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A highly efficient and stable Cu/SiO2 catalyst was prepared via 12-crown-4-ether (12C4)-assisted impregnation and used in the vapor-phase conversion of glycerol to 1,2-propanediol (propylene glycol, PG) via acetol formation in an ambient hydrogen flow. The 12C4-Cu/SiO2 catalyst gave a PG yield of >97% due to a low rate of C-C cleavage to generate ethylene glycol. Under optimum conditions, the high catalytic performance was maintained for 98 h of time on stream. [ABSTRACT FROM AUTHOR]

Silica-supported Cu (Cu/SiO2) catalyst prepared by using organic additive-assisted impregnation was employed for the chemoselective hydrogenation of a C=O bond in 6-methyl-5-hepten-2-one (1) to produce 6-methyl-5-hepten-2-ol (2) in a vapor phase at a temperature between 140 and 200 °C and an ambient pressure of H2 flow. The Cu was responsible for the selectivity to 2, and the organic additive increased the Cu surface area (SACu), which consecutively enhanced the performance of the Cu/SiO2 catalyst. The proportional correlation between the SACu and the formation rate of 2 further confirmed the benefits of the utilization of organic additives during the impregnation protocol. [ABSTRACT FROM AUTHOR]

Global supply of 1,3-butadiene (abbreviated as BD) is faced with problems such as unstable price of petrochemicals and variation of chemical feedstock in recent years. Many research works have been conducted to produce BD from some renewable resources instead of petroleum. Among them, biomass-derived C4 alcohols such as 1,3-butanediol (1,3-BDO), 2,3-butanediol (2,3-BDO), and 1,4-butanediol (1,4-BDO) have been considered as alternative resources to produce BD. Direct dehydration of butanediols (BDOs) into BD, however, needs high reaction temperatures while the dehydration into their corresponding unsaturated alcohols (UOLs) such as 3-buten-2-ol (3B2OL), 2-buten-1-ol (2B1OL), and 3-buten-1-ol (3B1OL) proceeds at rather low temperatures over specific catalysts. The latter step of BDO dehydration, dehydration of UOLs to BD, is readily catalyzed by solid acids even at lower temperatures than those at which BDOs are dehydrated completely. Thus, efficient formation of UOLs from BDOs would be a key process to produce BD with high selectivity. We summarize the BD production from C4 alcohols as well as the dehydration of BDOs to UOLs, in addition to the BD production via ethanol dimerization. [ABSTRACT FROM AUTHOR]

Vapor-phase catalytic dehydration of 2,3-butanediol (2,3-BDO) was investigated over rare earth oxide (REO) catalysts as well as In2O3. In the dehydration of 2,3-BDO, 3-buten-2-ol (3B2OL) was produced together with 3-hydroxy-2-butanone (3H2BO), butanone (MEK), 2-methylpropanal (IBA), 2-methyl-1-propanol (IBO), etc. Sc2O3 and In2O3 showed higher 3B2OL selectivities than other REOs. In particular, Sc2O3 converted 2,3- BDO into 3B2OL with an excellent selectivity of 85.0% at 99.9% conversion. [ABSTRACT FROM AUTHOR]

Vapor-phase catalytic dehydration of 1,2-propanediol was investigated over several solid acid catalysts, such as alumina, silica-alumina, HY zeolite, and β-zeolite. These acids catalyzed the dehydration of 1,2-propanediol to produce propanal (Figure 1), while zeolites were particularly deactivated because of deposition of carbonaceous species. An amorphous silica-alumina was modified with metals such as Ag and Cu to stabilize the catalytic activity under hydrogen flow conditions. Ag-modified silica-alumina is a promising catalyst for the production of propanal from 1,2-propanediol. [ABSTRACT FROM AUTHOR]

In the vapor-phase synthesis of 2,3-dimethyl-1,3-butadiene from pinacolone over modified alumina catalysts, it was found that alumina modified with transition metals such as Co stabilized the conversion of pinacolone and produced 2,3-dimethyl-1,3-butadiene selectively under hydrogen flow conditions, whereas the catalytic activity of pure alumina was seriously deteriorated irrespective of its high initial activity. [ABSTRACT FROM AUTHOR]

Silica-supported silver exhibited high catalytic activity in the dehydration of glycerol: glycerol was dehydrated into hydroxyacetone with the selectivity higher than 86% at 91% conversion over Ag/SiO2 in H2 flow at 240°C. Silver metal provides an active site and showed stable catalytic activity for the glycerol dehydration in H2 atmosphere, while the dehydration activity decreased in N2 atmosphere. The hydrogenation of hydroxyacetone into 1,2-propanediol and the decomposition to ethylene glycol did not proceed over silver. [ABSTRACT FROM AUTHOR]

Er2O3 nanorods were successfully prepared with hydro-thermal treatment without using organic additives such as surfactant, fatty acid, or alcohol. Er2O3 nanorods were obtained under high temperature and/or long reaction times. Er2O3 nanorods mainly exposed {440} and {400}facets on the surface. Er2O3 nanorods showed excellent catalytic activity compared to commercial Er2O3 nanoparticles in the dehydration of 1,4-butanediol to produce 3-buten-1-ol. [ABSTRACT FROM AUTHOR]