Bi ThBu Hu, ngi tn tnh hng dn trong tng chn ng
nghin cu thc hin ti.
Em cng gi li cm n n bn b v gia nh gip , ng vin, to iu
kin cho em vtinh thn ln vt cht em hon thnh lun vn ny.
Em xin by tlng bit n n tt cmi ngi.
Cn Th, ngy thng nm 2011
Bi Lin Khoa
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa i
GII THIUHin nay, th gii v ang phi i mt vi hai vn ln l hin trng
nhim mi trng do lng rc thi kh ln v tnh trng khan him ngun nhin liu
du m. Chnh v vy, vn c t ra l nghin cu tn dng ngun rc thi snxut ra nhin liu sinh hc thay thcho ngun nhin liu truyn thng.
Nhn vthc trng ngun nng lng tiu thtrn thgii ngy nay th du th
v kh tnhin l ngun nng lng quan trng nht. Cc ngun ti nguyn ny c
gii hn v khng ti to c. Nu cc ngun ny c sdng vi mc hin nay
th khnngthiu ht ngun nguyn liu c thxy ra. Hn na, vic sdng rng ri
nhin liu du mgy ra vn nhim mi trng. Do , c squan tm n
mt sngun nng lng thay th, trong diesel sinh hc l mt trong nhng nhin
liu thay thkh tt v thn thin vi mi trng. Tuy nhin, cc nghin cu tng hp
diesel sinh hc hin nay ch yu t cc ngun nguyn liu du m ng thc vt
nhng cha cp nhiu vdu bo tb c ph, mt ngun nguyn liu phthi kh
di do v rtin. Hng nm, thgii sn xut hn 2,72 tKg c ph. Cc nh khoa
hc c tnh rng, tb c ph qua sdng ny c thtng hp c khong 1287
triu lt du diesel sinh hc ng gp vo ngun nhin liu ca thgii.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa ii
MCLC
CHNG 1 TNG QUAN TI LIU .......................................................................... 1
I LIPID ......................................................................................................................... 1
I.1 Khi nim vlipid ............................................................................................... 1
I.2 Phn loi v lipid ................................................................................................. 2
I.2.1 Da vo phn ng x phng ha..2
I.2.2 Da vo ha tan...2
I.2.3 Da vo thnh phn cu to..2
I.3 Chc nng ca lipid ............................................................................................. 3
I.4 Tnh cht chung ca lipid .................................................................................... 3I.4.1 Tnh cht vt l.3
I.4.2 Tnh cht ha hc.4
II CC PHNG PHP THU LY DU BO TRONG B C PH ................... 6
II.1 Tch chit bng dung mi hu c...................................................................... 6
II.2 Tch chit bng CO2lng siu ti hn .............................................................. 7
II.3 Tch chit bng enzyme ..................................................................................... 7
II.4 p bng my ....................................................................................................... 7III BIODIESEL ............................................................................................................ 8
III.1 Nhin liu diesel ............................................................................................... 8
III.2 S lc v biodiesel .......................................................................................... 8
III.2.1 Khi nim ...8
III.2.2 Lch shnh thnh v pht trin ca biodiesel.10
III.2.3 Tnh hnh sdng biodiesel trn thgii v Vit Nam...10
III.3 Cc chtiu ha l ca biodiesel .................................................................... 11
III.3.1 nht .11
III.3.2 ChspH..11
III.3.3 Tro sulfate.11
III.3.4 Lu hunh,,,.11
III.3.5 Trscetane.....12
III.3.6 Chsacid....12 III.3.7 Glycerol tdo...12
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa iii
III.3.8 Glycerol tng....12
III.3.9 Hm lng tro phosphorus,,,12
III.3.10 Hm lng nc ln vo nhin liu...13
III.4 Nhng u, nhc im ca biodiesel ............................................................ 13
III.4.1 Nhng u im khi sdng biodiesel cho ng c diesel......13
III.4.1.1 Vmt mi trng13
III.4.1.2 Vmt kthut.14
III.4.2 Nhc im ca biodiesel...15
III.5 Cc phng php ha hc sdng trong tng hp biodiesel ........................ 15
III.5.1 Phn ng transester ha lipid...15
III.5.1.1 Cc phng php thc hin phn ng transester ha lipid16III.5.1.2 Xc tc sdng trong phn ng transester ha16
III.5.2 Phn ng ester ha acid carboxylic.19
III.6 Tng hp biodiesel da trn phn ng transester ha c sdng xc tc kim
................................................................................................................................ 21
III.6.1 i vi du thc vt hoc m ng vt c hm lng acid t do
thp............................................................................21
III.6.2 i vi du thc vt hoc m ng vt c hm lng acid bo t do
cao. 22
III.7 Tim nng sn xut biodiesel tb c ph ..................................................... 23
CHNG 2 PHNG TIN V PHNG PHP NGHIN CU ......................... 24
I NI DUNG NGHIN CU .................................................................................... 24
II PHNG TIN NGHIN CU ........................................................................... 24
II.1 Thit bv dng c ........................................................................................... 24
II.2 Ha cht ........................................................................................................... 24
II.3 Nguyn liu ...................................................................................................... 25
III PHNG PHP NGHIN CU ......................................................................... 25
III.1 Phng php ly trch du bo tb c ph ..................................................... 25
III.1.1 Phng php chit soxhlet ....................................................................... 25
III.1.2 Phng php ngm dm ........................................................................... 25
III.2 Xc nh cc chsha l ca du bo trch ly tb c ph phthi ........... 26
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa iv
III.2.1 Xc nh m b c ph v hm lng cht bay hi............................. 26
III.2.1.1 Nguyn tc.26
III.2.1.2 Tin hnh...26
III.2.1.3 Tnh kt qu...26
III.2.2 Chsacid (IA) ........................................................................................ 26
III.2.2.1 ngha...26
III.2.2.2 Nguyn tc.26
III.2.2.3 Tin hnh...26
III.2.2.4 Tnh kt qu...27
III.3 Tng hp biodiesel tdu bo ca b c ph phthi ................................... 27
CHNG 3 THC NGHIM..29 I Giai on ester ha .................................................................................................. 29
I.1 Cch btr th nghim: ...................................................................................... 30
I.2 Tin trnh thc hin ........................................................................................... 30
I.3 Tin trnh ra ..................................................................................................... 30
II Giai on transester ha ......................................................................................... 31
II.1 Cch btr th nghim ...................................................................................... 31
II.2 Tin trnh thc hin .......................................................................................... 31
II.3 Tin hnh phn ng .......................................................................................... 31
II.4 Tin trnh ra.................................................................................................... 32
III Tin trnh lm kh sn phm ................................................................................. 32
IV nh gi cht lng sn phm biodiesel .............................................................. 32
CHNG 4 KT QU- THO LUN ...................................................................... 33
I CC CHSHA L ........................................................................................... 33I.1 m ca b c ph phthi v hm lng cht bay hi ................................ 33
I.2 Hiu sut ly trch du bo tb c ph phthi................................................ 33
I.2.1 Phng php ngm dm..33
I.2.2 Phng php trch soxhlet.33
I.2.3 Nhn xt...33
I.3 Chsacid ca du bo ..................................................................................... 34
II QUY TRNH IU CHBIODIESEL TB C PH ..................................... 34
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa v
II.1 Phn ng ester ha ........................................................................................... 34
II.1.1 nh hng ca lng methanol....34
II.1.2 nh hng ca nhit phn ng.36
II.1.3 nh hng ca thi gian phn ng37
II.1.4 nh hng lng acid H2SO4................................................................39
II.1.5 iu kin ti u ca giai on ester ha....40
II.2 Phn ng transester ha ................................................................................... 41
II.2.1 nh hng ca lng methanol....41
II.2.2 nh hng ca nhit phn ng....43
II.2.3 nh hng ca thi gian...44
II.2.4 nh hng lng xc tc KOH.46 II.2.5 iu kin ti u ca giai on transester ha....48
II.3 nh gi cht lng sn phm biodiesel iu chc .................................. 49
CHNG 4 KT LUNKIN NGH ..................................................................... 51
I KT LUN .............................................................................................................. 51
II KIN NGH ............................................................................................................ 51
TI LIU THAM KHO ............................................................................................. 52
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa vi
MC LC CC BIU BNGBng 1 So snh mt schtiu gia biodiesel (RME) v diesel .................................... 9
Bng 2 Cc yu tcnh ............................................................................................ 35
Bng 3 nh hng lng methanol n chsacid ..................................................... 35
Bng 4 Cc yu tcnh ............................................................................................. 36
Bng 5 nh hng ca nhit phn ng n chsacid ........................................... 37
Bng 6 Cc yu tcnh ............................................................................................ 38
Bng 7 nh hng ca thi gian phn ng n chsacid .......................................... 38
Bng 8 Cc yu tcnh ............................................................................................. 39
Bng 9 nh hng ca lng xc tc H2SO4n chsacid ...................................... 40
Bng 10 Cc yu tcnh ........................................................................................... 41Bng 11 nh hng lng methanol n chsacid v hiu sut ca sn phm
biodiesel ......................................................................................................................... 42
Bng 12 Cc yu tcnh .......................................................................................... 43
Bng 13 nh hng nhit phn ng n chsacid v hiu sut ca sn phm
biodiesel ......................................................................................................................... 43
Bng 14 Cc yu tcnh ........................................................................................... 45
Bng 15 nh hng thi gian phn ng n chsacid v hiu sut ca sn phm
biodiesel ......................................................................................................................... 45
Bng 16 Cc yu tcnh nh hng lng KOH .................................................... 46
Bng 17 nh hng lng xc tc KOH n chsacid v hiu sut ca sn phm
biodiesel ......................................................................................................................... 47
Bng 18 Bng biodiesel chun theo QCVN 1: 2009/BKHCN ...................................... 49
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa vii
MC LC CC HNH V
Hnh 1 nh hng ca lng methanol n chsacid ............................................... 36
Hnh 2 nh hng ca nhit n chsacid ........................................................... 37
Hnh 3 nh hng ca thi gian phn ng n chsacid .......................................... 38
Hnh 4 nh hng ca lng xc tc H2SO4n chsacid ....................................... 40
Hnh 5 nh hng lng methanol n chsacid v hiu sut ca sn phm
biodiesel ......................................................................................................................... 42
Hnh 6 nh hng nhit phn ng n chsacid v hiu sut ca sn phm
biodiesel ......................................................................................................................... 44
Hnh 7 nh hng thi gian phn ng n chsacid v hiu sut ca sn phmbiodiesel ......................................................................................................................... 46
Hnh 8 nh hng lng xc tc KOH n chsacid v hiu sut ca sn phm
biodiesel ......................................................................................................................... 47
MC LC CC S
S 1 C chphn ng transester ha xc tc base ................................................... 18
S 2 C chphn ng ester ha ............................................................................... 20
S 3. Qui trnh tng hp biodiesel da trn phn ng transester ha c sdng xc
tc kim .......................................................................................................................... 21
S 4 Qui trnh hai bc tng hp biodiesel.............................................................. 29
CC CHVIT TT
ASTM: American Society for Testing and Materials
BKHCN: Bkhoa hc cng ngh
QCVN: Qui chun Vit Nam
RME: Rapeseed methyl ester
HFRR: High - frequency reciprocating rig
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 1
CHNG 1
TNG QUAN TI LIU
-----oooOooo-----
I LIPID
I.1 Khi nim v lipid[1]
Tn gi Lipid xut pht tchHi Lp Lipos c ngha l cht bo. Lipid l
mt hp cht hu c c chc nng v thnh phn ha hc khc nhau c ly trch t
ng vt hay thc vt nh cc dung mi ether, chloroform, methanol, l mt trongnhng thnh phn sinh ha c bn ca ng thc vt. Cc thnh phn ca thc n
thng c tp trung nghin cu l protein, lipid, glucid v mt svitamine, trong
lipid ng vai tr quan trng nh l ngun cung cp nng lng v cc acid bo cn
thit cho qu trnh sinh trng v pht trin ca ng vt. Lipid cng ng vai tr nh
cht vn chuyn vitamine tan trong du v sterol.
Vo nm 1920, con ngi bit bnh do thiu vitamine c lin quan n ba n
thiu lipid nht l cc nhm vitamine tan trong du. Nhtnh dn nhit km ca lipid
nn n c xem l chic o bo vthn nhit.
Thnh phn chyu ca lipid trong hu ht cc loi du thc vt v mng vt
l triglyceride hay glyceride hoc mtrung tnh. Ngoi ra, cn c cc acid bo tdo,
phospholipid v sterol.
Triglyceride l mt ester ca glycerol v acid bo, c cng thc tng qut l:
H2C
HC
H2C
O
O
O
C
C
C
O
O
O
R1
R2
R3
Trong R1, R2, R3: l cc gc acid bo.
Cc acid bo trong phn tlipid l acid no hoc khng no.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 2
Cc acid no thng gp l:
CH3 (CH2)12 COOH (Acid lauric )
CH3 (CH2)14 COOH (Acid palmitic)
Cc acid bo khng no thng gp l:
CH3 (CH2)7 CH CH (CH2)7 COOH (Acid oleic)
CH3 (CH2)4 CH CH CH2 CH CH (CH2)7 COOH (Acid linoleic)
I.2 Phn loi v lipid[1] [2]
C nhiu kiu phn loi lipid. Hin nay c ba cch phn loi chnh:
I.2.1 Da vo phn ng x phng haDa vo phn ng x phng ha ngi ta chia lipid ra thnh hai loi:
Lipid x phng ha c: gm cc glyceride, glycerophospholipid v sp. Ngha
l nhng lipid m trong phn tc cha ester ca acid bo cao phn t.
Lipid khng x phng ha c: l nhng lipid m trong phn t khng cha
nhm ester. Nhm ny gm cc hydrocarbon, cc cht mu v cc sterol.
I.2.2 Da vo ha tanDa vo ha tan lipid c chia thnh hai loi nh sau:
Lipid thc s: l nhng ester hoc amide ca acid bo (c tbn carbon trln)
vi mt ru gm glycerolipid (ester ca glycerol), sphingolipid (amide ca
sphingozin), ceride (ester ca ru cao phn t), steride (ester ca sterol), etolite
(ester tng hca hp cht a chc acid v ru).
Lipoid: l nhng cht c ha tan ging lipid bao gm: carotenoid, quinon (ccdn xut ca isoprene), sterol tdo.
I.2.3 Da vo thnh phn cuto
Cch phn loi thba v lipid l da vo thnh phn cu to. cch phn loi ny
lipid chia lm hai loi nh sau:
Lipid n gin: trong phn t chcha C, H, O, l ester ca ru v acid bo.
Thuc nhm ny c: triacylglycerine, sp (ceride) v steride.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 3
Lipid phc tp: ngoi C, H, O cn c mt snguyn tkhc nh N, P, S, do
trong phn tca chng ngoi ru v acid bo, cn c cc thnh phn khc nh
acid phosphoric, ng Lipid t do c nhim v cung cp nng lng, hm
lng lun thay i nhng lipid phc tp li c nhim vtham gia xy dng cc
cu tca tbo, hm lng khng thay i hay rt t thay i.
Ngoi ra, cn cc lipid khc nh: terpene, steroid v prostaglandin
I.3 Chc nng ca lipid[1]
- Cung cp nng lng: lipid l ngun cung cp nng lng tt nht cho c
th ng vt. Lng calo do lipid cung cp cao gp 2 ln lng calo do glucid v
protid cung cp. Lipid l cht dtrnng lng cho c th. Mt gam lipid cung cp
9,3 calo trong khi mt gam glucid hay protid chcho 4,1 calo.
- Hot tnh v cu thnh enzyme v hormone.
- Tham gia cu trc mng tbo: lipid phn cc hay phospholipid c mt vai
tr rt quan trng trong dinh dng v n tham gia vo cu trc ca tt ccc mng t
bo.
- Htrhp thu cc lipid khc: phospholipid givai tr quan trng trong s
vn chuyn v hp thlipid v tham gia vo cc qu trnh bin dng trung gian trong
c thsinh vt. Phospholipid ng vai tr nh cht nh tng ha gip cc acid bo,
mui mt v cc cht ha tan trong cht bo gn vo cc ht micelle nhli ti.
- Vn chuyn cc vitamine v mt scht khc: lipid l dung mi ha tan cc
vitamine tan trong du nh A, D, E, K v hydrocarbon. Do , trong khi c hp thu
v vn chuyn trong c thlipid cng mang theo cc cht ha tan trong lipid.
- Chc nng bo v c th: lipid gip c th chng li cc va p c hc,
chng lnh v bo vcc c quan bn trong.
I.4 Tnh cht chung ca lipid[1] [3]
I.4.1 Tnh cht vt l
Lipid c t trng thp hn nc (0,86-0,97). Mc khng no trong mch
hydrocarbon cng ln th lipid c ttrng cng cao.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 4
Lipid c c tnh chung l khng tan trong nc v tan trong cc dung mi hu
c nh: chloroform, benzene, ether.
Lipid khng tan trong nc, khi trn vi nc sto thnh hai lp: nc di
v cht bo trn, u -COO- tip xc vi nc, ui knc pha trn. Di tc
ng ca cht gy nh tng ha nh x phng (mui natri hay kali ca cc acid bo
bc cao hoc acid mt hay mui mt do gan tit ra) cht bo bchia nhra ging nh
dng sa gi l nh tng bn. Nhvy, x phng l cht ty ra du mtt chsau
cc dung mi hu c. iu cng gii thch c v sao cc bnh nhn bbnh gan
phi hn chn thc n c cha du mv trong c thca bnh nhn, du mtrong
thc n khng c nh tng ha, do lipase phn gii chm.
Tnh cht ca glyceride ph thuc vo thnh phn acid bo, chiu di mch
carbon v slng lin kt i trong phn t.
Mng vt cha nhiu acid bo no do trng thi bnh thng dng rn,
nht l mb, mcu. Du thc vt cng ty theo tlacid bo no v khng no m c
im nng chy khc nhau. V d du cacao cha 30% palmitic v 40% stearic c
im nng chy 30-40C. Ngc li du hng dng cha 85% acid bo khng no l
oleic v lenoleic nn c im nng chy rt thp (-21C). Do , du thc vt lun dng lng.
Nguyn nhn ca trng thi rn hay lng ca glyceride l do hm lng acid bo
no hay khng no v:
Cc acid bo no c mch carbon thng thng, khng gp khc to nn cu trc
n nh v cht, khng bph vnn nhit thng chng c trng thi rn.
Cc acid bo khng no c mch carbon bgp khc, to ssp xp lng lo db
ph v(do lc Van der Waals yu), do nhit thng chng trng thi
lng.
I.4.2 Tnh cht ha hc[3]
Phn ng thy phn v x phng ha
Vi shin din ca nc hoc hi nc v c xc tc ca enzyme lipase, du
mbthy phn sgii phng acid bo tdo v glycerol.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 5
Phng trnh thy phn triglyceride c biu din nh sau:
H2C
HC
OCOR1
H2C
OCOR2
OCOR3
H2Oenzyme lipase, +
R1COOH
R2COOH
R3COOH
H2C
HC
OH
H2C
OH
OH
Glycerol Acid boTriglyceride
Nu c mt mt lng kim (KOH, NaOH) th sau phn ng thy phn, acid bo
tc dng vi kim to thnh mui kim (x phng).
RCOOH + NaOH RCOONa + H2O
Tng qut:
H2C
HC
OCOR1
H2C
OCOR2
OCOR3
Triglyceride
+ 3NaOH
H2C
HC
OH
H2C
OH
OH
Glycerol
R1COONa
R2COONa
R3COONa
X phng
+
Phn ng cng hydro
L phn ng cng hydro vo cc ni i trn mch carbon ca acid bo vi s
hin din ca cht xc tc thch hp. Phn ng ny c ng dng trong cng ngh
thc phm nhm lm gim sni i trn dy carbon v lm cho du mn nh hn,
hn chkhnng boxi ha, trng hp ca du m, gip cho du mkhng btrmi
khi bo qun lu.
C C + H2xt H
CHC
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 6
Phn ng vi ru
H2C
HC
OCOR1
H2C
OCOR2
OCOR3
+ 3ROH
H2C
HC
OH
H2C
OH
OH
R1COOR
R2COOR
R3COOR
+
y l phn ng c bn bin triglyceride thnh alkyl ester ca acid bo.
Phn ng oxi ha
Cc loi du mc cha nhiu acid bo khng no sdboxi ha. Phn ng
xy ra trn ni i ca mch carbon. Du mcha nhiu acid bo no dbo qun, t
bin i. Du mbo qun lu c thc cc hng chuyn ha sau: Phn ng thy phnc xc tc enzyme lipase sinh ra glycerol v cc acid bo.
Phn ng oxi hacc ni i ca acid khng no tng tnh phn ng oxi ha
cc olefin, sinh ra cc hp cht cha oxygen nh: aldehyde, ketone, alcohol,
Cc phn ng trn vi stham gia ca enzyme, oxygen trong khng kh, v nc
lm cho mc mi hi, gim cht lng. V vy, trnh hin tng ny, trong cng
nghthc phm ngi ta thng bao kn trnh du mtip xc vi oxygen ngoikhng kh, nh nng chiu vo (nu c ssinh nhit, phn ng thy phn mdin ra
nhanh hn) hoc c ththm cht chng oxy ha thng l phenol, quinon
II CC PHNG PHP THU LY DUBO TRONG B
C PH
II.1 Tch chit bng dung mi hu c[4]
Bdng csohxlet vi nhiu kch c. Phng php ny c u im chsdng
mt lng t dung mi m c thchit kit c hot cht. Sly trch tng, lin
tc nn nhanh chng. Dng dung mi knc trch ly hon ton lipid tnguyn liu
c nghin nh. Mt s thnh phn ha tan trong cht bo cng c trch ly
theo bao gm sc t, cc vitamin tan trong cht bo, cc cht mi... tuy nhin hm
lng ca chng khng cao.
Nhc im ca phng php ny l khng chit c mt lng ln mu, nn
chthch hp cho cc nghin cu trong phng th nghim. Mt nhc im ln na l
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 7
trong sut qu trnh chit, mu lun c nhit bng nhit si ca dung mi nn
nhng hp cht km bn nhit c thbthy gii.
Ta c th dng phng php tch chit khc nh: phng php ngm dm,
phng php ngm kit ngc dng chit vi lng mu ln.
II.2 Tch chit bng CO2lng siu ti hn[5]
Thay v sdng cc dung mi hu c, ngi ta c thsdng CO2trng thi
siu ti hn (31,1C, 73 atm). t bit trng thi ny CO2va ging nh kh, va
ging nh lng, c nht thp hn pha lng (dxm nhp vo mu), c khnng
chuyn khi ln hn pha kh (chit xut c cn kit hot cht). Vi trng thi pha
lng ny n sl iu kin l tng trch cu ttrong mt thi gian ngn. Bng
cch kim sot nhit v p sut, mt v tc dung mi, CO2lng ti hn c th
thay thcc dung mi hu c (CHCl3, diethyl ether, petro ether, n-hexane). Nhkh
nng ha tan m ta c thvn dng chng vo vic tinh ch, trch ly, ngm chit, kt
tinh Nhit cao lm tng ng hc chit, trong khi p sut cao sgi cho dung
mi thot khi sun si. So snh vi phng php trch Shoxlet th r rng phng
php ny c nhiu mt tin li hn nhiu nh tit kim thi gian hn, chi ph dung mi
gim r, gim cht thi tdung mi. Tuy nhin vn ln nht gp phi l cn chi phln cho thit b, dng c, my mc.
II.3 Tch chitbng enzyme[6]
Vic tch chit du bo bng enzym c nhiu nh nghin cu quan tm
ng thi t c thnh cng nht nh. Chit xut du c ph bng enzyme cha
c nghin cu nhng chit sut du da bng enzyme cytolase c Vin
Nghin cu Du Thc vt- Tinh du- Hng liu- Mphm (Bcng nghip) kho
st v chit sut thnh cng du tinh khit, du c chit xut tenzyme cylolate c
cht lng cao, do c phm vi ng dng rng ri hn du da c sn xut bng
ccphng phpcng nghip cin.
II.4 p bng my[7]
Phng php p tuy n gin nhng khng trit , hm lng du ca b p cn
4-5%; i vi nguyn liu t du th hiu qukinh tthp. Trong cng nghip p du,
chc nhng loi ht c hm lng du t15-20% trln mi c gi trthc ttchc sn xut v m bo c cc hiu qukinh tkthut trong khi sn xut.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 8
III BIODIESEL
III.1 Nhin liu diesel
Nhin liu diesel l phn hydrocarbon ly t du m ra, c nhit si nm
trong gii hn t200 n 300C. Du diesel c mu nu nht, nng hn xng, nhhn
nc, ttrng t0,80 n 0,86[8].
Nhin liu diesel rtin hn xng nn c sdng rt rng ri trong cc ngnh
cng nghip. ng c diesel c dng nhiu xe vn ti nng, xe tng, tu thy, tu
ha, my pht in cln v.v
III.2 S lc v biodiesel
III.2.1 Khi nim
Biodiesel hay cn gi l diesel sinh hc, l mt loi nhin liu c tnh cht tng
tdiesel c ngun gc tdu mnhng c sn xut tdu thc vt hay mng
vt. Biodiesel c thnh phn chnh bao gm cc mono-alkyl ester ca chui cc acid
bo c ngun gc tthc vt hay mng vt[8].
Mono-alkyl ester l sn phm ca phn ng gia alcol mch thng (nh methanol
hoc ethanol) vi mng vt hoc du thc vt to thnh glycerol v ester ca acidbo mch di.
H2C
HC
OCOR1
H2C
OCOR2
OCOR3
+ CH3OH
H2C
HC
OH
H2C
OH
OH
R1COOCH3
R2COOCH3
R3COOCH3
+3
Triglyceride Methanol Glycerol Biodiesel
Ty thuc vo loi du thc vt v loi ru sdng m alkyl ester c tn khc
nhau.
Nu i t du cy u nnh (soybean) v methanol th ta thu c SME (soy
methyl esters). y l loi ester thng dng nht c sdng ti M.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 9
Nu i tdu cy ci du (rapeseed) v methanol th ta thu c RME (rapeseed
methyl esters). y l loi ester thng dng nht c sdng Chu u[9].
Biodiesel ph hp vi ng c diesel, cvnht, khi lng ring ln chs
cetane v n ging vi diesel du m. Bng 1 cho cc thng sso snh gia biodieselv diesel du m[10].
Bng 1So snh mts ch tiu gia biodiesel (RME) v diesel
Tnh cht nhin liu Biodiesel RME Diesel
Cng thc ha hc
Trng lng phn t
Chscetane
Khi lng ring (Kg/l) 15C
Trgi calo (MJ/Kg) 15C
Trgi calo (MJ/l) 15C
Tlkhng kh/ nhin liu (kg
khng kh/ kg nhin liu)
Hm lng oxy (Wt%)
nht (mm2/ giy) 20C
im chy (C)
Methyl ester
296
54
0,88
37,3
32,8
32,8 (20C)
9,211
7,4
91135
C12H26
170200
50
0,84
42,7
35,7
14,53
00,6
4
77
Biodiesel c thsdng trong cc ng c diesel thng thng dng nguyn
cht (100% biodiesel B100), hoc dng pha trn k hiu l BXX, trong XX l
phn trm biodiesel cn pha. Biodiesel thng c pha chvi du diesel to ra
cc loi nhin liu sau y:
- B5 gm 5% biodiesel pha vi 95% du diesel.
- B10 gm 10% biodiesel pha vi 90% du diesel.
- V B20 gm 20% biodiesel pha vi 80% du diesel.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 10
Biodiesel t c, khng gy nhim mi trng v l mt loi nng lng ti
to. Do mc d gi thnh cao hn so vi nhin liu diesel nhng biodiesel c
xem l ngun nng lng cho tng lai.
III.2.2 Lch shnh thnh v pht trin ca biodiesel
[9]
Biodiesel bt u c sn xut khong gia nm 1800, trong thi im
ngi ta chuyn ha du thc vt thu glycerol v thu c cc phphm l methyl
hoc ethyl ester gi chung l biodiesel. Ngy 10/08/1893, ln u tin Rudolf Diesel
sdng biodiesel do ng chto chy my. Nm 1912, ng dbo:Hin
nay, vic dng du thc vt cho nhin liu ng c c thkhng quan trng, nhng
trong tng lai, nhng loi du nh thchc chn sc gi trkhng thua g cc sn
phm nhin liu tdu mv than . tng nhngi c cng u tin on
c gi tr to ln ca biodiesel, t chc Nation Board Biodiesel quyt nh ly
ngy 10 thng 8 hng nm bt u t nm 2002 lm ngy Diesel sinh hc Quc t
(Internation Biodiesel Day). Trong nhng nm ca thp k90, Php trin khai sn
xut biodiesel tdu ht ci v c dng dng B5 (5% biodiesel vi 95% diesel) v
B30 (30% biodiesel trn vi 70% diesel).
III.2.3 Tnh hnh sdng biodiesel trn thgii v Vit Nam[9]
Theo xu hng chung trn thgii, ngi ta thng trn biodiesel vo diesel vi
thnh phn phi trn t5-30%. chu u theo chth2003/30/EC ca EU tngy 31
thng 12 nm 2005 t nht l 2% v cho n 31 thng 12 nm 2010 t nh t l 5,75%
thnh phn ca cc nhin liu dng chuyn chphi c ngun gc ti to.
Ti o, mt phn ca chthEU c thc hin sm hn v tngy 1 thng
11 nm 2005 chcn c du diesel cha 5% c ngun gc sinh hc (B5) l cphp bn.
Ti Australia, sdng B20 v B50 vo thng 2 nm 2005.
Ti Mnm 2005 sdng B20.
Ti Thi Lan trong nm 2006, sdng B5 ti Chiangmai v Bangkok.
Ti Vit Nam, Petro Vit Nam c k hoch a 10% Biodiesel (B10) vo
thnh phn diesel lu thng trn thtrng.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 11
III.3 Cc ch tiu ha l ca biodiesel[11]
Cht lng biodiesel c nh gi qua mt schtiu nh: chsacid, nht,
pH, tro sulfate, lu hunh, trscetane, glycerol tdo, glycerol tng, hm lng tro
phospho, mc bay hi, khi lng ring v hm lng nc cha trong nguyn
liu.
III.3.1 nht
nht ca nguyn liu th hin s lu chuyn nhin liu d dng trong h
thng cung cp v np liu vo bung t ca ng c. y l mt trong hng chtiu
quan trng ca nhin liu. Ngi ta dng my chuyn dng o nht.
nht cao: tnh lu chuyn hn ch, nhin liu kh vn chuyn v np liu vo
bung t.
nht thp: gim hsnp liu v tng smi mn ca bm nhin liu.
III.3.2 ChspH
ChspH ca nhin liu tt nht xp x7 v nu pH cao hay thp hn 7 u nh
hng n mc n mn thit b.
III.3.3 Tro sulfate
Cht lng tro c thtn ti trong diesel sinh hc gc di ba dng: (1) cc cht
rn c tnh mi mn, (2) x phng kim loi tan c v (3) cc cht xc tc khng loi
bc. Cc cht rn c tnh mi mn v cc cht xc tc khng loi bc sng
li vi phun, bm nhin liu, piston v ai bo v, ng thi cng to cn trong ng
c. X phng kim loi tan c c tnh n mn t, nhng li lm tt blc v to cn
trong ng c.III.3.4 Lu hunh
nh hng ca hm lng lu hunh rt khc nhau i vi sn mn ng c
v to cn lng. iu ny ph thuc nhiu vo cc iu kin vn hnh. Lu hunh
trong nhin liu cn nh hng n tnh nng ca h thng kim sot kh pht thi.
B100 l loi nhin liu hu nh khng c lu hunh.
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 12
III.3.5 Trscetane
Trscetane l i lng thhin khnng bc chy ca nhin liu, nh hng
schy v to khi trng. Yu cu vtrscetane phthuc vo thit k, kch cca
ng c, bn cht thay i v tc v ti trng v ph thuc vo iu kin mi
trng v iu kin khi ng.
III.3.6 Chsacid
L smg KOH cn thit trung ha ht lng acid bo tdo trong 1g cht bo.
Ch s acid l mt trong nhng ch tiu quan trng nh gi cht lng
nguyn liu. Tchsny, chng ta c thxc nh c hm lng acid tdo hin
din trong mu nguyn liu. Biodiesel cng cha nhiu acid bo tdo th c ch sacid cng cao. Chsacid thay i theo thi gian lu tr. Thi gian tn trcng di
th ch sacid cng tng v xy ra phng thy phn gii phng cc acid t do v
glycerol. Sthy phn ny xy ra khi mch carbon ca triglyceride ngn hoc di tc
dng ca enzyme lipase.
III.3.7 Glycerol tdo
p dng phng php xc nh glycerol tdo xc nh mc glycerol c trongnhin liu. Cc mc glycerol tdo cao c th to cn cho vi phun nhin liu, cng
nh lm tt hthng nhin liu v dn n stch ly glycerol tdo di y hthng
tn cha v cp nhin liu.
III.3.8 Glycerol tng
p dng phng php glycerin tng xc nh mc glycerin c trong nhin liu
bao gm cglycerin tdo v phn glycerin ca du hoc mkhng phn ng hoc
phn ng mt phn. Cc mc thp ca glycerin tng m bo du hoc mchuyn i
thnh ester mono-alkyl tt. Cc thnh phn mono-, di- v triglyceride c thgy cn
vi phun v tc ng xu khi vn hnh ng c kh hu lnh v lm tt blc.
III.3.9 Hm lng tro phosphorus
Phosphorus c thlm hng bchuyn i xc tc sdng trong hthng kim
sot kh thi v phi gii hn hm lng phosphorus thp. Bchuyn i xc tc tr
thnh phbin i vi thit bchy bng diesel do tiu chun kh pht thi btht cht,
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 13
v vy mc phosphorus thp cng trnn quan trng. Ch tiu ny c qui nh
m bo tt ccc loi diesel sinh hc gc chbin tcc ngun du, mu phi c
hm lng phosphorus thp.
III.3.10 Hm lng nc ln vo nhin liuCn trnh ln nc vo nhin liu v nc cng l yu t gy bin cht nhin
liu, tng phn ng oxy ha, gim nhit t chy trong ng c.
C nhiu phng php lm kh loi nc hoc dung mi ra khi sn phm
hay nguyn liu ban u. Ty theo bn cht ca sn phm hay nguyn liu ban u m
ta c thsdng mt sphng php phbin sau:
-
Chng ct: da vo s chnh lch nhit si ca cc cht thu c snphm tinh khit.
- Dng ha cht: yu cu ha cht khng tc dng vi nguyn liu, c khnng
ht nc mnh, khng ha tan trong nguyn liu, c tc dng lm kh nhanh, r
tin v phbin.
Sy chn khng: l phng php gia nhit trong mi trng chn khng.
III.4 Nhng u, nhc im ca biodiesel[12]III.4.1 Nhng u im khi s dng biodiesel cho ng c diesel
III.4.1.1 V mt mi trng
Qui trnh sn xut khng c cht thi v tt ccc sn phm phu c thtip
tc sdng.
Trong biodiesel hm lng lu hunh rt thp, khong 0,001%. Hm lng cc
hp cht khc trong kh thi nh: CO, SOx, hydrocarbon cha chy, bhng gim i
ng k, cth:
Gim ng kkh thi CO2gy hiu ng nh knh v sc khe con ngi.
Gim kh thi SOxgy nhim mi trng.
Khng cha hydrocarbon thm nn khng gy ung th. Theo cc nghiu cu
ca B Nng lng M c thc hin ti trng i hc Califonia, s dng
biodiesel tinh khit thay cho diesel khong c thgim 93,6% nguy c mc bnh ungthtkh thi ca ng c, do biodiesel c cha t cc hp cht thm, cha rt t lu
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 14
hunh, qu trnh chy ca biodiesel trit hn nn gim c nhiu thnh phn
hydrocarbon trong kh thi.
C khnng tphn hy v khng c (phn hy nhanh hn gp 4 ln diesel
khong, phn hy t85 88% trong nc sau 2128 ngy). Tuy nhin, sthun li
ny yu cu sch c bit vqu trnh bo qun nhin liu.
Gim nhim mi trng v nc.
Gim s tiu dng ca cc sn phm du m gy nhim mi trng trm
trng.
III.4.1.2 V mt k thut
c tnh t lu hunh ca biodiesel lm gim ng kkh thi SOxgy n mn
thit b. Chnh nhng cht cha lu hunh l nhng tc nhn gim ma st ca du
diesel khong, do vy du diesel khong c tnh bi trn khng tt v i hi vic s
dng thm cc phgia tng tnhbi trn.
Chscetane cao hn diesel khong: nhin liu diesel thng thng c chs
cetane t50-52 v 53-54 i vi ng c cao tc. Biodiesel l alkyl ester mch thng
do vy nhin liu ny c ch s cetane cao hn diesel khong. Ch s cetane ca
biodiesel thng t56-58. Vi chscetane nh vy, biodiesel hon ton c thp
ng ddng yu cu ca ng c i hi nhin liu cht lng cao vi khnng tbt
chy cao m khng cn phgia tng chscetane.
An ton vchy n tt hn: biodiesel c nhit chp chy cao hn 110C,
cao hn nhiu so vi diesel khong (khong 60C), v vy tnh cht nguy him ca n
thp hn, an ton hn trong tn cha v vn chuyn.
Qu trnh chy sch: do nhin liu biodiesel cha khong 11% oxy nn qu
trnh chy ca nhin liu xy ra hon ton. V vy vi nhng ng c sdng nhin
liu biodiesel th sto mui, ng cn trong ng c gim ng k.
Tnh linh ng ca biodiesel: c thtrn vi diesel theo bt ktlno.
Biodiesel c tnh bi trn tt: biodiesel c khnng bi trn bn trong rt tt.
Cc cuc kim tra chra rng, biodiesel c khnng bi trn tt hn diesel khong.
Khnng bi trn ca nhin liu c c trng bi gi trHFRR (High-frequency
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 15
recieprocating rig). Ni chung gi trHFRR cng thp th khnng bi trn ca nhin
liu cng tt. Diesel khong x l lu hunh c gi trHFRR ln hn hoc bng
500 khi khng c phgia, nhng gii hn c trng ca diesel l 450. V vy, diesel
khong yu cu phi c phgia tng khnngbi trn. Ngc li gi trHFRR ca
biodiesel khong 200. V vy, biodiesel cn nh l mt phgia rt tt i vi nhin
liu diesel thng thng. Khi thm biodiesel vo vi t lthch hp, smi mn ca
ng c c gim mnh. Thc nghim c chng minh sau khong 15.000 gilm
vic, smi mn vn khng c nhn thy.
Do c tnh nng tng t nh du diesel khong nn nhn chung khi s dng
khng cn ci thin bt kchi tit no ca ng c.
i tng sdng: Tt ccc loi ng c, my mc cngnghip sdng nhin
liu diesel.
III.4.2 Nhc im ca biodiesel
Dboxy ha nn snh hng n mt sbphn trong ng c.
Biodiesel dht m.
Biodiesel c nht cao, vic phn tn nhin liu kh mn, khng u nn gy
kh khn cho qu trnhphun nhin liu vo t.
Nhit trnhhn diesel nn trn cng mt qung ng di chuyn cn hao tn
lng nhin liu nhiu hn.
Gi thnh vn cn kh cao hn diesel. Tuy nhin theo tnh hnh bin ng du
mhin nay th vic tm ra mt ngun nhin liu mi srt c gi tr.
III.5 Cc phng php ha hc s dng trong tng hp biodiesel
[2][13][14]
III.5.1 Phn ng transester ha lipid
Qu trnh transester ha du bo thc vt v m ng vt c tin hnh vo
nm 1853 bi hai nh khoa hc E.duffy v J.Patrick.
Transester ha l phn ng gia mono-, di-, triglyceride vi ru cng vi s
hin din ca cht xc tc thch hp, to thnh cc alkyl ester ca cc acid bo v
glycerol.
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III.5.1.1 Cc phng php thc hin phn ng transester ha lipid
Phn ng transester ha thng c tin hnh bng nhng phng php sau
y:
Phng php khuygia nhit
y l phng php c in. Ngi ta s dng my khuy c hc hay my
khuy tc gia nhit khuy trn hn hp to nn stip xc tt gia hai pha ng
thi cung cp nhit cho qu trnh phn ng. Phng php ny dthc hin, c tht
c phn ng hon ton nhng i hi thi gian kh di.
Phng php siu m
Trong nhng nghin cu gn y, phng php siu m thng c p dngcho phn ng transeter ha v c u im l rt ngn thi gian phn ng, ng thi
phn ng t c chuyn ha cao.
Phng php vi sng
Vi sng cn c tn gi l sng vi ba (microwave) l sng in tlan truyn vi
vn tc nh sng, c bc sng trong khong t1cm (tn s30 GHz) n 1m (tn s
300MHz). Theo nguyn l hot ng ca sng vi ba, tt cnng lng sng thay it cc dng sang cc m trong mi chu k sng. Tc ca s thay i kh ln,
hng triu ln/giy. Cc phn tca cc cht, c bit l cc phn t lng cc, c
mt cc dng v mt cc m. Khi cc sng vi ba chiu x, chng to ra cc phn t
chuyn ng hn n, schuyn ng c thhng triu ln/giy. Chnh srung ng
ca cc phn tny to nn ma st lm nng cc cht.
III.5.1.2 Xc tc s dng trong phn ng transester ha
Cc cht xc tc s dng trong phn ng transester ha c th l acid, base,
enzyme hay zeolite.
Xc tc acid
Xc tc acid thng sdng trong phn ng transester ha l H2SO4m c.
Tuy hiu sut phn ng cao nhng phn ng li xy ra chm, i hi nhit trn
100C v 4 gimi t chuyn ha hon ton. Ngoi ra, phn ng trn phi c
thc hin trong mi trng khng c nc trnh c s cnh tranh to ra acid
carboxylic lm gim hiu sut phn ng. Thit bphn ng mau h do bn mn.
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Xc tc base
Phn ng transester ha du m ng thc vt s dng xc tc base din ra
nhanh, ng thi xc tc base t n mn thit bnn xc tc base rt c a chung
trong cng nghip.
Xc tc base thng c s dng trong cng nghip nh: NaOH, KOH,
carbonate kim loi kim, CH3ONa,... Tt ccc loi xc tc ny u c ththu c
ester cht lng cao. Nhng ty thuc vo cng sut ca cc nh my v nhng iu
kin cthkhc m ngi ta dng loi xc tc ny hoc xc tc khc.
dng thnh phm, NaOH v KOH u dng rn. to ra tc nhn xc tc
phn ng l CH3O-, ngi ta phi ha tan chng vo trong ru CH3OH trc khi cho
vo hn hp phn ng. Qu trnh ha tan ny ta nhit v rt nguy him v bn thn
CH3OH v kim rt c. Nh vy, nhng nh my sdng KOH, NaOH phi tn
thm chi ph cho khu chun bcht xc tc cng nh cc bin php xl an ton. Do
vy, Chu u v Mngi ta dng NaOH, KOH nhng nh my c cng sut nh
hn 5 triu galng.
Thm vo khi ha tan NaOH, KOH vi CH3OH, nc sinh ra theo phn ng:
NaOH + CH3OH CH3ONa + H2O
Nc gy thy phn triglyceride v ester to thnh, lm gim hiu sut ca phn
ng ng thi gy kh khn thm cho qu trnh loi bnc sau ny. KOH t hn
NaOH nhng KOH c li l tan rt tt trong CH3OH. Khc vi NaOH v KOH,
CH3ONa tan hon ton v khng sinh ra nc. CH3ONa thng dng dng ha tan
(25-30%) trong CH3OH do sn sng cho phn ng, khng mt thm chi ph cho
vic chun bcht xc tc. Khi sdng cht xc tc ny, hiu sut thu methyl ester l
cao nht trong khi tn t cht xc tc hn so vi trng hp NaOH v KOH. Thm vo
, glycerol thu c l tinh khit hn dn n lm gim chi ph cho qu trnh lm
sch glycerol khi mun iu chsn phm khc tglycerol.
Mc d CH3ONa c gi thnh cao (gp 2 ln KOH), nhng nhng li ch ca n
c thb li trong trng hp cng sut nh my ln (>5 triu galng).
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Trn thc t, 2/3 nh my sn sut methyl ester (biodiesel) cng sut ln Chu
u v 70% methyl ester sn xut ti Bc M s dng loi xc tc ny. Phn ng
transester ha du thc vt, mng vt sdng xc tc base c biu din nh sau:
H2C
HC
OCOR1
H2C
OCOR2
OCOR3
+ ROH
H2C
HC
OH
H2C
OH
OH
R1COOR
R2COOR
R3COOR
+3 KOH
Trong : R1, R2, R3l cc gc acid bo.
C chphn ng transester ha:
ROH + B + BH
R1COO CH2
CHR2COO
H2C
O
+
R1COO CH2
CHR2COO
H2C O C
OR
O
R3
(2)
(1)
R1COO CH2
CHR2COO
H2C O C
OR
O
R3
R1COO CH2
CHR2COO
H2C O
+ RCOOCR3 (3)
R1COO CH
2
CHR2COO
H2C O
+ BH
R1COO CH2
CHR2COO
H2C OH
+ B (4)
RO
OR
OCR3
S 1 C chphn ng tr ansester ha xc tc base
Xc tc enzyme
a scc enzyme lm xc tc u c thc hin iu kin bnh thng (nhitphn ng l 20-40C), khng tn nng lng v khng i hi thit bphc tp,
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hiu lc xc tc ln. Tuy nhin mi loi enzyme chxc tc mt scht nn v kiu
ni ha hc nht nh trong phn t. Ngoi ra, vic sdng xc tc enzyme c mt
hn ch l thi gian phn ng rt lu (20 gi), ng thi phi tm c loi enzyme
ph hp vi i tng nghin cu.
Xc tc zeol i te
Trong nhng nm gn y, ngi ta thng sdng xc tc acid, base rn, c
bit l zeolite. y l l loi xc tc hiu qu cho phn ng transester ha du m
ng, thc vt do c tnh chn lc cao, vic tch cc sn phm sau phn ng ddng,
hiu sut cao ng thi phn ng t sinh ra sn phm ph.
III.5.2 Phn ng ester ha acid carboxylic
Ester ha acid carboxylic l qu trnh tch nc gia acid v ru to thnh
ester.
Phn ng ester ha c tnh thun nghch, chiu thun c xc tc bng acid
mnh nh H2SO4m c, cn phn ng thy phn (chiu nghch) c thxc tc bng
acid hay base (trng hp thy phn bng base cn c gi l phn ng x phng
ha).
Phn ng ester ha cc acid carboxylic c th tin hnh khng cn xc tc, tuynhin n xy ra tng i chm v t c vn tc tng i cn nhit cao
(200-300C).
Phng trnhphn ng ester ha c biu din nh sau:
R1COOH+ ROH R1COOR + H2OH
C chphn ng ester ha c trnh by trong s sau:
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RC
O
OH + H RC
OH
OH
RC
OH
OH + CH3OH RC OH
OH
RC OH2
OCH3
OH
RC OH2
OCH3
OH
RC
OH
OCH3 + H2O
RC
OH
OCH3 RC
O
OCH3 + H
HOCH3+
RC OH
OH
HOCH3+
S 2 C ch phn ng ester ha
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III.6 Tng hp biodiesel da trn phn ng transester ha c s dngxc tc kim[15]
Trong cng nghip, biodiesel c sn xut nh trong s sau:
S 3 Qui trnh tng hp biodiesel da trn phn ng transester ha c s dngxc tc kim
III.6.1 i vi duthc vt hoc m ng vtc hm lng acid t do thp
Du nguyn liu, ru, v cht xc tc c trn trong l phn ng trong thi
gian thch hp (1-2 gi) nhit khong 60C. Qu trnh thu biodiesel c thlin
tc hoc theo chu k. Trn thc tqu trnh c thc hin lin tc qua hai giai on
(2 l phn ng), khong 80% lng ru v xc tc c dng l thnht, hn hp
phn ng sau khi tch khi pha glycerol c a vo l thhai kt thc phn ng
vi lng ru v xc tc cn li.
Glycerol to thnh c tch khi pha ester my li tm. Qu trnh tch thng
xy ra ddng v glycerol hu nh khng tan trong ester. Lng ru d c thlm
chm qu trnh tch v ru ha tan tt cglyxerol ln ester. Nhng khng thui
H2O
Lm kh
Ranc
H2O
CH3OH
LPhnng
Acid
Tch CH3OHGlycerol Chng ct
Phaester
PhaGlycerol
Biodiesel
Acid
- Trung ha- Loi CH3OH
CH3OH
Acid bo tdo
Du thc vt hocmng vt
Tch
Acid ha v tchacid bo tdo
Ncra
Xc tc kim
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lng ru d trc qu trnh tch pha v nh thsdch chuyn cn bng vpha to
ra glycerol.
Ester sau khi tch khi glycerol c a n khu trung ha v qua thp tch
methanol. khu trung ha ngi ta dng acid nh HCl, acid nitric trung ha
lng xc tc kim d v lng x phng to thnh:
RCOOK + HA RCOOH + KA
KOH + HA KA + H2O
Tt clng xc tc d, x phng, mui, methanol v glycerol tdo c tch
khi biodiesel bng qu trnh ra nc. Trung ha bng acid trc khi ra nc nhm
gim ti a lng x phng v lng nc ra cn dng do hn chc qu trnh
to nh tng (nc trong biodiesel v tc nhn to nh tng l x phng), gy kh
khn cho vic tch nc khi biodiesel. Biodiesel c lm sch trong thp bay hi.
Nu sn xut qui m nhngi ta thng dng cc mui kh ht nc. Mt s
ngun nguyn liu cha mt lng ln acid bo tdo. Acid bo tdo phn ng vi
xc tc kim sinh ra x phng v nc. Thc tcho thy rng qu trnh thu biodiesel
c thxy ra bnh thng vi hm lng acid tdo thp hn 5%. Khi , cn dng
thm xc tc trung ha acid bo tdo. Lng x phng to ra nm mc cho php.
III.6.2 i vi du thc vt hoc m ng vt c hm lng acid bo t do cao
Khi hm lng acid tdo cao hn 5%, lng x phng to ra lm chm qu trnh
tch pha ester v glycerol, ng thi tng mnh sto nh tng trong qu trnh ra
vi nc. gim hm lng acid bo tdo, trc phn ng chuyn vester, ngi ta
dng xc tc acid nh H2SO4, chuyn ha acid bo tdo thnh ester (phn ng ester
ha).
H2SO4RCOOH + CH3OH RCOOCH3 + H2O
V vy, hm lng acid bo tdo l yu tchnh trong vic la chn cng ngh
cho qu trnh sn xut biodiesel.
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III.7 Tim nng sn xut biodiesel t b c ph[16]
Theo hip hi C ph Vit Nam (VICOFA) v BNng nghip M (USDA),
tiu thc ph thtrng ni a Vit Nam nin v2010 sn mc 72 nghn tn
ht (chim 6,7% tng sn lng c ph sn xut ra). Nu qu trnh thu du mc 6,4
kg b c ph (t8,53 kg ht xanh do qu trnh rang hao ht 20-25%) sn xut c 1
lt biodiesel th ton blng b c ph thi ra nm 2010 scung cp thm cho ngnh
nng lng Vit Nam khong 6.921 tn biodiesl.
Vit Nam quan tm n ngun nhin liu biodiesel cch y 20 nm v
n pht trin ngnh nhin liu sinh hc n nm 2015, tm nhn n nm 2025 c
Th tng Chnh phph uyt ngy 20/11/2007. V tim nng c nhiu ngun
nguyn liu sn xut biodiesel bit nh:
1.Du mphthi qua sdng: gm cc phphm du mi tcc nh my
chbin du m, du m qua sdng, c thu hi sau qu trnh rn, nu tcc c
schbin thc n.
2. Vi to l gii php c thgii quyt vn din tch t trng v n c chu k
pht trin rt ngn, sng c khp ni c nh sng mt tri, nc v CO2.
3. Rng, ngcc, vng, lc, da, mc basa
4.Cy Jatropha c ngun gc tTrung M, di thc sang Chu Phi, n v
Nam M, cy chu hn, trng t kh cn v c nhiu loi. Nc ta c thtn dng 9
triu ha t hoang ha, dc ven cc ng quc l, trng cy Jatropha ly du.
B c ph phthi cng c khnng l tim nng mi, tn dng ngun nguyn
liu sn c, tit kim ti nguyn v gp phn bo vmi trng.
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CHNG 2
PHNG TIN V PHNG PHP NGHIN CU
-----oooOooo-----
I NI DUNG NGHIN CU
Mc tiu nghin cu ca ti ny l nghin cu xy dng quy trnh tng hp
du diesel sinh hc (biodiesel) tb c ph phthi.
t c mc tiu nghin cu trn, hai ni dung nghin cu chnh ca ti
nh sau:
- Nghin cu phng php trch ly du bo tb c ph.
- Nghin cu quy trnh tng hp biodiesel tdu bo trch ly tb c ph.
II PHNG TIN NGHIN CU
II.1 Thit b v dng c
- Bchit soxhlet thtch 400ml
- Hthng un hon lu
- My c quay chn khng (BuchiThy S)
- My khuy tgia nhit IKA RCT
- Cn phn tch GF-Series AND model GF-300
- Tsy Memmertc
-
Cc dng cthy tinh: Phu chit, buret, nhit k, bnh c quay, bnh nh mc,
bnh tam gic, bnh cu c nhm, cc thy tinh cc loi, ng ht, pipet, ng
ong, ng nghim,
II.2 Ha cht
- Dung mi petroleum ether (PE)
- Acid sulfuric (H2SO4) m c
- KOH khan
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- Methanol (CH3OH)
- Ethanol (C2H5OH)
- Nc ct
-
Sodium sulfate khan (Na2SO4)
- Phenolphthalein
II.3 Nguyn liu
Ngun b c ph c thu cc qun c ph khc nhau, trong qun c ph
Happy4 ng 91B thnh phCn Th l chim slng ln nht. B c ph c
thu ly, phi ngoi nng n kh. Sau tin hnh chit ly du bo v thc hin phn
ng.
III PHNG PHP NGHIN CU
III.1 Phng php ly trch du bo t b c ph
III.1.1 Phng phpchitSoxhlet
Dng dung mi petroleum ether ly trch du bo t b c ph. Cn 200 g
nguyn liu dng bt cho vo ti vi, t vo bnh trch soxhlet. Cho vo bnh cu 700
mL dung mi, lp vo bdng csoxhlet. un hon lu petroleum ether ly trch
du bo trong 5 gin khi dung mi trong bnh chit soxhlet khng cn mu ca vt
du. Ginguyn dung mi nhng thay 200 gnguyn liu mi v tip tc ly trch du
bo. Sau lc li dung mi cha du bo, c quay thu hi dung mi di p sut
km, cn lng du bo thu c. Lp li th nghim 3 ln vi mi mu.
III.1.2 Phng php ngm dm
B c ph kh (m khong 6,36%) c ngm vi dung mi petroleum ether
trong10 ngy theo tl: 1 kg b/ 3 lt dung mi.
Lc, c quay thu hi dung mi di p sut km.
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III.2 Xc nh cc ch s ha l ca dubo trch ly t b c ph phthi
III.2.1 Xc nh m b c ph v hm lng cht bay hi
III.2.1.1 Nguyn tc
Nguyn tc ca phng php ny l da trn sgim khi lng ca mu b cph sau khi sy trong t sy nhit 100-105C n khi lng khng thay i.
Lng cht bc i nhit ny chyu l nc, ngoi ra cn c mt scht hu c
dbc hi.
III.2.1.2 Tin hnh
Chun b3 mu, cn mi mu chnh xc 5g bt nguyn liu, sy 105C trong
2 gi, ly ra cn, tip tc sy n khi lng mu vn khng i. Lp li th nghim 3
ln. Ly kt qutrung bnh ca 3 ln o.
III.2.1.3 Tnh kt qu
1001
m
mmN
%
Trong : m l khi lng mu cn ban u (5g)
1m l khi lng sau sy kh 105C trong 2 gi(g)
N l m ca b c ph (%)
III.2.2 Ch sacid (IA)
III.2.2.1 ngha
Chsacid l smg KOH cn thit trung ha lng acid bo tdo c trong
1g cht bo.
III.2.2.2 Nguyn tc
Dng KOH trung ha lng acid bo tdo c trong cht bo, phn ng xy ra
RCOOH + KOH RCOOK + H2O
III.2.2.3 Tin hnh
- Cn chnh xc 0,13gam cht bo cho vo erlen 100 mL.
- Thm 5 mL ethanol tuyt i.
-
Thm 2 git phenolphthalein.
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- Lc nhha tan cht bo.
- Chun bng cch nh t t dung dch KOH 0,01N tburet vo erlen
trung ha acid tdo c trong cht bo cho n khi va xut hin mu hng nht v bn
trong 30 giy.
III.2.2.4 Tnh kt qu
Chsacid ca du mc tnh theo cng thc sau:
m
VIA
561,0
Trong :
V
: thtch dung dnh KOH 0,01N dng chun (mL).m : khi lng mu cht bo (gam).
III.3 Tng hp biodieesel t du bo ca b c ph ph thi
C nhiu cch lm gim chsacid ca du nguyn liu tnh cht ca n gn
ging vi tnh cht ca diesel truyn thng. Trong ti ny, chng ti s dng
phng php transester ha v y l phng php khng phc tp, c ththc hin
qui m nhv to ra sn phm c tnh cht ha l gn ging vi diesel truyn thng.Vmt k thut c nhiu phng php thc hin phn ng transester ha.
Trong ti ny chng ti sdng phng php khuy gia nhit iu chbiodiesel
v y l phng php dthc hin c tht c phn ng hon ton.
V loi xc tc dng cho phn ng transester ha nh xc tc acid, xc tc
base, xc tc enzyme, xc tc base khng ion. Chng ti sdng xc tc base v phn
ng transester ha khi din ra tng i nhanh v xc tc base t n mn thit b.C nhiu loi xc tc base nhng chng ti chn KOH v n d tm, hiu sut sn
phm cao v tng i rtin.
t c ni dung nghin cu trn, i vi phn ng tng hp du diesel
sinh hc chng ti s tp trung kho st nhng yu tquan trng nht c nh hng
n hiu sut phn ng nh lng ru, lng xc tc, nhit v thi gian phn ng.
Cch kho st nh sau: cnh mt syu tv thay i yu tcn kho st sao cho
lng sn phm biodiesel thu c l nhiu nht v chsacid t gi trnhnht c
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th. Qu trnh kho st c lp li i vi cc yu tcn li trn c ssdng gi tr
tt nht va tm c.
Do chsacid ca du nguyn liu c khnng thay i theo thi gian lu tr
nn ty vo chsacid ca nguyn liu m chng ti la chn quy trnh kho st
cho ph hp. Nu du c chsacid thp (IA5)
th chng ti kho st bng qui trnh 2 bc vi bc u thc hin phn ng ester ha
acid carboxylic nhm hchsacid (IA
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
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CHNG3
THC NGHIM
-----oooOooo-----i vi nguyn liu c chsacid tdo cao do tn trtrong thi gian di hoc
do bn cht nguyn liu th cn phi thc hin qui trnh hai bc tng hp
biodiesel. Do nguyn liu du trch c tb c ph c chsacid t8,11 19,46
nn chng ti p dng qui trnh tng hp hai bc. Du nguyn liu c xl bng
acid H2SO4m c. Sau sn phm c yn khong 2 gi, tch blp trn, ra
v lm kh sn phm. Tip sn phm c xl bng kim KOH. Sau cho hn
hp phn ng vo phu chit yn khong 15 pht. Sn phm biodiesel th c tin
hnh chit loi bglycerol, tip ra v lm kh sn phm th thu c biodiesel
tinh khit.
S 4 Qui trnh hai bc tng hp biodieselI Giai on ester ha
Trong qui trnh hai bc, nhim vca giai on phn ng u l lm gim ch
sacid ca nguyn liu xung thp hn 5 (IA
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
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I.1 Cch b tr th nghim:
Btr th nghim theo trt nh sau v mi th nghim lp li 3 ln v ly kt qu
trung bnh.
-
Lng methanol:Thay i lng methanol theo t lmethanol: du ln lt l: 0,35; 0,4; 0,45;
0,5; 0,55 v 0,6
- Nhit phn ng:
Thay i nhit phn ng (C) nhng gi trkhc nhau: 50; 60; 70 v 80
- Thi gian phn ng:
Thay i thi gian phn ng (pht) nhng gi tr khc nhau: 30, 60, 90 v
120.
- Lng H2SO4:
Thay i lng xc tc (%) nhng gi trkhc nhau: 0,5; 1; 1,5 v 2.
I.2 Tin trnh thc hin
Chun bnguyn liu
Cn lng du cn thit v cho vo bnh phn ng.
iu chnh nhit thch hp.
Cn lng methanol cn dng v cho vo bnh phn ng trn v bt u khuy.
Hn hp methanol v du c khuy trong 5 pht, tip cn thn cho lng
xc tc H2SO4m c vo bnh phn ng, tin hnh un nhit cn thit (nu s
dng nhit cao th phi sdng hthng un hon lu trnh tht thot dung mi).
Duy tr nhit phn ng trong thi gian u, thi gian 30 pht vn khuy
nhit phng.
I.3 Tin trnh ra
Hn hp giai on u ny yn trong phu chit khong 2 gi, bpha trn
(lng methanol d, H2SO4d,), pha di c ra nhiu ln vi nc cho n khi
nc sau khi ra c pH bng vi nc dng ra. Sau em sn phm i c quay nhit 70C nhm loi lng methanol v nc ln vo sn phm giai on ny.
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II Giai ontransester ha
II.1 Cch btr th nghim
Cc th nghim c btr theo trt tnh sau v mi th nghim c lp li 3 ln v
ly kt qutrung bnh.
- Lng methanol:
Thay i lng methanol theo tlmethanol: du nhng gi tr: 0,25; 0,3 v
0,35.
- Nhit phn ng:
Thay i nhit phn ng (C) nhng gi trkhc nhau: 40; 50; 60 v 70.- Thi gian phn ng:
Thay i thi gian phn ng (pht) nhng gi trkhc nhau: 30; 60; 90; 120 v
150.
- Lng xc tc KOH:
Thay i lng xc tc (%) nhng gi trkhc nhau: 0,5; 1; 1,5; 2.
II.2 Tin trnh thc hin
Cn lng methanol cn thit cho vo bnh tam gic 100 mL tip theo l lng
xc tc base cn thit. Thao tc cn phi nhanh v methanol dbay hi v KOH dht
m. Cho lng base trn vo bnh tam gic cha sn methanol, dng my khuy t
khuy. Mc ch ca cng vic ny l to ra mui methylate. Do KOH rt kh tan
trong methanol nn cn s dng my khuy t, v di tc dng ca my khuy t
gip cho cc cht phn ng tip xc nhau ddng.
II.3 Tin hnh phn ng
Cn chnh xc lng sn phm phn ng giai on trn cho vo bnh phn
ng v t ln my khuy t, iu chnh nhit cn thit. Cho vo ttdung dch
methanol vo bnh phn ng trn, gn hthng hon lu v tin hnh khuy vi tc
mnh to iu kin cho phn ng xy ra nhanh hn.
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II.4 Tin trnh ra
em hn hp sau phn ng yn trong phu chit khong 15 pht, cho n
khi tch pha r rt. Tch ly phn trn, ra bng nc ct, thng sdng khong 2
ln thtch biodiesel thu c v lp li nhiu ln cho n khi nc sau khi ra c pH
trung tnh.
Sau ra sn phm bng dung dch NaCl bo ha, thng s dng khong
50% so vi thtch biodiesel thu c. Mc ch ra li bng nc mui bo ha l
loi bnc trong sn phm biodiesel.
III Tin trnh lm kh sn phm
Sn phm biodiesel sau khi ra c thbln nc v c lm kh bng mt sphng php:
Chng ct: da vo schnh lch nhit si ca cc cht.
Dng ha cht: khng tc dng ha hc vi biodiesel, c tc dng lam kh
nhanh, r, dtm (thng sdng Na2SO4khan).
Sy chn khng: loi bnc ln trong sn phm bng cch gia nhit trong mi
trng chn khng.
Trong cc phng php lm kh sn phm trn chng ti chn phng php
dng ha cht. Ha cht chng ti s dng lm kh sn phm l Na2SO4 khan. Do
lng sn phm t nn phng php lm kh ny tng i tin li, nhanh.
IV nh gi cht lng sn phm Biodiesel
nh gi cht lng sn phm biodiesel da trn mt s cc ch tiu ha l
nh: pH, acid,
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 33
CHNG 4
KT QU- THO LUN-----oooOooo-----
I CC CH SHA L
I.1 mca b c ph ph thiv hm lng cht bay hi
Sau khi thu b c ph tcc qun c ph trong thnh phv, chng ti em
xc nh m ca b c ph. Kt qum ca mu b c ph trc khi phi c gi
trkhong 61,67%.
Mu b c ph c phi ngoi nng. Sau khi phi xong mu b c ph c
xc nh m. m ca b c ph sau khi phi kh c gi tr khong 6,36%.
m ca b c ph c nh hng n vn tc v kit ca du trch ly[17].
Khi tng lng m slm chm qu trnh khuch tn v lm tng skt dnh cc ht
bt trch ly do m trong bt trch ly stng tc vi protein v cc cht a nc khc
ngn cn sthm su ca dung mi vo bn trong ca cc ht trch ly lm chm qu
trnh khuch tn. Do , m ca b c ph c nh hng n hiu sut trch ly. m b c ph khong 6,36% tng i nh, v thc thtin hnh trch ly du.
I.2 Hiu sut ly trch du bot b c ph ph thi
I.2.1 Phng php ngm dm
T lb c ph v dung mi khong 1:3, ngm trong 10 ngy khi lng du
bo thu c l 10,73g. Hiu sut du thu c so vi khi lng b c ph l:
10,73%.
I.2.2 Phng php trch soxhlet
B c ph c trch ly bng phng php soxhlet c hiu sut du bo thu
c khong 15,27% (phn trm khi lng du bo so vi khi lng b c ph).
I.2.3 Nhn xt
Phng php ngm dm c hiu sut trch ly du bo tb c ph thp hn so
vi phng php trch ly du bo bng phng php soxhlet. V phng php trch
soxhlet c thtrch ly hon ton lng du bo trong b c ph. Nhng phng php
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
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trch soxhlet c cn n nhit , do vy ta phi cn thn khng nhit qu cao,
c thgy tn tht nhiu dung mi v gy bin tnh du.
I.3 Ch s acid ca du bo
Sau khi b c ph c ly trch du xong, chng ti tin hnh xc nh chsacid ca mu du bo. Kt quchsacid ca du bo nm trong khong t7,439 n
19,46.
II QUY TRNH IU CH BIODIESELT B C PH
Do mu du bo ly trch c c chsacid cao (IA>5). Do quy trnh iu
chbiodiesel ph hp nht l quy trnh hai bc. Bc mt chng ti thc hin phn
ng ester ha. Bc hai l phn ng transester ha.
II.1 Phn ng ester ha
Mc ch trong giai on ny l lm gim chsacid ca sn phm sau phn
ng. V trong phn ng ester ha th lng acid bo t do trong du nguyn liu
chuyn ha thnh biodiesel. V vy, phn ng c coi l c hiu qu nht khi sn
phm sau phn ng c chsacid thp nht c thv phi nhhn 5 (IA
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Bng 2 Cc yu t c nh
Yu tcnh Gi tr
Du bo b c ph 3g
Lng xc tc H2SO4 0,8% (so vi du nguyn liu)
Thi gian phn ng 60 pht
Nhit phn ng 60C
Tc khuy 700 vng/pht
Trong vic kho st nh hng ca lng methanol n phn ng ester ha th
lng methanol ca tng th nghim c thay i cc gi trda trn phn trm khi
lng ca methanol so vi du nguyn liu. Cc gi trphn trm khi lng methanol
so vi du thay i c lit k trong Bng 3.
Chng ti thc hin phn ng trong 60 pht, sau dng phn ng cho sn
phm vo phu chit yn trong 2 gi. Ly pha di, ra nhiu ln vi nc sao cho
nc ra c pH trung tnh. em sn phm c quay chn khng nhit 70C loi
methanol cn d v nc trong sn phm. Sau xc nh chsacid, kt quc
trnh by Bng 3.
Bng 3nh hng lng methanol n ch s acid
Lng methanol
(% methanol so vi du) 35% 40% 45% 50% 55% 60%
Chsacid (IA) 2,275 1,85 1,678 1,463 1,331 1,009
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2.275
1.85
1.678
1.4631.331
1.009
0.000
0.500
1.000
1.500
2.000
2.500
35% 40% 45% 50% 55% 60%
Lng methanol
Chs
acid
Hnh 1 nh hng ca lng methanol n ch s acid
Qua Bng 3 v Hnh 1 ta nhn thy: phn trm khi lng methanol so vi du
khong t 35-45% th ch s acid h xung nhanh. Nhng phn trm khi lng
methanol so vi du nguyn liu 45-60% th chsacid hxung khng nhiu. tit
kim lng methanol, trong phn ng ester ha kho st nh hng lng methanol
th chng ti chn phn trm khi lng methanol so vi du nguyn liu l 45%. V
th, ta cnh gi trphn trm khi lng methanol v du l 45% i tip kho st
cc nh hng khc.
II.1.2 nh hng ca nhit phn ng
kho st nh hng ca nhit n ester ha th chng ti cnh cc yutnhlng du, lng xc tc, lng methanol, thi gian phn ng v tc khuy.
Cc yu tcnh c gi trc trnh by Bng 4. Nhit phn ng c thay
i cc gi tr50C, 60C, 70C v 80C.
Bng 4 Cc yu t cnh
Yu tcnh Gi tr
Du bo b c ph 3g
Lng xc tc H2SO4 1% (so vi du nguyn liu)
Lng methanol 45% (so vi du nguyn liu)
Thi gian phn ng 60 pht
Tc khuy 700 vng/pht
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Sau 60 pht, cho dng phn ng, em phn ng cho vo phu chit yn 2
gi, tch ly lp di, ra hn hp sn phm nhiu ln vi nc cho n khi nc ra
c pH trung tnh. Mi th nghim lp li ba ln, tnh trung bnh cng v kt quc
trnh by trong Bng 5 v minh ha bng Hnh 2.
Bng 5nh hng ca nhit phn ngn chs acid
Nhit phn ng 50C 60C 70C 80C
Chsacid 4,34 1,697 0,806 1,54
4.34
1.679
0.806
1.54
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
50C 60C 70C 80C
Nhit phn ng
Chs
acid
Hnh 2nh hng ca nhit n ch s acid
Qua Bng 5 v Hnh 2 ta thy: nhit phn ng c nh hng ln n chs
acid ca hn hp sau phn ng. nhit t50-70C, chsacid t4,34-0,806, cho
thy nhit cng tng th chsacid htheo, do tng nhit th qu trnh phn ng
xy ra nhanh hn. Nhngnhit t70-80C th chsli tng t0,806-1,54, v nhit
tng cao th lng methanol bbay hi lm nh hng n phn ng. Nhit ti
u cho giai on ny nm 70C. V vy, chng ti cnh iu kin nhit 70C
v 45% lng methanol (phn trm khi lng methanol so vi du nguyn liu)
kho st tip cc nh hng ca yu tthi gian phn ng.
II.1.3 nh hng ca thi gian phn ng
kho st nh hng ca thi gian phn ng, chng ti thc hin cc phn
ng vi thi gian thay i cc gi tr30 pht, 60 pht, 90 pht v 120 pht. Cc yu
tcn li c cnh. Gi trcc yu tcnh c lit k Bng 6.
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Bng 6 Cc yu tcnh
Yu tcnh Gi tr
Du bo b c ph 3g
Lng methanol 45% (so vi du nguyn liu)
Lng xc tc H2SO4 1% (so vi du nguyn liu)
Nhit phn ng 70C
Tc khuy 700 vng/pht
Sau tng gi tr thi gian thc hin phn ng chng ti cho dng phn ng,em phn ng cho vo phu chit yn 2 gi, tch ly lp di, ra hn hp sn
phm nhiu ln vi nc cho n khi nc ra c pH tng ng vi nc trc khi
ra, em c quay v xc nh chsacid hn hp. Mi th nghim lp li ba ln, tnh
trung bnh cng v kt quc trnh by trong Bng 7 v minh ha bng Hnh 3.
Bng 7nh hng ca thi gian phn ng n chs acid
Thi gian phn ng 30 pht 60 pht 90 pht 120 pht
Chsacid 2,313 1,69 0,743 1,089
2.313
1.690
0.743
1.089
0.000
0.500
1.000
1.500
2.000
2.500
30 pht 60 pht 90 pht 120 pht
Thi gian phn ng
Chs
acid
(IA)
Hnh 3nh hng ca thi gian phn ng n ch s acid
Qua Bng 7 v Hnh 3 ta thy: thi gian phn ng nh hng nhiu n chs
acid ca sn phm sau giai on ny. khong thi gian t30 pht n 90 pht chs
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acid t2,313 hxung 0,743. Nhng t90 pht n 120 pht th chsacid bt u
tng t0,743 ln 1,089 do phn ng ester ha l phn ng thun nghch, nn cn mt
khong thi gian phn ng t trng thi cn bng nhng nu thi gian qu di s
to iu kin cho cc qu trnh khng mong mun xy ra tc l lm tng chsacid.
Qua kho st ny cho thy thi gian phn ng 90 pht l iu kin thi gian ti u
nht. Ta cnh yu tthi gian phn ng 90 pht kho st nh hng ca lng
acid i vi phn ng ester ha.
II.1.4 nh hng lng acid H2SO4
kho st nh hng ca lng acid H2SO4, chng ti thay i lng acid
cn dng trong phn ng nhng ng thi cnh cc yu t: lng du nguyn liu,
lng methanol, nhit , thi gian, tc khuy. Cc gi trca cc yu tcnhc trnh by Bng 8.
Bng 8 Cc yu t c nh
Yu tcnh Gi tr
Du bo b c ph 3g
Lng methanol 45% (so vi du nguyn liu)
Thi gian phn ng 90 pht
Nhit phn ng 70C
Tc khuy 700 vng/pht
Sau 90 pht, cho dng phn ng, em phn ng cho vo phu chit yn 2
gi, tch ly lp di, ra hn hp sn phm nhiu ln vi nc cho n khi nc ra
c pH trung tnh, em c quay v xc nh chsacid hn hp. Mi th nghim lp li
ba ln, tnh trung bnh cng v kt quc trnh by trong Bng 9 v minh ha bng
Hnh 4.
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Bng 9nh hng ca lng xc tc H2SO4n ch s acid
Lng xc tc H2SO4 0,5% 1% 1,5% 2%
Chsacid 5,678 0,57 0,5589 0,7736
5.6780
0.5700 0.5589 0.7736
0.0000
1.0000
2.0000
3.0000
4.0000
5.0000
6.0000
0.50% 1% 1.50% 2%
Lng xc tc
Chs
acid(IA)
Hnh 4nh hng ca lng xc tc H2SO4n ch s acid
Qua Bng 9 v Hnh 4 ta thy: Lng xc tc acid H2SO4c nh hng ln n
chsacid ca sn phm sau phn ng giai on ny. Khi phn trm khi lng xc
tc so vi du nguyn liu t0,5-1% th gi tracid gim t5,678 n 0,57. Nhng khi
tng lng acid th chsacid c chiu hng tng t0,57-0,7736. iu ny c giithch l do phn ng ester ha l mt phn ng thun nghch v sau phn ng c sinh
ra nc. Nc sinh ra lm gim nng acid sulfuric. Acid sulfuric ngoi vai tr lm
xc tc, cn c chc nng ht nc. Do khi tng lng acid th hiu quphn ng
tt hn (chsacid gim nhiu hn). Nhng nu dng qu nhiu acid, hiu sut phn
ng gim v acid cng c kh nng proton ha oxygen ca nhm hydroxyl ca
methanol to thnh ion methyl oxonium. iu ny dn ti s cnh tranh to thnh
olefin tru tlm gim tnh hiu quphn ng (chsacid cn cao). Ty cthkt lun lng xc tc H2SO4sdng l 1% so vi lng du l iu kin ti u
nht.
II.1.5 iu kin ti u ca giai on ester ha
Lng xc tc H2SO4: 1% (so vi nguyn liu du bo b c ph)
Lng tc cht methanol: 45% (so vi nguyn liu du bo b c ph)
Tc khuy: 700 vng/pht
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Thi gian phn ng: 90 pht
Nhit phn ng: 70C
Sau giai on ny sn phm c chsacid khong 0,57. Chsacid di 5 cho
php ta i tip giai on sau.
II.2 Phn ng transester ha
Phn ng transester ha nhm mc ch chuyn ha triglyceride thnh
biodiesel. Phn ng c xem l c hiu qukhi schuyn ha ny xy ra hon ton,
sn phm biodiesel to thnh c chsacid thp v cho hiu sut cao nht. Da vo
gi trchsacid v hiu sut phn ng chng ti tm iu kin ti u ca phn ng.
II.2.1 nh hng ca lng methanol
kho st nh hng ca lng methanol n mc chuyn ha ca phn
ng th lng methanol sdng c thay i theo phn trm khi lng so vi khi
lng sn phm ca giai on ester ha. Cc gi trkho st nh sau: 25%, 30%, 35%,
40%, 45%. Trong khi cc yu tphn ng khc c cnh. Cc gi trca cc
yu tcnh c lit k Bng 10.
Bng 10 Cc yu t c nh
Yu tcnh Gi tr
Sn phm giai on ester ha 3g
Lng xc tc KOH 1,5% (so vi sn phm giai on ester ha)
Thi gian phn ng 60 pht
Nhit phn ng 60C
Tc khuy 700 vng/pht
Thi gian thc hin phn ng l 60 pht. Sau 60 pht cho dng phn ng, em
phn ng cho vo phu chit yn khong 15 pht cho tch thnh 2 pha r rt, tch
ly lp trn, ra hn hp sn phm nhiu ln vi nc cho n khi nc ra c pH
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trung tnh v dung dch nc ra trong. Mi th nghim lp li ba ln, tnh trung bnh
cng v kt quc trnh by trong Bng 11 v minh ha bng Hnh 5.
Bng 11nh hng lng methanol n ch sacid v hiu sut ca sn phmbiodiesel
Lng methanol 25% 30% 35% 40%
Chsacid 0,262 0,276 0,328 0,382
Hiu sut 60,4% 67,7% 74,69% 64,18%
0.262 0.2760.328
0.382
60.40%
67.70%
74.69%
64.18%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
25% 30% 35% 40%
Lng methanol
Ch s acid
Hiu sut
Hnh 5nh hng lng methanol n ch s acid v hiu sut ca sn phmbiodiesel
Da vo Bng 11 v Hnh 5 ta thy: khi phn trm khi lng methanol so vi
khi lng sn phm ca giai on ester ha t25-35% th chsacid ca sn phm
biodiesel l: 0,262; 0,276; 0,236, cc gi tracid gn nh tng ng nhau. Nhng
khi lng methanol tng dn ln th hiu sut cng tng dn ln v y l phn ng
thun nghch nn khi tng hm lng mt trong hai tc cht th hiu sut phn ng s
tng theo, nhng v phn ng lc ny t trng thi cn bng nn d c tng lng
methanol ln th hiu sut gn nh khng thay i. Nhng khi phn trm lng
methanol tng ln t35-40% th hiu sut li gim. V methanol tan tt trong glycerol
v biodiesel, lm chm qu trnh tch lp ca sn phm gy kh khn v tng chi ph
cho qu trnh ra sn phm, lm gim hiu sut phn ng. Do vic sdng ru
cng phi ng liu lng, trnh hao tn ru khng cn thit. Theo Hnh 5 ta thy khiphn trm khi lng methanol so vi sn phm giai on ester ha l 35% th sn
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 43
phm c hiu sut cao nht v chsacid thp. Vy phn trm khi lng methanol so
vi sn phm giai on ester ha 35% l ti u trong giai on ny
II.2.2 nh hng ca nhit phn ng
Da trn mt syu tcnh tin hnh kho st phn ng trn c sthay inhit phn ng nhng gi trkhc nhau.
Bng 12 Cc yu t c nh
Yu tcnh Gi tr
Sn phm giai on ester ha 3g
Lng xc tc KOH 1,5(so vi sn phm giai on ester ha)
Thi gian phn ng 60 pht
Lng methanol 40%(so vi sn phm giai on ester ha)
Tc khuy 700 vng/pht
Sau 60 pht, cho dng phn ng, em phn ng cho vo phu chit yn
khong 15 pht cho tch thnh 2 pha r rt, tch ly lp trn, ra hn hp sn phm
nhiu ln vi nc cho n khi nc ra c pH trung tnh v dung dch nc ra
trong. Mi th nghim lp li ba ln, tnh trung bnh cng v kt quc trnh by
trong Bng 13 v minh ha bng Hnh 6.
Bng 13nh hng nhit phn ng n ch s acid v hiu sut ca sn phmbiodiesel
Nhit phn ng 40C 50C 60C 70C
Chsacid 0,385 0,224 0,272 0,282
Hiu sut 70,24% 71,83% 68,81% 63,31%
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LU N VN T T NGHIP Cn bhng dn: TS. Bi ThBu Hu
Sinh vin thc hin: Bi Lin Khoa 44
0.385
0.2240.272 0.282
70.24% 71.83% 68.81%63.31%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
40C 50C 60C 70C
Nhit phn ng
Ch s acid
Hiu sut
Hnh 6 nh hng nhit phn ng n ch s acid v hiu sut ca sn phmbiodiesel
Qua Bng 13 v Hnh 6 ta thy: khi nhit phn ng l 50C th hiu sut
biodiesel thu c kh cao. Nhng khi tng nhit ln 60-70C th hiu sut
biodiesel c chiu hng gim. iu ny chng tnhit c tc dng xc tin cho
phn ng. Khi tng nhit th khnng ha tan ca du v methanol tt hn lm cho
phn ng chuyn ha tt hn. Nhng nhit qu cao th mt phn lng methanol s
bha hi. Mc khc, nhit qu cao c thdn n phn hy sn phm hoc phn
ng s xy ra theo cc qu trnh khc lm gim hiu sut biodiesel. TBng 13 v
Hnh 6 ta thy khi thc hin phn ng 50C th