Sulfated Tin Oxide as Highly Selective Catalyst for the Chlorination of Methane to Methyl Chloride

The chlorination of methane (CH 4 ) is an attractive route to convert CH 4 into more valuable chemicals. The selective formation of methyl chloride (CH 3 Cl) is a key process, but it is rather difficult to achieve with high selectivity due to a radical reaction. Catalytic ionic processes can be a solution. Herein, sulfated tin oxide (STO) was employed in the gas-phase catalytic chlorination of CH 4 . The STO catalyst exhibited high selectivity to CH 3 Cl (>96%) even at high CH 4 conversion. By applying a suite of physicochemical characterizations, it is shown that the strong Lewis acid sites on STO generated by the interaction of Sn and surface sulfate groups are mainly responsible for the highly selective CH 4 conversion. DFT calculations further revealed that STO surface can activate more Cl 2 molecules in a heterolytic manner, leading to better catalytic performances as compared to SnO 2 and sulfated zirconia catalysts.