Development of Ni-Based Catalysts for Steam Reforming of Tar Derived from Biomass Pyrolysis

催化学报2012Chinese Journal of CatalysisVoL. 33 No.4Article ID: 0253-9837(2012)04 0583-12DOL: 10.1016/S1872 206711)60359-8Reriew:583 -594Development of Ni-Based Catalysts for Steam Reforming of TarDerived from Biomass PyrolysisDalin LI2, Yoshinao NAKAGAWA', Keiichi TOMISHIGE''Department of Applied Chemistry, School of Engineering, Tohoku Universit, Sendai 980-8579, JapanNational Engineering Research Center of Chemical Fertilzer Catalyst, Fuzhou Universiny, Fuzhou 30002, Fujian, ChinaAbstract: Nickel catalysts are efctive for the steam reforming of tar derived from biomass pyrolysis, but the improverment is needed interms of actity, stability, suppression of coke deposition and aggregation, and regencration. Our recent development of Ni-based catalystsfor the steam reformning of tar is revicwed including the modification with CeO2 (or MnO), trace Pt, and MgO. The role of additives such asCeO2, MnO, Pt, and MgO is also discussed.Key words: steam reforming; tar, biomass; nickel; ceria; manganese oxide; platinum; magnesiaCLC number: 0643Document code: AReceived 30 October 2011. Accepted 14 December 2011.*Corresponding anuthor Tel: +81-22-795-7214; Fax: +81-22-795-7214; E-mai!: tomi@erec.che toholku.acjpThis work was supported by Japan Science and Technology Agency (JST, Ministry of Education, Culture, Sports, Science and Technology,Japan.English edition available online at Elsevier ScienceDirect (tpt:/ww.cecdirec.comscience/jourmal18722067).Conversion of biomass to synthesis gas and bydrogen isgas and hydrogen. If the catalysts can be activated auto-one of the important technologies for the energy utilizationmatically by the introduction of the biomass tar at the reac-of biomass by the power generation and the production oftion temperature, this self- activation property can contributeliquid fuels by Fischer-Tropsch synthesis and chemicals byto the easier operation of the process. On the other hand, themethanol synthesis [1- 4]. The gasification of biomass tocoke deposited on the catalysts can be reduced to some ex-synthesis gas and hydrogen has been conventionally carriedent, but the complete suppression is difficult. The cokeout in a non-catalytic system at very high temperature (>removal such as by the combustion is necessary. However,1073 K) in order to decrease the concentration of the resid-the procedure for the coke removal can cause the catalystual tar [4]. In the non-calytic gasification, air is usuallydeactivation by the sintering of a support material and theused as a gasifying ageat. Therefore, the product gas is di-aggregation of metal particles. If the catalysts are recyclableluted with nitrogen and this makes the product gas unsuit-by the re- dispersion of the aggregated particles, the catalystable to the chemical conversion. Another gasificationcost can be decreased. The self-activation and self-regen-method is the catalytic steam reforming of tar derived fromeration properties as well as high steam reforming activitythe pyrolysis of biomass at much lower temperature than theand the suppression of coke formation can contribute to thecase of non-catalytic gasification with air. It has beendevelopment of more feasible process. Applicability of theknown that rapid pyrolysis at low temperature such as 773commercial and conventional steam reforming catalysts hasK gives high yield of the mixture of volatile organic com-been evaluated [5-10]. However, in fact, the performance ofpounds, which is called as tar or bio-oil. When steam re-the conventional catalysts is not satisfactory, and the devel-forming reaction of the tar can proceed at low temperatureopment of the catalysts for the steam reforming of tar de-comparable to the case of the pyrolysis, the combination ofrived from the biomass pyrolysis is highly needed.the rapid pyrolysis and catalytic steam reforming will en-Table 1 lists the examples of recent reports on Ni cata-able the low-temperature gasification of biomass to synthe-lysts for the tar conversion in the gasification of real bio-sis gas and hydrogen.mass. A nano-NiO/y-AI2O3 catalyst was reported by Li et al.In the steam reforming of tar, catalysts with high per-[11] to show中国煤化Tar and bhydrocar-formance in terms of the activity and stability are needed.bons. AnotheFyst was also de-Moreover, it is considered that high abilities in the catalystveloped by LYHCN M H Ghecalyst, theactivation and the catalyst regeneration are important prop-tar remove efficiency reached 99% at 1073 K, and the cokeerties in the process for the biomass conversion to synthesisdeposition and sintering effects were avoided, leading to a催化学报Chin. J. Catal, 2012, 33: 583- -594Table 1 Recent reports on Ni catalysts for biomass gasificationNi contentCatalystReactorBiomassRef.(w%)amount (8)___ (diameter x height, mm)Rice huskNiO/y-Al2O3121000fixed-bed (88 x 1200)1]SawdustNiO/q-Al2O,Ni-La-Fe/y-AIl.O38.6[12]Pine sawdustNiO-MgO19.52fuidized-bed (20x 800) [13]Ni/MgO192(fluidized-bed (20 x 800)I3]Niog.oMg.sr0O420fuidized-bed (20 x 800)Red pineNi/Al2O34:fixed-bed (53.5 x 610)[14]Ni/AlLO310[15]Nicoal char9[14,15]Ni/wood chars -2018fixed-bed (25 x 610)[16]5- -20Eucalyptus twig sawdustNiO/dolomite0.4 4.3fixed-bed (22 x 700)[17]CedarNi/oxide (oxide: Al;O, ZrO2, TiO2, CeO2, MgO)fixed-bed(10 x 290)Ni/CeO2/Al2O34,12fixed-bed (10 x 290)[27,28]edarM-N/CeO/Al2O3 M= Pr, Pd, Rh, R)4, 12[29,30]PVNi/CeO/Mg0/Al2O3[31]NiMnO/Al2O332]long lifetime of catalysts. Wang et al. [13] reported acally active site, and the amount of the interface hbas aNiO-MgO catalyst exhibiting high stable activity for themaximum with respect to the additive amount of the modi-reforming of raw fuel gas from gasifier. The highly stablefer, such as Rh-MMgO (M = Co, Ni, Fe) catalysts for theactivity was attibuted to the high dispersion of Ni particlescatalytic partial oxidation of methane [35 -37], Rh-MOx (Min the NiO-MgO solid solution structure and the promotion= Mo，Re) catalysts for the hydrogenolysis of bio-by catalyst reducibility. Recently, Le et al. [14] developed amass-derived polyols and cyclic ethers [38 42], Pt-ReOxNi-loaded brown coal char for the steam reforming of tar.catalysts for the preferential CO oxidation in a HrichCompared to conventional Ni/Al2O3, Ni-loaded brown coalstream [43,44], and so on. It has been known that Ni is onechar has a higher activity and stability with coke resistanceof the suitable components for the steam reforming of vari-[15]. It was also reported by Wang et al. [16] that coal charous organic compounds, and the effects of supports ancsupported Ni and wool char supported Ni catalysts are ef-additive oxides and other metals have been investigated.fective for tar removal, converting more than 97% of tars inOur group has reported that the addition of CeO2 [27,28]synthesis gas at 1073 K. Conujo et al. [17] reported that theand MnO [32] to Ni catalysts enhanced the catalytic per-use of NiO-loaded calcined dolomite catalysts led to a re-formance in terms of the activity and the suppression ofduction in the formation rate of tar and char and a 30% in-coke formation in the steam reforming of the biomass tar. Increase in the total product gas. As listed in Table 1, theparticular, the suppression of coke formation is related toamount of catalysts was rather large in most cases. Thisthe catalyst stability. We also atempted to attach thelarge amount of catalysts needed for the activity tests makesself-activation and self-regeneration properties to Ni/CeO/it difficult to optimize the catalyst composition, the prepara-Al2O3 catalysts by modification with a small amount of Pttion method, pre-treatment conditions, and so on. In fact, theand MgO [29 -31].number of the testedatalysts in most cases is so limited.This review article shows the development process ofOn the other hand, in our case, the reactor size is ratherNi/Al2O3 modified with CeO2, Pt, and MgO in order tosmall, and only 1 g catalyst is needed, then various catalystsmake the multi-functional catalyst for the steam reformingcan be easily tested and this enables the development of theof tar derived from the wood pyrolysis.catalysts tuned for the catalytic gasification of biomass[18- 25] and the steam reforming of the biomass tar [26- -34].1 Steam reforming of tar over Ni catalystsOn the other hand, addition of secondary metal or metalsupported on different oxides [26]oxide is a promising approach for tuning or design newcatalysts. In this approach, the optimum amount of the addi-Ni catalyst中国煤化工s, i.e, N/AlLO,tives is usually present. For example, in the case of metalNi/ZrOz, Ni/:YHC N M H Gwere prepared bycatalysts modified with oxides and secondary metals, thethe incipient wetness method using an aqueous solution ofinterface between metal and the modifier can be a catalyti-Ni(NOj):6H2O. The method for the preparation of the sup-.www.chxb.cnDalin LI et al: Development ofNi-Based Catalysts for Steam Reforming of Tar from Biomass Pyrolysis585port materials were described in our previous report [26].biomass feedstock for all experiments. Steam reforming ofThe calcination conditions for the preparation of the sup-tar was carried out in a laboratory-scale continuous feedingports are listed in Table 2. It should be noted that all thedual-bed reactor [26]. In this system, tar is formed by thealumina supports in this review were a-Al2O3. After im-rapid pyrolysis of cedar wood in the presence of steam, andpregnation, the sample was dried at 383 K for 12 h followedit is introduced to the secondary catalyst bed together withby calcination at 773 K for 3 h under air atmosphere. Thesteam. Before catalytic reaction, the catalyst wasloading amount of Ni is described in parentheses as masspre-reduced in H2 at 773 K for 0.5 h.percent on all the catalysts. Cedar wood was used as theThble2 Properties ofNi catalysts supported on dfferent oxides [26]Calcination conditionsBET surface area H2 adsorption'’Reduction degree Dispersion'. Particle size of Ni metal (nm)CatalystTemperature (K)_ Time (h)(m'/ga)(10* mo/gu)from TPR° (%)(%)H2 adsorption° XRD'Ni(12VAI2Os142382:1062.73631Ni(12)/ZrO210739.029Ni(12)/TiO2972.83421Ni(12)VCeO21.75658Ni(12)MgO2.56.d.°MgO support was used without precalcination.H2 adsorption is total adsorption at room temperature, and HNi = 1 is asumed.°Calculated by (Hz consumption in TPR profiles)(loading amount of Ni) x 100%, assumning that Nf2*+H2-→Ni° + 2H.Dispersion calculatedby 2x (H2 adsopion)(loadiog amount of Ni(reduction degree) x 100% [45,46].Particle size ofNi metal calculated by the relation: (particle size/nm) = 9.71/dispersion/%) x 10 [45,46].Particle size ofNi metal calculated fom the Scherrer equation, using the full width at half height of the strong intensity metal peak.Table 3 summarizes the results of various supported Niproducts, especially H2, increased drastically compared tocatalysts in steam reforming of tar at 823 K together withthe case of no catalyst. This result indicates that Ni catalyststhat in the absence of catalyst. Without catalyst, the tar yieldare effective for the conversion of tar to useful gases such aswas rather high and the formation rates of CO and H2 wereCo and hydrogen. It should be noted that the catalytic per-quite low. On the other hand, when Ni catalysts were used,formance was strongly dependent on support materials.the yield of tar decreased and the formation rate of gaseousTable3 Catalyst performance in steam refrning of tar derived from the pyrolysis of cedar wood over varous oxide supported Ni catalysts at 823K [26]Formation rate (umol/min)H2/COC-conversionChar (%)Coke (%)Tar (%)CHC2O2ratio(%Ni(12)/Al2O3706938157484201.591912.7Ni(12)/ZrOr6151222172.0!26.612.42450141115.112.9Ni(12)CeO265811249204.325.769417510.1610.4No catalyst0369_1389_0.031.0Reaction conditions: biomass 60 mg/min (H2O, 9.2%; C, 2320 pumol/min; H, 3220 umol/min; O, 1430 pumol/min), H20/C = 0.5, catalyst 1.0g, H2reduction at 773 K for 30 min.Figure 1(a) compares the yields of the residual tar andNiMgO > Ni/ZrO2 > Ni/CeO2, which cannot be explainedcoke in steam reforming of tar at 823 K over various Niby the amount of H2 adsorption, and this suggests that thecatalysts. In terms of the residual tar yield, the order of thefunction of the support oxide is very important. The tar andactivity at 823 K was as follows: Ni/Al2O3 > Ni/ZrO2 >coke yields on various Ni catalysts are plotted in Fig. 1(d).Ni/TiO2 > Ni/CeO2 > NiMgO > no catalyst. The amount ofThe coke dep卡formed by the中国煤化工oH2 adsorption listed in Table 2 explains the order of thedecompositionation ofCO as asteam reforming activity. Low activity of NiMgO is alsoproduct of steYHC N M H G yield increasesaffected by low reduction degree of Ni species. On the otherwith decreasing the tar yield, it is thought that the coke ishand, the coke yield was in the order: Ni/TiO2 > Ni/Al2O3 >mainly formed by the decomposition of tar. However, in.586催化学报Chin. J. Catal, 2012, 33: 583 -59420(a)、 Ni(l2)TiO, .15Ni(12)AILO,●Ni(12VA12O,Ni(I2YMgOi 10Ni(12)ZrO,Ni(2)CeO25-Ni(2)TiO,no catalyst1030Ni(12yCeO,Tar yield (%~C)Ni(12)MgO金(b)2734736738732500Ni(12VALO,Temperaure (K)Ni(12)TiO,Fig. 2. TPR profiles of various Ni catalysts [26]. Conditions: bheating号2000Ni(12)CeO2rate, 10 K/min; room temperature to 973 K, and the temperature wasmaintained at 973 K for 30 min; 5% H2/Ar, flow rate 30 ml/min.Ni(l2yMgO1500was also observed in the case of Rh-CeO2 catalysts [50].To investigate the catalyst ability for coke removal, we1000405(measured the reactivity of coke with catalysts using activeYield of tar + coke (%-C)carbon as a model compound of coke by means of thermo-gravimetric analysis (TGA). Figure 3 shows the TGA pro-files of active carbon + catalyst in 5% steam/N2. Comparedvarious Ni catalysts (a) and the relation between the yields of tar +to no catalyst, the presence of catalysts promoted steamcoke and formation rate of CO + H2 + 4CH4 over various Ni catalysts(6) [26]. Reaction conditions: biomass 60 mg/min (H2O, 9.2%; C,gasification of active carbon. In particular, Ni/CeO2 was2320 pumo/min; H, 3220 umo/min; O, 1430 pumo/min), steam 1110more effective than the other catalysts. The promotion ofumo/min, H2O/C = 0.5, 823 K, 15 min, catalyst 1.0 g, H2 reduction atreaction between steam and active carbon can cause low773 K for 30 min.coke yield in steam reforming of tar over Ni/CeO2. Thisproperty is due to high redox property of Ce species, andfact, the relation between tar and coke yields was complex,reduction and oxidation of Ce species proceed in the pres-suggesting that the coke is also formed by the co dispro-ence of steam and tar [50].portionation. In contrast, the relation between the formationrate ofCO+ H2 + 4CH4 and the yield of tar + coke (Fig.1(b)) is clear, and low yield of tar + coke is connected tohigher formation rate of the combustible gases. It is con-98cluded that the catalyst with high steam reforming activity. Ni(12)MgOand the suppression of coke formation is directly connected6f Ni(12)CeO2to the efficient production of synthesis gas.Figure 2 shows the TPR profiles of various Ni catalysts.号94Ni(2)TiO2The reduction degree estimated from the results of H2 con-Ni(12)/A12O3sumption in TPR profiles is listed in Table 2. Except for92NiMgO, the reduction degree of Ni was almost 100% andNi(12)ZrO2this indicates that all the Ni was reduced at about 800 K. Onthe other hand, the reduction degree of NiMg0 was only700800900 .1100about 20%. This can be because the strong interaction be-中国煤化工tween NiO and MgO decreases catalyst reducibilityFig.3. TGA pn: catalysts under air[47-49]. An important point is that the reduction profile ofatmnosphere [26]:MYHCNMHGatbon+5mgcataNi is strongly influenced by the support oxides, and Ni spe-lyst; heating rate, 15 K/min, room temperature to 1273 K; air flow rate,cies on CeO2 showed high reducibility. The similar behavior20 m/min..592催化学报Chin. J. Catal, 2012, 33: 583- 594Pt(0.1)Ni(12)CeO2(15)/AI2O3Pt(O.1)Ni(12)/CeO2(15/MgO(2)AI2O3after regeneration●j，■Niafter reaction●CeO2▲Al,O,▲Al203after reduction几3(3545254020/(°)Fig. 13. XRD pattemns of P(0.1)/Ni(12)CeO2(15)AI2O3 and Pt(0.)Ni(12)/CeO2(15) /MgO(2)VAl2O, after reduction, reaction (Fig. 12), and regen-eration (calcination at 873 K and reduction at 773 K) [31].prepared by the co-impregnation method using the mixed823 K, although almost no tar was observed above 873 K.aqueous solution of Ni(NO3)2:6H2O and Mn(NO3)2:6H2O inIn addition, at each reaction temperature, the order of thea similar way to that of Ni/CeO2/Al2O3(CI) [32]. The load-resistance to coke formation was Ni(12)/MnO(20)/Al2O; >ing amounts of Ni and MnO are described in parentheses asNi(12)/CeO2(15)/Al2O3. These results indicate that the addi-mass percent on the catalyst.tive effect of MnO was more significant than that of CeO2.Figure 14 compares the catalytic performance in steamThe promoting effect of MnOx addition can be explained inreforming of tar over Ni(12)MnO(20)/Al2O3 and Ni(12)/a similar way as that of CeO2 addition, that is, the oxygenCeO2(15)/Al2O3 catalysts. The activity of Ni(12)/MnO(20)/atoms derived from MnO, species can be supplied to the NiAl2O3 was so high that the tar was almost completely con-species to promote the reaction between carbonaceous spe-verted at all reaction temperatures. On the other hand, thecies on Ni and oxygen species [32].activity of Ni(12)/CeO2(15)/Al2O3 was not so high as that ofNi( 12)/MnO/(20)/Al2O3, and the residual tar was detected at6 ConclusionsH/CO ratioThe Ni catalyst supported on CeO2 was effective to the10.71.61.8.:2.12.2 1.4n 4500suppression of coke deposition in the steam reforming oftar, and this property can be related to the Ni on CeO2 witht 4000high reducibility. The addition of CeO2 to Ni/Al2O3 by theco-impregnation method led to strong interaction betweenar3500 工s冒Ni metal and CeO2 by the formation of Ni-CeO2 nanocom--3000 &posite structure. This Ni/CeO:/Al2O3 catalyst showed higho-网aactivity and resistance to coke deposition in the steam re-t 2500forming of tar. The addition of a small amount of Pt to0-2000Ni/CeO2/Al2O3 promoted the catalyst reducibility, and thecatalyst was reduced with tar and steam easily. Further addi-- J 1500tion of MgO to Pt/Ni/CeO2/Al2O3 enabled the re-dispersion923三873，823i923873823Ni(12)MnO(20)VAl2O, (C) Ni(12)CeO2(15)ALO, (CI)of the aggregated Ni particles via NiO-MgO solid solutionCatalyst and Temperature (K)formation and its reduction. High performance of Ni-CeO2Fig. 14. Comparison of catalytic performance in steam reforming ofby the redox property of CeO2 suggests the potential oftar over Ni(12)MnO(20)Al2O3 (CI) and Ni(12)/CeO2(15)/AlL2O3 (CI)other oxides中国煤化工t is found that[32]. Conditions: biomass, 60 mg/min (H2O, 9.2%; C, 2191 umo/min;manganese 0>-ditive on the NiH, 3543 pumol/min; O, 1475 pumol/min); steam, 110 pumol/min, (addedcatalysts forMYHc N M H Ghe developmentH2O)C = 0.5; catalyst, 0.5 g; H2 reduction, 773 K, 30 min. Loadingof the catalysts for the steam reforming of tar, the optimiza-amount: Ni, 12 wt%; MnO2, 20 w1%; CeO2, I5 wt%.tion of the additives and their composition is important, and.www.chxb.cnDalin LI et al: Development of Ni-Based Catalysts for Steam Reforming of Tar fom Biomass Pyrolysis593this can give various functions including high activity, sta-27 Tomishige K, Kimura T, Nishikawa J, Miyazawa T, KunimoriK. Catal Commun, 2007, 8: 1074bility, selfactivation, and self-regeneration properties ta28 Kimura T, Miyazawa T, Nishikawa J, Kado S, Okumura K,catalysts.Miyao T, Naito s, Kunimori K, Tomishige K A4ppl Catal B,2006, 68: 160References9 Nishikawa J, Miyazawa T, Nakamura K, Asadullah M,1 Mckendry P Bioresour Technol, 2002, 83: 55Kunimori K, Tomishige K. Catal Commun, 2008, 9: 1952 Huber G w, Iborra s, Corma A. Chem Rev, 2006, 106: 404430 Nishikawa J, Nakamura K, Asadullah M, Miyazawa T3 WangLJ, WellerC L, Jones D D, Hana M A BiomassKunimori K, Tomishige K. Catal Today, 2008, 131: 146Bioenerg, 2008, 32: 57331 Nakamura K, Miyazawa T, Sakurai T, Miyao T, Naito S,; de Lasa H, Salaices E, Mazumder J, Lucky R. Chem Rev,Begum N, Kunimori K, Tomishige K. Appl Catal B, 2009, 86:2011, 11: 5404365BakerEGMudgeLK,BrownMD.IndEngChemRes,2 Koike M, Ishikawa C, Li D L, Wang L, Nakagawa Y,1987, 26: 1335Tomishige K. Fuel, in press, doi: 10.1016/j.fuel.2012.01.0736 Aznar M R, Corella J, Delgado I, Lahoz J. Ind Eng Chem Res,33 Wang L, Li D L, Koike M, Koso s, Nakagawa Y, Xu Y,1993, 32:1Tomishige K 4ppl Catal A, 2011, 392: 2487 Aznar M P, Caballero M A, Gil J, Martin J A, Corella J. Ind34 Li D L, Wang L, Koike M, Nakagawa Y, Tomishige K. ApplEng Chem Res, 1998, 37: 2668Catal B, 2011, 102: 5288 Marquevich M, Czermik s, Chornet E, Montane D. Energy35 Tanaka H, Kaino R, Okumura K, Kizuka T, Nakagawa Y,Fuels, 1999, 13: 1160Tomishige K. Appl Catal A, 2010, 378: 1759 Czernik s, French R, Feik C, Chomet E. Ind Eng Chem Res,36 Tanaka H, Kaino R, Nakagawa Y, Tomishige K. Appl Catal A,2002, 41: 42092010, 378: 18710 Bangala D N, Abatzoglou N, Martin J P, Chomet E. Ind Eng7 Naito S, Tanaka H, Kado s, Miyao T, Naito s, Okumura K,Chem Res, 1997, 36: 4184Kunimori K, Tomishige K. J Catal, 2008, 259: 1381 LiJF, Liu JJ, Liao s y, Yan R. Int J Hydrogen Enengy, 2010,38 Koso S, Furikado I, Shimao A, Miyazawa T, Kunimori K,35: 7399Tomishige K. Chem Commun, 2009: 203512 LiJF, Xiao B, Yan R, Xu X R. Bioresour Technol, 2009, 100:39 Koso s, Ueda N, Shinmi Y, Okumura K, Kizuka T, Tomishige5295K. J Catal, 2009, 267: 893 Wang TJ, Chang I, Cui X Q, Zhang Q, Fu Y. Fuel Process40 Shinmi Y, Koso s, Kubota T, Nakagawa Y, Tomishige K ApplTechnol, 2006, 87: 421Catal B, 2010, 94: 31814 Le D D, Xiao X B, Morishita K, Takarada T. J Chem Eng Jpn,41 Chen K Y, Koso s, Kubota T, Nakagawa y, Tomishige K.2009, 42: 51ChemCatChem, 2010, 2: 5475 XiaoX B, Meng X L, Le D D, Takarada T. Bioresour Technol,2 Amada Y, Koso s, Nakagawa Y, Tomnishige K. ChemSusChem,2011, 102: 19752010, 3: 72816 Wang D, Yuan W Q, li W. Appl Enengy, 2011, 88: 165643 Ishida Y, Ebashi T, Ito S-I, Kubota T, Kunimori K, Tomishige17 Corujo A, Yerman L, Arizaga B, Brusoni M, Castiglioni J.K. Chem Commun, 2009: 5308Biomass Bioenerg, 2010. 34: 169544 Ebashi T, Ishida Y, Nakagawa Y, Ito S-L, Kubota T, Tomishige18 Asadullah M, Ito S-I, Kunimori K, Yamada M, Tomishige K.JK. JPhy Chem C, 2010, 114: 6518Catal, 2002, 208: 25545 Bartholomew C H, Pannell R B, Butler J L. J Catal, 1980, 65:19 Asadullah M, Miyazawa T, Ito S-I, Kunimori K, Yamada M,35Tomishige K. Appl Catal A, 2003, 255: 16946 Arena F, Horrell B A, Cocke D L, Parmaliana A, Giordano N.20 Asadullah M, Miyazawa T, Ito S-I, Kunimori K, Yamada M,JCatal, 1991, 132: 58Tomishige K. Appl Catal A, 2004. 267: 9547 Yamazaki O, Tomishige K, Fujimoto K. Appl Catal A, 1996,21 Asadullah M, Fujimoto K, Tomishige K Ind Eng Chem Res,136: 492001, 40: 589448 Tomishige K Chen Y G Fujimnoto K. J Catal, 1999, 181: 9122 Asaulah M, Ito S-I, Kunimori K, Yamada M, Tomishige K49 Nurunnabi M, Mukainakano Y, Kado S, Li B T, Kunimori K,Environ Sci Technol, 2002, 36: 4476Suzuki K, Fujimoto K, Tomishige K. Appl CatalA, 2006, 299:23 Asadullah M, Miyazawa T, Ito S-I, Kunimori K, Tomishige K.145A4ppl Catal A, 2003, 246: 1030 Miyazawa T, Okumura K, Kunimori K, Tomishige K. J Phys24 Tomishige K, Asadullah M, Kunimori K. Catal Today, 2004,Chem C, 2008, 112: 257489: 38951 ChenYG中国煤化Tmoto K Appl Catal5 Asadulah M, Miyazawa T, Ito S-I, Kunimori K, Koyama s,A, 1997, 16Tomishige K. Biomass Bioenerg, 2004, 26: 2692 LiDL, NeMHCN MH al.01.4026 Miyazawa T, Kimura T, Nishikawa J, Kado S, Kunimori K,53 Li B T, Kado s, Mukainakano Y, Miyazawa T, Miyao T, NaitoTomishige K. Catal Today, 2006, 115: 254S, Okumura K, Kunimori K, Tomishige K J Catal, 2007, 245:94催化学报Chin. J. Catal, 2012, 33: 583- -594144Catal, 2007, 250: 29954 Tomishige K, Kanazawa S, Sato M, Ikushima K, Kunimori K59 Li D L, Shishido T, Oumi Y, Sano T, Takcehira K Appl CatalA,Catal Lett, 2002, 84: 692007, 332: 98s5 Li B T, Kado s, Mukainakano Y, Nunnabi M, Miyao T,60 Li D L, Nishida K, Zhan Y Y, Shishido T, Oumi Y, Sano T,Naito s, Kunimori K, Tomishige K. Appl Catal A, 2006, 304:Takehira K. App! Catal A, 2008, 350: 22561 Nurunabi M, Li B T, Kunimori K, Suzuki K, Fujimoto K-I,56 Mukainakano Y, Li B T, Kado S, Miyazawa T, Okumura K,Tomishige K. Catal Lett, 2005, 103: 277Miyao T, Naito S, Kunimori K, Tomishige K. Appl Caral A,62 Nurunnabi M, L B T, Kunimori K, Suzuki K, Fujimoto K.I,2007, 318: 25257 Miyata T, Li D L, Shiraga M, Shishido τ, Oumi Y, Sano τ,63 Nununnabi M, Mukainakano Y, Kado S, Miyazawa T,Takehira K. Appl Catal A, 2006, 310: 97Okumura K, Miyao T, Naito S, Suzuki K, Fujimnoto K-,58 Li D L, Atake I, Shishido T, Oumi Y, Sano T, Takchira K JKunimori K, Tomishige K. Appl CatalA, 2006, 308: 1中国煤化工MHCNMHG.