Surface hydroxyls mediated CO2 methanation at ambient pressure over attapulgite-loaded Ni-TiO2 composite catalysts with high activity and reuse ability

Here we report a Ni/TiO 2 loaded on attapulgite (ATP) composite catalyst with fairly good CO 2 conversion performance amd outstanding reusability (up to 80 h re-use circles) at ambient pressure. The composite was prepared by sol-gel method using ATP powder as the matrix to load TiO 2 and Ni nanocrystals in an equivalent impregnation process. Catalytic activity of the newly synthesized catalysts was investigated towards hydrogenation of CO 2 at atmospheric pressure in varied temperature between 200 and 450 °C. And in the reaction process, the flow rate of CO 2 gas was 2.5 mL/min and the concentration ratio of H 2 : CO 2 is always 4. The GHSV was 30,000 h −1 . Among the investigated catalysts, the 8 % Ni-TiO 2 -ATP catalyst showed preferable activity at 450 ℃. Improved activity and reducibility were found when adding 8 % Ni due to the enhanced CO 2 activation compared with the pure TiO 2 or ATP matrix, as well as with the other Ni dosages. These improvements were obtained probably due to its higher surface area than TiO 2 catalyst, more surface hydroxyls, and better dispersion on the ATP matrix.