Efficient conversion of methane to commodity chemicals (i.e., olefins and aromatics) is crucial to resolve the environmental, supply, and reliability constraints of using natural gas. Non-oxidative methane dehydroaromatization (MDA) offers a direct route to produce benzene. However, MDA is thermodynamically unfavorable under practical conditions. A promising approach to overcome kinetic and thermodynamic limitations for MDA is integration of membrane materials to selectively remove hydrogen to drive the reaction towards benzene formation. Currently, the application of hydrogen-permeable membranes for MDA is very limited. We have explored the coupling of palladium membranes in fixed-bed reactors to improve MDA performance of benchmark Mo/HZSM-5 catalysts. Hydrogen permeation measurements were conducted under relevant conditions to understand the effects of reaction parameters on membrane performance. Our materials were characterized using a variety of techniques such as temperature-programmed hydrogenation/oxidation, X-ray photoelectron spectroscopy, and scanning electron microscopy to examine physical, chemical, and structural changes associated with coking. Upon hydrogen removal, methane conversion and benzene yield improve significantly over a wide range of space velocity in comparison to those achieved in conventional fixed-bed reactors. There exists a trade-off between catalytic activity and hydrogen recovery, which contributes to the maximum benzene yield enhancement at an intermediate space velocity. The effect of hydrogen removal on coking characteristics of the catalysts and membranes will be discussed.

Exploring hydrogen-permeable membranes for efficient catalytic methane dehydroaromatization

254th National Meeting (2017)

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