镍基催化剂上稻草水蒸气重整制富氢合成气

Chinese Journal of Catalysis 34 (2013) 1462-1468催化学报2013年第34卷第7期Iwww.chxb.cn信化了availableatwww.sciencedirect.comChinese Journai of CatalysisSciencedirectELSEVIERjournalhomepagewww.elsevier.com/locate/chnjcArticleCatalytic steam reforming of rice straw biomass to hydrogen-richsyngas over Ni-based catalystsLI Qingyuan, JI Shengfu*, HU Jinyong, JIANG SaiState Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technobgy, Beijing 100029, ChinaARTICLE IN F OA B STRACTArticle history:Ni-based catalysts with SiOz, Y-Al2O3, CaO, and TiOz as supports and Mg0-7.5% Ni/y- 03 catalystsReceived 29 December 2012with different contents of Mgo were prepared. The structure of the catalysts was characterized byAccepted 16 May 2013powder X-ray diffraction and Nz adsorption-desorption measurements. The performance of thePublished 20 July 2013catalysts in the steam reforming of rice straw biomass to syngas was evaluated. The effects of reac.tion conditions on the activity of the catalysts were also investigated Ni-based catalysts supportedeywords:on y-Al203 had higher catalytic activity than the catalysts supported on TiOz, CaO, and SiOz. The yieldickel-based catalystof H2 reached 1071.3 ml H2/g biomass and the ratio of Hz to Co was 1.4: 1 over a 7.5%Ni/Y-Al203Rice strawcatalyst Addition of Mgo to the 7.5% Ni/Y-Al203 catalyst improved its catalytic activity. The yield ofSteam reforminH2 reached 1194.6 ml Hz/g biomass and the ratio of H2 to CO was 3.9: 1 over the 1.0% Mg0-7.5%Ni/y-Al2O3 catalyst Mgo not only improves the steam reforming reaction of Ni-based catalysts, butcan also promote the water-gas shift reaction. This method shows promise for production of Hz-richsyngas from biomass@2013, Dalian Institute of Chemical Physics, Chinese Academy of SciencesPublished by Elsevier B V. All rights reserved.1. Introduction30%-50% is CO [2, 3 ]. Unfortunately, gas produced from thisprocess usually contains too much CO and unacceptable levelsChina is a large agricultural country, so the biomass re- of tar for intended applications. Tar can foul equipment such assources,e.g, straw and crop residues, available for energy use engines and turbines during the condensation process [4]. Pyare abundant. China produces more than 640 million tons of rolysis and gasification with steam is a process that can greatlystraw per year, and its production will increase as the crop decrease the yield of tar from biomass. Corella et al. [5] recogyield is improved. Straw is mainly used as a fertilizer feed and nized that steam is a more effective gasifying agent for tar refor burning in traditional agriculture [1]. Effective use of bio- moval than oxygen or a mixture of oxygen and steam under theronmeney sy is needed to solve agricultural, energy, and envi- same conditions. Moreover, H2 yields can be enhanced by usingprotection problems. An effective way to use straw steam as gasifying agent over other gases.involves thermal cracking, gasification, and catalytic conversionCatalytic reforming of biomass, which can convert biomasf straw resources to produce syngas and H2. This process is into syngas with little tar at relatively low reaction tempera-environmentally friendly and produces energy efficientlyture, has received wide attention recently. Rapagna et al.[6]The main products from pyrolysis and gasification of bio- used several kinds of catalysts in catalytic reforming of biomassmass are CO, H2, and other hydrocarbons, of which about for H2 production, including mineral resources such as dolo中国煤化工Corresponding author. Tel/Fax: +86-10-64419619; E-mamail. buctedu cnThis work was supported by the National Basic Research Program of China(973 Program, 20lHCNMHGgh Technology re-search and Development Program of China(863 Program,102425)Dol:10.1016/s1872-2067(12)60618-4ihttp://www.sciencedirect.com/science/journal/18722067IcHin.J.CatalvOl.34,No.7,July2013LI Qingyuan et al Chinese Journal of Catalysis 34(2013) 1462-14681463mite,magnesite, zeolite, and olivine, as well as Ni-based and Chemical Industrial Co., China), or Cao (Tianjin Fuchen Cheminoble metal catalysts. Dolomite is the most commonly used cal Reagents Factory, China) was added to an aqueous solutioncatalyst of this group because it is cheap and has a tar removal of Ni(NO3)2( Beijing Yili Fine Chemical Co., Ltd. Each mixturefunction. Despite its high catalytic activity, dolomite has some was stirred to form a uniform slurry and then left undisturbeddisadvantages such as low mechanical strength, which restricts at room temperature overnight. The samples were dried at 110its further application [7]. Ni-based catalysts have been used C for 12 h and then calcined at 550C for 5 h in air to give 7.5extensively for gasification, tar conversion, and reforming light wt% Ni-based catalysts on different supports. The same meth-hydrocarbons because of their high tar destruction activity and od was used to prepare Ni/y-Al203 catalysts with Ni contentsability to improve the content of syngas in the produced gas ranging from 2.5 wt% to 15 wt%. Mg0-7.5%Niyy-Al203 cata[8-13]. However, the rapid deactivation of Ni-based catalysts lysts with Mgo loadings of 0.5 wt%-20 wt% were also pre-by carbon deposition and sintering of active Ni particles seri- pared by incipient wetness impregnation. First, a Ni/y-Alz03ously impede their application. For these reasons, many novel precursor with a Ni loading of 7 5wt%was prepared. The pre-catalysts have been developed for gasification of biomascursor was then impregnated with mg(NO3)2 solution. Finally,Wang et al. [ 14] investigated biomass air-steam gasification the catalyst was dried at 100C overnight and calcined at 550in a bubbling bed biomass gasifier with Nio-Mgo as a catalyst. C for 5 h in airThey found that their Nio-Mgo catalyst showed better catalyticactivity and anti-coke ability at high temperature( 750C) 2. 2. Catalyst characterizationthan a commercial Ni-based reforming catalyst. Nakamura et al[15]reported that adding Mgo to Pt/Ni/CeOz/Al203 promotedThe phase structures of the samples were characterized bythe steam gasification of biomass. The addition of Mgo de- powder X-ray diffraction(XRD) using a Rigaku D/Max 2500creased the degree of reduction of Ni but increased the disper VB2+/PC diffractometer, with Cu Ka radiation operating at 40sion of Ni metal particles. Their Pt/Ni/CeO2/MgO/Al203 cata- mA and 40 kV. The specific surface area, pore volume, and porelyst exhibited high resistance to aggregation, which resulted in size distribution of the catalysts were characterized using ahigh stability. Jiang and coworkers [16] studied the pyrolysis Quadrasorb SI analyzer. Prior to adsorption, the samples weredat300°for2htowheat straw and sawdust, in a fluidized bed. They found that components. Specific surface areas were calculated using thethe gasification of rice straw produced more H2 than the other BET equation. Pore volume and pore size distribution weretypes of biomass investigated, and addition of Na2 CO3 simulta- determined by the bJH methodneously enhanced the content of H2 and decreased the contentof CO Umeki et al. [17 investigated pyrolysis and char reaction 23. Elemental analysisbehavior during rice straw gasification in detail to clarify theeffect of steam. The difference of Hz yield using steam versus anThe contents of C, H, N, and o in the catalysts were analyzedinert atmosphere was about twice the CO2 yield using a steam using a CHNS/0 analyzer. The ash, moisture, and volatile mat-atmosphere. This is because the water-gas shift reaction was ter contents of the catalysts were analyzed by a muffle furnaceaccelerated by the catalytic behavior of char and excess steam using the proximate analysis method of coal. The content offixed C was calculated by difference. The results of the aboveRecently, we prepared Ni-based catalysts for catalytic steam analysis for rice straw are presented in Table 1reforming of poplar leaves and found that Ni as the activecomponent of the catalysts exhibited good activity for this reac- 2. 4. Catalytic activitytion [18 Our catalysts were also effective for tar conversion. Inthis study, a series of Ni-based catalysts with TiOz, Cao, SioRice straw was collected from the countryside of Huangand y-Al203 as supports and Mg0-7.5% Ni/Y-Al203 catalysts gang, Hubei, China. Before reaction, the rice straw was driedwith different contents of Mgo are prepared. The performance naturally in the sun, crushed to 40-60 mesh powder using aof the catalysts for conversion of rice straw to syngas in a ball mill, and then dried at 50C in an oven until its mass wasfixed-bed reactor is investigated. The influence of Ni and Mgo constant.contents in the catalysts, reaction temperature, steam/biomassFigure 1 shows a schematic diagram of the experimentalratio, and biomass/ catalyst mass ratio on the steam reforming apparatus for steam reforming of rice straw, which consisted ofof rice straw to Hz-rich syngas are studied in detail.a fixed-bed continuous flow quartz reactor, steam generator,steam/gas feed line, condensing units, and measure-Table 12. 1. Catalyst preparationProximate and ultimate analyses of rice straw.The catalysts in this study were prepared by an incipient volatil中国煤化工_( dry basis).41.56wetness impregnation method. An appropriate amount of Fixed carbonCNMHGY-Al203(Shangdong Aluminum Co, China), TiOzCTianjin DamaoMoisture726Chemical Reagents Factory, China), SiOz (Qingdao Defeng Ash11521464Li Qingyuan et al. Chinese Journal of Catalysis 34 (2013)1462-1468v yAlO10203040506070809Fig. 1 Schematic diagram of the equipment for steam reforming of rice2(°straw.(1)Plunger pump;(2)Mass flow meter; (3)Valve(4)Evaporator;(5)Mixer;;(6) Heating belt; (7)Furnace;(8)Reactant bed;(9) g 2. XRD patterns of different Ni-based catalysts with different sup-Quartz reactor; (10)Cold trap; (11) Gas chromatographports. (1)7.5% Ni/SiOz;(2)7.5%Ni/Y-Al2O3;(3)7.5% Ni/CaO;(4)7.5%Ni/TiOzment/analysis devices.7.5%Ni/Y-Al203 catalyst gave the highest yield of H2, reachingPrior to reaction, the catalyst was reduced with H21071.3 ml/g. This could mainly due to the surface acidity of theml/min) at 700C for 3 h. Then, the rice straw powder arY-Al203 support that can promote the tar cracking reaction. Incatalyst were mixed sufficiently and packed into the reactoraddition, the interaction between y-Al2O3 and Ni benefitedWhen the reaction temperature was reached under Nz, steam dothermic reforming reactions and enhanced production of H2was immediately introduced into the reactor and the reforming [19,20). As a result, we decided to focus on the structure andof rice straw biomass began. Gas products were collected fromatalytic activity of Ni/Y-Al203 catalysts with different Ni conthe outlet and analyzed by an online gas chromatograph(Bei- tentsjing East West Electronics Institute, GC-4000 A)with aTable 2 also shows that 765. 2 ml/g of Co is obtained over aTDX-01 column and a TCD detector. The gas products such as 7.5% Ni/y-Al203 catalyst. This value is consistent with the re-CO, H2, and COz were calculated by the area normalization sults obtained from elemental analysis, which gave 775.8 ml/gmethod using N2(10 ml/min) as an internal standard. The yield of COof H2 was calculated by integration until no H2 was detectedThe reaction lasted for nearly 5 h, during which time the cata- 3. 2. Structure and catalytic activity of Ni/y-A1203 catalysts withlysts remained stable. CH4 and tar were not detected during the different Ni contentsreaction. After reaction the biomass residue was cooled toroom temperature under N2 protection and the catalyst wasXRD patterns of the Ni/y-Al203 catalysts with different Niremovedcontents and 7.5% Ni/y-Al203 catalysts reduced at 700C for 3h are depicted in Fig 3. The main diffraction peaks found at 203. Results and discussion37.2,46. 1, and 66.7 could be assigned to y-Al203 Nio dif-fraction peaks were not found for the 7.5%Ni/Y-Al203 catalysts3. 1. Structure and catalytic activity of Ni-based catalysts withprobably because of the low content and high dispersion of NiOifferent supportsparticles. As the Ni content increased, the intensity of Ni peaksincreased correspondingly. The 12.5% Ni/Y-Al2O3 and 15.0%Figure 2 shows the XRD patterns of the catalysts with 7.5Ni /y- Al203 catalysts had weak diffraction peaks from NiO nearwt%Ni supported on SiOz, Y-Al203, CaO, and TiOz Broad peaks 20=43.3 and 62.9, indicating thatonsistent with Nio were observed over 7.5%NiSiOz. This aggregated in these catalysts. Strong, sharp diffraction peaks atindicates that the nio grains were smaller on the Sioz support 20=44.5 51.8, and 76.3 for 7.5% Ni/Y-Al203 following re-than in the other catalysts. However, peaks from Nio were notobserved for 7.5%Ni/r-Al203. This is attributed to the high Table 2dispersion of Nio on the y-Al203 support. Relatively sharp Gas products formed over Ni-based catalysts with different supportspeaks of Nio were observed over 7.5% Ni/Ca0 and 7.5%Volume contents(%) H2/Co H2 yieldNi/TiOz, indicating that the Nio grains were larger on the CaotalystCOratioand TiOz supports than SiOz7.5%Ni/SiOz961.3Table 2 shows the catalytic activity of the Ni-based catalysts 7.-5% Ni/r-AI2031071.3with SiOz, Y-Al203, CaO, and TiOz supports for the steam re-7.5% Ni/CaC中国煤化工7.5%Ni/TiOzforming of rice straw to syngas. The activity of the catalystsReaction conditioCNMH02, mass of biomassdepended on the support. Among the four catalysts, 7.50. 2 g, biomass/catalyst =5/1Ni/ Ca0 showed the lowest yield of Hz of just 792.0 ml/g. The Volume of Hz produced per gram of biomass.Li Qingyuan et al Chinese Journal of Catalysis 34(2013) 1462-14681465Table 4vy-AlO, o Ni NiOGas products and H2 yield over Ni /y-Al2O3 catalystsVolume contents(9%) Hz/COH2COtio(ml/g20.314815.25.0% Ni/Y-Al2O330321.91475%Ni/yA2O33123.21410.0%N/y-A203329229m125%Ni/y-Al203301032.415.0%Ni/Y-A120328420.0141005.6Reaction conditions: T= 820C, steam/biomass =2.02, biomass mass0. 2 g, biomass/catalyst=5/1.This means the Ni content reached a saturation point. FromTable 4. as the Ni content increased from 2.5% to 7.5%, thevolume content of Hz and CO increased by 16% and 14%, re-102030405060708090spectively. Simultaneously, the H2 yield was increased by 31%20(°)and reached 1071.3 ml/g. After this point, the Hz yield did notFig. 3. XRD patterns of Ni/y-Al2O3 catalysts with different Ni contentsincrease any further with Ni content. This agrees with the con-clusions of a previous publication [26]. In our study, the opticatalyst in( 3)reduced at 700C for 3 h;( 8) The catalysts in (7)after 5h mum Hz yield was achieved when the Ni content was 7.5%Beyond this value, the Hz yield and Co content reduced slightlyas the Ni content increased. It was noteworthy that the ratio ofduction in H2 at 700C for 3 h revealed that large Nio particles H2 to Co was constant as the Ni content increased. From thehad formed [21]Ha/Co ratio and H2 yield, the theoretical C content is 40.98%,After the reforming reaction, the catalyst still exhibited dif- which was consistent with the elemental analysis data in Tablefraction peaks from Nio particles. This means that the active 1component of the catalyst retained its structure and activityBesides the influence of Ni content, reaction temperatureafter 5 h, which is consistent with previous publications was also an important factor, as shown in Fig 4. As the temper[22, 23]. The XRD pattern of the used catalyst was similar to ature increased, the volume content and yield of H2 increasedthat of 7.5%Ni/r-Al203 reduced in H2 at 700C for 3 h, further obviously, reaching 34. 2% and 1135.9 ml/g at 830oC, respec-indicating the stability of the catalyst. According to the Scherrer tively. Moreover, the volume content of syngas increased fromequation, the size of Nio particles before and after reaction was 48.4% to 59.9% when the temperature rose from 810 to 8302.6 and 3.2 nm, respectively. Therefore, the Nio grains in- .C. However, the ratio of Hz to co decreased from 1.60 to 1.33creased in size during the reforming reactionThus, increasing temperature did not always benefit the pro-The specific surface area and pore size distribution of the duction of H2-rich syngassamples are shown in Table 3. As the Ni loading increased, theThe large increase of gas yield as the steam reforming temspecific surface area and pore volume of the catalysts de- perature increased may be caused by three processes: ( 1)morecreased gradually, whereas the average pore diameter first unconverted volatile species were released with increasingincreased. This can be attributed to the aggregation of Ni active temperature,( 2)steam cracking and reforming of tar, whichcomponent [24, 25). In fact, two pore sizes were found for the increases with temperature, and(3) endothermic reactions ofcatalysts with higher Ni loading: around 3.8 and 4.9 nm. At a char gasification, which favors higher temperatures. An insuitable Ni loading, the main pore size was 4.9 nm. Howeverhen the Ni loading was excessive, the aggregation of Ni active120035F区zHcomponent increased, and the main pore size of the catalystsaCOdecreased to 3. 8 nmThe effect of Ni content within the range from 2.5%to80015.0% was studied, and the results are listed in Table 4. As theNi content increased, the h2 yield exhibited an optimum valueTable 305040Pore structure parameters of different Ni/y-Al2O3 catalystsCatalystPore volume Mean pore sizo(m2 /g(cm3/ g(nm).5%Ni/Y-Al2O3232.30.448305.0% Ni/Y-Al203204.2中国煤化工7.5%Ni/Y-Al2O320090.3710.0%Ni/yA2O3175.20.37Fig. 4. The diCNMHGHandco at different12. 5% Ni/Y-Al2O3168.10.34temperatures over 7.5%Ni/y-Al2O3 catalysts. Reaction conditions15.0% Ni/y-Al2O3166.80.343.9steam/biomass =2.02, biomass mass =0.2 g, biomass/ catalyst=5/1146LI Qingyuan et al. /Chinese Journal of Catalysis 34(2013)1462-1468Table 51200Gas products and H2 yield for different steam to biomass ratios overZH7.5% Ni/Y-Alz 03 catalystsA CO1000Stream/biomass Volume contents(%) H2/CoH2 yield250.8120.127,413525.71.032.0233.123.2143107133.401128.7Reaction conditions: T=820C, biomass mass =0.2 g, biomass/catalyst5/110200crease of temperature has different affects on different components of the gas product. When the steam reforming tem1:12:13:14:156:1perature exceeded 800C, a large decrease of COz and CHa andBiomass/catalyst ratioan increase of CO were observed with rising temperature, illttrating that the water-gas and methane steam reforming reac-Fig. 5. Yields of Hz and CO obtained by varying the ratio of biomass andcatalyst over 7.5%Ni/Y-Al2O3 catalysts. Reaction conditions: T=820Ctions played dominant roles to the water-gas shift reactionsteam/biomass = 2.02, biomass mass=0.2 g[27]. An increase of temperature disfavors the exothermic wa-ter-gas shift reaction, which affects the Hz yield and volume unnecessary to produce Hz-rich syngascontent of gas product. The increase of Co volume content wasfaster than that of H2 volume content, so the H2/Co ratio de-3.3. Structure and catalytic activity of Mgo-7.5% Ni/y-A1203creased, as shown in Fig 4.catalysts with different Mgo contentsSteam is a feasible reforming agent that is also used to pro-mote reforming of tar, hydrocarbons and the water-gas shiftMgo was doped into the 7.5%Ni/Y-Al203 catalyst toreaction in this study. As shown in Table 5, with the increprove the catalytic activity of the water-gas shift reactionsteam, the H2 yield, H2 volume fraction, and Ha/Co ratio in- patterns of Mg0-75% Ni/y-A1203 catalysts with different Mgocreased gradually, whereas the CO content decreased. This is contents and 1.0% Mg0-75% Ni/Y-Al203 catalyst reduced in Hzbecause more CO, CH4, and CnHm take part in the steam re- at 700C for 3 h are shown in Fig. 6. No MgO diffraction peakforming reaction as the steam rate is increased.was observed over all the samples. Nor were these catalystsIt is notable that Co can be generated by three possible re- observed after reduction in H2 for 3 h. This was attributed toaction pathways during steam reforming of rice straw: from the the low content and high dispersion of Mg species in the cataprimary pyrolysis of rice straw, from the secondary pyrolysis in lyststhe solid or gas phase, and the steam reforming of tar [28-30Diffraction peaks from Nio were not observed for samplesUnder the studied reaction temperatures, CO is mainly gener- containing 0-1.5% MgO, but a Nio peak was seen when Mgoated from secondary pyrolysis. Thus, the slight decrease of Co content was increased to 2.0%. This indicates that the dis-by steam possibly indicates incomplete steam reforming of the persed Nio grains may aggregate and grow large enough forgas phase.their diffraction peak to be observed when a suitable amount ofAs the steam/biomass ratio increased, the Hz/Co ratio also MgO promoter is added [32]increased and more syngas was generated. Thus, by controllingthe input of steam, the Hz/Co ratio in the syngas formed duringsteam gasification of biomass can be adjusted to a desired valY-Al2O3aNi·NiOSyngas with an H2/Co molar ratio in the higher range isdesirable for producing H2 for ammonia synthesis and can alsobe used to produce pure H2 for fuel cell applications [31].Altough a higher steam/biomass ratio is favorable for higher gasyields, it requires more external heat (from an external heater)or working at a low temperature [20], which is one of the mostimportant factors considered in this study. As a result, we chose2.02 as the optimum steam /biomass ratio for this reactionFigure 5 shows the effect of biomass/catalyst ratio on theyields of H2 and CO. It shows that the maximum Hz yield andvolume content of syngas were reached at a biomass/catalyst102030405060708090ratio of 5: 1 for biomass/catalyst. Compared with the H2 yieldand volume content, the ratio of Hz/CO was nearly constant. In中国煤化工Fig. 6. XRDTHatalysts. (1)7.5%other words, the composition of syngas was hardly affected by Ni/y-A1203:(2)CNMHG10%Mg0-7.5%the biomass/catalyst ratio. From the above, we can concludeNi/yA2O3;(4)1.5%Mg0-75%Ni/ Y-Al2O3:(5)2.0%Mg0-7.5%that the introduction of excessive catalyst into the reactor is Ni/r-Al2O3; (6)1.0%Mgo-.5% Ni/y-Al2 Os reduced at 700C for 3 hLi Qingyuan et aL / Chinese Journal of Catalysis 34(2013)1462-14681467creased from 12. 4% to 15.3%. This decrease in volume contentPore structure parameters of Mgo-7.5% Ni/y-Al20, catalysts with dif. is related to the decrease of the specific surface area of the cat-ferent MgO contentsalysts. Therefore, excessive Mgo doped in 7.5% Ni/Y-Al203CatalystAbet Pore volume Pore size not benefit the catalytic steam reforming reaction to produce(m2 /g (cm/g(nm H2- rich syngas7.5% Ni/Y-Al2O3200.9.37The positive direction of the water-gas shift reaction car05%Mg0-75%Ni/yAl2O3204.80.261.0%Mg0-75% Ni/r-Al20improve the Hz yield and volume content of gas product in the1.5%Mg0-75%N/y-Al2O189.33.8studied system. As a result, an increase of temperature hinders2.0%Mg0-7.5% NiY-Al203163.5this exothermic reaction because its Gibbs free energy gradally turns positive, so the reaction is suppressed. According toTable 6 shows the specific surface area and pore size distri-thermodynamics, a suitable increase of the partial pressure ofsteam and decrease of the concentration of co2 during the re-bution of the catalysts doped with various contents of MgO. The action could lower the Gibbs free energy of the system,which1.0%Mgo-7.5% Ni/Y-A1203 catalyst had a larger surface area should help to improve H2 yield. Calcium and magnesium oxthan the other catalysts, which may be caused by the dispersionof Mgo over the surface of this sample. The specific surfaceides, and therefore pre-calcined dolomite, can readily adsorbsteam and COz from air. It has also been demonstrated that forarea of the catalyst decreased from 206.1 to 163.5 m/g when metal-Ca0 interactions (as detected for iron), kinetic limita-the mass fraction of MgO exceeded 1.0%, and the average porediameter also decreased from 4.9 to 3. 8 nm. These are attions are less important than the case of metal-MgO interactributed to the aggregation of Nio and the extra mgo grainstions(as reported for nickel), revealing the role of free MgO inentering into the pores of 7.5%Ni/Y-Al203 to decrease porepromoting COz diffusion through the porous sorbent particlesdiameter34]. The highest amount of Hz production was achieved whenThe gas products and H2 yield from biomass gasificationnanosized Mgo was used, and at the same time, a significantlyover Mgo-7.5% Ni/Y-Al2O3 catalysts with different Mgo contents are presented in Table 7. Doping with Mgo resulted in catalysts. Therefore, Mgo can be used as a promoter to enhanceproduction of COz over 7. 5% Ni/Y-A1203. This was attributed to H2 production from biomass.the water-gas shift reaction: CO+ H20= CO2+H2, AH=-41.14. Conclusionsk]/moLThe volume content of COz decreased as the content of MgOincreased. This suggests that Mgo participated in the adsorp-Various Ni-based catalysts with different supports and contion reaction of CO z, which has been well-documented by Florin tents of Mgo promoter were prepared. The maximum yield ofet al. [33. Furthermore, the presence of Mgo may cause theH2 was achieved over a 7.5% Ni/y-Al203 catalyst. Addition ofGibbs free energy of the water-gas shift reaction to decrease Mgo increased the yield of H2 and improved the product dis-due to the absorption of CO2. In other words, the yield andtribution and quality of the syngas from steam reforming of ricestraw to H2-rich syngas, as well as decreasing the Co content involume content of Hz could be improved by the water-gas reac- the syngas. Mgo not only played the role of active catalytiction. Table 7 shows that the yield of Hz increased from 1071.3to 1194.6 ml/g as the content of Mgo increased from 0 to 1.0%component for the water-gas shift reaction but also behaved asand the volume content of Hz increased from 33. 1% to 48.9%an enhancer during catalytic steam reforming of rice straw. TheAt the same time. the volume content of co decreased from ratio of Hz to co reached 1.4: 1 and the Ha yield was 1071.323.2% to 12.4%. This change in volume content was much ml/g over 7.5% Ni/Y-A1203 catalyst at 820C After doping withlarger than that of Hz, which may be related to the formation of 1.0% MgO, these parameters reached 3. 9: 1 and 1194.6 ml/g.MgCO3 in the water-gas shift reaction. Subsequently, the H2/ coratio increased sharply from 1.4 to 3. 9, revealing the optimumconditions to produce H2-rich syngas.rencesOnce the Mgo content exceeded 1.0%, the H2 yield decreased to 1163. 2 ml/g and the volume content of CO in- L Han L I, Yan Q L Liu X Y, Hu Y Transcation of the Chinese Societyof Agricultural Engineering(韩鲁佳闫巧娟,刘向阳,胡金有.农业工程学报)200218(3:87Table 72] Lu P M, Chang ], Xiong Z H, Wu C Z, Chen Y. Coal ConversionBEGas products formed over MgO-7.5%Ni/Y-AlzO3 catalysts with different梅,常杰,熊祖鸿,吴创之,陈勇煤炭转化),2002,25(3:32Mgo contents3]Lu P M, Chang I, Fu Y, Wang T L, Wu C Z, Chen Y, Zhu )X Acta Ener-Volume contents(%) Hz/Co Hz yieldgiae Solaris Sinica(吕鹏梅,常杰,付严,王铁军,吴创之,陈勇,Hz Co CO2 ratio(ml/8)祝京旭太阳能学报)200,25(6):7697.5%Ni/Y-Alz0333.1232713[4] Devi L, Ptasinski K I, Janssen FJJ G. Biomass Bioenergy, 2003, 2405%Mg07.5%Ni/y-A0345416.7152271180.710%Mg0-75%Ni/y-Alz034891241433911946中国煤化工B615%MgO-75%Ni/yAl2034661351373.61182520%Mg075%Ni/AO3443125291163216g myHCNMH Gnn△cP U. Bi.Reaction conditions: T=820C steamnass= 2.02 biomass massomass Bioenergy, 2002, 22: 3770. 2 g, biomass/catalyst =5/1[7] HuG, Xu SP, Liu S Q Chemistry and Industry of Forest Products(AH146LI Qingyuan et aL. /Chinese Journal of Catalysis 34(2013)1462-1468Graphical AbstractChin. J. Cat201334:1462-1468do:10.1016/5187220670121606184Catalytic steam reforming of rice straw biomass to hydrogen-rich syngasover Ni-based catalystsH,+ CoH:+ cO3LI QinJISg JIANGBeijing University of Chemical TechnologyA series of supported Ni-based catalysts were prepared and used for steam re-forming of rice straw biomass to hydrogen-rich syngas. A 1.0% Mg0-7.5%Ni/r-Al2 03 catalyst exhibited the highest catalytic activity of the seriesupported Ni-based catalysts冠徐绍平,刘淑琴.林产化学与工业),2005,25(S1:161102:1975[8] Hashemnejad S M, Parvari M Chin/ Catal (E1#R), 2011, 32: [21] Chaudhari S T, Dalai A K, Bakhshi NN Energy Fuels, 2003, 17[9] Li D L, Nakagawa Y, Tomishige K. 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Bioresour Technol, 2011.Energy,2011,36:5296镍基催化剂上稻草水蒸气重整制富氢合成气李庆远,季生福,胡金勇,蒋赛北京化工大学化工资源有效利用国家重点实验室,北京100029摘要:采用浸渍法制备了SO2,y-Al2O3,CaO和TiO2负载的N催化剂,以及不同Mgo含量的MgO-7.5%Niy-Al2O3催化剂,利用X射线衍射和N2吸附-脱附技术表征了催化剂的结构,在固定床反应器上评价了它们在稻草水蒸气催化重整制合成气反应中的催化性能,考察了反应条件对催化剂性能的影响.结果表明,以yAl2O3为载体时N催化剂活性最高,其中75%Ni午Al2O3催化剂的H2收率可达10713mg,H2:CO的体积比为14:1;同时,MgO的添加进一步提高了该催化剂的性能,当MgO含量为1.0%时,H2收率可达11946mlg,H2CO体积比可达39:1.可见MgO的加入促进了N基催化剂上稻草水蒸气催化重整制合成气反应的进行,同时使得合成气中CO发生水汽转换反应,从而大大提高了合成气中H2含量关键词:镍基催化剂;稻草;水蒸气重整;合成气;氢气收稿日期:2012-12-29.接受日期:2013-05-16.出版日期:2013-07-20通讯联系人.电话/传真:(010)64419619;电子信箱:jisf@mail.buct.edu.cn基金来源:国家重点基础研究发展计划(973计划,2005C0B2214205;国家高技术研究2斗?∩nAA10本文的英文电子版由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect中国煤化工)25CNMHG