This study was performed for the development of a green and promising approach for the synthesis of methyl acrylate and acrylic acid by a one‐step aldol condensation reaction of dimethoxymethane and methyl acetate ov...This study was performed for the development of a green and promising approach for the synthesis of methyl acrylate and acrylic acid by a one‐step aldol condensation reaction of dimethoxymethane and methyl acetate over cesium oxide‐supported on ZSM‐35 zeolite catalysts; the effect of base sites as well as acid sites on the aldol condensation reaction was studied in detail. It was found that base sites were harmful for aldol condensation due to their failure in catalyzing the decomposition of dimethoxymethane precursor into formaldehyde, whereas the acid site was indispensable for the reaction to proceed. This reaction cannot take place without an acid site. Although acid sites in H‐form of the zeolite（HZSM‐35） are indispensable for the aldol condensation reaction, not all of them tend to favor this reaction. A strong acid catalyzes methanol‐to‐olefin‐like reactions resulting in hydrocarbon byproducts, which are finally transferred to hard coke. Medium strong acids and weak acids are great candidates for the target aldol condensation reaction with high activity and selectivity. A γ‐Al2O3 sample with abundant weak‐strength Lewis acid sites, together with a few medium‐strong‐strength acid sites, performs well with a high activity and considerable stability during the synthesis of methyl acrylate and acrylic acid.展开更多
Aqueous phase of acids as catalysts for the desulfurization of gasoline by condensation of thiophenes with form- aldehyde in a biphasic system was investigated. Two types of model gasoline with and without aromatics a...Aqueous phase of acids as catalysts for the desulfurization of gasoline by condensation of thiophenes with form- aldehyde in a biphasic system was investigated. Two types of model gasoline with and without aromatics and olefins were employed in this work. The desulfurization rates were above 90% on these two types of model gasoline using formic acid and HaPW12O40 （0.8 mol·L-1）, indicating that the presence of aromatics and olefins has no effect on the desulfurization rate. High temperature （above 90 ℃） was more favorable to the process for desulfurization. Four hours was considered to be the proper treating time for the sulfur removal. In addition, aqueous phase of acids could be recycled at least 4 times without decreasing desulfurization rate. Finally, the possible process for the integration of condensation desulfurization into the existing refinery process for the production of gasoline with low sulfur content was proposed.展开更多
An efficient reduction system of benzaldehyde with hydrogen under ambient pressure was developed using facile NiO catalyst. The non-aromatic solvents such as cyclohexane, tetrahydrofuran (THF) and n-hexane, and the ad...An efficient reduction system of benzaldehyde with hydrogen under ambient pressure was developed using facile NiO catalyst. The non-aromatic solvents such as cyclohexane, tetrahydrofuran (THF) and n-hexane, and the addi-tive with strong basicity e.g. KOH, were necessary for smooth conversion of the substrate. That the catalyst can be recov-ered and reused for nine times without loss of catalytic activity indicates that this catalyst is a recyclable one for benzal-dehyde reduction.展开更多
The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission elect...The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.展开更多
Acrylic acid(AA)and its ester,methyl acrylate(MA),were produced by a green one‐step aldol condensation reaction of dimethoxymethane and methyl acetate.The reaction was conducted over ZSM‐35 zeolites with different c...Acrylic acid(AA)and its ester,methyl acrylate(MA),were produced by a green one‐step aldol condensation reaction of dimethoxymethane and methyl acetate.The reaction was conducted over ZSM‐35 zeolites with different concentrations of Bronsted acid,which were prepared by the sodium ion‐exchange process with H‐form zeolite.The acidic property of HZSM‐35 was studied in detail through infrared experiments.About 51%of all bridging OH groups were distributed in cages,while 23%and 26%,respectively,were distributed in 10‐and 8‐ring channels.The catalytic performance was enhanced by a high concentration of Bronsted acid,indicating that Bronsted acid is an active site for the aldol condensation reaction.The ZSM‐35 zeolite possessing a concentration of Bronsted acid as high as 0.049 mmol/g demonstrated excellent performance with a MA+AA selectivity of up to 73%.展开更多
Based on the principle of biomimetic catalysis, β-cyclodextrin was applied to the acetalation reaction as a facile and efficient catalyst, and the synthesis was environmentally friendly with atomic economy. The influ...Based on the principle of biomimetic catalysis, β-cyclodextrin was applied to the acetalation reaction as a facile and efficient catalyst, and the synthesis was environmentally friendly with atomic economy. The influencing factors of the acetalation reaction e.g. the reaction time, the volume of water-carrying agent,the molar ratio of catalyst to benzaldehyde and the molar ratio of glycol to benzaldehyde had been studied.The yield of benzaldehyde glycol acetal would reach a maximum of 81.3% under the conditions approached.Six of other acetals were also synthesized. Moreover, a plausible reaction mechanism for the formation of acetal had been proposed.展开更多
A mononuclear copper(II) complex, [Cu(bipy)(naph)(ClO4)] (where bipy is bipyridine and naph is 2-hydroxy-1-naphthaldehyde), was synthesized and characterized by X-ray single-crystal structure analysis. The crystal is ...A mononuclear copper(II) complex, [Cu(bipy)(naph)(ClO4)] (where bipy is bipyridine and naph is 2-hydroxy-1-naphthaldehyde), was synthesized and characterized by X-ray single-crystal structure analysis. The crystal is triclinic, space group P ?with a = 9.245(4), b = 9.962(4), c = 10.809(7) ? a = 84.83(5), b =82.35(4), g = 81.02(4), V = 972.1 ?, C21H15ClCuN2O6 Mr = 490.36, Z = 2, F(000) = 498, Dx = 1.68 g/cm3, m = 13.05 cm-1, R = 0.078, Rw = 0.081 for 2295 observed reflections with I > 3s(I). The copper(II) ion is coordinated by two nitrogen atoms of bipy and two oxygen atoms of naph in the equatorial plane, with an axial perchlorate oxygen-copper(II) bond to copper(II) ion to form square-pyramidal coordination geometry. The coordination environment of copper(II) is similar to the active site of galactose oxidase and this compound may also be considered as the structural model of galactose oxidase.展开更多
A series of alditol derivatives were designed and synthesized with relatively high yield. On the basis of reaction between sorbitol and a series of substituted benzaldehyde in the presence of an acid catalyst, a serie...A series of alditol derivatives were designed and synthesized with relatively high yield. On the basis of reaction between sorbitol and a series of substituted benzaldehyde in the presence of an acid catalyst, a series of acetal derivatives were synthesized through free hydroxyl esterification. D-sorbitol acetal amido derivatives were prepared by reduction of nitryl and acylation of amino. D-sorbitol acetal carboxyl esterification derivatives were prepared through esterification and hydrolysis. By high performance liquid chromatography-mass spectra (HPLC-MS) and 1H nuclear magnetic resonance spectra (1H-NMR), 36 compounds prepared were identified. Among these derivatives prepared, 26 compounds have not been reported in the previous literatures.展开更多
文摘This study was performed for the development of a green and promising approach for the synthesis of methyl acrylate and acrylic acid by a one‐step aldol condensation reaction of dimethoxymethane and methyl acetate over cesium oxide‐supported on ZSM‐35 zeolite catalysts; the effect of base sites as well as acid sites on the aldol condensation reaction was studied in detail. It was found that base sites were harmful for aldol condensation due to their failure in catalyzing the decomposition of dimethoxymethane precursor into formaldehyde, whereas the acid site was indispensable for the reaction to proceed. This reaction cannot take place without an acid site. Although acid sites in H‐form of the zeolite（HZSM‐35） are indispensable for the aldol condensation reaction, not all of them tend to favor this reaction. A strong acid catalyzes methanol‐to‐olefin‐like reactions resulting in hydrocarbon byproducts, which are finally transferred to hard coke. Medium strong acids and weak acids are great candidates for the target aldol condensation reaction with high activity and selectivity. A γ‐Al2O3 sample with abundant weak‐strength Lewis acid sites, together with a few medium‐strong‐strength acid sites, performs well with a high activity and considerable stability during the synthesis of methyl acrylate and acrylic acid.
基金Supported by the National Natural Science Foundation of China(No.20126008)
文摘Aqueous phase of acids as catalysts for the desulfurization of gasoline by condensation of thiophenes with form- aldehyde in a biphasic system was investigated. Two types of model gasoline with and without aromatics and olefins were employed in this work. The desulfurization rates were above 90% on these two types of model gasoline using formic acid and HaPW12O40 （0.8 mol·L-1）, indicating that the presence of aromatics and olefins has no effect on the desulfurization rate. High temperature （above 90 ℃） was more favorable to the process for desulfurization. Four hours was considered to be the proper treating time for the sulfur removal. In addition, aqueous phase of acids could be recycled at least 4 times without decreasing desulfurization rate. Finally, the possible process for the integration of condensation desulfurization into the existing refinery process for the production of gasoline with low sulfur content was proposed.
基金Supported by the National Natural Science Foundation of China (Nos.20576045, 20306009 and 202225620).
文摘An efficient reduction system of benzaldehyde with hydrogen under ambient pressure was developed using facile NiO catalyst. The non-aromatic solvents such as cyclohexane, tetrahydrofuran (THF) and n-hexane, and the addi-tive with strong basicity e.g. KOH, were necessary for smooth conversion of the substrate. That the catalyst can be recov-ered and reused for nine times without loss of catalytic activity indicates that this catalyst is a recyclable one for benzal-dehyde reduction.
基金Projects(51102026,51272032) supported by the Program for the National Natural Science Foundation of ChinaProject(11A014) supported by the Scientific Research Fund of Hunan Provincial Education DepartmentProject supported by the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Hunan Province,China
文摘The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.
文摘Acrylic acid(AA)and its ester,methyl acrylate(MA),were produced by a green one‐step aldol condensation reaction of dimethoxymethane and methyl acetate.The reaction was conducted over ZSM‐35 zeolites with different concentrations of Bronsted acid,which were prepared by the sodium ion‐exchange process with H‐form zeolite.The acidic property of HZSM‐35 was studied in detail through infrared experiments.About 51%of all bridging OH groups were distributed in cages,while 23%and 26%,respectively,were distributed in 10‐and 8‐ring channels.The catalytic performance was enhanced by a high concentration of Bronsted acid,indicating that Bronsted acid is an active site for the aldol condensation reaction.The ZSM‐35 zeolite possessing a concentration of Bronsted acid as high as 0.049 mmol/g demonstrated excellent performance with a MA+AA selectivity of up to 73%.
基金Supported by the National Natural Science Foundation of China(21376265)
文摘Based on the principle of biomimetic catalysis, β-cyclodextrin was applied to the acetalation reaction as a facile and efficient catalyst, and the synthesis was environmentally friendly with atomic economy. The influencing factors of the acetalation reaction e.g. the reaction time, the volume of water-carrying agent,the molar ratio of catalyst to benzaldehyde and the molar ratio of glycol to benzaldehyde had been studied.The yield of benzaldehyde glycol acetal would reach a maximum of 81.3% under the conditions approached.Six of other acetals were also synthesized. Moreover, a plausible reaction mechanism for the formation of acetal had been proposed.
基金Supported by the National Natural Science Foundation of China (No. 29971017) the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE China.
文摘A mononuclear copper(II) complex, [Cu(bipy)(naph)(ClO4)] (where bipy is bipyridine and naph is 2-hydroxy-1-naphthaldehyde), was synthesized and characterized by X-ray single-crystal structure analysis. The crystal is triclinic, space group P ?with a = 9.245(4), b = 9.962(4), c = 10.809(7) ? a = 84.83(5), b =82.35(4), g = 81.02(4), V = 972.1 ?, C21H15ClCuN2O6 Mr = 490.36, Z = 2, F(000) = 498, Dx = 1.68 g/cm3, m = 13.05 cm-1, R = 0.078, Rw = 0.081 for 2295 observed reflections with I > 3s(I). The copper(II) ion is coordinated by two nitrogen atoms of bipy and two oxygen atoms of naph in the equatorial plane, with an axial perchlorate oxygen-copper(II) bond to copper(II) ion to form square-pyramidal coordination geometry. The coordination environment of copper(II) is similar to the active site of galactose oxidase and this compound may also be considered as the structural model of galactose oxidase.
基金National Natural Science Foundation of China (No 20306022)
文摘A series of alditol derivatives were designed and synthesized with relatively high yield. On the basis of reaction between sorbitol and a series of substituted benzaldehyde in the presence of an acid catalyst, a series of acetal derivatives were synthesized through free hydroxyl esterification. D-sorbitol acetal amido derivatives were prepared by reduction of nitryl and acylation of amino. D-sorbitol acetal carboxyl esterification derivatives were prepared through esterification and hydrolysis. By high performance liquid chromatography-mass spectra (HPLC-MS) and 1H nuclear magnetic resonance spectra (1H-NMR), 36 compounds prepared were identified. Among these derivatives prepared, 26 compounds have not been reported in the previous literatures.
