Methane dehydroaromatization over Mo/HZSM-5 in periodic CH4-H2 switching operation mode

Periodically switching flows of CH4 and H-2 through beds of 3 wt% Mo/HZSM-5 at 973 K have revealed that coke formed in durations of the CH4 flow over the catalyst is removed in the following H-2 flow, and then consequently, the high initial activity of the catalyst for the dehydroaromatization of CH4 to benzene and naphthalene is almost completely recovered and/or maintained. Continuous composition analysis of the effluent streams of the H-2 flow has further shown that the coke formed in the CH4 exposures is gasified back by H-2 to CH4 and also that duration of the H-2 flow required to gasify most of the coke formed on the catalyst depends on the CH4 exposure duration. (C) 2002 Elsevier Science B.V. All rights reserved.