The 0.4%Pt/xSTA-MIL-101(Cr)metal-acid bifunctional catalysts were prepared by impregnation using STA-MIL-101(Cr)as the support.The synthesized samples were verified to exhibit a typical octahedral structure of MIL-101...The 0.4%Pt/xSTA-MIL-101(Cr)metal-acid bifunctional catalysts were prepared by impregnation using STA-MIL-101(Cr)as the support.The synthesized samples were verified to exhibit a typical octahedral structure of MIL-101(Cr)and the pore structure was arranged orderly.The specific surface area of the samples was extremely high and the samples were made of micro-mesoporous composite materials.Silicotungstic acid could retain its Keggin structure in the 0.4%Pt/xSTA-MIL-101(Cr)samples and the catalyst possessed moderately strong Brønsted acid sites.Besides,the dispersion of Pt particles in MIL-101(Cr)was relatively high.n-Heptane isomerization was first used as a probe to test the novel 0.4%Pt/xSTA-MIL-10(Cr)catalyst.Compared with the conventional silicate catalysts,the catalytic performance of 0.4%Pt/30%STA-MIL-101(Cr)was significantly improved with a n-heptane conversion of 58.93%and an iso-heptane selectivity of 95.68%,respectively,under conditions covering a reaction time of 2 h and a reaction temperature of 260°C.The catalyst could still maintain a relatively high catalytic performance after a reaction time of 5 h.Compared with the non-noble metal catalyst,the catalytic efficiency of 0.4%Pt/30%STA-MIL-101(Cr)is relatively high.The mechanism model of n-heptane isomerization over 0.4%Pt/xSTA-MIL-101(Cr)catalyst was established.展开更多
Highly dispersed silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-_(15) (WZ/SBA-_(15)) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (...Highly dispersed silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-_(15) (WZ/SBA-_(15)) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (IWI) method that active ingredients, ZrO_(2) and WO_(3), were impregnated into the channels of SBA-_(15) simultaneously with a subsequent calcination process. The relationship between catalyst nature and performance was explored by high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N_(2) adsorption-desorption, NH_(3) temperature-programmed desorption (NH_(3)-TPD), and FT-IR of pyridine adsorption (Py-IR) characterization techniques. The catalytic performance of W_(12)Z_(15)/SBA-_(15) is not only greater than that of single component solid acid catalysts, WO_(3)/SBA-_(15) and ZrO_(2)/SBA-_(15), but also W_(12)/Z_(15)/SBA-_(15) prepared by impregnating active ingredients, ZrO_(2) and WO_(3), into SBA-_(15) in sequence. The outstanding performance of W_(12)Z_(15)/SBA-_(15) is derived from the strong interaction between ZrO_(2) and WO_(3), which results in more acid sites, and relatively high specific surface area, large pore volume, and ordered mesoporous structure of SBA-_(15). The characterization and reaction results clearly demonstrate that the synergy of ZrO_(2) and WO_(3) has a clear boost for the alkenylation. The optimized W_(12)Z_(15)/SBA-_(15)-500 achieves a 99.4% conversion of phenylacetylene and a 92.3% selectivity of main product α-arylstyrene for the alkenylation of p-xylene with phenylacetylene, with very low level of oligomers producing at the same time. Moreover, W_(12)Z_(15)/SBA-_(15)-500 shows excellent catalytic stability and regeneration. Therefore, W_(12)Z_(15)/SBA-_(15)-500 is a promising solid acid catalyst for the alkenylation.展开更多
A 1D chain-like organic-inorganic hybrid rare earth derivative of polyoxometalate H0.5[Sm(H2O)6]0.25[Sm(H2O)5]0.25{[Sm(H2O)7][Sm(H2O)2(DMSO)][SiW11O39]}·4.5H2O has been firstly synthesized by reaction ...A 1D chain-like organic-inorganic hybrid rare earth derivative of polyoxometalate H0.5[Sm(H2O)6]0.25[Sm(H2O)5]0.25{[Sm(H2O)7][Sm(H2O)2(DMSO)][SiW11O39]}·4.5H2O has been firstly synthesized by reaction of α-K8SiW11O39.13H2O, HClO4, Sm2O3 with dimethyl sulfoxide (DMSO) and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. The neighboring polyanionic units {[Sm(H2O)7][Sm(H2O)2(DMSO)][SiWHO39]}^2- are bridged together to a 1D chain structure by means of [Sm(H2O)2(DMSO)]^3+ ion.展开更多
A simple and efficient method for the synthesis of pyrazoles through a silicotungstic acid (H_(4)SiW_(12)O_(40))-catalyzed cyclization of epoxides/aldehydes and sulfonyl hydrazides has been developed. Various epoxides...A simple and efficient method for the synthesis of pyrazoles through a silicotungstic acid (H_(4)SiW_(12)O_(40))-catalyzed cyclization of epoxides/aldehydes and sulfonyl hydrazides has been developed. Various epoxides/aldehydes were smoothly reacted with sulfonyl hydrazides to furnish regioselectivity 3,4-disubstituted 1H-pyrazoles. The application of such an earth-abundant, readily accessible, and nontoxic catalyst provides a green approach for the construction of 3,4-disubstituted 1H-pyrazoles. A plausible reaction mechanism has been proposed on the basis of control experiments, GC-MS and DFT calculations.展开更多
文摘The 0.4%Pt/xSTA-MIL-101(Cr)metal-acid bifunctional catalysts were prepared by impregnation using STA-MIL-101(Cr)as the support.The synthesized samples were verified to exhibit a typical octahedral structure of MIL-101(Cr)and the pore structure was arranged orderly.The specific surface area of the samples was extremely high and the samples were made of micro-mesoporous composite materials.Silicotungstic acid could retain its Keggin structure in the 0.4%Pt/xSTA-MIL-101(Cr)samples and the catalyst possessed moderately strong Brønsted acid sites.Besides,the dispersion of Pt particles in MIL-101(Cr)was relatively high.n-Heptane isomerization was first used as a probe to test the novel 0.4%Pt/xSTA-MIL-10(Cr)catalyst.Compared with the conventional silicate catalysts,the catalytic performance of 0.4%Pt/30%STA-MIL-101(Cr)was significantly improved with a n-heptane conversion of 58.93%and an iso-heptane selectivity of 95.68%,respectively,under conditions covering a reaction time of 2 h and a reaction temperature of 260°C.The catalyst could still maintain a relatively high catalytic performance after a reaction time of 5 h.Compared with the non-noble metal catalyst,the catalytic efficiency of 0.4%Pt/30%STA-MIL-101(Cr)is relatively high.The mechanism model of n-heptane isomerization over 0.4%Pt/xSTA-MIL-101(Cr)catalyst was established.
基金financially supported by the National Natural Science Foundation of China (No. 21276041)Chinese Ministry of Education via the Program for New Century Excellent Talents in University (No. NCET-12-0079)。
文摘Highly dispersed silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-_(15) (WZ/SBA-_(15)) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (IWI) method that active ingredients, ZrO_(2) and WO_(3), were impregnated into the channels of SBA-_(15) simultaneously with a subsequent calcination process. The relationship between catalyst nature and performance was explored by high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N_(2) adsorption-desorption, NH_(3) temperature-programmed desorption (NH_(3)-TPD), and FT-IR of pyridine adsorption (Py-IR) characterization techniques. The catalytic performance of W_(12)Z_(15)/SBA-_(15) is not only greater than that of single component solid acid catalysts, WO_(3)/SBA-_(15) and ZrO_(2)/SBA-_(15), but also W_(12)/Z_(15)/SBA-_(15) prepared by impregnating active ingredients, ZrO_(2) and WO_(3), into SBA-_(15) in sequence. The outstanding performance of W_(12)Z_(15)/SBA-_(15) is derived from the strong interaction between ZrO_(2) and WO_(3), which results in more acid sites, and relatively high specific surface area, large pore volume, and ordered mesoporous structure of SBA-_(15). The characterization and reaction results clearly demonstrate that the synergy of ZrO_(2) and WO_(3) has a clear boost for the alkenylation. The optimized W_(12)Z_(15)/SBA-_(15)-500 achieves a 99.4% conversion of phenylacetylene and a 92.3% selectivity of main product α-arylstyrene for the alkenylation of p-xylene with phenylacetylene, with very low level of oligomers producing at the same time. Moreover, W_(12)Z_(15)/SBA-_(15)-500 shows excellent catalytic stability and regeneration. Therefore, W_(12)Z_(15)/SBA-_(15)-500 is a promising solid acid catalyst for the alkenylation.
文摘A 1D chain-like organic-inorganic hybrid rare earth derivative of polyoxometalate H0.5[Sm(H2O)6]0.25[Sm(H2O)5]0.25{[Sm(H2O)7][Sm(H2O)2(DMSO)][SiW11O39]}·4.5H2O has been firstly synthesized by reaction of α-K8SiW11O39.13H2O, HClO4, Sm2O3 with dimethyl sulfoxide (DMSO) and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. The neighboring polyanionic units {[Sm(H2O)7][Sm(H2O)2(DMSO)][SiWHO39]}^2- are bridged together to a 1D chain structure by means of [Sm(H2O)2(DMSO)]^3+ ion.
基金financially supported by the National Natural Science Foundation of China (Nos. 22001034 and 21804019)the Open Fund of the Jiangxi Province Key Laboratory of Synthetic Chemistry (No. JXSC202008)the Research Found of East China University of Technology (Nos. DHBK2019264, DHBK2019265 and DHBK2019267)。
文摘A simple and efficient method for the synthesis of pyrazoles through a silicotungstic acid (H_(4)SiW_(12)O_(40))-catalyzed cyclization of epoxides/aldehydes and sulfonyl hydrazides has been developed. Various epoxides/aldehydes were smoothly reacted with sulfonyl hydrazides to furnish regioselectivity 3,4-disubstituted 1H-pyrazoles. The application of such an earth-abundant, readily accessible, and nontoxic catalyst provides a green approach for the construction of 3,4-disubstituted 1H-pyrazoles. A plausible reaction mechanism has been proposed on the basis of control experiments, GC-MS and DFT calculations.