Highly selective syngas/H 2 production via partial oxidation of CH 4 using (Ni, Co and Ni-Co)/ZrO 2 -Al 2 O 3 catalysts: Influence of calcination temperature

Abstract

In this study, Ni, Co and Ni-Co catalysts supported on binary oxide ZrO 2 -Al 2 O 3 were synthesized by sol-gel method and characterized by means of various analytical techniques such as XRD, BET, TPR, TPD, TGA, SEM, and TEM. This catalytic system was then tested for syngas respective H 2 production via partial oxidation of methane at 700 °C and 800 °C. The influence of calcination temperatures was studied and their impact on catalytic activity and stability was evaluated. It was observed that increasing the calcination temperature from 550 °C to 800 °C and addition of ZrO 2 to Al 2 O 3 enhances Ni metal-support interaction. This increases the catalytic activity and sintering resistance. Furthermore, ZrO 2 provides higher oxygen storage capacity and stronger Lewis basicity which contributed to coke suppression, eventually leading to a more stable catalyst. It was also observed that, contrary to bimetallic catalysts, monometallic catalysts exhibit higher activity with higher calcination temperature. At the same time, Co and Ni-Co-based catalysts exhibit higher activity than Ni-based catalysts which was not expected. The Co-based catalyst calcined at 800 °C demonstrated excellent stability over 24 h on stream. In general, all catalysts demonstrated high CH 4 conversion and exceptionally high selectivity to H 2 (~98%) at 700 °C.