Hydrogenation Of Methyl Acrylate Research Articles

Effect of Carbon Modification on Properties of NiMo/γ-Al2O3 and Its Catalytic Performance in the Hydrogenation of Methyl Acrylate

Effect of Carbon Modification on Properties of NiMo/γ-Al₂O₃ and Its Catalytic Performance in the Hydrogenation of Methyl Acrylate

Preparation of methyl acrylate from methyl acetate and methanol with mild catalysis of cobalt complex

The activation and selectivity are the challenging problems always existing in the utilization of methanol as C1 resource. Herein, a novel cobalt complex catalyzed process for preparation of methyl acrylate from methyl acetate and methanol at 50 °C–80 °C was firstly developed. Such cobalt complex stabilized with a PN5P-type pincer ligand, which can be easily prepared in gram scale, has high catalytic performance with the loading amount of only 5 mol.%. Systematic mechanism investigation revealed the cobalt complex activated by sodium methoxide via salt elimination could simultaneously interact with and catalyze the dehydrogenation of two-fold methanol into formaldehyde, followed by proceeding aldol condensation with methyl acetate in the presence of sodium methoxide. Besides the reaction atmosphere of O2 was proved to be crucial for preventing the further hydrogenation of methyl acrylate into methyl propionate. Also, the mechanism-based kinetic model indicated the dehydrogenation of methanol was rate-controlling step with the activation energy of 89.0 ± 1.1 kJ/mol.

Further insight in the minor/major concept using hydrogen pressure effect in asymmetric hydrogenation

The catalytic system prepared from [Rh(COD)2]BF4 and (R,R)-Me-BPE provides a spectacular detrimental hydrogen pressure effect on ee from 94% down to 56% in the hydrogenation of methylacrylate, whereas it has a strong beneficial effect on the hydrogenation of E-emap (from 42% up to 72%). The kinetic parameters have been determined for both systems and have helped to identify the most enantioselective controlling steps (MECS). Accordingly, further explanations for the structure-ee and hydrogen pressure relationship are proposed.

Facile Fabrication of Nanoparticles in the Nanospace of Ultrathin TiO2-Gel Films: Composition, Morphology and Catalytic Activity

ABSTRACTIn this article, we present in-situ synthesis of nanoparticles of various compositions and morphologies in the nanospace of ultrathin TiO2-gel films using low temperature H2 and O2 plasmas as reductant and oxidant, respectively. Parameters that influence the formation of nanoparticles were investigated and discussed. Reversible chemical transformation was found to give monodisperse nanoparticles. Catalytic activities of Pd monometallic and Ag-core/Pd-shell bimetallic nanoparticles were tested for hydrogenation of methyl acrylate. The much enhanced catalytic activity is attributed mainly to a large ratio of the surface Pd atoms.

Effect of quantity of polymer on catalysis and superstructure size of polymer-protected Pt nanoclusters

Platinum nanoclusters protected by poly(N-vinyl-2-pyrrolidone) (PVP) were prepared by ethanol reduction of hexachloroplatinic(IV) acid in the presence of PVP. The PVP-protected platinum nanoclusters, prepared at various mole ratios of PVP to platinum, were characterized by transmission electron microscopy (TEM), atomic force microscopy and the Taylor dispersion method. Hydrogenation of methyl acrylate in ethanol under 1 atm of hydrogen at 30°C was used for evaluation of the catalytic activities, revealing that the catalytic activity of platinum nanoclusters depends on the superstructure size of the PVP-protected nanoclusters in dispersion, which can be estimated on the basis of measurements by TEM and the Taylor dispersion method.

Promotion effect of lanthanoid ions on catalytic activity of polymer-immobilized palladium nanoparticles

Hydrogenation of acrylic acid was catalyzed by the Pd nanoparticles protected by lanthanoid polyacrylate (PAA-Pd-Ln). In comparison with the case without lanthanoid ions (Ln 3+), the hydrogenation rate was accelerated by Ln 3+ and independent of the concentration of substrate. These results indicate that Ln 3+ ions were concentrated so fast around the Pd nanoparticles by ion exchanging of Na + ions with the Ln 3+ ions in polyacrylate located near the Pd nanoparticles. This is also supported by the result that no promotion effect was observed when using PVP as a protective polymer, which has a weak coordination ability to Ln 3+ in place of polyacrylate. The promotion by Nd 3+ ions was observed in the PAA-Pd-catalyzed hydrogenation of methyl acrylate and allyl amine, but not of 1-hexene. This fact again indicates that the coordination of Ln3+ ions to the substrates containing an oxygen or a nitrogen atom(s) is an important factor for the promotion effect by Ln 3+. On the other hand, it was clarified from XPS and TPD measurements that the dissociative hydrogen adsorption on the surface of Pd nanoparticles can be accelerated by the presence of Ln 3+ ions, probably due to an electron transfer from Ln 3+ to Pd nanoparticles, although this is thought to contribute slightly to the present promotion effect.

Effects of chemical modification of supports on properties of tertiary amino resin dispersed palladium catalysts for the hydrogenation of methyl acrylate

Tertiary amino resins (TAR) were chemically modified by quaternization with methyl iodide. By this route six partly quaternized tertiary amino resins (PQTAR) with different I/N mole ratio were synthesized. Four different reducing agents, i.e., NaH, LiAlH4, CH3OH-NaOH and NaBH4, were tested for the preparation of palladium catalysts dispersed on TAR or PQTAR. The rate of hydrogenation of methyl acrylate and the amount of Pd leached from the catalysts during the hydrogenation reaction were found to be dependent not only on the type of reducing agent but also on the structure of polymer support. Both the rate of hydrogenation and the amount of Pd eluted closely relate to the I/N mole ratio of the polymer supports.

Hydroformylation and Hydrogenation of Methylacrylate in Presence of Dicobalt Octacarbonyl or Iron Pentacarbonyl. Dependence of Reaction Rate on Partial Pressures of Carbon Monoxide and Hydrogen

Abstract Hydroformylation of methylacrylate in the presence of dicobalt octacarbonyl was investigated by paying a special attention to the effect of varying ratios of carbon monoxide to hydrogen on the rate. The rate attains the maximum value at a certain partial pressure of carbon monoxide, and increases with the increasing partial pressure of hydrogen. The tendencies agree with the results obtained by G. Natta on the hydroformylation of cyclohexene. The rate equation proposed by A. R. Martin with respect to the rate of hydroformylation of di-isobutene can represent the tendencies observed in the present results. In the presence of iron pentacarbonyl, methylacrylate has been found to be reduced to methylpropionate under high pressure of hydrogen containing carbon monoxide. The reduction becomes more difficult with the increasing partial pressure of carbon monoxide, but was made catalytically neither by an iron catalyst reduced from iron oxide nor by the one produced by the thermal decomposition of iron pentacarbonyl.