Methane oxybromination over Rh-based catalysts: Effect of supports

Bromine mediation has been regarded as one of the most efficient ways to activate and convert methane to useful organics. This article reports the effects of active components (Rh, Ru, Pd and Pt) and supports (SiO₂, MgO and Al₂O₃) on the catalysis of methane oxybromination. Among the prepared catalysts, Rh/SiO₂ is the best in performance (CH₄ conversion of ca. 20% and CH₃Br selectivity exceeding 70%). The results reveal that support type has a notable influence on the catalytic performance of Rh, especially on product distribution. The high selectivity to CH₃Br over Rh/SiO₂ is attributed to its low propensity for CH₃Br oxidation. It was found that Rh small in particle size shows high catalytic activity and CH₃Br selectivity. Although silicalite-1 zeolite suffers from a certain degree of structural damage due to the presence of high temperature steam, the use of silicalite-1 as support results in a performance comparable to that of Rh/SiO₂.