CO2 capture and adsorption kinetic study of amine-modified MIL-101 (Cr)

MIL-101 (Cr) was synthesized by a hydrothermal method and used as support to prepare a series of polyethylenimine (PEI) incorporated MIL-101 (Cr) by wet impregnation method. All characterization results revealed that the structure of MIL-101 (Cr) was well-maintained by the incorporation of polyethylenimine and confirmed the presence of PEI within MIL-101 (Cr). The CO2 adsorption studies were carried out in a fixed bed reactor from 30 to 90 degrees C, 1 bar. The adsorption of CO2 has been increased by the incorporation of PEI. It was due to the chemical interaction between the -NH2 and CO2 groups to form a carbamate. The high CO2 adsorption capacity 3.81 mmol g(-1) was shown by 70 wt% PEI loaded MIL-101(Cr) at 75 degrees C,1 bar, because of more number of NH2 groups and a high number of CO2 molecules diffusion. Its adsorption capacity was 4.7 times higher than the adsorption capacity of MIL-101 (Cr) (0.80 mmol g(-1)). Moreover, in moisture condition, CO2 adsorption capacity was increased to 4.4 mmol g(-1) by the formation of ammonium bicarbonate and showed good adsorption stability throughout each adsorption-desorption cycle. The Avrami adsorption kinetic model was well fitted with experimental breakthrough CO2 adsorption data of MIL-101 (Cr)-PEI-70. It suggested that the adsorption of CO2 on PEI incorporated material was chemical adsorption. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Tuning Y-zeolite based catalyst with copper for enhanced activity and selectivity in vapor phase hydrogenolysis of glycerol to 1,2-propanediol

Highly dispersed copper oxide species supported on a Y-zeolite with different Si/Al ratios (5.1, 12, 30, and 60) were synthesized by an incipient wet impregnation method. The catalysts were characterized by X-ray diffraction (XRD), N-2 adsorption (BET), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffused reflectance spectroscopy (UV-DRS), N2O chemisorption, Pyridine-adsorption Fourier transform Infrared Spectroscopy (Py-FTIR), NH3 temperature programmed desorption (NH3-TPD) and temperature programmed reduction (TPR). Copper dispersion and metallic area were measured by the N2O decomposition method. The amount of Bronsted and Lewis acidic sites was analyzed by Pyridine adsorption followed by FT-IR. Performance of the prepared catalysts in vapor phase hydrogenolysis of glycerol to 1,2-propanediol was evaluated by using a fixed-bed stainless-steel reactor at 0.2 MPa and 210 degrees C. The studies revealed that the 3 wt.% CuO/Y-zeolite (Si/Al = 5.1) catalyst was highly active in glycerol hydrogenolysis showing 92% conversion of glycerol and 83% selectivity to 1,2-propanediol. This seems to originate from high dispersion of Cu, smaller Cu crystallite size, and the presence of a high amount of surface beneficial acido-basic properties

Mesoporous carbon supported MgO for CO2 capture and separation of CO2/N-2

Mesoporous carbon derived from pongamia pinnata fruit hulls was used as support to incorporate magnesium oxide for the study of CO2 adsorption and separation of CO2/N-2. All synthesized adsorbents were characterized by PXRD, N-2 adsorption-desorption isotherms, Raman and SEM with EDX techniques. Characterization results revealed the existence of magnesium oxide on mesoporous carbon. CO2 adsorption on MgO incorporated mesoporous carbon was higher than bulk mesoporous carbon, due to the electrostatic interaction between magnesium oxide and CO2. High CO2 adsorption capacity 1.68 mmol/g was obtained for 10 wt% MgO incorporated mesoporous carbon at 298 K, 1 bar compared to remaining loadings, because of the high content of MgO. However, the N-2 adsorption capacity decreased with the increase of MgO content due to a decrease in surface area and no interaction of the N-2 molecule with the adsorbent. The selectivity of CO2/N-2 was higher on 10 wt% MgO incorporated mesoporous carbon and the value was 40. The heat of CO2 adsorption was 36KJ/mol at low coverage of CO2, and CO2 adsorption capacity was constant in each adsorption cycle over the same adsorbent

Direct cascade hydrogenation of biorenewable levulinic acid to valeric acid biofuel additives over metal (M = Nb, Ti, and Zr) supported SBA-15 catalysts

Chemoselective hydrogenation of biomass platform molecules into value-added chemicals and fuels is essential for the exploitation of biomass, and SBA-15 based metal catalysts with hydrogenation centers and acid sites seem promising in this regard. Valeric acid (VA) is the most important platform molecule for valeric biofuels and value-added chemicals production. The main issue with using such bifunctional catalysts for biomass conversion is maintaining the catalyst's stability in the liquid phase under harsh conditions. In-addition, direct one-pot selective hydrogenation of levulinic acid (LA) into VA synthesis is challenging due to its complex reaction conditions involved. Herein, we design a bifunctional mesoporous catalysts (SBA-15 mesoporous material doped with various metals Nb, Ti, and Zr) investigated for this reaction under the vapour phase. Different instrumental approaches were used to examine the structure, phase composition, morphology, and surface elemental analyses of catalysts as-prepared. Among those catalysts, Zr-doped mesoporous SBA-15 catalyst showed the 91% conversion of LA and the 68% selectivity toward VA and promising stability in a 52 h time on-stream run. Metal dispersion inside the SBA-15 and their surface acidity (sufficient number of acid sites and surface-active metal oxide species) and higher surface area are beneficial for the selectivity of VA. This work offers a highly-efficient bifunctional catalyst for selective hydrogenation of biomass feedstocks

High Dispersion of Platinum Nanoparticles over Functionalized Zirconia for Effective Transformation of Levulinic Acid to Alkyl Levulinate Biofuel Additives in the Vapor Phase

In recent years, functionalized metal oxides have been gaining popularity for biomass conversion to fuels and chemicals due to the global energy crisis. This study reports a novel catalyst based on noble metal immobilization on functionalized zirconia that has been successfully used in the production of biofuel alkyl levulinates (ALs) from lignocellulosic biomass-derived levulinic acid (LA) under vapor-phase. The wet impregnation method was used to immobilize Pt-metal nanoparticles on zirconia-based supports (silicotungstic acid zirconia, STA-ZrO2; sulfated zirconia, S-ZrO2; and tetragonal zirconia, t-ZrO2). A variety of physicochemical techniques were used to characterize the prepared catalysts, and these were tested under atmospheric pressure in continuous flow esterification of LA. The order of catalytic activity followed when ethyl levulinate was produced from levulinic acid via esterification: Pt/STA-ZrO2 ≫ Pt/S-ZrO2 ≫ Pt/t-ZrO2. Moreover, it was found that ALs synthesis from LA with different alcohols utilizing Pt/STA-ZrO2 catalyst followed the order ethyl levulinate ≫ methyl levulinate ≫ propyl levulinate≫ butyl levulinate. This work outlines an excellent approach to designing efficient catalysts for biofuels and value-added compounds made from biomass

High Dispersion of Platinum Nanoparticles over Functionalized Zirconia for Effective Transformation of Levulinic Acid to Alkyl Levulinate Biofuel Additives in the Vapor Phase

In recent years, functionalized metal oxides have been gaining popularity for biomass conversion to fuels and chemicals due to the global energy crisis. This study reports a novel catalyst based on noble metal immobilization on functionalized zirconia that has been successfully used in the production of biofuel alkyl levulinates (ALs) from lignocellulosic biomass-derived levulinic acid (LA) under vapor-phase. The wet impregnation method was used to immobilize Pt-metal nanoparticles on zirconia-based supports (silicotungstic acid zirconia, STA-ZrO2; sulfated zirconia, S-ZrO2; and tetragonal zirconia, t-ZrO2). A variety of physicochemical techniques were used to characterize the prepared catalysts, and these were tested under atmospheric pressure in continuous flow esterification of LA. The order of catalytic activity followed when ethyl levulinate was produced from levulinic acid via esterification: Pt/STA-ZrO2 ≫ Pt/S-ZrO2 ≫ Pt/t-ZrO2. Moreover, it was found that ALs synthesis from LA with different alcohols utilizing Pt/STA-ZrO2 catalyst followed the order ethyl levulinate ≫ methyl levulinate ≫ propyl levulinate≫ butyl levulinate. This work outlines an excellent approach to designing efficient catalysts for biofuels and value-added compounds made from biomass

Insights into the influence of Pd loading on CeO2 catalysts for CO2 hydrogenation to methanol

One of the most significant industrial processes is the catalytic methanol synthesis from carbon dioxide because methanol is a future energy carrier for producing fuels and high-value-added commodities, the so-called “methanol economy” is carbon neutral. As a solution to climate change, the widespread belief that carbon dioxide can be recycled by hydrogenation into methanol has motivated the development of more efficient and selective catalysts. Efficient 2 wt% Pd/CeO2 catalysts for thermochemical CO2 hydrogenation have recently been investigated. However, the rationale behind the low Pd loading (2 wt%) in CeO2 needs to be clarified, and comprehensive research into Pd tuning is lacking. In this article, we describe the synthesis ofvarious palladium contents (0.5, 1, 2, 4, and 6 wt%) supported on ceria nanorods (Pd/CeO2) for selective hydrogenation of CO2 to methanol under vapor-phase. The impact of Pd on the physicochemical properties of CeO2 was examined using various characterization techniques. The enhanced catalytic activity was caused by the 2 wt% Pd/CeO2 catalyst's most significant level of metallic Pd species, strong interactions between Pd and CeO2, uniform Pd dispersion on CeO2, increased reducibility, oxygen mobility, and weak basic sites. This study reveals that changing the percentage of metal in the catalyst supports a valuable technique for designing efficient oxides-supported metal-based catalysts for CO2 conversions

Monomer recycling of polyethylene terephthalate, polycarbonate and polyethers : scalable processes to achieve high carbon circularity

Abstract: This review presents a comprehensive description of the current pathways used in the chemical recycling of oxygenated plastics, with a specific focus on poly(ethylene terephthalate) (PET), poly(bisphenol-A carbonate) (PC), and polyethers including anhydride-cured epoxies. For PC and PET, the emphasis is on processes that achieve high depolymerization efficiencies as well as monomer selectivity and the potential to simplify downstream processing for the recovery of pure monomers. In the case of epoxies, this work focuses on depolymerization processes that produce curable molecules, as studies on epoxy depolymerization are scarce. To assess scalability, different depolymerization pathways are compared for each polymer based on the process conditions and monomer yields. The review concludes with the discussion on potentials and challenges of the distinct depolymerization pathways that have been developed for oxygenated plastics, such as hydrolysis, alcoholysis, and reductive depolymerization. (c) 2023 Elsevier Ltd. All rights reserved

Efficient vapor‐phase selective hydrogenolysis of bio‐levulinic acid to γ‐valerolactone using cu supported on hydrotalcite catalysts

Abstract In this work, Cu nanoparticles (Cu NPs, 2‐20 nm) supported on Hydrotalcite catalysts exhibit enhanced selectivity for γ‐valerolactone (GVL) during hydrogenolysis of levulinic acid (LA). At 260 °C, over 3 wt% Cu achieved 87.5% of LA conversion with a maximum GVL selectivity (95%). In contrast, LA hydrogenolysis over 3Cu/Hydrotalcite catalyst is highly active and stable toward the production of GVL due to balanced acido‐basicity and higher Cu dispersion with ultrasmall particle sizes, which are investigated through the temperature programmed desorption (TPD) of ammonia, N₂O titration, and transmission electron microscopy (TEM) analysis. Hydrotalcite in combination with inexpensive Cu catalyst is found to be an efficient and environmentally benign for LA hydrogenolysis