The hydrogen diffusion membrane may be applied to the upstream surface of a porous or microporous support and the methanation catalyst may be applied to {HEAD ~ the downstream surface} of {TAIL ~ the porous or microporous support} 
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The hydrogen diffusion membrane may be applied to the upstream surface of a porous or microporous support and the methanation catalyst may be applied to { HEAD ~ the downstream surface } of { TAIL ~ the porous or microporous support }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL