Coke study on MgO-promoted Ni/Al2O3 catalyst in combined H2O and CO2 reforming of methane for gas to liquid (GTL) process Original Research Article

MgO-promoted Ni/Al2O3 catalysts have been investigated with respect to catalytic activity and coke formation in combined steam and carbon dioxide reforming of methane (CSCRM) to develop a highly active and stable catalyst for gas to liquid (GTL) processes. Ni/Al2O3 catalysts were promoted through varying the MgO content by the incipient wetness method. X-ray diffraction (XRD), BET surface area, H2-temperature programmed reduction (TPR), H2-chemisorption and CO2-temperature programmed desorption (TPD) were used to observe the characteristics of the prepared catalysts. The coke formation and amount in used catalysts were examined by SEM and TGA, respectively. H2/CO ratio of 2 was achieved in CSCRM by controlling the feed H2O/CO2 ratio. The catalysts prepared with 20 wt.% MgO exhibit the highest catalytic performance and have high coke resistance in CSCRM. MgO promotion forms MgAl2O4 spinel phase, which is stable at high temperatures and effectively prevents coke formation by increasing the CO2 adsorption due to the increase in base strength on the surface of catalyst.