Acrylic acid Catalyst materials

Coating materials may be based on short or medium-oil alkyds (e.g. primers for door and window frames) nitrocellulose or thermoplastic acrylics (e.g. lacquers for paper or furniture finishes) amino resin-alkyd coatings, with or without nitrocellulose inclusions, but with a strong acid catalyst to promote low temperature cure (furniture finishes) two-pack polyurethanes (furniture, flat boards) unsaturated polyester resins in styrene with free-radical cure initiated by peroxides (furniture) or unsaturated acrylic oligomers and monomers cured by u.v. radiation or electron beams (coatings for record sleeves paperback covers, knock-down furniture or flush interior doors). 

As a chemical raw material, ethanol is used for the production of a range of monomers and solvents, and is essential in pharmaceutical purification. In the presence of an acid catalyst ethanol reacts with carboxylic acids to produce ethyl esters. The two largest-volume ethyl esters are ethyl acrylate (from ethanol and acrylic acid) and ethyl acetate (from ethanol and acetic acid). Ethyl acrylate is a... 

The important role Transmission Electron Microscopy (TEM) can play in this process is demonstrated on the development of an oxidation catalyst for the production of acrylic acid. Acrylic acid is produced by BASF in quantities of several 100.000 tons per year in a two step gas phase oxidation process starting from propene, which is oxidised to acrolein in the first step and then further oxidised to acrylic acid in a second step, each step requiring a special developed catalyst. Acrylic acid is used as a base material for the production of superabsorbents for nappies, dispersions and emulsions for adhesives and construction materials. 

A possible economically attractive alternative would be the production of acrylic acid in a single step process starting from the cheaper base material propane. In the nineteen nineties the Mitsubishi Chemical cooperation published a MoVTeNb-oxide, which could directly oxidise propane to acrylic acid in one step [6], Own preparations of this material yielded a highly crystalline substance. Careful analysis of single crystal electron diffraction patterns revealed that the MoVTeNb-oxide consists of two crystalline phases- a hexagonal so called K-Phase and an orthorhombic I-phase, which is the actual active catalyst phase, as could be shown by preparing the pure phases and testing them separately. 

A clear-cut molecular relay system is materialized with the combination of two nucleophile moieties such as hydroxamic acid and imidazole introduced in a polymer (38, 40, 82). Hydroxamate anion has a high nucleophilicity but deacylation of the acylhydroxamate is very slow. The significance of the deacylation step in the hydrolysis in polymer catalyst is pointed out in several works, for example, the deacylation of acetylated poly(4(5)-vinylimidazole) (83,84) and the aminolysis of nitrophenyl ester of poly(styrene-co-acrylic acid) (85—87). To promote the deacylation velosity of the acylated hydroxamic acid imidazole moiety is introduced in the hydroxamic acid-containing polymer. The polymers are shown in tire following page. 

Single-reaction-step processes have been studied. However, higher selectivity is possible by optimizing catalyst composition and reaction conditions for each of these two steps (40,41). This more efficient utilization of raw material has led to two separate oxidation stages in all commercial facilities. A two-step continuous process without isolation of the intermediate acrolein was first described by the Toyo Soda Company (42). A mixture of propylene, air, and steam is converted to acrolein in the first reactor. The effluent from the first reactor is then passed directly7 to the second reactor where the acrolein is oxidized to acrylic acid. The products are absorbed in water to give about 30—60% aqueous acrylic acid in about 80—85% yield based on propylene. 

The same technique can be used to dye a material that is otherwise difficult to dye. An ethylene-propylene copolymer rubber was reacted first with maleic anhydride, then with an aromatic amine dye in an extruder to produce a dyed rubber.81 Dye sites can also be inserted into polyolefins by grafting them with dimethylaminoethyl methacrylate, using azo or peroxide catalysts in an extruder.82 jV-Vinylimidazole has been grafted to polyethylene in an extruder with the help of dicumylperoxide.83 The product was mixed with an acrylic acid-modified polypropylene and used to compatibilize polyethylene and polypropylene. This could be helpful in the recycling of mixed polyolefins from municipal solid waste. Recycling of cross-linked (thermoset) polymers is more of a problem because they cannot be remelted in an extruder. However, they can be if... 

Poly(ethylene oxide) (PEO) has been employed frequently as a water-soluble catalyst support [9]. Further water-soluble polymers investigated include other linear polymers such as poly(acrylic acid) [10], poly(N-alkylacrylamide)s [11], and copolymers of maleic anhydride and methylvinylether [12], as well as dendritic materials such as poly(ethyleneimin) [10a, c] or PEO derivatives of polyaryl ethers [13]. The term dendritic refers to a highly branched, tree-like structure and includes perfectly branched dendrimers as well as statistically branched, hyperbranched macromolecules. 

Our work on latent biphasic systems has focused on linear polymers [165]. Initially these studies focused on poly(JV-alkylacrylamide)s like PNODAM because we had earlier shown that these lipophilic materials are very phase-selectively soluble in heptane [158,165]. This initial work used the PNODAM-bound SCS-Pd catalyst 116 in a DMA-heptane mixture with iodobenzene and acrylic acid as substrates and triethylamine as a base. This catalyst mixture was initially homogeneous at 25 On heating, Heck chemistry occurred to form cinnamic acid. Subsequent cooling of this reaction mixture formed a biphasic mixture even without addition of water because the reaction had formed some triethyl ammonium iodide, and this ammonium salt functioned as the perturbant. 

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