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Mn–Al and Mg–Mn–Al hydrotalcite-like compounds (HTlcs) were synthesized by a coprecipitation method. The activity of the calcined HTlcs for hydrogenation of methyl benzoate to benzaldehyde was tested. The effects of Mn/Al and Mg/Mn ratio, preparation and reaction conditions, and potassium promoter on the catalytic performance of the catalysts were investigated. The prepared catalysts give better performance than conventional 10% Mn/γ-Al2O3 catalyst. The conversion of methyl benzoate and selectivity to benzaldehyde on 3% K/Mg0.2Mn1.8Al1 catalyst at 390 °C are 90.0 and 88.0%, respectively. XRD, TPR and CO2-TPD studies show that the redox and basic properties of the catalysts play important roles in the reaction. A suitable degree of reduction and a small number of basic sites on the catalyst lead to a high activity and selectivity to benzaldehyde. [Copyright &y& Elsevier]

Abstract: The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). Due to the strong interaction between Ni2+ and –COOH, PAA-g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated with Ni nanoparticles (Ni-MWNTs) for α, β-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC). [Copyright &y& Elsevier]

Abstract: The effect of alkali species on performance of MnO/γ-Al2O3 catalysts for methyl benzoate hydrogenation was investigated in fixed-bed reactor. Doping alkali species on MnO/γ-Al2O3 catalysts enhanced the selectivity of benzaldehyde significantly, toluene and benzyl methyl ether were greatly suppressed. The infrared spectra of adsorbed pyridine adsorption was acquired to study the surface acid properties, the results revealed that doping alkali species weakened the acid strength of MnO/γ-Al2O3 catalysts, which lead to restrain from the formation of toluene and benzyl methyl ether. [Copyright &y& Elsevier]

Abstract: Pt was introduced into pure and polyacrylic acid (PAA) grafting multi-walled carbon nanotubes (MWNTs) by electroless metal deposition method and used as catalysts for hydrogenation of citral. The catalysts exhibited higher activity in the hydrogenation of citral when compared with Pt impregnated active carbon (AC) catalyst, while the selectivity of the catalysts on different MWNTs supports were quite different. The catalyst characterization results reveal that the selectivity of products is related with the morphology of the MWNTs and Pt(111) facet, functionalized carbon nanotubes will orient Pt facet and facilitate its dispersion on support. [Copyright &y& Elsevier]