Microreactors are increasingly used for green and safe chemical processes owing to their benefits of superior mass and heat transfer,increased yield,safety,and simplicity of control.However,immobilizing catalysts in m...Microreactors are increasingly used for green and safe chemical processes owing to their benefits of superior mass and heat transfer,increased yield,safety,and simplicity of control.However,immobilizing catalysts in microreactors remains challenging.In this investigation,a technique for creating Cu_(2)O/montmorillonite catalyst coating,using electrostatic attraction for layer-by-layer self-assembly,was proposed.The montmorillonite film's morphology and thickness could be efficiently regulated by adjusting the degree of exfoliation and surface charge of montmorillonite,alongside layer-by-layer coating times.The Cu_(2)O nanoparticles were immobilized using the flow deposition approach.The resulting Cu_(2)O@montmorillonite-film-coated capillary microreactor successfully transformed glycerol into dihydroxyacetone.The conversion of glycerol and product selectivity could be controlled by adjusting the molar ratio of reactants,temperature,residence time,and Cu_(2)O loading.The maximum glycerol conversion observed was 47.6%,with a 27%selectivity toward dihydroxyacetone.The study presents a technique for immobilizing montmorillonite-based catalyst coatings in capillary tubing,which can serve as a foundation for the future application of microreactors in glycerol conversion.展开更多
Glycerol monolaurate(GML)is a widely used industrial chemical with excellent emulsification and antibacterial effect.The direct esterification of glycerol with lauric acid is the main method to synthesize GML.In this ...Glycerol monolaurate(GML)is a widely used industrial chemical with excellent emulsification and antibacterial effect.The direct esterification of glycerol with lauric acid is the main method to synthesize GML.In this work,the kinetic process of direct esterification was systematically studied using p-toluenesulfonic acid as catalyst.A complete kinetic model of consecutive esterification reaction has been established,and the kinetic equation of acid catalysis was deduced.The isomerization reactions of GML and glycerol dilaurate were investigated.It was found that the reaction was an equilibrium reaction and the reaction rate was faster than the esterification reaction.The kinetic equations of the consecutive esterification reaction were obtained by experiments as k_(1)=(276+92261Xcat)exp(-37720/RT)and k_(2)=(80+4413Xcat)exp(-32240/RT).The kinetic results are beneficial to the optimization of operating conditions and reactor design in GML production process.展开更多
The selective aqueous-phase glycerol hydrogenolysis is a promising reaction to produce commercially useful 1,3-propanediol(1,3-PDO).The Pt-WOx bifunctional catalyst can catalyse the glycerol hydrogenol-ysis but the ca...The selective aqueous-phase glycerol hydrogenolysis is a promising reaction to produce commercially useful 1,3-propanediol(1,3-PDO).The Pt-WOx bifunctional catalyst can catalyse the glycerol hydrogenol-ysis but the catalyst deactivation via sintering,metal leaching,and coking can predominantly occur in the aqueous phase reaction.In this work,the effect of reaction temperature,pressure and second promoter(Cu,Fe,Rh,Mn,Re,Ru,Ir,Sn,B,and P)on catalytic performance and deactivation behaviour of Pt/WOx/-Al2O3 was investigated.When doped with Rh,Mn,Re,Ru,Ir,B,and P,the second promoter boosts catalytic activity by promoting great dispersion of Pt on support and increasing Pt surface area.The increased Bronsted acid sites lead to selective synthesis of 1,3-PDO than 1,2-propanediol(1,2-PDO).The characterization studies of fresh and spent catalysts reveal that the main cause of catalyst deactivation is the Pt sintering,as interpreted based on XRD,CO chemisorption,and TEM analyses.The Pt sintering is affected depending on the second promoter that can either or reduce the interaction between Pt,WO_(χ)/γ and Al_(2)O_(3).As an electron acceptor of Pt in Pt/WO_(χ)/γ-Al_(2)O_(3),Re and Mn as second promoters resulted in increased Pt^(2+) on the catalytic surface,which strengthens the contact between Pt andγ-Al_(2)O_(3) and WO_(χ),resulting in a decrease in Pt sintering.The metal leaching and coking are not affected by the presence of second promoter.The catalyst modified with a second promoter possesses improved catalytic activity and 1,3-PDO production,however the stability continues to remain a challenge.The present work unrav-elled the determining parameters of catalytic activity and deactivation,thus providing a promising pro-tocol toward effective catalysts for glycerol hydrogenolysis.展开更多
Hydrogen production from electrolytic water is an important sustainable technology to realize renewable energy conversion and carbon neutrality.However,it is limited by the high overpotential of oxygen evolution react...Hydrogen production from electrolytic water is an important sustainable technology to realize renewable energy conversion and carbon neutrality.However,it is limited by the high overpotential of oxygen evolution reaction(OER)at the anode.To reduce the operating voltage of electrolyzer,herein thermodynamically favorable glycerol oxidation reaction(GOR)is proposed to replace the OER.Moreover,vertical Ni O flakes and NiMoNH nanopillars are developed to boost the reaction kinetics of anodic GOR and cathodic hydrogen evolution,respectively.Meanwhile,excluding the explosion risk of mixed H_2/O_(2),a cheap organic membrane is used to replace the expensive anion exchange membrane in the electrolyzer.Impressively,the electrolyzer delivers a remarkable reduction of operation voltage by 280 mV,and exhibits good long-term stability.This work provides a new paradigm of hydrogen production with low cost and good feasibility.展开更多
Glycerol(electrochemical) oxidation reaction(GOR) producing organic small molecule acid and coupling with hydrogen evolution reaction is a critical aspect of ensuring balanced glycerol capacity and promoting hydrogen ...Glycerol(electrochemical) oxidation reaction(GOR) producing organic small molecule acid and coupling with hydrogen evolution reaction is a critical aspect of ensuring balanced glycerol capacity and promoting hydrogen generation on a large scale. However, the development of highly efficient and selective non-noble metal-based GOR electrocatalysts is still a key problem. Here, an S-doped CuO nanorod array catalyst(S-CuO/CF) constructed by sulfur leaching and oxidative remodeling is used to drive GOR at low potentials: It requires potentials of only 1.23 and 1.33 V versus RHE to provide currents of 100 and 500 mA cm^(-2), respectively. Moreover, it shows satisfactory comprehensive performance(at 100 mA cm^(-2), V_(cell) = 1.37 V) when assembled as the anode in asymmetric coupled electrolytic cell. Furthermore, we propose a detailed cycle reaction pathway(in alkaline environment) of S-doped CuO surface promoting GOR to produce formic acid and glycolic acid. Among them, the C–C bond breaking and lattice oxygen deintercalation steps frequently involved in the reaction pathway are the key factors to determine the catalytic performance and product selectivity. This research provides valuable guidance for the development of transition metal-based electrocatalysts for GOR and valuable insights into the glycerol oxidation cycle reaction pathway.展开更多
基金support from the National Natural Science Foundation of China(2207213641672033)+2 种基金the research grants from Engineering Research Center of Non-metallic Minerals of Zhejiang Province(ZD2023K01)the projects from Qing Yang Institute for Industrial Minerals(KYYHX-20220336KYY-HX-20170557).
文摘Microreactors are increasingly used for green and safe chemical processes owing to their benefits of superior mass and heat transfer,increased yield,safety,and simplicity of control.However,immobilizing catalysts in microreactors remains challenging.In this investigation,a technique for creating Cu_(2)O/montmorillonite catalyst coating,using electrostatic attraction for layer-by-layer self-assembly,was proposed.The montmorillonite film's morphology and thickness could be efficiently regulated by adjusting the degree of exfoliation and surface charge of montmorillonite,alongside layer-by-layer coating times.The Cu_(2)O nanoparticles were immobilized using the flow deposition approach.The resulting Cu_(2)O@montmorillonite-film-coated capillary microreactor successfully transformed glycerol into dihydroxyacetone.The conversion of glycerol and product selectivity could be controlled by adjusting the molar ratio of reactants,temperature,residence time,and Cu_(2)O loading.The maximum glycerol conversion observed was 47.6%,with a 27%selectivity toward dihydroxyacetone.The study presents a technique for immobilizing montmorillonite-based catalyst coatings in capillary tubing,which can serve as a foundation for the future application of microreactors in glycerol conversion.
基金supported by the National Research and Development Program of China(2021YFC3001100)the National Natural Science Foundation of China(22288102).
文摘Glycerol monolaurate(GML)is a widely used industrial chemical with excellent emulsification and antibacterial effect.The direct esterification of glycerol with lauric acid is the main method to synthesize GML.In this work,the kinetic process of direct esterification was systematically studied using p-toluenesulfonic acid as catalyst.A complete kinetic model of consecutive esterification reaction has been established,and the kinetic equation of acid catalysis was deduced.The isomerization reactions of GML and glycerol dilaurate were investigated.It was found that the reaction was an equilibrium reaction and the reaction rate was faster than the esterification reaction.The kinetic equations of the consecutive esterification reaction were obtained by experiments as k_(1)=(276+92261Xcat)exp(-37720/RT)and k_(2)=(80+4413Xcat)exp(-32240/RT).The kinetic results are beneficial to the optimization of operating conditions and reactor design in GML production process.
基金funded by the National Research Council of Thailand (NRCT)the Second Century Foundation (C2F),Chulalongkorn University,ThailandResearcher Supporting Project RSP2024RR400,King Saud University,Saudi Arabia
文摘The selective aqueous-phase glycerol hydrogenolysis is a promising reaction to produce commercially useful 1,3-propanediol(1,3-PDO).The Pt-WOx bifunctional catalyst can catalyse the glycerol hydrogenol-ysis but the catalyst deactivation via sintering,metal leaching,and coking can predominantly occur in the aqueous phase reaction.In this work,the effect of reaction temperature,pressure and second promoter(Cu,Fe,Rh,Mn,Re,Ru,Ir,Sn,B,and P)on catalytic performance and deactivation behaviour of Pt/WOx/-Al2O3 was investigated.When doped with Rh,Mn,Re,Ru,Ir,B,and P,the second promoter boosts catalytic activity by promoting great dispersion of Pt on support and increasing Pt surface area.The increased Bronsted acid sites lead to selective synthesis of 1,3-PDO than 1,2-propanediol(1,2-PDO).The characterization studies of fresh and spent catalysts reveal that the main cause of catalyst deactivation is the Pt sintering,as interpreted based on XRD,CO chemisorption,and TEM analyses.The Pt sintering is affected depending on the second promoter that can either or reduce the interaction between Pt,WO_(χ)/γ and Al_(2)O_(3).As an electron acceptor of Pt in Pt/WO_(χ)/γ-Al_(2)O_(3),Re and Mn as second promoters resulted in increased Pt^(2+) on the catalytic surface,which strengthens the contact between Pt andγ-Al_(2)O_(3) and WO_(χ),resulting in a decrease in Pt sintering.The metal leaching and coking are not affected by the presence of second promoter.The catalyst modified with a second promoter possesses improved catalytic activity and 1,3-PDO production,however the stability continues to remain a challenge.The present work unrav-elled the determining parameters of catalytic activity and deactivation,thus providing a promising pro-tocol toward effective catalysts for glycerol hydrogenolysis.
基金the financial support from National Natural Science Foundation of China(92163117,52072389,52172058,51972006)。
文摘Hydrogen production from electrolytic water is an important sustainable technology to realize renewable energy conversion and carbon neutrality.However,it is limited by the high overpotential of oxygen evolution reaction(OER)at the anode.To reduce the operating voltage of electrolyzer,herein thermodynamically favorable glycerol oxidation reaction(GOR)is proposed to replace the OER.Moreover,vertical Ni O flakes and NiMoNH nanopillars are developed to boost the reaction kinetics of anodic GOR and cathodic hydrogen evolution,respectively.Meanwhile,excluding the explosion risk of mixed H_2/O_(2),a cheap organic membrane is used to replace the expensive anion exchange membrane in the electrolyzer.Impressively,the electrolyzer delivers a remarkable reduction of operation voltage by 280 mV,and exhibits good long-term stability.This work provides a new paradigm of hydrogen production with low cost and good feasibility.
基金financially supported by National Natural Science Foundation of China (52174283 and 52274308)。
文摘Glycerol(electrochemical) oxidation reaction(GOR) producing organic small molecule acid and coupling with hydrogen evolution reaction is a critical aspect of ensuring balanced glycerol capacity and promoting hydrogen generation on a large scale. However, the development of highly efficient and selective non-noble metal-based GOR electrocatalysts is still a key problem. Here, an S-doped CuO nanorod array catalyst(S-CuO/CF) constructed by sulfur leaching and oxidative remodeling is used to drive GOR at low potentials: It requires potentials of only 1.23 and 1.33 V versus RHE to provide currents of 100 and 500 mA cm^(-2), respectively. Moreover, it shows satisfactory comprehensive performance(at 100 mA cm^(-2), V_(cell) = 1.37 V) when assembled as the anode in asymmetric coupled electrolytic cell. Furthermore, we propose a detailed cycle reaction pathway(in alkaline environment) of S-doped CuO surface promoting GOR to produce formic acid and glycolic acid. Among them, the C–C bond breaking and lattice oxygen deintercalation steps frequently involved in the reaction pathway are the key factors to determine the catalytic performance and product selectivity. This research provides valuable guidance for the development of transition metal-based electrocatalysts for GOR and valuable insights into the glycerol oxidation cycle reaction pathway.
