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

Abstract

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 La5.5W0.6Mo0.4O11.25−δ (LWM0.4) has been used for the in situ 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 gcat –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.

Innovative steam methane reforming for coproducing CO‐free hydrogen and syngas in proton conducting membrane reactor

“…16,31,32 In this work, by coupling steam methane reforming with in-situ H 2 removal in a proton conducting membrane reactor, the coke deposition is expected to be inhibited in the presence of steam on methane side. In fact, when using proton conducting membrane 5,33,34 to replace oxygen-permeable membrane, [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] the reaction on methane side changes from POM to SMR that is more coke-resistant, and also a mature commercial process. After 100 hr reaction, temperature programmed oxidation (TPO) and thermogravimetric analysis (TGA)…”

“…Then, the produced hydrogen molecules can chemically adsorb and dissociate into protons (H + ) on membrane surface, which can be further in-situ removed as H + to the other side if there is a gradient of hydrogen partial pressure across the dense proton conducting membrane. 33,34 Meanwhile, the electrons migrate in the same direction to maintain the local charge neutrality. It is worth mentioning that hydrogen permeation here is based on diffusion of protons through the oxide lattice of dense ceramic membrane.…”

“…First, methane and water are sent to the feed side of the membrane. At high temperatures, steam methane reforming (SMR) takes place over Ni‐based catalyst packed on the membrane surface, forming syngas with a H 2 /CO ratio of 3 according to CH 4 + H 2 O → 3H 2 + CO. Then, the produced hydrogen molecules can chemically adsorb and dissociate into protons (H + ) on membrane surface, which can be further in‐situ removed as H + to the other side if there is a gradient of hydrogen partial pressure across the dense proton conducting membrane . Meanwhile, the electrons migrate in the same direction to maintain the local charge neutrality.…”

Flow rate dependent continuous hydrolysis of protein isolates

“…They can be produced to have relatively high levels of mechanical strength, corrosion resistance and stability under high temperatures and pressures and they do not show any swelling behavior in liquid media. The pore diameter can be adapted to its purpose such as bacteria filtration (Kroll et al 2010 ), oil–water separation (Zhu et al 2016 ) or gas-conversion (Xue et al 2016 ). However, to combine reaction and separation within the same unit, modifications of the ceramic capillary surface are necessary.…”

Chemical stability in H2S and creep characterization of the mixed protonic conductor Nd5.5WO11.25-δ

“…Recently, methane steam reforming has been accomplished using a BaZr0.7Ce0.2Y0.1O2.9 based electrochemical reactor, obtaining an important improvement of the H2 yield [32]. Non-oxidative methane dehydrogenation (MDA) has also been accomplished using La5.5W0.6Mo0.4O11.25-δ [33] that was previously realized using a SrCe0.95Yb0.05O3−δ membrane [34]. In both cases, Mo/H-ZSM5 was used as catalyst.…”