Effect of phosphorus on the activity of Cu/SiO 2 catalysts in the hydrogenolysis of glycerol

Copper Phosphinate Complexes as Molecular Precursors for Ethanol Dehydrogenation Catalysts

Nowadays, the production of acetaldehyde heavily relies on the petroleum industry. Developing new catalysts for the ethanol dehydrogenation process that could sustainably substitute current acetaldehyde production methods is highly desired. Among the ethanol dehydrogenation catalysts, copper-based materials have been intensively studied. Unfortunately, the Cu-based catalysts suffer from sintering and coking, which lead to rapid deactivation with time-on-stream. Phosphorus doping has been demonstrated to diminish coking in methanol dehydrogenation, fluid catalytic cracking, and ethanol-to-olefin reactions. This work reports a pioneering application of the well-characterized copper phosphinate complexes as molecular precursors for copper-based ethanol dehydrogenation catalysts enriched with phosphate groups (Cu-phosphate/SiO2). Three new catalysts (CuP-1, CuP-2, and CuP-3), prepared by the deposition of complexes {Cu(SAAP)}n (1), [Cu6(BSAAP)6] (2), and [Cu3(NAAP)3] (3) on the surface of commercial SiO2, calcination at 500 °C, and reduction in the stream of the forming gas 5% H2/N2 at 400 °C, exhibited unusual properties. First, the catalysts showed a rapid increase in catalytic activity. After reaching the maximum conversion, the catalyst started to deactivate. The unusual behavior could be explained by the presence of the phosphate phase, which made Cu2+ reduction more difficult. The phosphorus content gradually decreased during time-on-stream, copper was reduced, and the activity increased. The deactivation of the catalyst could be related to the copper diffusion processes. The most active CuP-1 catalyst reaches a maximum of 73% ethanol conversion and over 98% acetaldehyde selectivity at 325 °C and WHSV = 2.37 h-1.

Hydrogenolysis of Glycerol on the ZrO2-TiO2 Supported Pt-WOx Catalyst

A series of Pt/WOx-ZrO2-TiO2 catalysts with different Ti/Zr molar ratios was prepared by an evaporation induced self-assembly method, and used to efficient hydrogenolysis of glycerol to 1-PO and 1,3-PDO. BET, XRD, Raman, TEM, XPS and Py-IR were employed to characterize the physicochemical properties of the catalysts. The structural and acidic properties of the catalysts were affected by the Ti/Zr ratio of the support ZrO2-TiO2. Two new crystalline phases of ZrTiO4 and Ti2ZrO6 and the amount of acid sites were detected in the Pt/WOx-ZrO2-TiO2 catalysts. 1-PO is dominant in all products of glycerol hydrogenolysis over the supported Pt-WOx catalysts, which is attributed to more Lewis acid sites on the catalyst surface. The Pt/WOx-ZrO2-TiO2 catalyst with a Ti/Zr ratio of 7/3 showed the highest 1,3-PDO yield (25.3%) and 1-PO yield (42.3%), due to its more acid sites including Brønsted and Lewis, and higher concentration of surface Pt0.

Thermal Modification Effect on Supported Cu-Based Activated Carbon Catalyst in Hydrogenolysis of Glycerol

Glycerol hydrogenolysis to 1,2-propanediol (1,2-PDO) was performed over activated carbon supported copper-based catalysts. The catalysts were prepared by impregnation using a pristine carbon support and thermally-treated carbon supports (450, 600, 750, and 1000 °C). The final hydrogen adsorption capacity, porous structure, and total acidity of the catalysts were found to be important descriptors to understand catalytic performance. Oxygen surface groups on the support controlled copper dispersion by modifying acidic and adsorption properties. The amount of oxygen species of thermally modified carbon supports was also found to be a function of its specific surface area. Carbon supports with high specific surface areas contained large amount of oxygen surface species, inducing homogeneous distribution of Cu species on the carbon support during impregnation. The oxygen surface groups likely acted as anchorage centers, whereby the more stable oxygen surface groups after the reduction treatment produced an increase in the interaction of the copper species with the carbon support, and determined catalytic performances.

The route towards sustainable production of ethylene glycol from a renewable resource, biodiesel waste: a review

Ethylene glycol (EG) is a commodity chemical commercially produced via oxidation of the petrochemical-based resource, ethylene.

The promoter effect of Co on the catalytic activity of the Cu oxide active phase supported on Al2O3 in the hydrogenolysis of glycerol

The CuCo₂O₄ species formed by CoO addition on CuO/Al₂O₃ had a beneficial effect on the catalytic activity in the hydrogenolysis of glycerol.