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 H2 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 H2 co-feeds can be interpreted in terms of an approach to equilibrium.