Acrylic acid metal supported

Transition metal oxides or their combinations with metal oxides from the lower row 5 a elements were found to be effective catalysts for the oxidation of propene to acrolein. Examples of commercially used catalysts are supported CuO (used in the Shell process) and Bi203/Mo03 (used in the Sohio process). In both processes, the reaction is carried out at temperature and pressure ranges of 300-360°C and 1-2 atmospheres. In the Sohio process, a mixture of propylene, air, and steam is introduced to the reactor. The hot effluent is quenched to cool the product mixture and to remove the gases. Acrylic acid, a by-product from the oxidation reaction, is separated in a stripping tower where the acrolein-acetaldehyde mixture enters as an overhead stream. Acrolein is then separated from acetaldehyde in a solvent extraction tower. Finally, acrolein is distilled and the solvent recycled. 

The metallic layers were examined either by conventional or cross-section TEM in a Jeol 200 Cx microscope. For the cross section preparation a sandwich of two laminates is made, glued face to face with an epoxy, cut in small pieces, mechanically polished, and then ion milled to a final TEM observation thickness. The plane section TEM sample are prepared by dissolving the PET in trifluoroacetic acid for 5 to 10 mn. The area observed, on plane section TEM, for the grain size calculation is close to 0.2 urn. For the adhesion measurements, test pieces consist of aluminum support (1 mm thick) double sided tape (Permacel P-94) PET (12pm) / evaporated aluminum/ ethylene acrylic acid (EAA) copolymer film. These laminates are prepared for the peel test by compression under 1.3 105 N.m2 at 120°C for 10 seconds. The peel test is performed by peeling the EAA copolymer sheet from the laminate in an INSTRON tensile tester at 180° peel angle and 5 cm min peel rate. 

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert silica or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acrylic acid were prepared from bismuth, cobalt, iron, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic silicic acids. Preferred second-stage catatysts generally7 are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity7 and productivity7 (39,45,46). 

Reaction over Base Catalysts. - The reaction of HCHO with acetic acid to form acrylic acid was studied by Vitcha and Sims using various supported metal hydroxides as catalysts. The best catalytic performances are obtained with alkaline earth metal cation exchanged Decalso (a synthetic sodium alimonosilicate), though silica-supported hydrox-... 

Pearson also reported that the reaction over silica-supported alkali metal hydroxide catalysts is promoted markedly by the presence of water in the range of water/HCHO molar ratio = 1 to 5. With an acetic acid/HCHO/water molar ratio of 4.9/1/2.7, an SV of 750 h and a temperature of 405 °C, the yield of acrylic acid reaches 41.4 mol% based on the charged HCHO (8.5 mol% based on acetic acid) at the conversion of 53% the selectivity to acrylic acid is 78 mol% based on HCHO. 

Gel-immobilized catalytic systems (GCS) represent swelled polymer composites in which active sites of the particular metal complex are inunobilized. Graft copolymers of ethylene-propylene rubber (EPRu) and ligands of 4-vinylpyridine, acrylic acid, vinylpyrrolidone, organophosphorus compounds etc. act as a polymeric supports (polymeric phases) [140]. The structure of metal complex sites immobilized in a polymer gel is presented by the following scheme ... 

New types of metal-containing polymers can be effectively produced 1 construction of polymer supports in the form of gels which, in use, are capable of swelling, insoluble in the reaction medium, but permeable to the molecules, substrate and solvent (23-25). they are based on ethylene-prcpylene rubbers and also ternary copolymers of ethylene, propylene and nonconjugated diene, siloxane rubbers with the radically grafted vinylpyridine, acrylic acid (AAc), methylmethacrylate (MMA), etc. Fu2 her cross-linking of the rubber base allows the syntheses of three-dimensional networks to avoid the dispersion of these particles in the reaction media. MX is bound within these networks. Such polymers were termed mosaic their structure is shown in Fig. 2. It is evident... 

Further, silica-supported poly-y-aminopropylsilane transition metal complexes derived from Ni(II), Cu(II) and Co(II) salts were probed in arylation reactions of acrylic acid (16), methyl acrylate (1) and styrene (2) using iodobenzene derivatives. The most efficient catalysis was again observed with the nickel-based recyclable catalyst [23,25]. 

Acetyl ligands, in niobium complexes, C-H BDEs, 1, 298 Achiral phosphines, on polymer-supported peptides, 12, 698 Acid halides, indium compound reactions, 9, 683 Acidity, one-electron oxidized metal hydrides, 1, 294 Acid leaching, in organometallic stability studies, 12, 612 Acid-platinum rf-monoalkynes, interactions, 8, 641 Acrylate, polymerization with aluminum catalysts, 3, 280 Acrylic monomers, lanthanide-catalyzed polymerization,... 

Another approach to the preparation of polymer-supported metal Lewis acids is based on polymerization of functional monomers. If synthesis of the functional monomer is not difficult, polymerization should afford structurally pure functional polymers, because the polymer formed requires no further complicated chemical modification. A variety of substituted styrene monomers are now commercially available styrene monomers with an appropriate ligand structure can be prepared from these. Several other interesting functional monomers such as glycidyl methacrylate, 2-hydr-oxyethyl methacrylate, and other acrylics have also been used extensively to prepare functional polymers. 

---