Gas to Liquids: Natural Gas Conversion to Aromatic Fuels and Chemicals in a Hydrogen-Permeable Ceramic Hollow Fiber Membrane Reactor

The performance of a dense ceramic hydrogen-permeable membrane reactor for the nonoxidative methane dehydroaromatization (MDA), according to the equilibrium reaction 6CH₄ ⇆ C₆H₆ + 9H₂ with a 6 wt % Mo/HZSM-5 bifunctional catalyst was investigated. A U-shaped ceramic hollow fiber membrane of the composition La_5.5W_0.6Mo_0.4O_11.25−δ (LWM_0.4) has been used for the <i>in situ</i> removal of H₂ to overcome thermodynamic constraints. The yield of aromatics (benzene, toluene, naphthalene) in the MDA could be increased in the beginning of the aromatization reaction by ∼50%–70%, in comparison with the fixed-bed reactor, because 40%–60% of the H₂ abstracted have been extracted at 700 °C with a weight hourly space velocity (WHSV) of 840 cm³ g_cat^–1 h^–1. These advantages of the membrane reactor operation decrease with time on stream, since the removal of H₂ boosts not only CH₄ conversion and yield of aromatics, but also catalyst deactivation by deposition of carbonaceous deposits. However, the catalyst system could be regenerated by burning the coke away with air