Non-oxidative dehydroaromatization of methane: an effective reaction–regeneration cyclic operation for catalyst life extension

Abstract

Non-oxidative methane aromatization is an attractive direct route for producing higher hydrocarbons. It is highly selective to benzene despite the low conversion due to thermodynamic limitations, and Mo/H-ZSM-5, the first catalyst proposed for this reaction, is still considered as one of the most adequate. The major problem of this process is the severe catalyst deactivation due to the rapid build-up of carbonaceous deposits on the catalysts. Here we present an effective regeneration procedure that extends the life of Mo/zeolite based catalysts by combining reaction periods of 1.5 h with 0.5 h regeneration steps in a continuous cyclic mode and methane activation after each regeneration stage. Benzene productivity obtained with Mo/ZSM-5 is shown to be almost constant for increasing TOS ranges when applying this new cyclic protocol, and threefold values are achieved for an 18 h on stream period by limiting the reaction steps to the first 1.5 h of maximum benzene selectivity (97 vs. 33 g benzene per kg cat h) compared to a conventional single run.