HYDROGENATION OF CO2 OVER A RICE HUSK ASH SUPPORTED NICKEL-CATALYST PREPARED BY DEPOSITION-PRECIPITATION

The rice husk ash supported nickel catalysts was prepared by depositio n-precipitation and used for hydrogenation of CO2 from a H-2/CO2 (4/1) mixture. The reaction exhibited high selectivity (80%) for CH4 format ion when carried out at 673-873 K with the supported nickel. The effec ts of nickel loading, deposition-precipitation time, calcination, and reduction of temperature on the catalytic performance were also extens ively studied. These results show that nickel loading increases with a n increase in the deposition-precipitation time up to 24 h, while meta l dispersion increases with a decrease in nickel loading. The conversi on of CO2 and the yield of CH4 were found to be independent of the cal cination temperature and time. Furthermore, the conversion and yield i ncrease with an increasing reaction temperature up to 723 K, but decre ase with a further increase in the reaction temperature. Moreover, ric e husk ash has been found to be preferable over silica gel as a cataly st support as revealed by the temperature-programed desorption techniq ues and the reaction test.