(515g) Catalytic Activity and Stability Enhancement Using CeO2 and TiO2 Doping to Ni/Co-MCM-41 Catalysts

Hydrogen (H₂) has myriads of applications in industry with current focus shifted to production of hydrocarbon fuels and valuable oxygenates using the Fischer-Tropsch technology and direct use in proton exchange membrane fuel cell (PEMFC). Hydrogen is generally produced via steam reforming of natural gas or alcohols such as methanol and ethanol. Glycerol, a by-product of biodiesel production process, is considered to be one of the most attractive sources of sustainable H₂ due to its high H/C ratio (7 moles H₂ from 1 mole of glycerol) and bio-based origin.  Ni and Co based catalysts have been reported to be active in GSR, however, deactivation of the catalysts by carbon deposition and sintering under GSR operating conditions is a  major challenge at present. In this study, a series of catalysts with Ni and Co nanoparticles incorporated in CeO₂ and TiO₂ modified high surface area MCM-41 have been synthesized using one-pot method. The catalysts were tested for GSR (at H₂O/Glycerol mole ratio of 12 and GHSV of 2200 h^-1) to study the effect of support modification and reaction temperature (450 - 700 ^oC) on the product selectivity and long term stability. The GSR results revealed that most of the catalysts performed significantly well exhibiting over 85% glycerol conversion at 650 °C except Ni based catalysts showed better low temperature activities compared to Co based catalysts. Deactivation studies conducted at 650 °C indicated that among the different studied catalysts, 10%Ni-5%TiO₂-MCM-41 and 10%Ni-5%CeO₂-MCM-41 showed excellent resistance to deactivation with ~100% glycerol conversion throughout the 40 h. On the other hand, 10%Co-5%TiO₂-MCM-41 performed worst with catalyst rapidly deactivating after 12 h to ~20% glycerol conversion at 40 h. WAXRD and TGA-DSC analysis of spent catalysts indicated a significant amount of coke deposition causing catalysts deactivation. Furthermore, a complete change in shape of the original type IV isotherm with drastic reduction of catalyst specific surface areas were also responsible for observed drop in catalyst activity. The results from our ongoing studies will be presented.