CH4 dehydroaromatization on Mo/H-ZSM-5: 1. Effects of co-processing H2 and CH3COOH

The co-processing of acetic acid with methane (CH3COOH/CH4 = 0.04-0.10) on Mo/ZSM-5 formulations at 950 K and atmospheric pressure in an effort to couple deoxygenation and dehydrogenation reaction sequences results instead in a stratified reactor bed with upstream CH4 reforming with acetic acid and downstream CH4 pyrolysis. X-ray absorption spectroscopy and chemical transient experiments show that molybdenum carbide is formed inside zeolite micropores during CH4 reactions. The introduction of acetic acid oxidizes a fraction of these carbide moieties upstream while producing H-2 and CO mixtures until completely consumed. Forward rates of CH4 pyrolysis are unperturbed in the presence of an acetic acid or hydrogen co-feed after rigorously accounting for the reversibility of pyrolysis rates and the fraction of molybdenum carbide oxidized by CH3COOH implying that all consequences of CH3COOH and H-2 co-feeds can be interpreted in terms of an approach to equilibrium. (C) 2013 Elsevier Inc. All rights reserved.