Processes For The Production of Methanol Using Sweep-Based Membrane Separation Steps
AssigneeMembrane Technology and Research, Inc.
InventorNicholas P. Wynn
Life of this patent
Estimating the term…
Abstract
Disclosed herein are methanol production processes that include a sweep-based membrane separation step using a membrane that is selective to carbon dioxide over hydrogen. Using the processes of the invention, the efficiency of methanol production from syngas is increased by reducing the compression requirements of the process and/or improving the methanol product yield. In certain embodiments, a hydrogen-rich stream is generated; this hydrogen-rich stream can be sent for other uses. An additional benefit is that the processes of the invention may debottleneck existing methanol plants if more syngas or carbon dioxide is available, allowing for feed of imported carbon dioxide into the synthesis loop. This is a way of sequestering carbon dioxide.
Claims18
A methanol synthesis loop production process comprising the following steps:
- (a) providing a source of syngas, wherein the syngas has a composition parameter R1, where R1>2;
- (b) performing a methanol synthesis reaction to react the syngas to produce methanol;
- (c) performing a condensation step to recover methanol;
- (d) withdrawing a purge stream from the condensation step to limit the concentration of inerts and excess hydrogen;
- (e) withdrawing non-condensed methanol synthesis loop syngas from the condensation step;
- (f) performing a sweep-based membrane separation step comprising,
- (i) providing a membrane having a feed side and a permeate side, where the membrane exhibits a selectivity to carbon dioxide over hydrogen,
- (ii) passing a carbon dioxide-containing gas across the feed side,
- (iii) passing at least a portion of the methanol synthesis loop syngas as a sweep stream across the permeate side,
- (iv) withdrawing from the feed side a carbon dioxide-depleted residue stream,
- (v) withdrawing from the permeate side a carbon dioxide-enriched permeate stream;
- (g) compressing the permeate stream;
- and
- (h) passing the compressed permeate stream to the methanol synthesis reaction.
A methanol synthesis loop production process comprising the following steps:
- (a) providing a source of syngas, wherein the syngas has a composition parameter R1, where R1>2;
- (b) performing a methanol synthesis reaction to react the syngas to produce methanol;
- (c) performing a condensation step to recover methanol;
- (d) withdrawing a purge stream of composition parameter R3 from the condensation step to limit the concentration of inerts and excess hydrogen;
- (e) withdrawing non-condensed methanol synthesis loop syngas from the condensation step;
- (f) performing a first membrane separation step comprising,
- (i) 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 and carbon monoxide,
- (ii) passing at least a portion of the purge stream across the first feed side,
- (iii) withdrawing from the first permeate side a hydrogen-enriched first permeate stream, wherein the first permeate stream has a composition parameter R4, where R4>R3, and
- (iv) withdrawing from the first feed side a hydrogen-depleted first residue stream;
- (g) performing a second, sweep-based membrane separation step comprising,
- (i) 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,
- (ii) passing at least a portion of the first residue stream across the second feed side,
- (iii) passing at least a portion of the methanol synthesis loop syngas as a sweep stream across the second permeate side,
- (iv) withdrawing from the second feed side a carbon dioxide-depleted second residue stream;
- (v) withdrawing from the second permeate side a carbon dioxide-enriched second permeate stream, wherein the second permeate stream has a composition parameter R5, where R5<R3;
- (h) compressing the second permeate stream;
- and
- (i) passing the compressed second permeate stream to the methanol synthesis reaction.
Dependencies are inferred from the claim text.