PROCESSES FOR BIOCONVERTING SYNGAS TO OXYGENATED HYDROCARBONACEOUS COMPOUNDS

摘要

Continuous processes for the anaerobic bioconversion of syngas to oxygenated hydrocarbonaceous products, in particular lower alkanols, are disclosed in which nutrients, including micronutrients, and lower carboxylate anion are recovered from at least a portion of an aqueous distillation fraction from a distillation unit operation to recover lower alkanols by using a “tight” ultrafiltration membrane. At least about 75 percent of the water permeates the ultrafiltration membrane. The tight ultrafiltration membrane rejects sufficient components that are adverse to the microorganisms used in the bioconversion that continuous fermentation operations over long durations can be achieved.

主权项

1. A continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen and carbon dioxide in an aqueous broth containing microorganisms suitable for converting said substrate to oxygenated hydrocarbonaceous compound, which process comprises:
a. continuously contacting said gas substrate with said aqueous broth under acidic, anaerobic fermentation conditions including the presence of nutrients to bioconvert gas substrate to oxygenated hydrocarbonaceous compounds and provide a oxygenated hydrocarbonaceous compound-containing broth and a depleted gas phase, said anaerobic fermentation conditions also producing an co-produced, lower carboxylate anion and metabolites adverse to said microorganisms; b. continuously withdrawing the depleted gas phase from said aqueous broth; c. continuously or intermittently withdrawing a portion of said broth for recovery of said oxygenated hydrocarbonaceous compound, said withdrawal being sufficient to maintain the oxygenated hydrocarbonaceous compound in said broth below a concentration that unduly adversely affects the microorganisms; d. continuously separating by distillation oxygenated hydrocarbonaceous compound from the withdrawn portion of said broth to provide at least one fraction rich in said at least one oxygenated hydrocarbonaceous compound and an aqueous distillation fraction containing said at least one co-produced carboxylate anion and said adverse metabolites, wherein said distillation denatures said broth and generates free proteins; e. optionally recycling a portion of the aqueous distillation fraction to step (a); f. subjecting at least a portion of the aqueous distillation fraction to ultrafiltration to permeate at least about 75 percent of the water contained in said portion, said ultrafiltration using an ultrafiltration membrane having a cut-off in the range of between about 750 and 8000 Daltons to provide a permeate; and g. recycling the permeated water of step (f) to step (a).