Effect of Ni-Ta ratio on the catalytic selectivity of fibrous Ni-Ta/ZSM-5 for dry reforming of methane

Abstract

A series of Ni-Ta catalysts supported on fibrous ZSM-5 were synthesized by microemulsion and impregnation method. Catalytic activity and selectivity were influenced by incorporation of Ta into Ni catalyst. The side reaction (Boudouard, methane cracking, and reverse water gas shift reaction) tests gave more insights on source of coking, where 10Ni catalyst was more inclined towards methane cracking. The 7Ni-3Ta catalyst showed the best performance (CO2 and CH4 conversions of 95% and 93%, respectively) due to the inherent activity of Ni, and anti-sintering impact of Ta as affirmed by TEM and Raman spectra. Its TGA analysis revealed 9.8% carbon content after 100 h. Furthermore, activation energy of CO2 and CH4 conversions were reduced by 15% and 10% respectively. Thus, addition of small amount of Ta to Ni catalyst was able to dilute Ni surface and limit the degree of graphitization of carbon which is prerequisite for stable performance in DRM.