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Title: Recovery of propylene glycol from dilute aqueous solutions via reversible reaction with aldehydes

Abstract

A means is proposed for separating propylene glycol and other compounds bearing multiple hydroxyl groups by reversible chemical reaction. Glycols react with aldehydes in cyclic acetalization reactions to form substituted dioxolanes. Propylene glycol reacts with formaldehyde and acetaldehyde to form 4-methyl-1,3-dioxolane and 2,4-dimethyl-1,3-dioxolane. The reaction is catalyzed homogeneously by strong mineral acids or heterogeneously by cation exchange resins in the acid form. Separation processes utilizing this reaction would include an acetalization step, several distillative separation steps and finally a hydrolysis step in which the reaction is reversed. Both reaction steps must be forced to completion by removing the reaction product simultaneously. The equilibrium and kinetics of the reaction with formaldehyde were studied experimentally in systems catalyzed by Amberlite IR-120 ion exchange resin. A number of solvents were screened for their ability to extract 2,4-dimethyl-1,3-dioxolane from aqueous solution. Aromatic hydrocarbons exhibited the highest distribution into the organic phase. To achieve an effective separation of propylene glycol from aqueous solution by combined reaction with formaldehyde and distillation, formaldehyde would have to be present in excess and would be difficult and costly to separate from the aqueous solution. In reactive distillation using acetaldehyde as a reactant this is not a problem. A largemore » flow of acetaldehyde would be necessary to recover the propylene glycol sufficiently in a distillative process. In a process combining reaction and extraction into an organic solvent this problem is avoided. Process simulation indicates the energy input of such a process is less than half of the energy required in a triple-effect evaporation process. This benefit is offset by higher capital costs and increased complexity in the reaction/extraction process.« less

Authors:
; ;  [1]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering
Publication Date:
Research Org.:
Lawrence Berkeley Lab., CA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10129183
Report Number(s):
LBL-35155
ON: DE94007499; TRN: 94:003228
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Dec 1993
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; GLYCOLS; MATERIALS RECOVERY; AQUEOUS SOLUTIONS; SEPARATION PROCESSES; ALDEHYDES; CHEMICAL REACTIONS; CHEMICAL REACTION KINETICS; HETEROGENEOUS CATALYSIS; HOMOGENEOUS CATALYSIS; DISTILLATION; ION EXCHANGE MATERIALS; ACTIVATION ENERGY; EVAPORATION; 400105; 400201; SEPARATION PROCEDURES; CHEMICAL AND PHYSICOCHEMICAL PROPERTIES

Citation Formats

Broekhuis, R R, Lynn, S, King, C J, and Lawrence Berkeley Lab., CA. Recovery of propylene glycol from dilute aqueous solutions via reversible reaction with aldehydes. United States: N. p., 1993. Web. doi:10.2172/10129183.
Broekhuis, R R, Lynn, S, King, C J, & Lawrence Berkeley Lab., CA. Recovery of propylene glycol from dilute aqueous solutions via reversible reaction with aldehydes. United States. doi:10.2172/10129183.
Broekhuis, R R, Lynn, S, King, C J, and Lawrence Berkeley Lab., CA. Wed . "Recovery of propylene glycol from dilute aqueous solutions via reversible reaction with aldehydes". United States. doi:10.2172/10129183. https://www.osti.gov/servlets/purl/10129183.
@article{osti_10129183,
title = {Recovery of propylene glycol from dilute aqueous solutions via reversible reaction with aldehydes},
author = {Broekhuis, R R and Lynn, S and King, C J and Lawrence Berkeley Lab., CA},
abstractNote = {A means is proposed for separating propylene glycol and other compounds bearing multiple hydroxyl groups by reversible chemical reaction. Glycols react with aldehydes in cyclic acetalization reactions to form substituted dioxolanes. Propylene glycol reacts with formaldehyde and acetaldehyde to form 4-methyl-1,3-dioxolane and 2,4-dimethyl-1,3-dioxolane. The reaction is catalyzed homogeneously by strong mineral acids or heterogeneously by cation exchange resins in the acid form. Separation processes utilizing this reaction would include an acetalization step, several distillative separation steps and finally a hydrolysis step in which the reaction is reversed. Both reaction steps must be forced to completion by removing the reaction product simultaneously. The equilibrium and kinetics of the reaction with formaldehyde were studied experimentally in systems catalyzed by Amberlite IR-120 ion exchange resin. A number of solvents were screened for their ability to extract 2,4-dimethyl-1,3-dioxolane from aqueous solution. Aromatic hydrocarbons exhibited the highest distribution into the organic phase. To achieve an effective separation of propylene glycol from aqueous solution by combined reaction with formaldehyde and distillation, formaldehyde would have to be present in excess and would be difficult and costly to separate from the aqueous solution. In reactive distillation using acetaldehyde as a reactant this is not a problem. A large flow of acetaldehyde would be necessary to recover the propylene glycol sufficiently in a distillative process. In a process combining reaction and extraction into an organic solvent this problem is avoided. Process simulation indicates the energy input of such a process is less than half of the energy required in a triple-effect evaporation process. This benefit is offset by higher capital costs and increased complexity in the reaction/extraction process.},
doi = {10.2172/10129183},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1993},
month = {12}
}