Esterification of methyl alcohol with acetic acid catalysed by Amberlyst-15 (cation-exchange resin) was carried out in a batch reactor in the temperature ranging between 318-338 K, at atmospheric pressure. The reactio...Esterification of methyl alcohol with acetic acid catalysed by Amberlyst-15 (cation-exchange resin) was carried out in a batch reactor in the temperature ranging between 318-338 K, at atmospheric pressure. The reaction rate increased with increase in catalyst concentration and reaction temperature, but decreased with an increase in water concentration. Stirrer speed had virtually no effect on the rate under the experimental conditions. The rate data were correlated with a second-order kinetic model based on homogeneous reaction. The apparent activation energy was found to be 22.9kJ mol-1 for the formation of methyl acetate. The methyl acetate production was carried out as batch and continuous in a packed bed reactive distillation column with high purity methyl acetate produced.展开更多
Carbon dioxide-based polyols with ultra-low molecular weight(ULMW,Mn<1000 g/mol)are emergent polyurethane precursors with economic and environmental benefits.However,the lack of effective proton-tolerant catalytic ...Carbon dioxide-based polyols with ultra-low molecular weight(ULMW,Mn<1000 g/mol)are emergent polyurethane precursors with economic and environmental benefits.However,the lack of effective proton-tolerant catalytic systems limits the development of this field.In this work,the polymeric aluminum porphyrin catalyst(PAPC)system was applied to the copolymerization of CO_(2)and propylene oxide,where sebacic acid,bisphenol A,poly(ethylene glycol),and water were used as chain transfer agents to achieve the controlled synthesis of CO_(2)-polyols.The molecular weight of the resulting CO_(2)-polyols could be facilely regulated in the range of 400–930 g/mol at low catalyst loadings,fully demonstrating its catalytic advantages of high activity,high product selectivity,and excellent proton tolerance of PAPC.Meanwhile,the catalytic efficiency of PAPC could reach up to 2.1–5.2 kg/g under organic CTA conditions,even reaching 1.9 kg/g using water as the CTA.The cPC content could be controlled within 1.0 wt%under the optimized conditions,indicating the excellent controllability of the PAPC system.ULMW CO_(2)-polyols combines the advantages of low viscosity(∼3000 mPa s at 25°C),low glass transition temperature(∼−73°C),and high carbonate unit content(∼40%),which is important for the development of high-performance polyurethanes.展开更多
Ring-opening copolymerization of CO_(2) and epoxides is a promising way to manufacture high value-added materials.Despite a variety of catalyst systems have been reported,the reaction is still limited by low activity ...Ring-opening copolymerization of CO_(2) and epoxides is a promising way to manufacture high value-added materials.Despite a variety of catalyst systems have been reported,the reaction is still limited by low activity and polymer selectivity.Herein,a strategy of polymerization-enhanced Lewis acidity is reported to construct a series of highly efficient polymeric aluminum porphyrin catalysts(PAPCs).The characterization of the coordination equilibrium constant(K_(eq))showed significantly enhanced Lewis acidity of PAPC(K_(eg)=18.2 L/mol)compared to the monomeric counterpart(K_(eq)=6.4 L/mol),accompanied with increased turnover frequency(TOF)from 136 h^(-1) to 5500 h^(-1).Through detailed regulation of Lewis acidity,the highly Lewis acidic PAPC-OTs displayed a record high TOF of 30,200 h^(-1) with polymer selectivity of up to 99%.展开更多
Catalyst design strategies such as bi-functional and di-nuclear catalysts have been developed based on intramolecular interactions,achieving excellent catalytic performance.However,most of these catalysts work in a st...Catalyst design strategies such as bi-functional and di-nuclear catalysts have been developed based on intramolecular interactions,achieving excellent catalytic performance.However,most of these catalysts work in a state of disunity.To make progress in this direction,we reckoned that enhancing the neglected intermolecular interactions of these catalysts might be a suitable approach.Herein,we report a strategy of constructing homogeneous polymeric catalysts based on the philosophy of“unity makes strength”to convert the intermolecular interactions into stronger intramolecular interactions.We united discrete active centers of aluminum(Al)porphyrin and tertiary amine(methyl methacrylate;MMA)via a random copolymerization process into one polymer chain with the subsequent metallization using low-toxic metal AlEt_(2)Cl,to construct polymeric catalysts for selective copolymerization of CO_(2)/epoxide.The spatial confinement enabled the multiple interactions among the active centers,which was distinct from the“point-to-point”interacting systems such as binary,bi-functional,or di-nuclear complexes.Through detailed tuning of the multiple synergistic effects between porphyrin/porphyrin(metal synergistic effect)and Al porphyrin/tertiary amine(Lewis pair effect),the optimized polymeric catalyst showed significantly boosted catalytic activity of 4300 h^(−1),much higher than their mono-nuclear(∼0 h^(−1))and homo-polymeric(750 h^(−1))counterparts.Our present approach for designing polymeric catalysts based on multiple synergistic effects provides a platform for developing highly active catalysts.展开更多
Photocatalytic CO_(2)reduction to C1 fuels is considered to be an important way for alleviating increasingly serious energy crisis and environmental pollution.Due to the environment-friendly,simple preparation,easy fo...Photocatalytic CO_(2)reduction to C1 fuels is considered to be an important way for alleviating increasingly serious energy crisis and environmental pollution.Due to the environment-friendly,simple preparation,easy formation of highly-stable metal-nitrogen(M-Nx)coordination bonds,and suitable band structure,polymeric carbon nitride-based single-atom catalysts(C_(3)N_(4)-based SACs)are expected to become a potential for CO_(2)reduction under visible-light irradiation.In this review,we summarize the recent advancement on C_(3)N_(4)-based SACs for photocatalytic CO_(2)reduction to C1 products,including the reaction mechanism for photocatalytic CO_(2)reduction to C1 products,the structure and synthesis methods of C_(3)N_(4)-based SACs and their applications toward photocatalytic CO_(2)reduction reaction(CO_(2)RR)for C1 production.The current challenges and future opportunities of C_(3)N_(4)-based SACs for photoreduction of CO_(2)are also discussed.展开更多
Network crewn ether polymer with pendant sulfide side ohain in the networkstructure units has been synthesized via ring- opening copolymerization of β-ethylthioethyl glycidyl ether and diethylene glycol bisglycidyl e...Network crewn ether polymer with pendant sulfide side ohain in the networkstructure units has been synthesized via ring- opening copolymerization of β-ethylthioethyl glycidyl ether and diethylene glycol bisglycidyl ether. A kind of active catalyst suitable for this reaction was suggested. The title polymer was found tobe a good ligand for platinous chloride, and the platinous complex could catalyze thehydrosilylation of olefins with triethoxysilane efficiently.展开更多
A modified method of preparing crown functionalized linear polysiloxane has been described.4'-allylbenzo-15-crown-5 was subjected to hydrosilylation with methyldichlorosilane,followed bypolycondensation with silan...A modified method of preparing crown functionalized linear polysiloxane has been described.4'-allylbenzo-15-crown-5 was subjected to hydrosilylation with methyldichlorosilane,followed bypolycondensation with silanol-terminated polydimethylsiloxane to give the title crownfunctionalized linear polysiloxane. It was found that the polysiloxane could be coordinated withplatinum salt to form platinum complex, which could catalyze the hydrosilylation of olefins withtriethoxysilane efficiently.展开更多
A porous polymeric ligand(PPL)has been synthesized and complexed with copper to generate a heterogeneous catalyst(Cu@PPL)that has facilitated the efficient C-N coupling with various(hetero)aryl chlorides under mild co...A porous polymeric ligand(PPL)has been synthesized and complexed with copper to generate a heterogeneous catalyst(Cu@PPL)that has facilitated the efficient C-N coupling with various(hetero)aryl chlorides under mild conditions of visiblelight irradiation at 80°C(58 examples,up to 99%yields).This method could be applied to both aqueous ammonia and substituted amines,and is compatible to a variety of functional groups and heterocycles,as well as allows tandem C-N couplings with conjunctive dihalides.Furthermore,the heterogeneous characteristic of Cu@PPL has enabled a straightforward catalyst separation in multiple times of recycling with negligible catalytic efficiency loss by simple filtration,affording reaction mixtures containing less than 1 ppm of Cu residue.展开更多
基金the Research Fund of Istanbul University. Project number: 944/090597.
文摘Esterification of methyl alcohol with acetic acid catalysed by Amberlyst-15 (cation-exchange resin) was carried out in a batch reactor in the temperature ranging between 318-338 K, at atmospheric pressure. The reaction rate increased with increase in catalyst concentration and reaction temperature, but decreased with an increase in water concentration. Stirrer speed had virtually no effect on the rate under the experimental conditions. The rate data were correlated with a second-order kinetic model based on homogeneous reaction. The apparent activation energy was found to be 22.9kJ mol-1 for the formation of methyl acetate. The methyl acetate production was carried out as batch and continuous in a packed bed reactive distillation column with high purity methyl acetate produced.
基金The authors greatly appreciated the financial support from National Natural Science Foundation of China(Nos.22101277,51988102,22271275,22201280).
文摘Carbon dioxide-based polyols with ultra-low molecular weight(ULMW,Mn<1000 g/mol)are emergent polyurethane precursors with economic and environmental benefits.However,the lack of effective proton-tolerant catalytic systems limits the development of this field.In this work,the polymeric aluminum porphyrin catalyst(PAPC)system was applied to the copolymerization of CO_(2)and propylene oxide,where sebacic acid,bisphenol A,poly(ethylene glycol),and water were used as chain transfer agents to achieve the controlled synthesis of CO_(2)-polyols.The molecular weight of the resulting CO_(2)-polyols could be facilely regulated in the range of 400–930 g/mol at low catalyst loadings,fully demonstrating its catalytic advantages of high activity,high product selectivity,and excellent proton tolerance of PAPC.Meanwhile,the catalytic efficiency of PAPC could reach up to 2.1–5.2 kg/g under organic CTA conditions,even reaching 1.9 kg/g using water as the CTA.The cPC content could be controlled within 1.0 wt%under the optimized conditions,indicating the excellent controllability of the PAPC system.ULMW CO_(2)-polyols combines the advantages of low viscosity(∼3000 mPa s at 25°C),low glass transition temperature(∼−73°C),and high carbonate unit content(∼40%),which is important for the development of high-performance polyurethanes.
基金supported by National Natural Science Foundation of China(Nos.51988102,22271275,22201280,22101277)Special Project of High-tech Industrialization of Cooperation between Jilin Province and Chinese Academy of Sciences(No.2022SYHz0004)Changchun Science and Technology Development Plan Funding Project(No.21ZY10).
文摘Ring-opening copolymerization of CO_(2) and epoxides is a promising way to manufacture high value-added materials.Despite a variety of catalyst systems have been reported,the reaction is still limited by low activity and polymer selectivity.Herein,a strategy of polymerization-enhanced Lewis acidity is reported to construct a series of highly efficient polymeric aluminum porphyrin catalysts(PAPCs).The characterization of the coordination equilibrium constant(K_(eq))showed significantly enhanced Lewis acidity of PAPC(K_(eg)=18.2 L/mol)compared to the monomeric counterpart(K_(eq)=6.4 L/mol),accompanied with increased turnover frequency(TOF)from 136 h^(-1) to 5500 h^(-1).Through detailed regulation of Lewis acidity,the highly Lewis acidic PAPC-OTs displayed a record high TOF of 30,200 h^(-1) with polymer selectivity of up to 99%.
基金The authors greatly appreciate the financial support from the National Natural Science Foundation of China(grant no.51988102)Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS,grant no.QYZDJ-SSW-JSC017).
文摘Catalyst design strategies such as bi-functional and di-nuclear catalysts have been developed based on intramolecular interactions,achieving excellent catalytic performance.However,most of these catalysts work in a state of disunity.To make progress in this direction,we reckoned that enhancing the neglected intermolecular interactions of these catalysts might be a suitable approach.Herein,we report a strategy of constructing homogeneous polymeric catalysts based on the philosophy of“unity makes strength”to convert the intermolecular interactions into stronger intramolecular interactions.We united discrete active centers of aluminum(Al)porphyrin and tertiary amine(methyl methacrylate;MMA)via a random copolymerization process into one polymer chain with the subsequent metallization using low-toxic metal AlEt_(2)Cl,to construct polymeric catalysts for selective copolymerization of CO_(2)/epoxide.The spatial confinement enabled the multiple interactions among the active centers,which was distinct from the“point-to-point”interacting systems such as binary,bi-functional,or di-nuclear complexes.Through detailed tuning of the multiple synergistic effects between porphyrin/porphyrin(metal synergistic effect)and Al porphyrin/tertiary amine(Lewis pair effect),the optimized polymeric catalyst showed significantly boosted catalytic activity of 4300 h^(−1),much higher than their mono-nuclear(∼0 h^(−1))and homo-polymeric(750 h^(−1))counterparts.Our present approach for designing polymeric catalysts based on multiple synergistic effects provides a platform for developing highly active catalysts.
基金National Key Research and Development Program of China(No.2018YFA0209401)National Natural Science Foundation of China(Nos.22175022,21905025,22025502,21975051).
文摘Photocatalytic CO_(2)reduction to C1 fuels is considered to be an important way for alleviating increasingly serious energy crisis and environmental pollution.Due to the environment-friendly,simple preparation,easy formation of highly-stable metal-nitrogen(M-Nx)coordination bonds,and suitable band structure,polymeric carbon nitride-based single-atom catalysts(C_(3)N_(4)-based SACs)are expected to become a potential for CO_(2)reduction under visible-light irradiation.In this review,we summarize the recent advancement on C_(3)N_(4)-based SACs for photocatalytic CO_(2)reduction to C1 products,including the reaction mechanism for photocatalytic CO_(2)reduction to C1 products,the structure and synthesis methods of C_(3)N_(4)-based SACs and their applications toward photocatalytic CO_(2)reduction reaction(CO_(2)RR)for C1 production.The current challenges and future opportunities of C_(3)N_(4)-based SACs for photoreduction of CO_(2)are also discussed.
文摘Network crewn ether polymer with pendant sulfide side ohain in the networkstructure units has been synthesized via ring- opening copolymerization of β-ethylthioethyl glycidyl ether and diethylene glycol bisglycidyl ether. A kind of active catalyst suitable for this reaction was suggested. The title polymer was found tobe a good ligand for platinous chloride, and the platinous complex could catalyze thehydrosilylation of olefins with triethoxysilane efficiently.
基金This work was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Hubei Province
文摘A modified method of preparing crown functionalized linear polysiloxane has been described.4'-allylbenzo-15-crown-5 was subjected to hydrosilylation with methyldichlorosilane,followed bypolycondensation with silanol-terminated polydimethylsiloxane to give the title crownfunctionalized linear polysiloxane. It was found that the polysiloxane could be coordinated withplatinum salt to form platinum complex, which could catalyze the hydrosilylation of olefins withtriethoxysilane efficiently.
基金the National Natural Science Foundation of China(21704016,21971044)。
文摘A porous polymeric ligand(PPL)has been synthesized and complexed with copper to generate a heterogeneous catalyst(Cu@PPL)that has facilitated the efficient C-N coupling with various(hetero)aryl chlorides under mild conditions of visiblelight irradiation at 80°C(58 examples,up to 99%yields).This method could be applied to both aqueous ammonia and substituted amines,and is compatible to a variety of functional groups and heterocycles,as well as allows tandem C-N couplings with conjunctive dihalides.Furthermore,the heterogeneous characteristic of Cu@PPL has enabled a straightforward catalyst separation in multiple times of recycling with negligible catalytic efficiency loss by simple filtration,affording reaction mixtures containing less than 1 ppm of Cu residue.
