TitleThermal analysis of the catalytic action of colloids (I) :catalytic decomposition of hydrogen peroxide by colloidalplatinum
Author(s) 水渡, 英二
Citation 物理化學の進歩 (1939), 13(3): 74-86
Issue Date 1939-06-30
URL http://hdl.handle.net/2433/46184
Right
Type Departmental Bulletin Paper
Textversion publisher
Kyoto University
9fiT~lt~olit€~ Vol. 13n No. 3 (1939)
THERMAL Ai~ALYSIS OF THE CATALYTIC ACTION OF
COLLOIDS. (1)*
Catalytic .Decomposition. of Hydrogen Peroxide by
Colloidal Platinum.
sy EtJI SUITO.
]3redig and his collaborators'/ first made comprehensive researches on the
catalytic action by various colloidal solutions. They called the action of hydrosol of metal or metal oxide and hydroxide " Anorganische Ferments " because of
the similarity of the .action to that of enzyme. Since then, numerous investiga-
tions bout been made and most of them done concerning the catalytic decom-
position of hydrogen peroxide by colloidal platinum-> In aIl of these studies chemical analysis such as titration of t}te solution or the measurement of the evolved oxygen has been adopted for the deterntiitation of the reaction velocity.
The .present author investig.ded the said reaction by the thereto-analytical
method'/, which originated with Yrof. S. Horiba and was successfully applicable
for continued measurements of the reaction velocity, especially for the initial part
of the reaction, in order to elucidate the mecltartism of the decomposition and
colloidal catalysis.
Experimental. Materials.
The platinum aol was prepared by Bredi;;'s electric dispersion method, using a duect current {qo volts, 6 ampere) cooled in an ice-bath. After about t boar it became so dark
brown that no electric spark was seen. The concentration then determined by precipitating with a little electrolyte was 60~8o mg. of platinum per litre. After standing Cor scveml days to permit the lar,er platinum panicles to settle, the rol was carefully siphoned olf and diluted
*' This is the English rmnslarinn of the paper which apl.earcd in Rev, Phw. Chrm. Ja/.nn, 10, z5r (r936)•
a) G. iiredig and co-.corkers, Z. phytfk. Ckrnt., 31, z59 (r899); 37, +. 3a3 Gmr); 66, r6z (r9o9); 70. 34 (r9o9): 81, 385 (r9rz): Rer., 37, 798 (r8oq) rtr.
z) T. 5. Prim and A. D. Donning, 7,. fkyrik. Cfrm., 16, 89 (igo;); D. A. 1(c(nnes, J. Bm. Chem. Sot., 36, 878 (r9rq); J• Groh, 1, pkv>ik. Chem., 88, 4rq (r9r4); T. Iredale, J C/tem. Sac, 119,
ro9 (rgv ), I21,.r536 (t9zz); II. V. Tartar and N. K. Schallar, J. Bra. Ckem. Sx., 3Q, zboq QgzB): n1. A. Heath and J. P[. Waltnn, J. Pkyt. Ckrvt., 37, 979 (r933) rlt.
3) 5, Hnriha and T. Iehikawa, Rev. Pkyt. Cheer. tepee, 1, tq5 (t9z7); T. Ichiknwa, G fhyrik. Ckem., (Ti) 10, 2990930); S. (Ioriha, Rev. Phyt. C/tent. Jnpttt, I1, r89 (r937): T. KJsaki, i/iiJ.,
12, 21 0938); II. ]tatsuyama, ibid., 12, [68 (x938) ert.
9fiT~1t~~it€1 Vol. 13n No.
Yo. , CATALI'TIC ACTION OF COLLOIT)S 7i
4 times. 't'his stock solution was so. stable ~+•ithout any addilimt of -a protective colloid or
peptizer that coo precipitate was noticed after several months; and it never coagulated after the decomposition of hydrogen peroxide.
7/ic 7ydrogen yeraxide so&tlion was n diluted 1\lerk's `Perhydrol '.
All the water used was a conductivity water prepared thus: hvice distilled water was
reiistilled by means of a Pyres condenser and then the air without CQ was passed- for several
days. All the vessels used were made of `1'eles' glass'[ and were steamed out.
Apparatus and Procedure.
In the thermal analysis in the liquid system, the measurement of the temperature change.
of the reaction spstenr teas made by means of a glass calorimeter as shown in Fig. t. ]n the
e Bgurc, A is a glass Dewar vessel holding about too cc. ~~ r a n l o(a solution. B a glass vessel which holds about 6o c.c., C a normal Brd:mann's thermometer, D a glass stirzer
F ~ s rotating gootzo times per minute, and F, a heater with
B
r
a
1
A
Fig. x.
hydrogen peroxide solution
blowing from f. Lxstantly
a-tme moment, Reckmaixn's
initial concentration of hyd
standard potassium pcrman
Cal
The principle of the t
dT _ dT dt dt
Nheie ~~ is the tempemt due to the temperature d
thermostat, Q • ~~ is the
q) The 'Telex' lass m
U rotating gootzo times per minute, and F, a heater with
a platinum wire resistance movable up and down.
5oc.c. of plntinuro sot was. introduced into A and a solution of hydrogen peroxide in B to let just 5o c.c:
flow out of b". The lid which supports $ C, ll and E
was put on A ti~hlly and then P' was connected. The whole
apparatus was dipped in a thermostat at 3oto.ooz C. The
platimm~ sot in A .vas heated to almost the same tempe• r ratum tis 0tat of the thermosl.•t[ b}• E, and then E was
drawn on[ to avoid the catalytic rlecomposilion by il. After • thermal eyui]ibrium had been obtained abotic x hour later,
was siphoned o!f into platinum sot in A within 3-4 seconds, first
they ++•ere mired with each other and the reaction started. :\t the
thermometer which eras tapped automatically was read on. The
rogen peroxide e:vs determined in atxother Oask by titration +vit6
ganatc solution.
culation Method of Thermal Analysis.
hermal anal}'sis can be expmssed by the following equation
O dx t4' da
ore change in the reaction system, - dt is the cooling velocity iHerence between a reaction system and its surroundings, i.e. the
hu:u quantity produced by the reaction per snit time (Q and d~
ana(actured by Tot:}'o Electric l'a. Ltd. is similar to ' F ,rrer in quality.
3 (1939)
9fif~lt~mii~~ Vol. 13n No. 3 (1939)
78 F.. 3UIT0 Vol. Xlyl
are the reaction heat and the reaction velocity respectively), and If' the water equivalent of
the reaction s}•stem.-
Cooling Constant andWatcr Equivalent.
In the calculation of the reaction velocity anct reaction heat according to equation {r), it
is necessary to know - ~~ and W which are particular to the rrction system, ic. the apparatus. In this case the cooling follows Nex•ton's law, that is, it is proportional to the
temperature Difference, dT, between the reaction system and the thermostat. This was
empirically justified with some rnrrection, B or r, caused by stirring heat or others.et There-
fore,
d6 ... .
Thus, by the measurement of natural cooling velocity o/ the reaction system the cooling mn-
starrt K anti tbecorrection term B or r can be obtained.
Let r represent the resistance of the platinum wire of the heater and i the intensity
of the electric current transmitted through it, then the heat gaantity per minute q' liberated
by the current is r4 860 (cal.). Putting q' for Q• ~ in equation (r), we have
Accordingly, the water equivalent FV is obtained from the measurement of the rate of the
temperature rise. of the reaction system by electric heating.°~ 1'he resistance of the heater y
w•as measured preliminarily by a potentiometric method under the same condition as in the
calculation of Che water:equivalent and wag found to be o.M1g3 ohm. "Phe values of If and
fV obtained are given in Table I.
Table I.
No.r
(°C)B (rt) XIt (^) ~ (amP•) It'
(~•)N.H.
z
oo[gtz
oooozq it oot393 ~ 0.8I$ , 1390 ~ LO
n6.8q[t6.g5 }pnre walcr
3
456
Lg 30 tS95t397
I tqo;[38i
O.OI,39t[qoo[394
rgr
0.8no08o.g
t r6.57n6.38[[6q5u5.7o
solutian afterreactinn
7 t8 zo t3gz [397
Mean values: r=ooxS, 0=o.owz, A=o.ot39, iV=xxG.6
5) ~=A'; B u the rare of tempemturc rise by stirring; r is the temperature difference between the reaction system and the thermostat at thermal egoilibriam, being due to stirring heal.
G) The platinum wire of the heater is dipped in the solalien in this case and not in case of the reaction. Consequently, the water equivalent for the reaction must be eaactly IV-0.0x4, because
the weight of the patinum wire is oqG gm. and the specific heat _h o.o;[z. This cornctiox5 howeveq is negligible av compared with ~hevalue of ff!
7) As to the value of A; (n) was obtained from graphical method and (b) from calculation. Srq S. Iioriba and K. Sato, Rte. Ph~•r. Ckrm. Jajvtn, 6, z5 (x93z} ,
9fi(~1t~mi~~ Vol. 13n No. 3 (1939)
No. 3 CATALYTIC ACTION OF COLLOIDS i7
Reaction Velocity.
Substituting equation (z') in the fundamental formula (t), ~6e have
tit +If(dT-r)= Q ~i ....................................... (4) As dT is the inclination of the reaction curve (dT t curve), the value of ~ dx tit FV . tit can be easily obtained from equation (4)• In this case W is known and Q can he obtained as shoivn below; hencethe reaction velocity tit at a cer4lin time can be calculated. ;;ven if N~ and O are unknown; both are constants and so the plot of ~ • tit for a time t makes thereaction velocity curve.
If the reaction is of the Hrst order, dx =kr(a-x)=k,a x e ( ) ti
t -hr ......................................... j
where d•, is the velocity constant and a is the initial concentration. Putting (5) in equation
(4) and. taking logarithms, vve have dT Q ~lx _ Qk,a _ 1.•,t l~~ tit +K(dT-r)~=log ~' ~tC-IOg W 2.303....... (6)
Accordingly, plotting the value of l!!!og ~ tit (or a time t, a straight line will I>c obtained and the slope of this line will give k,.
Reactioa heat.
From equations (r) and (z), the following equation is obtained
dT +KdT -B= O dx ........................................... (4r) tit W tit
Integrating this equation from 1=o to t=t, a certain time after the rompletion of the reaction,
we have
Q= !a lJ dT+Kf dT•dt-Bt} .................................... (7)
Hence, if the value of S= f rdT• dl is calculated by the graphical integration of the dT t
v
curve, the reaction heat Q can be ob~lined. Irr the case of the first order reaction, the intersection of log Q dx-~-t line with the
Qk, a lV tit ordinate represents ]og iv as seen 6~om ey nation (6). Accordingly, From the initial con-
centration ¢, the velocity constant k„ and the water eyuivalent ITV, .the reaction heat. Q can >x calculated.
Experimental Results and their Consideration.
One of the results obtained is given in Table II. The curve obtained by
plotting dT(=T-T~) for t is shown as (a) in Figs, g, q., 6, ~ and 8.
(a) Series 7, EzPt• 4• ({kG 3, [935)
Pbsal
I{:Oo
3o°C
IOC.G
o.ozq g: mo1f1i1re
(mom temp.-IB--zz°C)
E. SUITO
4'aUle II.
9fiI~lt~mi~1 Vol. 13n No.
Vol. X1Ii
(b) Series IV„Expt. 3.,(Beb.S; 1936) Phsol 2oGC.
IisO; o.ozSg,-mol~litre
3o°C (room- temp. zo°C)
3 (1939)
T ~°C)
z~499
i
5co
Sz0
530
540
550 560
570
580 590 600
6[a Gzo
630 640
650
670
6So
690
Ton
7to
7z0
730 740
750
770
7fSo
790 So0
mm
T (°C)
f in)•(sec
z.8xo
3zo
830
Sqo
850
.857
861
867
87z
876
879
881
S83
887
S88
889
890
Sgo
Sgo
840
889
888
837
885
883
881
879
877
875
871
30
51
3 • 12
xz
z8
5'-
1xz
30
54
z ! tz
3x
53
1G
38
03
3z
I9
M
09
34
07
18
07
4z
x6
4•
5•
6•
7•
S•
9•
m
~ 1 • .37
5z •i5
13•~
5z
qo • o0
4~ •~
qz.• o0
4.i • .i0 45 m
T (e~
2.!368
S62
858
852
844
838
S;o
825
x.4
Sob
794
784
776
76fi
757
748
738
729
yzx
7x2
706
Ggo
679
668
660
650
(po
6zz
608
t min)•(secJ
qG . 30
q8 • ao
50 • ao
5z . ao
54.00
56•ao
58• m
60 . ao
63•ao
GG • o0
69 • o0
72.00
75 • ao
78 • o0
3x • ao
84 . o0
87.00
90 • o0
93 • o0
g6 • o0
99 • o0
xo2 • ao
xo5•m
xio • o0
tx5 . o0
xzo . o0
x25 • o0
x3o . o0
xqo . ao
x5o . m
T (°C)
z.5oo
T Sxo Szo 530 540 550 560 570 580 590 600 6xo 6zo b:;o Gqo 650 660
670 680 690
700 7xo 720 730 740 750 i7o 780 790 Sao 8xo Szo 830
T ~°L)
z.Rgo
Ssa
S6o
870
RRa
900
9ro
gzo
930
9qo
950
95R
9W
970
973
977
979
qRr
g8z
9R3
9R3
9R3
9R3
98r 'I7R
973
gLz
95~
93R
9zR
qtC
903 S93
L
(min){sec)
3.56 4' • ~
Ig
3x 44 56 5 I I :ice
49 6.08
31 7 . o0 io S•oo
30 9.00
30 ii fo . o0
30 II •00
;o 12.00
;o t3 - o0 i4 . 00 x5 . o0 ab • 00 18 . o0 zo. • o0 zz • ao 'zq • o0 a6 ~ rio z3 . o0 30 . o0
Using the values
ing to equation
dran•n as (h) in
nearly linear as
To=z.Soo
of Q d1 and log ~, d1 obtained from (q), as an example in Table III, the reaction Fi and 8. And the to dx ~• 3, 4, 7 g Q ~
(c) in Digs. 3, q, b,`j and 8, and from it+ slop
Ta=a5oo
this. curve accord-
velocity curve was
~-...t curve- is seen
k, was obtained.
9fiI~lt~mi~~ Vol. 13n No. 3 (1939)
No. CA'1'AL\'T1C ACTIONOF COLLOI US
'table TIi.
79
t (min.J
O
IA
.A
q.o
SA
4a
7.0
S.o
9.0
to.o
n.o
t zo
X3.0
iq.o
i5.o
iGo
i7.o
iS.o
~ g.o
zo:o
2Y.o
zzo
z3.a
z4•o
z5.o
dT (°~~)
-o.aol
}OA3405~ 083,
1 II2
I3T
h'(d T-r)
-0 .0003
~FO.oooi
~s
i6
~g
as
z5
as
31
33
35
37
39
4a
qa
4a
44
45
qG
47
4~
qs
49
Sa
+O
r (min.)
zh.0
2~.0
25.0
29.0
30.0
j2A
34.0
36A
38.0
4oA
42A
44'0
46A
48.0
5oA
55.0
60A
G5.0
BOA
75.0
SOA
55A
f0.0
300.0
tI0.0
I?OA
dT (°C)
to.38z
3~
388
389
390
390
389
387
383
379
37q
368
363
3i8
34i
3zi
3~
zgz
z76
z6a x3$',
~'9
203
r7gi
X60
(dT-r)
}o.msa
5~
5~'.
Ss
5~
5~
Sj
5~
5~
So
So
49
qS
4S
47
45
43
4~
3S
3~~
33
3a
zS
z;
zz
r9
dT
d!
+ooo
sa
~8
[3
-0.0001
:a
zi
z5
z7
z9
3~
33
35
33
3a
~a
z9
z7
z5
zz
p er Tv er
}ooo7G
73
6
SS
3
9
5
2
0
8
3
z
z
2
1
z6
12
og
r
5
4
7
l
O
Q Ar ~~{V dede
3• ~:;
~.
838
go7
780
744
703
6z6
5~9
qbz
398
34z
Sot
z55
zoq
079
(b)
k,=o.o5gx
e oT A'(JT _)i dT Q dsI
I ~ nT ~."(J T-r dT Q Js Q dsTv e'~ logty ei(min.) ( c~ m Tv dl
log Q ~ (nun.) (C) ~ Jl0.5
o.ooo -omo3
to.ogo; +0.0003
}0A~20
iogo
toAgi z • y6+il 6.5 to43S +o.ao58,xo;3, y • ox8i 7A 4.io~
}o.oz3o
i85
}OA2$
a45
z ' 459
~ 339Lo
i.5
II
i5o, x8
izoo
1000
uti oS3
xox>~ 003~7~5 4i& 6I8.0 46q~ 6z
t5a
l;a
2II
igz
3z-0
z83
z.o
25
tg6 zq
zgcj z&ogzo
sos
• 975
83 9zz
8-5 ~ 47a 639.0 ~ 474; 63
xo .5
oSa
i68
i43
zz5
x55
3.0 z8d 3fi 7zo 756 S79 9.5 477 6q Sa iiq 057
3.5 3i5~ 4i 6qc 6Si S 33 io.o 479 6q 4a ioq ox7
4.0 344 45 540 sxs 767 /LO 4gI 6q 034 3 • 9zq
4.5 370'' 49 460 So9 707 Izo 4g3 Gq a bq SoG
5.0 z 4~ 45z 655 i3•a q3z 6q -oml5 qr~ b9o
5.5
39xi 54 w 54 360 4I4 6r7 tq.o qSx Gq 30 34 53~
G.o 4z7. 56 z8o 33G 5z6 x5.o 478 Gq Ga oq
k~mo.zyz5
i
i
9fiI~1t~~itl~ Vol. 13n No. 3 (1939)
h0 - S . SUITO Vul . XRI
Five series of the experiments were carried out as follows (sf . Table IV) I and IL The concentration. of hydrogen peroxide was kept constant , add
that of platinum sol was varied. The activity of platinum of varied during the
stock as proved in Series . III. Series II were carried out on the sol , whose activity beca~i~e extremely high in half a ~ilonth's stock :after series I.
.III. The change of activity of the colloid caused with aging ryas examined . 1V and V. The concentration of hydrogen peroxide ryas changed . -The time
. Tahle 1V.
F.zpt. No.
x
3
4
5
z
3
4
2
i
a
~~
z~
s'
z
s
a
s
6
7
I
z
3
4
II
m
Iv
V
Date
Dec 5. 1935•
Nov. 30
Dec z'
•, 3
„ q
,~ -iy
., i8
„ t6
„ i9
~, iS } I5 days 8 »
~, z6 f 39 » FeL. 3
Deo. 4}'l .,
,~ t9.
,~ i7} 8 .~ Feb. 5~ i93G.
.. q 6
4
zo
i9 „ zx
Conc. of k3e0.
ratio
3.7
8 4
3.5
3
2.5
E
8 5
3 2
mo g: 1, litr /e
o.ozg
z9
zg
,y
z9
29
zg
z9
''-9
z~
z9
zg
zg
s9
,y
zy
6z
3I
z7
zq
zo
ib
03
G3
3g
zq
r6
io 5- 7
4
(min.)
t
t+
z
3
4
s
2
i
3
2
2
4
3
x
z
3
z
ki
(minri).
0.4677
zt9o i53z
o39z
02i0
X753
oy86
O$O7 O~(i7
os9z
0986 i ~b3
0686
0zta
oz67
oz6g
(z6zS)
335 z9zg~
3335
3346.
33zi 3316
(o75.i) 0675
o6ro
o91q
e
( CaL lg: moJ z3.94G
z4 474
24467
z3.88o
z4~r93
z3,6r3
zga63
(z3•>~J
(z3.6r;) z3 344
z'.78n
23:632
r.98q
23.653
z4•o45
z4.ogz
z3:5oz
z3,Gi5
z;.5zj
2;.683
23:568
z3.99o
mean z3•SS6
(Note) (i) The stock solution of P[-sot No. z. prepared on Nov. iz, r935 was used I,.II, III & V, and No.;-prepared oo I+eb.;, rg;6 (or Series IV.
(z) The concentrations of I~.O_ aad PI-sot indicate those al the reaction, after the miring of both solutioaA.
Cur
it,
Serjes
those
peroxide by metalic colloids is etther
of the fiat order or nearly of the first
order with some deviation. Lven in the
present experiments, if ki is calculated by
an ordinary method (k,= t In ~ > t a-x
neglecting the initial stage, it does not
become constant and the reaction does
not exactly appear to be of the first
order over the whole region. By the
ordinary titration method the initial
stage twill never be noticed, because this.
stage is too short for the time interval
of measurements. But it is interesting
to mention that by the thermo-analy-
tical method the initial stage was found,
which twill 6e discussed later.
(2} The Effect of Concen
From the experimental results of Set
the duration of time of the initial stag)
decreased as the concentration of the
constant k, is nearly proportional to th
as seen in Fig. 5 s~
$) The deviation of [hc plots of N~spls. I and z by taking into aceooot the increase in Uu
uu[ first and Exp[. I last in this seriee.
9fiI~lt~mitf 1 Vol. 13n No.
No. 3 CATALYTIC AC"PEON Ol+ COLLOIDS 81
of the reaction was shortened and both series were completed within a few days
to lessen the change of the activity. Series V were examined with the object of considering the initial part of the reaction.
(1} Reaction Type.
The reaction always proceeds as shown schematically in. Fig. ? : it proceeds
in the two stages-the initial stage (ab) and the later stage (cde). The later
stage, which is the. main part of the reaction, is exactly of the first order (for the
line c' d' e' is straight), and before this stage a special stage appears.
It has been admitted that the ta)
catalytic decomposition of hydrogen I ~~
a
i
/Be
E
F
3 (1939)
big
dl~ i
5~
~.I,a ..~
6
C
d
(81
2
-.1
Concentration
of Series I an
1 stage u (th
f the sol is it
to the square
. x and z from the :e in Ure nclivitf
_ --~/ ••~_ -•0303 fcl vb c
d'
e'
Fig. a.
of Platinum Sol.
d 11 as shown in Figs. 3 and 4,
e 7dt column in 'T'able IV) is !creased. The reaction velocity
of the concentration of the sol,
straight line n( Series I eau Le explained with aging and that Cpl. x w:u tacri<d
i
s~
a
O.j:
~~~1'~
'10.1
S`
-..+w
In/
9fi~~lt~mi~~ Vol.
J Q_
4
aYS
13n No. 3 (1939)
a ~?
did
i
/bl
Sa-. !{mina
Vol. XIII
r. m 0
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.,
~~
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javf(
too
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I L~ ~ )r.l, l
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l0.0
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5.0 ~~
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,~
f
5 ~o ~$ ~ =5 --(Conc. of Phv~l)-.
I•~g. S..
~~
Geuerall
catalysis, the
the amount
sol, and the f
So
Z'~` ~ icr
dl~
a
•'t '•+. 3
t'iGt 4.
y speakin„ in the
reaction ve]ocity is.
of catalyst, i.a. the-
ollowing relation ho
z
~ -~ ~~ ~* ' ~~' are [he veloci consta
-. t (min.Jtoo
case of cc111oi
not proi:ortional
concentration of
lds that is,
dal
to
the
where k and ty ~its'~ ftir c and-
c', the concentra[ions of the sol. For the valuesof ~i;
Bredig and his co-tdorken°' have obtained t.3-ri.6;
t.t~i.q gild ~ in the decompositioiis of hydrogeii
peroxide by Yt-soL Au-sol and Tr-sol respectively. In the prescnt experiment, iY tuffs as high as z,
y) Gx. til.
9fiT~1t~o1it1=1 Vol. 13n No.
Nd. g CATAi,YTTC ACTION GP COLLOiI1S 33
[3) The-.Change in the Activity'oE"the Colloid'. with-Time.
In the comparison between the experimental results Series I and II obtained with 5 c.c. and io c c. of the sol; it tuns formt3 that the reaction velocity ivas larger in Series II than in Series I. To make clear tliis change iu the activity. the clperimental results Ivitli some addition are shown in Fib- ~ as Series III.. It was found that the activity of colloid increased with aging, reached the
ors ca, maximum and. dten diminished. And it is to be noted that the.
o duration of the initial-stage' a tends e~'
, ~~ a ~~~~~ to become short with the time. 1t is interesting'tbat in colloidal
_o - I~ ~- catalysis the activity does not gra;
` Y ici dually diminish as in the common ~`•r e~p ny,. . p p_,p_,p ,,,,,,,,,, case of heterogeneous catalysts but
0-®~ ~ "' '" raffier increases to the maximum .~'~= -
T 3, ~ ~~• rs. s
has found in the dcwt
dispersity is high, r,e.
also .low. This rclatio
as a general rule to c
kith the sol which wa
contain many other su
as applicable to owe c
is due Yo the growth
that the phenomena is
colloid:
A liiore definite
periments: And fhe r activity is an interesti
activity falls off after
in the concentration o
lo) Gr Rnnmlano, Cn i x) S. Rusznyak„ Z, p ~
nposition o
the size
n behveen
olloidal cata
s prepared
bstances act
ase, we ma
of the col
radter du
interpretati
elation Betts
ng question
a long time
f the so] by
mom!. xm2., lZO, h ink, CF.rm... R.
This result G. Rocasoland01 has.
`~ attributed to die effect of oxygen contained in the_sol. $. Rusznyak"1
f hydrogen peroxide by Ag-sol that )vhen the of the. colloidal particle is small, ;the activity is
the particle size and activil}~ can. not be applied
ly;is; becaose his experiments were carried out cheliiically by reducing method and seemed to
ing as a poison ; but i( we regard 'his results
y thfnh that the increase in activiri• with aging loid particles. However; it is probably inferred
e to the change in the. surface nature of the
on of this phenomenon will require further ea-~een ttte size of the particle of a colloid and its
in the colloidal catalysis. The fact that the
as i~ Exl,t. ¢ may be ascribed to the decrease
precipit2tion•
3 (1939)
U
a
i
a (a
~~~
i
tJ:
a~a_
9fiT~1t~~i~1 Vol. 13n No. 3
84 E, SUITO Vol. X1II
(4) The Effect.. of -0oneelitration of Hydrogen Peroxide Solution.
'The experimental results (Series IV and V) obtained with . various concentra-
tionsof hydrogen peroxide areshownin I'IQS. y:and 3."'
0.8 IR1
tflf p
0.5 / ~ ® U F1
1 /~ o v
ff a oq fl ,- ® > m
1 ~
1 l 1
IO 20 O.D$ 2n Qn
o.I6 per`. ~~ Ibl
y ,, t,.a,so....l
ID 8 _
® 3.5 -
m,
~~ ~ 20 yp 4 , ~<, Y
is
P, °a„
3 1' ,-
r-;g. s.
It is that the initial reaction velocity
nearly p p of hydrogen peroxide, :and that
Iz) 7n all the experiments, except F.xpt. I in Series IV and V, the temperature difference (d7) of the reaction system is below o.5°C, and .within this temperature the effect of the velocity con-
xtnnt r3ue to tempen+nve rim may be negliGible. Expt. I in Series N and V was carried qut with lemp:ranire difference over I°C, only to examine the initial port of reactibri. Deviation of kt in Exyl. 3 in Series IV is probably ascribed to some error of the enncentratinn of the saL.
IO p
., ~~~'~ ~' -
a
- .~
.. Z,:,yw "o j 1 Fig. 7.
seen from the reaction velocity curve
ro ortiotia} to the initial concentration
(1939)
9fiI~lt~mi~~ Vol. 13n No. 3 (1939)
Na. 3' -' CATALYTIC ACTION•OF COLLOIDS Su
eac(t reaction. ends .almost at the same. lime. Nest, that the. linear part of tl:e
]oR Q `~"t ̂rt curve runs in parallel shows. that the reaction velocityconstant bV rit
d, agrees well with one another. The duration of the initial stage u is; about t
min. -in Series IV and z-3 min. in Series V.
{5) The Heat of Decomposition of H:Oe.
The reaction heat Q calculated according to equation. (y) is z3.9±o.g Cal.
per t g.-mol, being in considerably good agreement as shown in the last column of Table IV.
Let as mmparc this result witb those of .other 'un'cstigators. 14Tatheson and. Nlass'a%
obtained z3.4j Cal. as the decomposition of bydrogen peroxide solution with small, articles
of \~InO. by means of adiaMtic calorimeter.. Roth, Gran and Meichsner" I oh4•fined-. z3.gz
Cal. (a[ zo'C.) for a 9~.z7q solution and za.Cq C'al. for e.339o soluion. Frntn thermo-chemical
data's'. -zz~-zj Cal. ryas calculated as the heat of formation from water and oxygen gas.
In cmnpadsou .witk these values it is seen that the author's value is proper.
(6) The Initial Part of the Reaction.
As to the initial part of the ruction, the deviation of the curve from the
first order is very slight. But it is aso~ibed not to the errors of the apparatus,
such . as the time lag of Beckmann's thermometer, absorption of heat by the calori-
meter, etc., -but to the reaction itself as is clear from the following three points.
(t) The deviation can not be noticed in the case of electric heating.
(z) When the reaction heat was calculated from the intersection of the ex-
tension of the straight part in the log Q, !L ~..t curve with the ordinate under the assumption that the reaction proceeds according to the first order from the
beginning, the value obtained is generally larger than that obtained before, and there is no agreement in the value of each exlxriment.
(g) As to the duration of the initial stage rs, inspecting from the results of Series I and II, iE is found that the higher the concentration of the sol is, the
shorter the duration becomes. If the difference among the duration -is to be regarded as due. to the initial reaction velocity, that is, the rate of temperature rise; the error to be caused by the apparatus also should be taken into account. But; as seen. from the results of Series IV and. V, even though the initial reaction
velocity is different, when the concentration of the sol is definite, U is- nearly
a5) G. L. Matheson ~ O. Mass, J. Am. Clruie. Snc., 51, 674 (r929)• rq) W. A. Rotlt, R. C;ran u. A. Meichsner, 7.. a>rarg. Clunr., 193, t65 (rg3o).
r5) M. Relthelot, C'omjt. mrC., 90, 35t, 897 (r88o); P.. de Furcrand, iGid., I30, rz5o (rgoo); J. Thomsoq Tnernrochemirche U.ilernrcJrvul<n; ela.
9fiT~1t~~itt1 Vol. 13n No.
R(i E. SUITO Vnl. XUT
constant. itlorever; in comparison behveen the results of these two series it is
found that variation in the concentrations of the sol leads to the different value
of a even in the same initial velocity. Tlrerefore, it is inkrred that u is affected
not by the rate oLtemperature rise but by the reaction itself, and probably it is
related to the amount of the colloid.
The reaction velocity curve of the initial stage is indefinite iat each experi-ment, beinn not always linear. Therefore, the nature of the reaction of this
stage can not bz made clear. The appearance of this sage may depend upon the adsorption of hydrogen peroxide on the surface of colloid, namely, to reach
the adsorption equilibrium in liquid system may need a considerable time, which
will be tbe duration of initial stage rz. And in colloidal system the electric
double layer of its surface will play an important role for the adsorption (diffu-
sion). This preswnption is not certain and theoretical consideration on this
colloidal catalysis will he required.
Summary.
t) By the method of thermal analysis the catalytic decomposition of
hydrogen peroxide solution b}' platinum sol has been studied, especially the effect
of the concentration of platinum sol and that of hydrogen peroxide.
3) 1t has been found that the reaction proceeds in two stages: the initial
stage and the later stage. The duration of the initial stage is practically in-
dependent oP- the concentration of hydrogen peroxide. and is nearly ~n inverse
proportion to concentration of the sol. The later stage, which is tite main part of reaction, is of the first order with respect to hydrogen peroxide and the reaction velocity constant is proportional to the square of the concentration of
the sol, i.e., dx = k, (HOa), 6•, w(Pt-so!)=. d
t
g) The .activity of the colloidal catalyst increases at first with aging. q) The value of the decomposition heat of hydrogen peroxide .has been
found to be zg.q Cal. per g.•mol.
In conclusiat, the author has great pleasure in expressing his sincere thanks
to Yrof. S. Horiba for his valuable guidance during the course of this research.
Tlae LrsLoratary of Physical C)umiataq. I:yolo Lnperial Uaaiueraily,
(I.eceived.\faq t5, r939)
3 (1939)