Patent ID: 8623926

Claim:
A process for the production of methanol comprising the following steps: (a) providing a source of syngas, wherein the syngas has a first composition parameter R 1 , where R 1 >2; (b) passing the syngas to a methanol synthesis loop to produce a condensed methanol product stream; (c) withdrawing a purge stream from the methanol synthesis loop to limit the concentration of inerts and excess hydrogen; (d) providing a first membrane having a first feed side and a first permeate side, where the first membrane exhibits a selectivity to hydrogen over carbon dioxide of at least about 5, and a selectivity to hydrogen over carbon monoxide of at least about 20; (e) passing at least a portion of the purge stream across the first feed side; (f) withdrawing from the first permeate side a hydrogen-rich first permeate stream, wherein the first permeate stream has a second composition parameter R 2 , where R 2 <R 1 ; (g) withdrawing from the first feed side a hydrogen-depleted first residue stream; (h) providing a second membrane having a second feed side and a second permeate side, where the second membrane is selective for carbon dioxide over hydrogen and methane; (i) passing the first residue stream across the second feed side; (j) withdrawing from the second feed side a carbon dioxide-depleted second residue stream; (k) withdrawing from the second permeate side a carbon dioxide-enriched second permeate stream, wherein the second permeate stream has a third composition parameter R 3 , where R 3 <R 2 ; and (l) passing the second permeate stream to the methanol synthesis loop.