Purge gas in methanol synthesis
AssigneeE. I. Du Pont de Nemours and Company
InventorEdward B. Bowman
Life of this patent
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Abstract
Utilization of hydrocarbon feedstocks in the manufacture of methanol by catalytic conversion of synthesis gas is improved by adding a carbon oxide to a hydrogen-rich purge gas from the process and catalytically converting the carbon oxide-enriched purge gas in a secondary reactor to form additional methanol. The secondary reactor effluent consists essentially of methanol, water and unreacted gases. Methanol is readily separated therefrom.
Claims23
A process for the manufacture of methanol using a hydrogen-containing gaseous purge stream from a chemical manufacturing process comprising:
- (a) raising the pressure of a second hydrogen-containing gaseous stream at a lower pressure than the purge stream by combining the two streams and feeding the combined streams to a hydrogen-enrichment zone;
- (b) raising the hydrogen concentration in the combined stream in the hydrogen-enrichment zone by removing gaseous materials therefrom which are inert with respect to a methanol synthesis reaction;
- (c) adjusting the hydrogen to carbon oxide molar ratio of the hydrogen-enriched gas stream to a level within the range of about 2:1 to 12:1 by addition of a carbon oxide thereto;
- (d) feeding the carbon oxide-adjusted hydrogen-enriched gas stream to a methanol synthesis zone containing a methanol synthesis catalyst and forming a methanol-containing gaseous effluent, said zone maintained at a temperature below which any substantial methanation occurs and at a pressure no higher than the pressure of the purge stream;
- and
- (e) recovering methanol from the gaseous effluent.
In a process for the manufacture of methanol by (1) catalytic conversion of synthesis gas in a primary methanol synthesis zone to form an effluent comprising a mixture of crude methanol, hydrogen, methane, water, carbon monoxide, carbon dioxide and nitrogen;
- (2) separation of crude methanol and water from the effluent to form a hydrogen-rich gas stream containing carbon oxides and materials which are inert with respect to the methanol conversion reaction;
- (3) recycling the hydrogen-rich gas stream to the inlet of the primary synthesis zone by which the level of inert gases in the hydrogen-rich gas stream therefrom is increased and (4) purging a portion of the hydrogen-rich gas stream from the process cycle to maintain the inert gas level in the recycled hydrogen-rich gas stream below preselected maximum limits, the improvement comprising:
- (a) raising the pressure of a second hydrogen-containing gaseous stream at a lower pressure than the purge stream by combining the two streams and feeding the combined streams to a hydrogen-enrichment zone;
- (b) raising the hydrogen concentration of the combined stream by removing inert gaseous materials therefrom in the hydrogen-enrichment zone;
- (c) adjusting the hydrogen to carbon oxide molar ratio of the hydrogen-enriched gas stream from which inert gases have been removed to a level of between about 2:1 and about 12:1 by addition of a carbon oxide thereto;
- (d) catalytically converting the carbon oxide-adjusted hydrogen-enriched gas stream in a secondary methanol synthesis zone at a pressure no higher than the pressure in the primary synthesis zone to form an effluent comprising a mixture of methanol, water and unreacted gases;
- (e) maintaining the temperature within the secondary synthesis zone at a level below which any substantial methanation occurs by indirect transfer of heat from the secondary synthesis zone effluent to the carbon oxide-adjusted hydrogen-enriched gaseous feed thereto;
- and
- (f) separating methanol and water from the secondary synthesis zone effluent.
Dependencies are inferred from the claim text.