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

Abstract

Here we report a Ni/TiO2 loaded on attapulgite (ATP) composite catalyst with fairly good CO2 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 TiO2 and Ni nanocrystals in an equivalent impregnation process. Catalytic activity of the newly synthesized catalysts was investigated towards hydrogenation of CO2 at atmospheric pressure in varied temperature between 200 and 450 °C. And in the reaction process, the flow rate of CO2 gas was 2.5 mL/min and the concentration ratio of H2 : CO2 is always 4. The GHSV was 30,000 h−1. Among the investigated catalysts, the 8 % Ni-TiO2-ATP catalyst showed preferable activity at 450 ℃. Improved activity and reducibility were found when adding 8 % Ni due to the enhanced CO2 activation compared with the pure TiO2 or ATP matrix, as well as with the other Ni dosages. These improvements were obtained probably due to its higher surface area than TiO2 catalyst, more surface hydroxyls, and better dispersion on the ATP matrix.