Synthesis gas production to desired hydrogen to carbon monoxide ratios by tri-reforming of methane using Ni-MgO-(Ce,Zr)O2 catalysts

This paper highlights the performance of Ni-MgO-(Ce,Zr)O-2 tri-reforming catalysts under various reaction conditions and explains results using catalyst characterization. Testing under controlled reaction conditions and the use of several catalyst characterization techniques (BET, XRD, TPR, SEM-EDS, and XPS) were employed to better explain the effects of the synthesis parameters on the reaction performances. The support Ce:Zr ratio, metal loading techniques, metal wt%, and Ni:Mg ratios all had a pronounced influence on the catalyst performance. An even ratio of Ce:Zr for the support and an even ratio of Ni:Mg gave the best performance. The wet impregnation method consistently showed more resistance to coke formation when compared to the deposition precipitation method, but the difference was attributed to a better ability to load Mg by wet impregnation. Lower than previously reported H2O concentrations in the feed gas composition also led to desired H-2:CO ratios needed for FT synthesis while maintaining high conversions of CO2 and resistance to coke formation. High GHSV (61,000 h(-1)) yielded significantly higher H-2:CO ratios when compared to reactions run at lower GHSV (25,000 h(-1)). These results suggest that steam reforming reactions are kept further from equilibrium at higher GHSV and result in higher H2 production. The tested tri-reforming catalyst produced desired H2 :CO ratios with minimal deactivation, high reactant conversions, and extended catalyst lifetime. (C) 2012 Elsevier BM. All rights reserved.