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