The invention provides a process for refining bio-based propylene glycol, wherein impurities having boiling points close to that of propylene glycol are separated. In this process, C.sub.5-C.sub.20 oleophilic alcohol compounds, C.sub.5-C.sub.20 alkanes and/or C.sub.4-C.sub.20 oleophilic ketone compounds are subjected to azeotropism as an azeotropic solvent together with the bio-based propylene glycol to obtain an azeotrope containing propylene glycol. Then the azeotropic solvent in the azeotrope is separated to obtain a crude propylene glycol which is further purified to obtain propylene glycol.

The invention provides a process for the separation of a diol from a product stream. The process includes the steps of: i) separating the product stream comprising three or more C2 to C6 diols, C3 to C6 sugar alcohols, and C4 to C6 polyhydric alcohols with at least 3 hydroxyl groups in the molecule, and a catalyst, to produce a first stream comprising the three or more C2 to C6 diols; ii) separating the first stream comprising the three or more C2 to C6 diols into a) a second stream comprising a first diol and unsaturated hydrocarbons and/or one or more compounds with a carbonyl group and b) a third stream comprising two or more diols; iii) hydrogenating the second stream comprising a first diol and unsaturated hydrocarbons and/or one or more compounds with a carbonyl group to provide a purified diol stream.

The invention provides a process for the separation of a diol from a product stream. The process includes the steps of: i) separating the product stream comprising three or more C2 to C6 diols, C3 to C6 sugar alcohols, and C4 to C6 polyhydric alcohols with at least 3 hydroxyl groups in the molecule, and a catalyst, to produce a first stream comprising the three or more C2 to C6 diols; ii) separating the first stream comprising the three or more C2 to C6 diols into a) a second stream comprising a first diol and unsaturated hydrocarbons and/or one or more compounds with a carbonyl group and b) a third stream comprising two or more diols; iii) hydrogenating the second stream comprising a first diol and unsaturated hydrocarbons and/or one or more compounds with a carbonyl group to provide a purified diol stream.

A system of concentrating and separating waste solvent liquid includes a distillation tower, an extracting distillation unit, an extract agent recovery unit, and a vapor permeation film unit. The scheme of centrifugal distillation is specifically employed to collocate with vapor permeation to effectively concentrate the content of isopropanol in the waste solvent liquid to generate a final produce with ultra high concentration of isopropanol, and constantly recovers the extract agent. The system is able to be quickly settled to a steady state of operation with low power consumption because the extracting distillation unit has smaller size. Since no liquid is left in the extract agent recovery unit, operation risk is greatly reduced. In addition, the input feed is almost processed, overall efficiency is thus improved. The vapor permeation film unit further removes considerably little content of water from the organic solvent to increase the content of isopropanol up to 99.9% or more.

A system of concentrating and separating waste solvent liquid includes a distillation tower, an extracting distillation unit, an extract agent recovery unit, and a vapor permeation film unit. The scheme of centrifugal distillation is specifically employed to collocate with vapor permeation to effectively concentrate the content of isopropanol in the waste solvent liquid to generate a final produce with ultra high concentration of isopropanol, and constantly recovers the extract agent. The system is able to be quickly settled to a steady state of operation with low power consumption because the extracting distillation unit has smaller size. Since no liquid is left in the extract agent recovery unit, operation risk is greatly reduced. In addition, the input feed is almost processed, overall efficiency is thus improved. The vapor permeation film unit further removes considerably little content of water from the organic solvent to increase the content of isopropanol up to 99.9% or more.

A system of concentrating and separating waste solvent liquid includes a distillation tower, an extracting distillation unit, an extract agent recovery unit, and a vapor permeation film unit. The scheme of centrifugal distillation is specifically employed to collocate with vapor permeation to effectively concentrate the content of isopropanol in the waste solvent liquid to generate a final produce with ultra high concentration of isopropanol, and constantly recovers the extract agent. The system is able to be quickly settled to a steady state of operation with low power consumption because the extracting distillation unit has smaller size. Since no liquid is left in the extract agent recovery unit, operation risk is greatly reduced. In addition, the input feed is almost processed, overall efficiency is thus improved. The vapor permeation film unit further removes considerably little content of water from the organic solvent to increase the content of isopropanol up to 99.9% or more.

A system of concentrating and separating waste solvent liquid includes a distillation tower, an extracting distillation unit, an extract agent recovery unit, and a vapor permeation film unit. The scheme of centrifugal distillation is specifically employed to collocate with vapor permeation to effectively concentrate the content of isopropanol in the waste solvent liquid to generate a final produce with ultra high concentration of isopropanol, and constantly recovers the extract agent. The system is able to be quickly settled to a steady state of operation with low power consumption because the extracting distillation unit has smaller size. Since no liquid is left in the extract agent recovery unit, operation risk is greatly reduced. In addition, the input feed is almost processed, overall efficiency is thus improved. The vapor permeation film unit further removes considerably little content of water from the organic solvent to increase the content of isopropanol up to 99.9% or more.

Provided is a process for hydrating and oligomerizing a hydrocarbon feed comprising mixed olefins, by contacting the feed with water and a catalyst in a fixed bed reactor, wherein the catalyst hydrates mixed olefins to mixed alcohols and oligomerizes mixed olefins into oligomers; introducing the resulting stream into a first separator that separates an organic phase from an aqueous phase; introducing the organic phase into a second separator that separates unreacted olefins from mixed alcohols/oligomers; introducing the aqueous phase into a third separator that separates an alcohol-water azeotrope from water; introducing the second stream into a fourth separator that separates sec-butyl alcohol to produce a third stream comprising mixed butanols and oligomers and an SBA stream; f) mixing the third stream and a first portion of the SBA stream to produce a final product stream; and g) recycling a second portion of the SBA stream to the second separator.

Provided is a process for hydrating and oligomerizing a hydrocarbon feed comprising mixed olefins, by contacting the feed with water and a catalyst in a fixed bed reactor, wherein the catalyst hydrates mixed olefins to mixed alcohols and oligomerizes mixed olefins into oligomers; introducing the resulting stream into a first separator that separates an organic phase from an aqueous phase; introducing the organic phase into a second separator that separates unreacted olefins from mixed alcohols/oligomers; introducing the aqueous phase into a third separator that separates an alcohol-water azeotrope from water; introducing the second stream into a fourth separator that separates sec-butyl alcohol to produce a third stream comprising mixed butanols and oligomers and an SBA stream; f) mixing the third stream and a first portion of the SBA stream to produce a final product stream; and g) recycling a second portion of the SBA stream to the second separator.

Provided is a process for hydrating and oligomerizing a hydrocarbon feed comprising mixed olefins, by contacting the feed with water and a catalyst in a fixed bed reactor, wherein the catalyst hydrates mixed olefins to mixed alcohols and oligomerizes mixed olefins into oligomers; introducing the resulting stream into a first separator that separates an organic phase from an aqueous phase; introducing the organic phase into a second separator that separates unreacted olefins from mixed alcohols/oligomers; introducing the aqueous phase into a third separator that separates an alcohol-water azeotrope from water; introducing the second stream into a fourth separator that separates sec-butyl alcohol to produce a third stream comprising mixed butanols and oligomers and an SBA stream; f) mixing the third stream and a first portion of the SBA stream to produce a final product stream; and g) recycling a second portion of the SBA stream to the second separator.