Towards coupling direct activation of methane with in situ generation of H 2 O 2

Due to the explosive nature of H 2 , O 2 and CH 4 mixtures, the concept of coupling in situ synthesis of H 2 O 2 with low-temperature single-step methane conversion to methanol has not received sufficient attention. This study aimed to investigate this process using a microchannel reactor, which offers the opportunity to explore the process under a wide range of concentrations. Direct methane activation with in situ generation of H 2 O 2 was successfully demonstrated in a microcapillary containing Au–Pd nanoparticles embedded on its silica-coated walls. The effect of H 2 , O 2 and CH 4 partial pressures, H 2 /O 2 molar ratio, gas-to-liquid (G/L) ratio and liquid phase weight-hourly-space-velocity (WHSV) on the productivity and product distribution was investigated. CH 4 partial pressure had the most significant effect on the productivity, while H 2 and O 2 partial pressures influenced the productivity less. The methane activation rate was found to be correlated with the H 2 O 2 formation rate. With only O 2 or pre-formed stabilized H 2 O 2 methane activation was not found, in situ H 2 O 2 synthesis was therefore essential. G/L affected neither the product distribution nor the productivity, however, lowering WHSV altered the product distribution favoring methanol formation.