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Journal of Hazardous Materials 229– 230 (2012) 258– 264

Contents lists available at SciVerse ScienceDirect

Journal of Hazardous Materials

j our na l ho me p age: www.elsev ier .com/ locate / jhazmat

Combustion of isopropyl alcohol using a green manufactured CuFe2O4

Yao-Jen Tua,∗, Chien-Kuei Changb, Chen-Feng Youa,∗

a Earth Dynamic System Research Center, National Cheng-Kung University, No. 1, University Road, Tainan City 701, Taiwan, ROCb Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Science, No. 415, Chien Kung Road, Kaohsiung 807, Taiwan, ROC

h i g h l i g h t s

� A green method for manufacturingCuFe2O4 was developed from indus-trial Cu sludge.

� The green manufactured CuFe2O4

was effective for combustion of iso-propyl alcohol.

� 96-h decay test shows the catalysthas a good thermal stability anddurability.

� Magnetic property may solve the cat-alyst recovery problem in fluidizedsystem.

� This work achieved the goal of cleanproduction and sustainable develop-ment.

g r a p h i c a l a b s t r a c t

a r t i c l e i n f o

Article history:Received 17 February 2012Received in revised form 2 May 2012Accepted 30 May 2012Available online 5 June 2012

Keywords:Industrial Cu sludgeCuFe2O4

Catalytic combustionIsopropyl alcoholVolatile organic compounds

a b s t r a c t

A green method for manufacturing CuFe2O4 from industrial Cu sludge was successfully developed bya combination of acid leaching, chemical exchange and ferrite process. The CuFe2O4 was applied forcombustion of volatile organic compounds (VOCs) derived from isopropyl alcohol (IPA). The results showthat IPA was reacted to form intermediate acetone and CO2 at the temperature range of 110–170 ◦C.When the temperature was increased to 180 ◦C, IPA can be 100% converted into CO2. The 96-h decaytests indicated that the catalyst has a good thermal stability and durability under the conditions of gashourly space velocity 30,000 h−1, oxygen content 21%, IPA inlet concentration 2000 ppm, and reactiontemperature 180 ◦C. The results demonstrate great potential that our manufactured CuFe2O4 catalyst canbe used in combustion IPA streams to eliminate the emission of IPA.

Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved.

1. Introduction

Volatile organic compounds (VOCs) are defined as organic com-pounds with high vapor pressure that are easily vaporized underambient temperature and pressure conditions [1]. The WorldHealth Organization (WHO) definition of VOCs includes all organiccompounds or substances that are made up predominantly carbon

∗ Corresponding authors. Fax: +886 6 2758682.E-mail addresses: [email protected] (Y.-J. Tu), [email protected]

(C.-F. You).

and hydrogen with boiling temperatures in the range of 50–260 ◦C,excluding pesticides [2]. Goldstein and Galbally (2009) reportedthat anthropogenic sources emit about 142 tera-grams carbon peryear in the form of VOCs [3]. The huge VOCs emission generatedfrom industrial processes, such as aliphatic, aromatic, isopropylalcohol, benzene and toluene, are considered as severe air pol-lutants because of their high toxicity to ecological system andcarcinogenicity to human health [4,5].

Isopropyl alcohol (IPA), so called 2-propanol (dimethylcarbinol), is commonly used as solvent and reactant in the chem-ical industries. With the toxicity to central nervous system, eyes,nose, throat, and lung [6,7], it is classified nowadays among the

0304-3894/$ – see front matter. Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved.http://dx.doi.org/10.1016/j.jhazmat.2012.05.100


Y.-J. Tu et al. / Journal of Hazardous Materials 229– 230 (2012) 258– 264 259

most hazardous atmospheric pollutants. IPA is also used in dryingbaths for electroplating [8] and in cleaning items in the productionof thin film transistor (TFT)-liquidcrystal display, ion chromatogra-phy, and photonics industries [9]. From these drying and cleaningprocedures, IPA raises concerns of VOCs.

The catalytic combustion, due to its versatile for low concentra-tions organic emission, is one of the most popular techniques totreat the harmful VOCs [9]. The precious metals, such as Pt, Pd, Rh,Au, and V2O5, are always the most critical points for the activationcenter of catalysts and are the most commonly used metals in theenvironmental industry. Nevertheless, the high cost of these pre-cious metals makes the catalysts less economic competition in themarket. An alternative approach for reducing the catalysts cost isto use a common and cheap metal.

Copper ferrite (CuFe2O4), with the spinel structure, has a cubicclose-packed arrangement of the oxygen ions with Cu2+ and Fe3+

ions at two different crystallographic sites [10]. It is a relativelycheap catalyst for replacing those of precious metal catalysts. Ourprevious work showed that hydrothermal synthesized manganeseferrite (MnFe2O4) could convert IPA into CO2 at space velocity of24,000 h−1, oxygen content 21%, 1700 ppm IPA, and at reactiontemperature of 200 ◦C [11]. Although copper ferrite has superiorcatalytic activity [12–14], its effect on the thermal decompositionof IPA has not yet been reported.

Several methods were reported to manufacture copper ferrite,include co-precipitation [15], auto-combustion [16], and sol–gelmethod [17]. If these catalysts can be obtained from industrialsludge, the operation price could be further reduced.

Printed circuit board, denoted by PCB, is one of the most essen-tial components for almost all electronic products. The amount ofwaste sludge generated from PCB industry is rather substantial dueto its high demand in market. Our previous work has successfullyrecycled copper powder from PCB industry by a combination ofacid leaching, chemical exchange, and ferrite process [18]. Underthe optimal conditions, almost 95% copper powder could be recy-cled. Furthermore, the ferrite process conducted can meet not onlythe supernatant but also the sludge to the environmental rules.The sludge generated from the ferrite process hence is regarded asa general industrial waste due to its high stability. If the sludge doesnot have other utility, it can be buried in a landfill.

We attempt to resource this sludge as a catalyst in this studyand apply to the combustion feasibility of VOCs derived from IPA.The ultimate goal is to reach a clean production and sustainabledevelopment, by transforming hazardous waste into valuable by-products and to reduce the amount of waste and treatment costs.

2. Materials and methods

2.1. CuFe2O4 catalyst preparation

The CuFe2O4 catalyst was manufactured from a PCB industryaccording to our previous procedures by combining acid leach,chemical exchange, and ferrite process [18]. Briefly, acid leachingwas conducted using 500 g industrial sludge and 10 L dilute sulfuricacid was added for extracting heavy metals. The controlled factorsinclude the concentration of sulfuric acid (0.5 N, 1 N, 2 N), leachingtemperature (25 ◦C, 40 ◦C, 50 ◦C), and reaction time (10 min, 20 min,40 min, 60 min, 90 min). The optimal acid leaching conditions werefound at 1 N sulfuric acid, temperature 50 ◦C and last for 60 min.

In the chemical exchange, Fe powder was used as the sacrificedmetal to substitute Cu2+ in the liquid. The dosage of Fe pow-der (Fe/Cu molar ratio 1.0, 2.0, 5.0), reaction temperature (25 ◦C,40 ◦C, 50 ◦C), pH value (1.0, 2.0, 3.0) and agitation speed (200 rpm,300 rpm, 400 rpm) were controlling factors in the experiments. Theoptimal conditions in the chemical exchange experiments were

1. pH contr oll er 2. ORP co ntroller 3. Temp. co ntroller

4. Flow rate meter

5. Air inlet

Acid leac hing

rea ctor

Chem ical exchang e

reactor

Ferrite proces s

reactor

7

pH ORP

Temper ature

1

2

3 5

4

6

8

7

8

9 9

9

7

8

6. Air co mpre ssor 7. Agit ati on cont roller

8. Agit ator

9. Sampler

Flow rate meter

Fig. 1. Batch reaction system of acid leaching, chemical exchange and ferrite pro-cess.

summarized as followed: Fe powder dosage Fe/Cu 5.0, pH 2.0, reac-tion temperature 50 ◦C and agitation speed 200 rpm.

At the final stage, ferrite process was performed to ensure thequality of supernatant and sludge for the EPA regulation. Parame-ters include the dosage of FeSO4 (Fe/Cu molar ratio = 10.0), reactiontemperature (80 ◦C), pH value (9.0) and air supply rate (3.0 L/min/Lwastewater) were evaluated. The sludge generated from ferriteprocess was then used as a catalyst for testing its combustion per-formance in VOCs derived from IPA.

Fig. 1 shows the batch reaction system for acid leaching, chemi-cal exchange, and ferrite process applied in this study. It is made ofstainless steel where the diameter and length of the acid leachingtank was 30 cm and 45 cm, respectively. A mixer with a rotationspeed of 200–1200 rpm was installed in the tank. The structureof the chemical exchange tank is the same as the leaching tank.In the ferrite process tank, diameter and length was 23 cm and40 cm, respectively and had installed a temperature controller, anair supplier, and a pH controller.

The manufactured catalyst was collected using a magnetic sepa-ration method by Nd–Fe–B magnet whose shape was in 4 cm length,2 cm wide, and 1 cm thickness. The product was then washed withde-ionized water several times until the pH of the solution reachedaround 7. The solids were then dried at 50 ◦C for 24 h in an ovenand stored for further tests.

2.2. Catalyst characterization

Scanning electron microscopy (JSM-6330, Japan) was used tostudy the morphology and microstructure of the manufactured cat-alyst. X-ray powder diffraction (XRD) was performed to determinethe crystalline structure of CuFe2O4 on Bruker D8-Advance diffrac-tometer with Cu-K� radiation (� = 0.15406 nm). The catalyst wasscanned from 10◦ to 80◦ (2�) with a scanning rate 0.5◦ min−1 anda step size 0.02◦·Superconducting Quantum Interference Device(MPMS-XL7, Quantum Design, USA) was commissioned to revealthe saturation magnetization of the sludge generated from theFP. BET surface area (m2 g−1), pore volume (cm3 g−1), and aver-age pore size (A) were determined by ASAP 2010 surface analyzer(Micromeritics Co., USA).


260 Y.-J. Tu et al. / Journal of Hazardous Materials 229– 230 (2012) 258– 264

Fig. 2. A schematic diagram of the catalytic incineration procedures.

2.3. IPA catalytic combustion system

To understand the IPA combustion performance, various param-eters including the blank test, the IPA inlet concentration, the spacevelocity, and the oxygen content were investigated.

Fig. 2 illustrates the experimental apparatus, which includes anIPA feeding system, a catalytic reaction system, a product samplingand analysis system. The IPA feeding system use herein includedIPA, nitrogen, and air gases, which were delivered to the reactionsystem through individual stainless steel pipes. The gases were fil-tered using a filter (GFIMS 100, SGE) to eliminate moisture andimpurities that may damage to the flow meter. Additionally, themass flow meter was used to control the flow rate precisely. Thegases were uniformly mixed in a chamber before entered the reac-tion system.

A catalytic reaction system was set up to heat a catalytic reactiontube inside a furnace. The reaction tube was made of quartz, witha length of 30 cm and a diameter of 2.54 cm; a quartz spacer wasplaced in the center of the tube to support the catalysts. Before thecatalysts were installed, a layer of glass wool and 5 g glass sand wereintroduced to prevent the catalysts from being removed and clog-ging the pores of the catalytic bed to cause any pressure drop. Thecatalysts were screened to ensure they were uniform in size beforethey were packed. After they had been packed, a layer of glass sandwas placed above the catalysts to ensure that the gases entered thecatalytic bed uniformly, to prevent turbulence on the catalytic bed.A K-type thermocouple was placed above the catalytic bed to mea-sure the temperature inside the tube. Additionally, a temperaturecontroller was installed to control heating in the furnace.

As the mixed gases passed the catalytic reaction system, theyreacted and then were collected in the sampling bags before beinginjected into a gas chromatograph (GC) for IPA concentration anal-yses using a flame ionization detector. A flue gas analyzer (IMR

2000) and GC/thermal conductivity detector (GC-14A TCD system,Shimadzu) were used to monitor oxygen (O2) content and measurethe amount of carbon dioxide (CO2) produced.

3. Results and discussion

3.1. The properties of PCB industrial sludge

The important properties of PCB industrial sludge used here isits abundance in copper. More detailed information on this sludgematerial can be referred to our previous work [18]. Briefly, thesludge contains 60% water and has an average pH of 7.05. Sixheavy metals, including Cu, Pb, Cd, Zn, Ni, and Cr, were less than105 mg kg−1 (dry base) except Cu 158,000 mg kg−1 (dry base). Thismeans about 15.8% Cu in the sludge, indicating its high recyclevalue.

3.2. Manufacturing of CuFe2O4 catalyst

As mentioned in Section 2.1, 500 g of the industrial sludge wasacid leaching with 10 L dilute sulfuric acid to extract copper fromsolids. Fe powder was used as sacrificed metal to substitute Cu2+

in the liquid during chemical exchange. To further ensure thatsupernatant would qualify to fulfill the effluent standards, ferriteprocess was performed after the chemical exchange. A green low-cost catalyst copper ferrite (CuFe2O4) was then manufactured afterthe ferrite process. The corresponding reactions of acid leaching,chemical exchange, and ferrite process are described as Eq. (1)–(3),respectively.

Cu-sludge(s) + H2SO4(aq) → Cu2+(aq) + sludge(s) (1)

Fe0(s) + Cu2+

(aq) → Fe2+(aq) + Cu0

(s) (2)



Fig. 3. Effect of temperature on IPA conversion in blank test. Test conditions: inletconcentration = 2000 ppm, GHSV = 30,000 h−1, O2 = 21%. The relative error of thethree times replicates in all points were below 2%.

Cu2+(aq) + 2Fe2+

(aq) + 6OH−(aq) + 1/2O2(aq) → CuFe2O4(s) + 3H2O

(3)

3.3. IPA catalytic combustion

3.3.1. Blank testTo determine if the thermal decomposition of IPA was signifi-

cant at the selected reaction conditions, a blank test in atmospherewas conducted from 30 ◦C to 500 ◦C. No catalyst was added to thereactor in this experiment. The glass wool, with same volume cata-lyst, was put on the reactive bed to represent catalyst. The effect oftemperature on IPA conversion in the blank test was demonstratedin Fig. 3. It shows that only 12% IPA could be converted at 200 ◦Cwithout catalyst. Even when combustion temperature was raisedto 500 ◦C, only 75% conversion of IPA was completed. This impliesthat the decomposition of IPA is associated with much energy con-sumption when no catalyst used. On the other hand, the lowesttemperature required for IPA combustion was rather different inthe presence or absence of CuFe2O4. If no CuFe2O4, the IPA combus-tion started at about 120 ◦C, which is much higher than in the caseof CuFe2O4 presence. This is consistent with the MnFe2O4 catalyston IPA combustion [11].

3.3.2. Effect of oxygen contentT50, the temperature needed to attain 50% IPA conversion, of

the three investigated oxygen content ranges (10%, 15%, and 21%)was 140, 120, and 110 ◦C, respectively. It shows that the conversionof IPA increases with oxygen content (Fig. 4). On the other hand,the oxygen content influenced strongly the conversion at 150 ◦C.The IPA conversion increases 26% at oxygen content of 21% com-pared with at 10%. Nevertheless, the conversion was independentof oxygen content when the temperature exceeded 180 ◦C. Similarobservations were reported in literatures [11,19]. It is suggestivethat the amount of oxygen demanded in the IPA catalytic com-bustion should be exceeded the theoretical oxygen. Apparently,the contacting opportunities between the IPA and oxygen wereincreasing at high oxygen content and thus promoting conversion[11].

Fig. 4. Effect of temperature on IPA conversion at different oxygen content. Testconditions: inlet concentration = 2000 ppm, GHSV = 30,000 h−1. The relative error ofthe three times replicates in all points were below 2%.

3.3.3. Effect of space velocityGas hourly space velocity (GHSV) is defined as reactant gas flow

rate/reactor volume. The formula can be expressed as Eq. (4).

GHSV (h−1) = Q (m3 h−1)V (m3)

(4)

where Q is the reactant gas flow rate (m3 h−1) and V is the reactorvolume (m3). In other words, GHSV is the inverse of time, indicat-ing a lower GHSV corresponds to a longer retention time. Increasingthe retention time will enhance the extent of reaction. Hence, theconversion rises as the space velocity decreases [20]. The relation-ship between the IPA conversion and the GHSV was demonstratedin Fig. 5. The results indicate that a smaller conversion is associatedwith a larger GHSV at a given temperature. At 150 ◦C, the IPA con-version was 98% under GHSV 8000 h−1. However, it fells to 85% and67% when GHSV increased to 15,000 h−1 and 30,000 h−1, respec-tively. The conversion decreases generally as the GHSV increased,but the GHSV only slightly affected the conversion when tempera-ture exceeded 180 ◦C.

Fig. 5. The relationship between temperature and IPA conversion under differentGHSV conditions. Test conditions: inlet concentration = 2000 ppm, O2 = 21%. The rel-ative error of the three times replicates in all points were below 2%.



Fig. 6. The relationship between temperature and IPA conversion at different inletconcentrations. Test conditions: GHSV = 30,000 h−1, O2 = 21%. The relative error ofthe three times replicates in all points were below 2%.

3.3.4. Effect of IPA inlet concentrationThe catalytic combustion method has become the most popular

technique, mainly because of its economical for organic emissions<5000 ppm [9]. Generally speaking, the concentration of catalyticincineration was in accordance with 1/4 lower explosive limit(LEL) of target pollutant (LEL = 2.02% (V/V) for IPA). The safety IPAcombustion concentration, therefore, must be controlled at below5000 ppm. The VOC inlet concentration will theoretically affect theconversion efficiency. Thus three IPA inlet concentrations (500,1000, and 2000 ppm) were selected to understand their combustionconversions. The relationships between temperature and IPA con-version at different inlet concentrations under GHSV = 30,000 h−1

and oxygen content = 21% were shown in Fig. 6. The IPA conver-sion increases apparently with decreasing inlet concentrations. Itseems that the differences of T50 at three IPA inlet concentrations(500, 1000, and 2000 ppm) were rather small at 105, 110, and 115 ◦C(Fig. 6). In addition, the IPA conversion could achieve 100, 97, and89% at the IPA concentrations of 500, 1000, and 2000 ppm at 170 ◦C.However, the concentrations became irrelevant when the temper-ature reached at 180 ◦C, the conversions were all near 100%.

3.3.5. Catalytic combustion productionSelection of the catalytic material for various organic pollutants

decomposition has been the subject of many literature studies. Thereactants and catalysts typically control the products of catalyticreaction. It is known that primary alcohol can be oxidized to alde-hyde and secondary alcohol can be oxidized to acetone [21]. Eqs. (5)and (6) specify the oxidation of IPA (secondary alcohol) to acetoneand the complete oxidation of IPA to CO2, respectively.

C3H7OH + 1/2O2 → CH3COCH3 + H2O (5)

C3H7OH + 9/2O2 → 3CO2 + 4H2O (6)

The catalytic combustion products associated with the investigatedtemperatures show in Fig. 7. Detailed results of IPA conversions aresummarized in the Supplementary Information (Table S1). Theseresults indicate that CO2 was the final product when IPA reactedwith CuFe2O4 catalyst at temperature over 190 ◦C. It is evident thatthe percentage of IPA conversion is proportional to the productionof CO2. IPA was reacted to form intermediate acetone and CO2 atthe temperature range of 110–170 ◦C, where the amount of acetonedecreased when temperature increased. IPA was 100% converted

Fig. 7. Catalytic combustion productions associated with various investigatedtemperatures. Test conditions: inlet concentration = 2000 ppm, GHSV = 30000 h−1,O2 = 21%. The relative error of the three times replicates in all points were below 2%.

into CO2 when the temperature increased to 190 ◦C. Comparedwith results in our previous study [11], this green manufacturedcatalyst CuFe2O4 shows better performance than the synthesizedMnFe2O4 on IPA combustion, supporting the potential applicationof CuFe2O4. In addition, Lou and Chang (2006) reported that onlyfew metals, such as Cu and Mn, could not adsorb CO2, showing thatCu and Mn is favorable for the CO2 desorption from the surface ofcatalyst [22]. Thus CuFe2O4 and MnFe2O4 have better performancesin converting CO to CO2. The final product in this study is also CO2,indicating that desorption of CO2 plays an important role in IPAcombustion process, and further indicates the CuFe2O4 generatedfrom PCB industry performs well in IPA combustion.

3.4. Characterization of the catalyst CuFe2O4

The BET properties of surface area, pore volume, and aver-age pore size of the fresh and used catalyst were summarized inTable 1. They showed no much difference and reflect stable thermalproperty of the CuFe2O4. Its crystalline appearance indicates thatpowder of catalyst aggregated by numerous of fine particles (Fig. 8).The SEM photo shows primary particle sizes ranged from tens to110 nm. The average pore diameter (18.57 A) measured was causedby intervals of numerous random stacked particles. The measuredsurface area (69.06 m2 g−1) and the pore volume (0.11 cm3 g−1) arefar lower than normal porous materials, demonstrating the surfacearea of this catalyst is attributed to the outside surface.

The XRD spectra of freshly made and used (thermally reacted)catalysts were demonstrated in Fig. 9. The XRD pattern of the freshlymade catalyst presents the diffraction peaks at d-spacings of 4.790,2.960, 2.517, 2.100, 1.613, 1.479, 1.272, 1.087, and 0.964 A, whichmatched well with the CuFe2O4 (JCPDS file number 00-025-0283).These results indicate the XRD pattern of the used catalyst did

Table 1BET properties of the fresh and used catalyst.

Catalyst Specific surfacearea (m2 g−1)

Pore volume(cm3 g−1)

Average poresize (A)

Fresh CuFe2O4 69.06 0.11 18.57Used CuFe2O4

a 68. 83 0.10 18.84

Conditions of each cycle: temperature = 200 ◦C; inlet concentration = 2000 ppm;reacted time = 24 h.

a The used CuFe2O4 refers to the catalyst after 5th reused cycles.



Fig. 8. SEM photo of the catalyst.

Fig. 9. The XRD spectra of the freshly made and used catalysts CuFe2O4. (Fresh cat-alyst means the catalyst just manufactured after acid leaching, chemical exchange,and ferrite process. Used catalyst means after 24 h reaction under the conditionsof inlet concentration = 2000 ppm, GHSV = 30,000 h−1, O2 = 21%. The relative error ofthe three times replicates in all points were below 2%.).

not change to other crystalline phases, supporting that our man-ufactured CuFe2O4 was stable after 24 h thermal reaction at inletconcentration = 2000 ppm, GHSV = 30,000 h−1 and O2 = 21%.

3.5. Reusability of CuFe2O4

Five combustion cycles were conducted to estimate thereusability of the CuFe2O4 catalyst for the IPA combustion. In eachcycle, the combustion temperature was started at room temper-ature to check the catalyst tolerance of temperature variation andthe same catalyst was reused without any treatment in subsequentcycle. The results reveal that IPA combustion efficiency could attainto 99% in all five cycles. There was almost no activity loss of CuFe2O4after the first cycle, then achieved a more stable state in the sub-sequent cycles. These results confirm that our green manufacturedcatalyst CuFe2O4 has a good tolerance to temperature variation andhas high potential to be reused for many cycles.

The 96-h catalyst decay experiment was conducted to under-stand the thermal stability and durability of the CuFe2O4thoroughly. The results of IPA conversions in the 96-h decay tests at150, 175, and 200 ◦C are compared (Fig. 10). These results show thatIPA conversion reduced slightly at the beginning of 24-h period. Theactivity of CuFe2O4 was stabilized 24 h later and reached a constantequilibrium rate at each given temperatures during the 96-h decayexperiment.

Fig. 10. The comparison of IPA conversion with time at different tempera-ture during the 96 h-decay test. Test conditions: inlet concentration = 2000 ppm,GHSV = 30,000 h−1, O2 = 21%. The relative error of the three times replicates in allpoints were below 2%.

Furthermore, the saturation magnetization of the catalyst wasdetermined to be 62.52 emu g−1 (Fig. S1). No remanence wasdetected in the sample, confirming that this magnetic catalyst wassuperparamagnetic. This magnetic catalyst can be collected usinga magnet in the experiments. When the external magnetic fieldwas removed, the materials could be well re-dispersed again. Thismagnetic property has great potential for applying the catalyst tocatalytic combustion in fluidized bed system, solving the recoveryproblems of relatively fine catalysts.

4. Conclusion

A green manufactured catalyst CuFe2O4 was successfully devel-oped from industrial wastes sludge. The catalytic combustionfeasibility of VOC derived from IPA on this catalyst has been inves-tigated in detail. The results reveal that the combustion of IPA usingcatalyst CuFe2O4 could be ignited at a rather low temperature. Onehundred percent conversion was achieved under the conditionsof GHSV 30,000 h−1, oxygen content 21%, IPA inlet concentration2000 ppm, and reaction temperature 180 ◦C. The reaction temper-ature is the most important factor during the catalytic combustionprocess. In this study, IPA could be completely converted into CO2and H2O at temperature >180 ◦C whatever the conditions of GHSVor inlet concentration. More importantly, the catalyst has a goodthermal stability and durability during 96-h decay test. The mag-netism of this catalyst has great potential for studying catalyticcombustion in fluidized bed system and solving the recovery prob-lems of relatively fine catalysts particles.

Appendix A. Supplementary data

Supplementary data associated with this article can befound, in the online version, at http://dx.doi.org/10.1016/j.jhazmat.2012.05.100.

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