Preparation Of High-Dispersion Ni-Co/C Catalyst And Its Performance In Catalytic Reforming Of Corncob Volatiles

The removal of tar under low temperature is one of the key technologies required to be breakthrough in the industrialization of biomass gasification.The preparation of Ni/C via ion-exchange with modified lignite char as carbon precursor was proved to be efficient and economic in tar removal under low temperature,but the poor stability of catalyst limits its application.In this work,promoter Co was introduced using the precursor Ni/C to prepare a series of highly dispersed Ni-Co/C bimetallic catalyst.The two-stage falling-bed quartz reactor was used to investigate the low-temperature?450^oC?reforming of corncob pyrolysis volatiles,and the catalytic steam reforming?CSR?experiment using toluene as model compound was to explore the synergy of the bimetallic catalyst.This work provides important theoretical basis and technical support for development of biomass gasification technology for syngas production under mild conditions.In this paper,Shengli lignite?SL?was firstly modified by HCl,then the acid washed SL?AWSL?was ion-exchanged with Ni solution to prepare Ni/AWSL precursor.Promoter Co with different content was loaded over the precursor via impregnation method.The as prepared Ni-Co/AWSL catalyst was characterized by XRD,XPS,H₂-TPR,SEM,TEM etc.and compared with monometallic Ni/AWSL and Co/AWSL catalyst by the method of ion-exchange to investigate the varied occurrence of metal Ni and Co.The addition of Co not only preserved the good texture properties of original Ni/AWSL,but simultaneously increased the dispersibility and reductivity of metal,and the electronic properties of metal was modified.In the experiment of biomass gasification,promoter Co significantly improved the activity and stability of catalyst during the CSR of corncob volatiles under low temperature.Among them,Ni-10%Co/AWSL with 10 wt%Co loadings achieved the complete removal of the pyrolysis tar.The total gas yield was as high as 57.6 mmol/g,with H₂ yield of 36.3mmol/g.Then the total gas yield can retain at a level of 45.7 mmol/g after 7 turnovers of experiment and the final formation rate of?H₂+CO+4CH₄?was kept at 570.5mmol/min/g.In CSR of toluene,Ni-10%Co/AWSL exhibited the best performance under CT of 550 ^oC with 100 mL/min Ar rate.The conversion of toluene was decreased gradually from 95%to around 80%after 15 h test,much superior to other catalyst and reaction conditions.Additionally,the result of syngas composition and characterization of spent Ni-10%Co/AWSL displayed that promoter Co promoted H₂ selectivity and resistance of coke.The reaction mechanism of Ni-Co bimetallic catalyst was probed and found that the synergy between the metal Ni and Co led to the enhancement of active sites,the improvement of the anti-coking performance and the direction of water gas?shift?reactions over catalyst,thereby increasing the catalyst activity and stability,optimizing the composition of syngas.The paper has 45 pictures,10 tables,118 references.