The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Junchul Choi - One of the best experts on this subject based on the ideXlab platform.
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calcium carbide as a Dehydrating Agent for the synthesis of carbamates glycerol carbonate and cyclic carbonates from carbon dioxide
Green Chemistry, 2020Co-Authors: Qiao Zhang, Haoyu Yuan, Norihisa Fukaya, Tadahiro Fujitani, Kazuhiko Sato, Junchul ChoiAbstract:Carbon dioxide (CO2) is a nontoxic and inexpensive C1 building block, which can be used for the synthesis of valuable chemicals such as aromatic carbamates from anilines and methanol (MeOH), glycerol carbonate from glycerol, and cyclic carbonates from diols. However, these reactions generate water as the byproduct and suffer from thermodynamic limits, which lead to low yields. Calcium carbide (CaC2) is a renewable chemical, which can be recycled from calcium that is abundant in the Earth's crust. Furthermore, CaC2 rapidly reacts with water. In this work, we used CaC2 as a Dehydrating Agent for the direct synthesis of carbamates (including polyurethane precursors) from amines, CO2, and MeOH. All reAgents were commercially available. In addition, CaC2 was employed for the synthesis of glycerol carbonate from glycerol and CO2 with a zinc catalyst and N-donor ligand. A similar protocol was applied to synthesize cyclic carbonates from diols and CO2.
Atsushi Urakawa - One of the best experts on this subject based on the ideXlab platform.
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catalysis under microscope unraveling the mechanism of catalyst de and re activation in the continuous dimethyl carbonate synthesis from co2 and methanol in the presence of a Dehydrating Agent
Catalysis Today, 2017Co-Authors: Dragos Stoian, Atul Bansode, F Medina, Atsushi UrakawaAbstract:Abstract The high efficiency of 2-cyanopyridine (2-CP) as Dehydrating Agent in the direct dimethyl carbonate (DMC) synthesis from CO 2 and methanol over CeO 2 catalysts has been recently demonstrated with excellent DMC yields (>90%) in both batch and continuous operations. The catalytic reaction is expected to involve a complex three-phase boundary due to the high boiling points of 2-CP and also 2-picolinamide (2-PA) formed by hydration of 2-CP. The catalyst is also known to deactivate noticeably in the time-scale of days during the continuous operation. The aim of this work is to gain visual information of the catalyst under operando conditions by means of an optically transparent, fused quartz reactor to understand the behavior of catalyst deactivation and to learn about the phase behavior of the reaction mixture. The catalytic tests using the fused quartz reactor could reproduce the results observed in a common stainless steel reactor, and the effects of reaction temperature and pressure (up to 30 bar) were examined in detail to show that there is an optimum condition (30 bar, 120 °C) to achieve the best catalytic performance. The visual inspection was further combined with IR and Raman spectroscopic studies to identify the origin of the catalyst deactivation and establish an efficient catalyst reactivation protocol. Interestingly, not coke but 2-PA surface adsorption was found responsible for the catalyst deactivation. The operando visual inspection evidenced that the surface of the CeO 2 catalyst particles is constantly wet and also coated with some crystallites (likely of 2-PA) during the reaction, whereas the bulk of the CeO 2 particle is still accessible for the reactants and thus available for the reaction.
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continuous dmc synthesis from co2 and methanol over a ceo2 catalyst in a fixed bed reactor in the presence of a Dehydrating Agent
ACS Catalysis, 2014Co-Authors: Atul Bansode, Atsushi UrakawaAbstract:Methanol and carbon dioxide are continuously and efficiently converted to dimethyl carbonate (DMC) over a CeO2 catalyst using 2-cyanopyridine as a recyclable Dehydrating Agent in a fixed bed reactor. The process was operated over a wide range of pressure (1–300 bar) by feeding CO2 and the stoichiometric amount of methanol and 2-cyanopyridine mixture into the reactor. The study shows a successful demonstration of direct DMC synthesis mediated by a Dehydrating Agent with outstanding methanol conversion (>95%) and dimethyl carbonate selectivity (>99%) under optimized conditions. Remarkably higher reaction rates were achieved compared to those in batch operation.
Liangnian He - One of the best experts on this subject based on the ideXlab platform.
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propylene oxide as a Dehydrating Agent potassium carbonate catalyzed carboxylative cyclization of propylene glycol with co2 in a polyethylene glycol co2 biphasic system
RSC Advances, 2016Co-Authors: Zhenfeng Diao, Zhihua Zhou, Bing Yu, Liangnian HeAbstract:The synthesis of propylene carbonate (PC) from 1,2-propylene glycol (PG) and CO2 was smoothly performed in a PEG800 (polyethylene glycol)/CO2 biphasic system with K2CO3 as a catalyst and propylene oxide (PO) as a Dehydrating Agent. In the reaction of PG with CO2, PO presumably removes the water produced, and simultaneously generates more PG, both of which shift the thermodynamic control process and thus accelerate the PC synthesis. The PC yield directly from PG and CO2 reached 78% under relatively mild reaction conditions (4 MPa, 120 °C, 10 h). Notably, no additional by-product was detected in this process, resulting in economic benefits and the ease of workup procedure.
Meng Zhang - One of the best experts on this subject based on the ideXlab platform.
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diethyl carbonate synthesis from co 2 with Dehydrating Agent of ethylene over catalysts of supported and mixed ni cu na 3 pw 12 o 40
Chemical Papers, 2020Co-Authors: Meng ZhangAbstract:Excessive CO2 emissions and alternative energy fuels are two major difficult issues. The utilization of CO2 into fine chemicals is an optimal route. Diethyl carbonate (DEC) is an extremely versatile chemical intermediate. DEC is used in gasoline, pharmaceutical, chemical and other fields. DEC synthesis from CO2 and ethanol is a typical green synthetic route. Ni–Cu@Na3PW12O40 catalysts were synthesized by two novel methods of supported and mixed. The catalyst prepared by mixed method showed nice catalytic performance. It was confirmed that water removal was the key to improving conversion efficiency. In the presence of Dehydrating Agent of ethylene, ethanol conversion increased from ca. 3% to ca. 40%. Propylene oxide (PO) participated in the reaction and ethanol conversion continued to reach to ca. 90% while DEC selectivity dropped by half. Under optimal conditions, our Ni–Cu@Na3PW12O40 catalyst effectively solved the two major issues above.
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Diethyl carbonate synthesis from CO 2 with Dehydrating Agent of ethylene over catalysts of supported and mixed Ni–Cu@Na 3 PW 12 O 40
Chemical Papers, 2020Co-Authors: Meng ZhangAbstract:Excessive CO2 emissions and alternative energy fuels are two major difficult issues. The utilization of CO2 into fine chemicals is an optimal route. Diethyl carbonate (DEC) is an extremely versatile chemical intermediate. DEC is used in gasoline, pharmaceutical, chemical and other fields. DEC synthesis from CO2 and ethanol is a typical green synthetic route. Ni–Cu@Na3PW12O40 catalysts were synthesized by two novel methods of supported and mixed. The catalyst prepared by mixed method showed nice catalytic performance. It was confirmed that water removal was the key to improving conversion efficiency. In the presence of Dehydrating Agent of ethylene, ethanol conversion increased from ca. 3% to ca. 40%. Propylene oxide (PO) participated in the reaction and ethanol conversion continued to reach to ca. 90% while DEC selectivity dropped by half. Under optimal conditions, our Ni–Cu@Na3PW12O40 catalyst effectively solved the two major issues above.
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Diethyl Carbonate Synthesis from CO2, Ethanol and Propylene Oxide in the presence of Dehydrating Agent of Ethylene over the novel catalysts of Supported Ni-Cu@Na3PW12O40 and Mixed Ni-Cu@Na3PW12O40
2020Co-Authors: Meng ZhangAbstract:Excessive CO2 emissions and alternative energy fuels are two major difficult issues. The utilization of CO2 into fine chemicals is an optimal route. Diethyl carbonate (DEC) is an extremely versatile chemical intermediate. DEC is used in gasoline, pharmaceutical, chemical and other fields. DEC synthesis from CO2 and ethanol is a typical green synthetic route. Ni-Cu@Na3PW12O40 catalysts were synthesized by two novel methods of supported and mixed. The catalyst prepared by mixed method showed nice catalytic performance. It was confirmed that water removal was the key to improving conversion efficiency. In the presence of Dehydrating Agent of ethylene, ethanol conversion increased from ca. 3% to ca. 40%. Propylene oxide (PO) was participated in the reaction and ethanol conversion continued to reach to ca.90% while DEC selectivity dropped by half. Under optimal conditions, our Ni-Cu@Na3PW12O40 catalyst effectively solved the two major issues above.
Qiao Zhang - One of the best experts on this subject based on the ideXlab platform.
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calcium carbide as a Dehydrating Agent for the synthesis of carbamates glycerol carbonate and cyclic carbonates from carbon dioxide
Green Chemistry, 2020Co-Authors: Qiao Zhang, Haoyu Yuan, Norihisa Fukaya, Tadahiro Fujitani, Kazuhiko Sato, Junchul ChoiAbstract:Carbon dioxide (CO2) is a nontoxic and inexpensive C1 building block, which can be used for the synthesis of valuable chemicals such as aromatic carbamates from anilines and methanol (MeOH), glycerol carbonate from glycerol, and cyclic carbonates from diols. However, these reactions generate water as the byproduct and suffer from thermodynamic limits, which lead to low yields. Calcium carbide (CaC2) is a renewable chemical, which can be recycled from calcium that is abundant in the Earth's crust. Furthermore, CaC2 rapidly reacts with water. In this work, we used CaC2 as a Dehydrating Agent for the direct synthesis of carbamates (including polyurethane precursors) from amines, CO2, and MeOH. All reAgents were commercially available. In addition, CaC2 was employed for the synthesis of glycerol carbonate from glycerol and CO2 with a zinc catalyst and N-donor ligand. A similar protocol was applied to synthesize cyclic carbonates from diols and CO2.