Process for purification of products

Inventors

Gillespie, Ralph • Kocal, Michelle • Allen, Wyatt Eric • Rosin, Richard R • Tran, Donovan

Assignees

Lanzatech Inc

Abstract

The disclosure is directed to an apparatus and method for recovering ethanol from a fermentation broth. The fermentation broth comprises microbial biomass, ethanol, methanol, ethyl acetate, at least one thiol, and at least one compound having 3 or more carbon atoms. The method comprises separating at least microbial biomass from the fermentation broth to generate a process stream; removing, in any order, from the process stream: ethyl acetate by reacting ethyl acetate with a base compound followed by distillation; at least one thiol by adsorption or reaction to disulfide; methanol by distillation; compounds having 3 or more carbon atoms by distillation; and recovering ethanol by distillation; wherein the distillations may be conducted in a single column or two or more columns.

Core Innovation

The invention concerns a composition comprising at least one fermentation product recovered from a fermentation broth comprising microbial biomass, at least one fermentation product, and at least two by-products, where at least one of the by-products is a thiol. The recovery includes separating at least microbial biomass from the fermentation broth to generate a process stream comprising the at least one fermentation product and the at least two by-products.

The fermentation product is recovered from the process stream by a combination of reaction of at least one of the two by-products, distillation, and adsorption. In this context, thiol by-products are addressed as part of the recovery sequence, and other by-products are separated as part of the combined approach using distillation and adsorption.

The process is directed to recovering high-purity ethanol from a fermentation broth containing microbial biomass and components including ethanol, methanol, ethyl acetate, thiols, and at least one C3+ compound. After biomass separation, ethyl acetate is removed by alkaline hydrolysis followed by distillation, thiols are removed by adsorption and/or conversion to disulfides, and methanol and C3+ compounds are removed by distillation in one or multiple columns with distillation sequencing optionally varied.

Additional recovery steps are described for impurities, including optional reducing of acetaldehyde to acetate and/or aldehydes to alcohols using metals or reactive metals, along with adsorbent polishing for additional impurities. Further impurity control may include removal of fusel oils and sulfur species via distillation side draws, and residual ethanol may be dehydrated using membranes or PSA with an inert atmosphere used to avoid unwanted acetaldehyde formation.

Claims Coverage

The claims cover recovery of a fermentation product from a fermentation broth containing microbial biomass and multiple by-products, with inventive features based on forming a biomass-depleted process stream and separating the fermentation product using a combined approach of reacting thiol by-products, distillation, and adsorption. The independent claim includes three principal inventive aspects, and dependent claims further narrow the fermentation product to gas fermentation and specify by-product types including methanol and a C3+ compound.

Overall, the claims emphasize a recovery scheme where microbial biomass is separated to form a process stream, and the fermentation product is recovered using a combination of reacting a by-product, distillation, and adsorption; further claim scope narrows the fermentation product to gas fermentation derived from syngas and specifies by-product types including methanol and a C3+ compound.

Stated Advantages

Documented Applications