摘要:
A process for converting a salt of a hydroxycarboxylic acid to an unsaturated carboxylic acid, or esters thereof. The process involves converting an ammonium salt of a hydroxycarboxylic acid in aqueous solution to a corresponding hydroxycarboxylic acid and ammonium cation in aqueous solution; and separating the ammonium cation from the aqueous solution, leaving the hydroxycarboxylic acid in aqueous solution. The converting and separating steps may be accomplished by employing a hydrophobic acid or an acid ion exchange resin, each of which must have an acid dissociation constant, i.e., pKa, at least 0.5 less that that of the salt of the hydroxycarboxylic acid. Where a hydrophobic acid is used, it must be immiscible in water, and its salt must also be immiscible in water, and the resulting multi-phase solution comprises an aqueous phase comprising the corresponding hydroxycarboxylic acid, as well as a non-aqueous phase comprising a neutralized acid. Alternatively, where the ion exchange resin is used, the aqueous solution of the ammonium salt of a hydroxycarboxylic acid is contacted with the resin, thereby converting the salt to a hydroxycarboxylic acid and capturing the ammonium cations on the resin. In either case, the aqueous solution is treated, such as by heating, to separate and recover the hydroxycarboxylic acid. The non-aqueous phase or resin is treated to separate and recover ammonia useful for preparing additional ammonium salt of a hydroxycarboxylic acid.
摘要:
The present invention relates to a process for producing acrolein by liquid phase dehydration of glycerol by preparing a mixture of a catalyst suspended in an organic solvent comprising one or more vinyl polymers and glycerol; and then mixing and heating the mixture to between 150° C. and 350° C. to dehydrate the glycerol and form acrolein. The vinyl polymers are selected from the group consisting of polyolefins, polystyrene, and mixtures thereof. The polyolefins may be polyethylene, polypropylene, polybutylene, polyisobutylene, polyisoprene, polypentene, or mixtures thereof. The acrolein may be subjected to vapor phase oxidation in the presence of a catalyst, such as a mixed metal oxide, to produce acrylic acid.