Process for the production of alcohols
View Patent ↗Process for producing C2+ alcohols from a methane-containing feedstock, by passing the methane-containing feedstock and CO 2 to a non-oxidative reforming process to produce a product stream containing CO, H 2 and CO 2 , optionally in the presence of steam, provided that where steam is present in the feed to the reforming process, the steam and CO 2 are present in a molar ratio of less than 5:1. The CO, H 2 and CO 2 stream is passed to a bacterial fermentation step where it is converted to a liquid product stream containing one or more C2+ alcohols and a gaseous product stream containing CO, H 2 and CO 2 . The fermentation step is operated to provide a conversion of CO of at least 60%. CO, H 2 and CO 2 are recycled from the gaseous product stream to the reforming process such that the H 2 reacts with carbon dioxide in the reforming process.
1. A process for the production of C2+ alcohols from a methane-containing feedstock, which process comprises:
(a) passing said methane-containing feedstock and carbon dioxide to a non-oxidative reforming process to produce a first product stream comprising CO, H 2 and CO 2 , optionally in the presence of steam, but with the proviso that where steam is present in the feed to the reforming process the steam and CO 2 are present in a molar ratio of less than 5:1,
(b) passing the first product stream comprising CO, H 2 and CO 2 to a bacterial fermentation step wherein it is converted to produce a second product stream comprising one or more C2+ alcohols in the liquid phase and a gaseous third product stream comprising CO, H 2 and CO 2 , the fermentation step being operated to provide a conversion of CO of at least 60%,
wherein CO, H 2 and CO 2 are recycled from the gaseous third product stream to the reforming process of step (a) wherein at least 80% of the CO and 80% of the CO 2 in the gaseous third stream are recycled to the reforming process, and wherein the H 2 reacts with carbon dioxide in the reforming process.
2. A process as claimed in claim 1 wherein the reforming process is dry-gas reforming or steam methane reforming.
3. A process as claimed in claim 2 wherein the reforming process is a sulphur passivated reforming.
4. A process as claimed in claim 1 wherein no specific separation of carbon monoxide from carbon dioxide in the product stream is performed prior to recycle.
5. A process as claimed in claim 1 wherein some of the hydrogen in the gaseous third product stream is separated and utilised as a fuel gas.
6. A process as claimed in claim 1 wherein, where steam is present, the steam:CO 2 molar ratio is <1:1.
7. A process as claimed in claim 1 wherein both the reforming and fermentation steps are operated at a pressure is in the range 2 to 12 barg.
8. A process as claimed in claim 1 wherein a purge is taken from the recycled stream to prevent build-up of inerts.
9. A process as claimed in claim 1 wherein the fermentation process uses acetogenic anaerobic bacteria.
10. A process as claimed in claim 9 wherein the bacteria is selected from Acetogenium kivui, Acetobacterium woodii, Acetoanaerobium noterae, Clostridium Aceticum, Butyribacterium methylotrophicum, Clostridium acetobutylicum, Clostridium thermoaceticum, Eubacterium limosum, Peptostreptococcus productus, Clostridium ljungdahlii and Clostridium carboxydivorans.
11. A process as claimed in claim 10 wherein the bacteria is Clostridium ljungdahlii.
12. A process as claimed in claim 11 wherein the Clostridium ljungdahlii strain is selected from Clostridium ljungdahlii PETC, Clostridium ljungdahlii ERI2, Clostridium ljungdahlii C01, Clostridium ljungdahlii 0-52.