La2O2CO3 supported Ni-Fe catalysts for hydrogen production from steam reforming of ethanol

Availableonlineatwww.sciencedirect.comScience DirectRARE EARTHSELSEVIERJOURNAL OF RARE EARTHS, VoL 29, No 9, Sep 2011, P. 861www.re-journal.com/en/La2O2CO3 supported Ni-Fe catalysts for hydrogen production fromsteam reforming of ethanolSHI Qiujie(石秋杰), PENG Ziqing(彭子青, CHEN Weiqing(谌伟庆), ZHANG Ning(张宁)ansninute of Applied Chemistry, Nanchang University, Nanchang 33003 China)Received 23 March 2011; revised 10 May 2011Abstract: La O-CO, was prepared by calcination of La2(CO,)3 in the air Catalysts Ni-Fe/La202CO, with different mole ratios of Ni to Fe,Ni/La202CO, and Fe/La2O2CO3 were prepared by impregnation method. The catalytic properties were evaluated on steam reforming of etha-nol (SRE)from 300 to 700C under atmospheric pressure and the samples were characterized by Brunauer-Emmett-Teller method(BET),X-ray diffraction(XRD)and temperature programmed reduction(TPR). The results showed that Ni-Fe bimetallic catalysts exhibited higheractivities than single metallic catalysts, which was attributed to the co-existence of well dispersed Ni, Fe and LaFe,Ni Oj. It was found thatthe catalyst Ni-Fe/La2O2CO3 containing 10 wt%Ni and 3 wt %-5 wt Fe showed the best performance, the conversion of ethanol was100%, the selectivity of H2 was higher than 90%, and the selectivity of Co was lower than 1. 5% at 400C.Keywords: hydrogen production; steam reforming of ethanol; Ni-Fe; La2O2CO3, rare earthsEnergy crisis and environmental problems are two diffi- lysts. The second challenge is the carbon deposition. Forcult problems in current world. Hydrogen energy attracts SRE, the carbon deposition can take place via the hydro-much attention because it is a clean abundantly available genation of Co and CO2 at low temperature and via decom-and high energy content source. Hydrogen can be produced position of methane, ethane, and ethylene and Boudouardfrom different methods and resources, such as coal, natural reaction at high temperature 8. In addition, nickel is alsogas, gasoline, methane, etc. Among the sources, ethanol is a tive for methanation", leading to relatively high methanegood candidate for several reasons easily stored, safely selectivity and low hydrogen productionhandled, non-toxic, renewable and easily decomposed in the Iron is well-known for its abundance and magnetism; if it ispresence of water to generate hydrogen-rich mixture. As successfully employed as one of active components, the ob-aqueous ethanol can be used for steam reforming without tained catalysts naturally combine the advantages of low costextensive elimination of water, steam reforming of ethanol and an easy recovery function derived from use of an extermal(SRE)for hydrogen production is attracting more and more magnetic field, especially, it will create a positive effect on theattention, especially bioethanol from saccharification or fer- water gas shift reaction. From the AlO3 supported metal(Rh,mentation of biomass, which includes plant cultivation and Pt, Ni, Cu, Zn, Fe)catalyst in SRE studied by Fabien 2, it wase SRE over Ni, Co, Cu, and noble metals(Pd, Pt, Rh, and followed as: Rh10%Ni/La202 CO3>10%Fe/La2O2CO3>10%Ni-5%Fe/La2O2CO3The catalytic experiments were performed in a fixed bednicro-U-type stainless-steel flow reactor with an inner di- 2.2 XRD resultsameter of 4 mm. the dead volume of reactor was filled withXRD pattens of NL, NFLl, NFL3, NFL5 and NFL7 arequartz beads. The reactor was encased in a furnace, which presented in Fig. 1. It can be seen that the diffraction peakswas controlled by a programmable temperature controller of all the samples are mainly corresponding to hexagonalwith temperature measured by means of K-type thermocou- La, 0, CO, (JCPDS-ICDD 37-804, 20-25. 9, 30.20, 44.2ple placed in the furnace. Prior to reaction, 0. I g of fresh which indicates that the precursor La(CO,), was trans-powder catalyst was placed in the reactor and reduced in situ formed into La,02 CO,. No peaks corresponding to the metalat 550C for 3 h under a hydrogen flow of 30 ml/min, then Ni and Fe or their oxides can be detected in XRD pattens ofcooled down to the reaction temperature. The ethanol and the catalysts except NFL7, in which a little phase of NiOwater mixture with CHSOH: H 0=1: 4(v/)was introduced tothe reactor by using HPLC Pump(Lab Alliance Inc )at a Table I Specin中国煤化工rate of 0.05 ml/min and vaporized at 150C. The inlet gas Samples LaodCNMHG10%/Ni-S%FeLa coand outlet gas passed through a stainless steel tube which Ser(m/g)4.838SHI Qiujie et al, Lator, supported Ni-Fe catalysts for hydrogen production from steam reforming of ethanol(2036.5, 43.0, 62.3%)can be found. It is known that both was more difficult to be reduced than that in single metallicFeand Ni"can serve as B site ions to form ABO,(A is La catalysts(NL and FL), which maybe result in a long termin this paper) series perovskite oxides, the B site ions could stability of the bimetallic catalysts. The peak center at aboutbe theoretically either Fe, Ni"or both of them. The XRD 507C in FL can be assigned to the partial reduction of Fe'pattens indicated that the characteristic peak of LaNi Fe1-0, to Fe*l6 there is one peak in NL except the reductionstructure appeared between 32.00 and 33.5. Different B site peak of support, centering at 370C, which can be attributedion may result in some shifts of the corresponding diffraction to the reduction of Ni"*to Ni*in LaNio, or to the reduc-peaks),which was attributed to the difference of the ion tion of bulk-like Nio phase. It can be found that single broadradius between Fe and Ni. Considered that and compeak appeared in the bimetallic catalysts below 600C,dicating the overlapping of Ni species and Fe species, whiclintensive peak on range between 20-33 and 350 in Fig. 1 was possibly attributed to the reduction of Ni-Fe alloy orcan be assigned to the perovskite structure. With the increase perovskite LaFe Ni -,(17, 18. Combined with the results ofof Ni content in the LaFe Ni] -O,, the shift of the peakXRD, it is reasonable that LaFe Ni -O3 was formed in thecome more significant and the diffraction peak also become Ni-Fe bimetallic catalysts supported on La202CO3. Andstronger. All above showed that LaFe, Ni -o, was formed main peak shifted to higher temperature(from 350 to 600and a strong chemical interaction between Ni and Fe existed with the increase of Fe content. Therefore, strong chemicalin bimetallic catalystsinteraction between metal and support existed in the Ni-Febimetallic catalysts2.3 TPR resultsThe TPR Profiles of the samples are exhibited in Fig. 2.A 2.4 Catalytic properties for SREpeak at high temperature(about 720C)existed in all theFig. 3 shows the ethanol conversion versus temperatureprofiles, which could be attributed to the reduction of La in the variation on NFlI and nfl5 are about the same ItLa2O2CO3. Compared with NL and FL, it was obviously well known that SRe reaction is endothermic, so the ethanolseen that the peak of La in bimetallic catalysts(NFL1, conversion increases with temperature. It is easy to find thatNFL3, NFL5 and NFL7) shifted towards higher temperature. the single metallic catalyst NL performs better than FL fromIt is shown that the La202CO, in Ni-Fe bimetallic catalysts 300 to 500C. Similar results have been reported by Aupre-()NFL7tre et al. Nir-Al2O3 was superior to Fery-Al2O3 for SRE(2)NFLSThe ethanol conversions on nFl3. NFL5 and NFl were()NFL3(4)NFLlmore than 90% at 300C and 100% at 400 oC. while the(5)NLethanol conversion on NL, fL were only 63%, 58% at 300"C and 90%, 70% at 400 C, respectively. The resultsshowed that bimetallic catalysts performed better activitiesthan single metallic ones(NL and FL)at low temperature.WnA-4huMhAlthough the surface area of NFL5 was much smaller thanNL and FL, the ethanol conversion on nfl5 is better. frorthat we can infer that the catalytic activity may have no olvious association with its physical property, it may due to the12202836445260687684strong interaction between Ni, Fe and La, which causes the26/()C-C rupture ability on bimetallic catalysts much strongerFig. 1 XRD patterms of the samples(all samples were reduced atthan Nl or fl550°cfor3b)Fig. 4 shows that the selectivity of H2 over the catalysts()NFLI (5)NL(2)NFL5(6)L(3)NFL7(NFL3370NFLINFL3NFL(4)中国煤化工CNMHGTemperature/℃Fig. 3 Variations of ethanol conversion with reaction temperatureFig. 2 TPR profiles of NFLl, NFL3, NFL5, NFL7, FL and NLover different catalysts864JOURNAL OF RARE EARTHS, VoL 29, No 9, Sep 20119588NFL-P NFL合-NFL7一FL300Temperature/℃Temperature/℃NFLFL4.035东NFL3B- NFLs一☆-NFL7500e/℃Fig. 4 Variations of selectivity toward H2, CO, O2 and CH with reaction temperatureNFLl, NFL3, NFL5 and NFL were higher than FL, NLover the whole studied temperature. Obviously, nLF5 is the2.5 Stability and resistance to carbon deposition ofbest,94.8%at 500C Earlier study)has discovered that thecatalystsstrong interaction between metals can improve the activity Fig. 5 shows that the ethanol conversion keeps 100%and selectivity of catalysts. Therefore, the same mechanism without any depression for 350 h. The selectivity of Hof action between Ni and Fe maybe exist in Ni-Fe/La CO3, CH4, Co and co2 almost keep at about 90%, 5%, 2.5%,which is in accordance with the tpr results. furthermore, it 2%, respectively. We have researchedNILa2O2CO3 athas been reported2 that Fe played a main role in water gas the same condition for 20 h and found that it was also sta-shift reaction(WGSR). So Fe could improve the selectivity ble Ni-Fe/La2O2CO3 exhibited high activity and selectivityof H2 and decrease the selectivity of Cotoward hydrogen and, more importantly, long term stabilityIt can be seen that the selectivity of CO over bimetallic for SREcatalysts are similar from 400 to 600C, bur it increases ob-viously over FL catalyst at 700C. The selectivity of COover Fe catalyst is the minimum at 300C, and the additionof 3%Fe into Ni catalyst can reduce the selectivity of CO.Atlow temperature 300C, the dehydrogenation of ethanoL,decomposition reaction of acetaldehyde and ethanol and|FM4~Nr时SRE occurred: CH3CH2OH-C2H4O-+H2, CH,*CH4+CO, CH_CH2OH-+CO+CH4+H2, C2H5OH+H20-2C0-+4H2,C2H5OH+3H0-+2C02+6H]. At 400 C, the selectivity ofCO reduced over all catalysts, which is possibly due to thereaction of SRE, WGSR and inverse methanation reaction,60which makes the selectivity of CO2 increase but the selectiv-50100150200250300350ity of CO and CH, decrease Ni catalyst was beneficial to themethanation response, so the selectivity of CO and COz over Fig. 5 Effect"V凵中国煤化工 n of ethanol and theit reduced, but the methane selectivity elevated from 300 toCNMH Geding rate was 0.05400℃.and une reacuon temperature was kept at 500C)SHI Qiujie ef aL, Lay0 CO, supported Ni-Fe catalysts for hydrogen production from steam reforming of ethanol8650.I0[6]Ni M, Leung D, Leung M. Hydrogen production in solid elec-100}…9965%trolyte membrane reactors(SEMRs). International Journal of0.089829%Hya007,32(1):[7 Frusteri F, Freni S. Bio-ethanol, a suitable fuel to producehydrogen for a molten carbonate fuel cell. Journal of Power0.04[8]Laosiripojana N, Assabumrungrat S. Catalytic002of ethanol over high surface area CeO The role of Ceo2 as an94intemal pre-reforming catalyst. Applied Catalysis BEn[9]Kim SH, Nam Sw, Lim T H, Lee H L Effect of pretreatmenton the activity of Ni catalyst for CO removal reaction byFig 6 TG curves of NFL5 used for 350 hEnvironmental,2008,81(1-2):97[10] Czekaj L, Lovat F, Raimondi F, Wambach J Biollaz S, WokaunThe TG curves of NFLS used for 350 h(Fig. 6) exhibitedA, Characterization of surfacetwo stages of mass loss. The first below 150C was the losscatalyst during the methanation of biomass-derived synthesisof moisture and the second from 150 to 526C was the lossgas: X-ray photoelectron spectroscopy (XPS). Appliedof coke formed during ESR reaction(around 1.36%)20).TheCatalysis A: General, 2007, 329(1): 68.high stability of this catalyst may be due to the scavenging of[11] Habazaki H, Yamasaki M, Kawashima A, Hashimoto K.Methanation of carbon dioxide on Ni/(Zr-Sm)O, catalystscoke deposition on the Ni surface by lanthanum oxocarbon-Applied Organometallic Chemistry, 2000, 14(12): 803ate species existing in the catalyst under reaction condi-[12] Aupretre F, Descorme C, Duprez D. Bio-ethanol catalyticsteam reforming over supported metal catalysts. Catalysisommunications, 2002, 3(6): 263.3 Conclusions[13]Provendier H, Petit C, Schmitt J L, Kiennemann A, ChaumontC. Characterisation of the solid solution La(Ni, Fe)O, preparedIn this work, La2O2CO3 supported Ni-Fe bimetallic catavia a sol-gel related method using propionic acid. 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