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The role of the crystalline phase of Mo3VO x in the catalytic oxidation of allyl alcohol over four kinds of crystalline (orthorhombic, trigonal, tetragonal, amorphous) Mo3VO x catalysts was investigated to determine the active sites for the reactions. Tetragonal Mo3VO x was found less active for the formation of acrylic acid from allyl alcohol, although acrolein was obtained selectively at higher temperature. For orthorhombic and trigonal Mo3VO x catalyst, allyl alcohol converted to acrolein and propanal competitively at the mouth of the heptagonal channel over the a- b plane of the rod-type crystalline particles, and these aldehydes were oxidized consecutively to acrylic acid. Acrylic acid was formed effectively at increased reaction temperature over orthorhombic, trigonal and amorphous Mo3VO x catalysts, and the maximum yields of acrylic acid were 73 % for the orthorhombic Mo3VO x catalyst and 72 % for the trigonal Mo3VO x catalyst at 350 °C. [ABSTRACT FROM AUTHOR]

This study focuses on the effects of the localization of Co species, zeolite structure, and acidity on the performance of Co bifunctional catalysts promoted with Pt for the direct synthesis of iso-paraffins from syngas. ZSM-5, MOR, and BEA were chosen as zeolites with different structures and pore diameters. The catalysts were prepared either by incipient wetness impregnation or by the mechanical mixing of the zeolite with a conventional silica-supported Co catalyst. The increase in the pore size and open character of the zeolite structure from ZSM-5 to BEA resulted in a higher fraction of Co located inside the pores of the catalysts prepared by impregnation. The catalytic performance was affected strongly by the zeolite acidity, pore structure, and Co distribution between the pores and the external surface. The selectivity to short-chain iso-paraffins is affected principally by the zeolite acidity, whereas the selectivity to long-chain branched hydrocarbons mostly depends on steric effects. [ABSTRACT FROM AUTHOR]