Glycerol Transformation to Value-Added 1,3-Propanediol Production: A Paradigm for a Sustainable Biorefinery Process

The impact of diminishing fossil fuel resources, rising environmental issues as well as the global demand for energy, fuels and chemicals has significantly directed to the use of renewable biomass for sustainable production of fuels and chemicals. Glycerol, a three carbon feedstock, is one of the most promising biomass resources which at present is obtained as a by-product in large quantities during the biodiesel production. This stimulated a lot of interest in developing new valorization technologies to produce high-value tonnage chemicals from glycerol by sustainable processes such as oxidation, dehydration, hydrogenolysis, steam reforming, carboxylation, acetalization, esterification and chlorination. In this chapter, we intend to focus on the hydrogenolysis of glycerol which produces important commodity chemicals such as propanediols, propanols and ethylene glycol. In particular, the selective hydrogenolysis of glycerol to 1,3-propanediol performed in both liquid phase and vapor phase reaction processes is described. Furthermore, the most significant progress in the development of the catalytic materials for glycerol hydrogenolysis including the reaction pathways is herein summarized

Toward the sustainable synthesis of propanols from renewable glycerol over MoO₃-Al₂O₃ supported palladium catalysts

The catalytic conversion of glycerol to value-added propanols is a promising synthetic route that holds the potential to overcome the glycerol oversupply from the biodiesel industry. In this study, selective hydrogenolysis of 10 wt% aqueous bio-glycerol to 1-propanol and 2-propanol was performed in the vapor phase, fixed-bed reactor by using environmentally friendly bifunctional Pd/MoO3-Al2O3 catalysts prepared by wetness impregnation method. The physicochemical properties of these catalysts were derived from various techniques such as X-ray diffraction, NH3-temperature programmed desorption, scanning electron microscopy, 27Al NMR spectroscopy, surface area analysis, and thermogravimetric analysis. The catalytic activity results depicted that a high catalytic activity (>80%) with very high selectivity (>90%) to 1-propanol and 2-propanol was obtained over all the catalysts evaluated in a continuously fed, fixed-bed reactor. However, among all others, 2 wt% Pd/MoO3-Al2O3 catalyst was the most active and selective to propanols. The synergic interaction between the palladium and MoO3 on Al2O3 support and high strength weak to moderate acid sites of the catalyst were solely responsible for the high catalytic activity. The maximum glycerol conversion of 88.4% with 91.3% selectivity to propanols was achieved at an optimum reaction condition of 210 ∘ C and 1 bar pressure after 3 h of glycerol hydrogenolysis reaction

Evaluation of Porous Honeycomb-Shaped CuO/CeO2 Catalyst in Vapour Phase Glycerol Reforming for Sustainable Hydrogen Production

This study presented an optimisation study of two-stage vapour-phase catalytic glycerol reforming (VPCGR) using response surface methodology (RSM) with a central composite experimental design (CCD) approach. Characterisation through Brunauer–Emmett–Teller analysis (BET), small-angle X-ray scattering (SAXS), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX), atomic force microscopy (AFM) and particle X-ray diffraction (PXRD) were carried out to understand the physiochemical activity of the honeycomb morphology CuO/CeO2 catalyst. Notably, in this study, we achieved the desired result of glycerol conversion (94%) and H2 production (81 vol.%) under the reaction condition of Cu species loading (10 wt.%), reaction temperature (823 K), WHSV (2 h−1) and glycerol concentration (15 wt.%). From the RSM analysis, an optimum predicted model for VPCGR was obtained and further integrated into Microsoft Excel and Aspen Plus to perform an energy analysis of the VPCGR plant at a scale of 100 kg h−1 of glycerol feed. As a whole, this study aimed to provide an overview of the technical operation and energy aspect for a sustainable frontier in glycerol reforming

Evaluation of Porous Honeycomb-Shaped CuO/CeO₂ Catalyst in Vapour Phase Glycerol Reforming for Sustainable Hydrogen Production

This study presented an optimisation study of two-stage vapour-phase catalytic glycerol reforming (VPCGR) using response surface methodology (RSM) with a central composite experimental design (CCD) approach. Characterisation through Brunauer–Emmett–Teller analysis (BET), small-angle X-ray scattering (SAXS), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX), atomic force microscopy (AFM) and particle X-ray diffraction (PXRD) were carried out to understand the physiochemical activity of the honeycomb morphology CuO/CeO2 catalyst. Notably, in this study, we achieved the desired result of glycerol conversion (94%) and H2 production (81 vol.%) under the reaction condition of Cu species loading (10 wt.%), reaction temperature (823 K), WHSV (2 h−1) and glycerol concentration (15 wt.%). From the RSM analysis, an optimum predicted model for VPCGR was obtained and further integrated into Microsoft Excel and Aspen Plus to perform an energy analysis of the VPCGR plant at a scale of 100 kg h−1 of glycerol feed. As a whole, this study aimed to provide an overview of the technical operation and energy aspect for a sustainable frontier in glycerol reforming

Catalytic functionalities of nano Ru catalysts supported on TiO2-ZrO2 mixed oxide for vapor phase hydrogenolysis of glycerol to propanediols

Vapor phase hydrogenolysis of glycerol was studied over Ru catalysts supported on TiO2-ZrO2 binary oxide. Ru catalysts with various ruthenium loadings from 1.0 to 6.0 wt% were prepared by deposition-precipitation method on the TiO2-ZrO2 mixed oxide support. These catalysts were characterized by X-ray diffraction, H-2 temperature-programmed reduction, NH3 temperature-programmed 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 NH3-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 TiO2-ZrO2 which further contributed to the superior catalytic activity for glycerol hydrogenolysis

Activity and Selectivity of Platinum–Copper Bimetallic Catalysts Supported on Mordenite for Glycerol Hydrogenolysis to 1,3-Propanediol

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, NH₃-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, H₂ 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 1,3-propanediol

High Efficiency Conversion of Glycerol to 1,3-Propanediol Using a Novel Platinum–Tungsten Catalyst Supported on SBA-15

The hydrogenolysis of glycerol to 1,3-propanediol was conducted over a series of Pt-WO₃/SBA-15 catalysts with Pt content ranging from 0.5 to 3 wt % and W content of 10 wt % in vapor phase under atmospheric pressure for the first time. The catalysts prepared via sequential impregnation method were systematically characterized using XRD, NH₃-TPD, Py-IR, CO chemisorption, TPR, TEM, and surface area measurements. The catalysts exhibited unprecedented activity for selective formation of 1,3-propanediol via hydrogenolysis of glycerol. The effect of various reaction parameters such as catalyst loading, reaction temperature, hydrogen flow rate, glycerol concentration and reaction time were studied. The optimized reaction conditions showed that a high glycerol conversion (86%) and 1,3-propanediol selectivity (42%) was obtained over 2Pt-10WO₃/SBA-15 catalyst illustrating the potential of SBA-15 supported platinum–tungsten catalyst to be highly active and efficient. The Brønsted acid sites of the catalyst formed due to addition of WO₃ enhanced selective formation of 1,3-propanediol

Platinum Supported on H‑Mordenite: A Highly Efficient Catalyst for Selective Hydrogenolysis of Glycerol to 1,3-Propanediol

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