![]() As developed by Shell, this process produces MMA in one step reaction with 99% yield with a catalyst derived from palladium acetate, phosphine ligands, and Bronsted acids as catalyst: CH≡CCH 3 + CO + CH 3OH → CH 2=C(CH 3)CO 2CH 3 Isobutylene routes Using Reppe chemistry, methyl acetylene is converted to MMA. Metal oxides catalyse this process: (CH 3) 2CHCO 2H + O → CH 2=C(CH 3)CO 2H + H 2O Methyl acetylene (propyne) process Oxidative dehydrogenation of the isobutyric acid yields methacrylic acid. Air oxidation of methacrolein to methacrylic acid completes the synthesis of the acid: CH 3CH 2CHO + HCHO → CH 2=C(CH 3)CHO + H 2O CH 2=C(CH 3)CHO + 1⁄ 2 O 2 → CH 2=C(CH 3)CO 2H From isobutyric acid Īs developed by Atochem and Röhm, isobutyric acid is produced by hydrocarboxylation of propene, using HF as a catalyst:ĬH 2=CHCH 3 + CO + H 2O → (CH 3) 2CHCO 2H Other routes to MMA Via propionaldehyde Įthylene is first hydroformylated to give propanal, which is then condensed with formaldehyde to produce methacrolein, The condensation is catalyzed by a secondary amine. This process plant was cheaper to build and run than conventional systems, produces virtually no waste and the feedstocks can even be made from biomass. In 2008, Lucite International commissioned an Alpha MMA plant on Jurong Island in Singapore. The separated streams are returned to the process there being only a small heavy ester purge stream, which is disposed of in a thermal oxidizer with heat recovered for use in the process. MMA (>99.9%) is purified by vacuum distillations. Unreacted MeP and water are recycled via the formaldehyde dehydration process. The reactor product stream is separated in a primary distillation so that a crude MMA product stream, free from water, MeP and formaldehyde, is produced. The coke is easily removed and catalyst activity and selectivity restored by controlled, in-situ regeneration. The formation of a small amount of heavy, relatively involatile compounds poisons the catalyst. This catalyst, caesium oxide on silica, achieves good selectivity to MMA from MeP. The reaction of MeP and formaldehyde takes place over a fixed bed of catalyst. In a second set of reactions, MeP is condensed with formaldehyde in a single heterogeneous reaction step to form MMA: CH 3CH 2CO 2CH 3 + CH 2O → CH 3(CH 2)CCO 2CH 3 + H 2O ![]() The MeP synthesis is conducted in a continuous-stirred tank reactor at moderate temperature and pressure using proprietary agitation and gas-liquid mixing arrangement. The first stage involves carboalkoxylation of ethylene to produce methyl propionate (MeP): C 2H 4 + CO + CH 3OH → CH 3CH 2CO 2CH 3 The economics of the ACH route have been heavily optimized. ![]() This technology affords more than 3 billion kilograms per year. Disposal of this salt is energy intensive. (CH 3) 2C(OSO 3H)C(O)NH 2 + CH 3OH → CH 2 =C(CH 3)C(O)OCH 3 + NH 4HSO 4Īs indicated in the last reaction, each kilogram of methyl methacrylate produced yields roughly 1.1 kg of ammonium hydrogen sulfate. The sulfate ester is then methanolyzed (reacted with methanol): H 2SO 4), which is removed in a cracking step. In fact the sulfate ester of the amide is initially produced as an adduct with sulfuric acid ((CH 3) 2C(OSO 3H)C(O)NH 2. Although widely used, the ACH route coproduces substantial amounts of ammonium sulfate. Methanolysis of this ester gives ammonium bisulfate and MMA. The cyanohydrin is hydrolyzed in the presence of sulfuric acid to a sulfate ester of the methacrylamide. ACH is produced by condensation of acetone and hydrogen cyanide. The compound is manufactured by several methods, the principal one being the acetone cyanohydrin (ACH) route. Two principal routes appear to be commonly practiced. Given the scale of production, many methods have been developed starting from diverse two- to four-carbon precursors. This colorless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA). Methyl methacrylate ( MMA) is an organic compound with the formula CH 2=C(CH 3)COOCH 3.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |