The selective production of 1,3-propanediol from glycerol under mild reaction conditions is of high interest. The current work describes the use of a highly selective catalyst consisting of platinum supported on mordenite zeolite employed for the first time for vapor phase hydrogenolysis of glycerol to 1,3-propanediol under atmospheric pressure. The catalysts with varying Pt content (0.5−3 wt %) were prepared and thoroughly characterized by X-ray diffraction, temperature-programmed desorption of ammonia, FT-IR of adsorbed pyridine, CO chemisorptions, transmission electron microscopy, X-ray photoelectron spectroscopy, and BET surface area. The influence of reaction parameters has been studied to unveil the optimized reaction conditions. A high 1,3-propanediol selectivity (48.6%) was obtained over a 2 wt % Pt/H−mordenite catalyst at 94.9% glycerol conversion. According to the results obtained, the selectivity to 1,3-propanediol is better influenced by Pt dispersion and Brønsted acidity of the support. A plausible reaction mechanism has been presented. The spent catalyst exhibited consistent activity and selectivity toward the desired product during the glycerol hydrogenolysis reaction.
Biomass derived glycerol is considered an ideal feedstock with a prospective to be converted into a number of valuable compounds. Catalytic glycerol hydrogenolysis to produce 1,3-propanediol is one of the pioneering biosustainable pathways. Bimetallic Pt−Cu catalysts supported on H-mordenite were synthesized with various copper loadings and applied in the selective glycerol hyrogenolysis to 1,3-propanediol in a continuous fixed bed reactor performed in vapor phase under atmospheric pressure. Several techniques such as XRD, ICP-AES, NH 3 -TPD, Pyr FTIR, BET, TPR, HR-TEM, XPS, and solid state NMR were employed to characterize the physical and chemical properties of Pt−Cu/Mor catalysts. A detailed reaction parametric study has been carried out. The results designated that well dispersed Pt−Cu catalysts with small particle size, supported on a Brønsted acidic H-mordenite with a multiple pore system and strong bimetallic phase-support interaction, promote the selectivity to 1,3-propanediol. Over the Pt−Cu/Mor catalyst of optimum composition (2% Pt and 5% Cu by weight) and under the optimum reaction conditions (210 °C, H 2 flow rate of 80 mL min −1 , and gly concentration of 10 wt %), the glycerol conversion and 1,3-PD selectivity reached 90% and 58.5%, respectively. Structural characterizations and reusability of the Pt-5Cu/Mor catalyst were also performed. With evident advantages of selective C−O hydrogenolysis with low C−C cleavages, the bimetallic Pt−Cu/Mor catalysts hold great potential as high-performance catalysts for glycerol conversion to 1,3propanediol.
Vapor phase hydrogenolysis of glycerol was studied over Ru catalysts supported on TiO 2 -ZrO 2 binary oxide. Ru catalysts with various ruthenium loadings from 1.0 to 6.0 wt% were prepared by deposition-precipitation method on the TiO 2 -ZrO 2 mixed oxide support. These catalysts were characterized by X-ray diffraction, H 2 temperature-programmed reduction, NH 3 temperatureprogrammed desorption, transmission electron microscopy, BET surface area, XPS and CO chemisorption measurements. The catalysts exhibited superior performance for the vapor phase hydrogenolysis of glycerol at moderate temperature and atmospheric pressure. The mixed oxide support plays a significant role in improving the catalytic activity for the production of propanediols. The glycerol conversion and the selectivity of various products depend on the catalyst preparation method and also on the Ru content. The influence of acidity of the catalyst and its correlation to the catalytic performance (selectivity and conversion) has been studied. The weak and strong acidic sites of the catalysts measured by NH 3 -TPD play a key role in selective formation of 1,2-propanediol and 1,3-propanediol. XRD, TEM, XPS and CO chemisorption studies revealed that ruthenium was well dispersed on TiO 2 -ZrO 2 which further contributed to the superior catalytic activity for glycerol hydrogenolysis.
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