Acrylic acid recovery process

Acrylic Acid Recovery. The process flow sheet (Fig. 3) shows equipment and conditions for the separations step. The acryUc acid is extracted from the absorber effluent with a solvent, such as butyl acetate, xylene, diisobutyl ketone, or mixtures, chosen for high selectivity for acryUc acid and low solubihty for water and by-products. The extraction is performed using 5—10 theoretical stages in a tower or centrifiigal extractor (46,61—65). 

The bottoms from the solvent recovery (or azeotropic dehydration column) are fed to the foreruns column where acetic acid, some acrylic acid, and final traces of water are removed overhead. The overhead mixture is sent to an acetic acid purification column where a technical grade of acetic acid suitable for ester manufacture is recovered as a by-product. The bottoms from the acetic acid recovery column are recycled to the reflux to the foreruns column. The bottoms from the foreruns column are fed to the product column where the glacial acrylic acid of commerce is taken overhead. Bottoms from the product column are stripped to recover acrylic acid values and the high boilers are burned. The principal losses of acrylic acid in this process are to the aqueous raffinate and to the aqueous layer from the dehydration column and to dimerization of acrylic acid to 3-acryloxypropionic acid. If necessary, the product column bottoms stripper may include provision for a short-contact-time cracker to crack this dimer back to acrylic acid (60). 

The potential exists for obtaining a higher purity acetonitrile product with lower recovery and purification costs, since the number and amount of coproducts are less with ethane ammoxidation than with the propylene ammoxidation process. The latter produces acrylonitrile, HCN, acrylic acid, and acrolein in addition to acetonitrile. 

Resin Recovery Process. Typically, the polymer is recovered by the addition of coagulants which destabilize the ABS latex. Different coagulants are used depending on the surfactant. Thus, strong and weak acids work well with fatty acid soaps, and metal salts are used with acid stable soaps (106). The use of nonionic coagulants has also been reported (107,108). Acrylic latices have been... 

The first large scale application of ion exchange to effluent treatment was in the recovery of water, ammonia, and basic copper sulfate from the waste streams encountered in the cuprammonium rayon process. Originally a phenolic type condensation resin was employed, but more recently carboxylic acid acrylic-based exchangers have been introduced. A similar process exists for zinc recovery from the spinning acids of viscose rayon plants, except that in this operation a sulfonic acid resin is employed. 

Biochemical Processing. Potential ELM applications in biochemical processing (44) include the separation of aminoacids (L-phenylalanine), biochemicals (acrylic and propionic acids), and antibiotics (penicillin G) from fermentation broths. A typical ELM system for the recovery of L>phenylalanine from fermentation broths is given in Table DC (45,46). The recovery from a broth containing 12-35 g/L of L-phenylalanine can be about 80% with a single batch extraction. Hong et al. (45) obtained a recovery of about 99% with four serial batch extractions in simulating their proposed continuous process with mixer-settler extractors. 

---