A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh_3-Pd） exhibi...A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh_3-Pd） exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.展开更多
Rod-like, hexagonal and fiber-like SBA-15 mesoporous silicas were synthesized to support MnO_x for toluene oxidation. This study showed that the morphology of the supports greatly influenced the catalytic activity in ...Rod-like, hexagonal and fiber-like SBA-15 mesoporous silicas were synthesized to support MnO_x for toluene oxidation. This study showed that the morphology of the supports greatly influenced the catalytic activity in toluene oxidation. MnO_x supported on rod-like SBA-15(R-SBA-15) displayed the best catalytic activity and the conversion at 230°C reached more than 90%, which was higher than the other two catalysts. MnO_x species consisted of coexisting MnO_2 and Mn_2O_3 on the three kinds of SBA-15 samples. Large amounts of Mn_2O_3 species were formed on the surface and high oxygen mobility was obtained on MnO_x supported on R-SBA-15, according to the H_2 temperature programmed reduction(H_2-TPR)and X-ray photoelectron spectroscopy(XPS) results. The Mn/R-SBA-15 catalyst with greater amounts of Mn_2O_3 species possessed a large amount of surface lattice oxygen, which accelerated the catalytic reaction rate. Therefore, the surface lattice oxygen and high oxygen mobility were critical factors on the catalytic activity of the Mn/R-SBA-15 catalyst.展开更多
The catalytic properties of PtSn-based catalysts supported on siliceous SBA-15 and Al-modified SBA-15, such as Al-incorporated SBA-15 （AlSBA-15） and alumina-modified SBA-15 （Al2O3/SBA-15）, for propane dehydrogenat...The catalytic properties of PtSn-based catalysts supported on siliceous SBA-15 and Al-modified SBA-15, such as Al-incorporated SBA-15 （AlSBA-15） and alumina-modified SBA-15 （Al2O3/SBA-15）, for propane dehydrogenation were investigated. Al2O3/SBA-15 was prepared either by an impregnation method using aluminum nitrate aqueous solution, or by the treatment of SBA-15 with a Al（OC3H7）3 solution in anhydrous toluene. N2-physisorption, FT-IR spectroscopy, solid-state 27Al MAS NMR spectroscopy, hydrogen chemisorption, XRF, NH3 temperature-programmed desorption, X-ray photoelectron spectroscopy and TPO were used to characterize these samples. Among these catalysts, the PtSn-based catalyst supported on Al2O3/SBA-15, which was grafted with Al（OC3H7）3, exhibited the best catalytic performance in terms of activity and stability The possible reason was due to the high Pt metal dispersion and/or the strong interactions among Pt, Sn, and the support.展开更多
Preparation of dispersed transition metal oxides catalyst with low oxidation state still remains a challenging task in heterogeneous catalysis.In this study,vanadium oxides supported on zeolite SBA-15 have been prepar...Preparation of dispersed transition metal oxides catalyst with low oxidation state still remains a challenging task in heterogeneous catalysis.In this study,vanadium oxides supported on zeolite SBA-15 have been prepared under hydrothermal condition using V 2 O 5 and oxalic acid as sources of vanadium and reductant,respectively.The structures of samples,especially the oxidation state of vanadium,and the surface distribution of vanadium oxide species,have been thoroughly characterized using various techniques,including N 2-physisorption,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,UV-visible spectra（UV-Vis） and UV-visible-near infrared spectra（UV-Vis-NIR）.It is found that the majority of supported vanadium was in the form of vanadium（IV） oxide species with the low valence of vanadium.By adjusting hydrothermal treatment time,the surface distribution of vanadium（IV） oxide species can be tuned from vanadium（IV） oxide cluster to crystallites.These materials have been tested in the hydroxylation of benzene to phenol in liquid-phase with molecular oxygen in the absence of reductant.The catalyst exhibits high selectivity for phenol（61%） at benzene conversion of 4.6%,which is a relatively good result in comparison with other studies employing molecular oxygen as the oxidant.展开更多
Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia load...Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The Mg O–SBA-15 supports and Pd–Pb/Mg O–SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of Mg O improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3 Pb particles on magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts was smaller than that on the pure silica-based Pd–Pb/SBA-15 catalysts. The experiments on catalyst performance showed that the magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts had higher activity than pure silica-based Pd–Pb/SBA-15 catalysts, showing the strong dependence of catalytic activity on the average size of active particles. The difference of activity between Pd–Pb/SBA-15 catalysts and Pd–Pb/Mg O–SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by Mg O, which led to the different Pd3 Pb particle sizes and then resulted in the different number of active sites. Besides magnesia loadings, other factors, such as hydrochloric acid molar concentration and magnesium precursors, had considerable influences on the catalytic activity.展开更多
Dehydrogenation of propane on Pt or Pt Sn catalyst over Al2O3 or SBA-15 support was investigated. The catalysts were characterized by CO-pulse chemisorption, thermogravimetry, temperature-programmed-reduction of H2,an...Dehydrogenation of propane on Pt or Pt Sn catalyst over Al2O3 or SBA-15 support was investigated. The catalysts were characterized by CO-pulse chemisorption, thermogravimetry, temperature-programmed-reduction of H2,and diffuse reflectance infrared Fourier transform spectroscopy of absorbed CO. The results show that the platinum species is in oxidation state in the catalyst on Al2O3 support, so the catalyst must be reduced in H2 before dehydrogenation reaction. Addition of Sn improves the Pt dispersion, but the catalyst deactivates rapidly because of the coke formation. The interaction of Pt and Al2O3 is strong. On SBA-15 support, the platinum species is completely reduced to Pt0 in the calcination process, so the reduction is not needed. Addition of Sn improves the activity and selectivity of the catalyst. The interaction of Pt and SBA-15 is weak, so it is easy for Pt particles to sinter.展开更多
SBA-15 supported Mo catalysts （Moy/SBA-15） were prepared by an ultrasonic assisted incipient-wetness impregnation method. The physical and chemical properties of the catalysts were characterized by means of N2-adsor...SBA-15 supported Mo catalysts （Moy/SBA-15） were prepared by an ultrasonic assisted incipient-wetness impregnation method. The physical and chemical properties of the catalysts were characterized by means of N2-adsorption-desorption, XRD, TEM, UV-Vis, Raman, XANES and H2-TPR. The results showed that a trace amount of MoO3 was produced on high Mo content samples. Tum-over frequency （TOF） and product selectivity are dependent on the molybdenum content. Both Mo0.75/SBA-15 and Mo1.75/SBA-15 catalysts give the higher catalytic activity and the selectivity to the total aldehydes for the selective oxidation of C2H6. At the reaction temperature of 625℃, the maximum yield of aldehydes reached 4.2% over Mo0.75/SBA-15 catalyst. The improvement of the activity and selectivity was related with the state of MoOx species.展开更多
The steam reforming of glycerol has been studied at 500 and 600 oC using Co/SBA-15 and Co/M/SBA-15（M: Zr, Ce, or La） promoted catalysts. The prepared materials were characterized by inductively coupled plasma atomic...The steam reforming of glycerol has been studied at 500 and 600 oC using Co/SBA-15 and Co/M/SBA-15（M: Zr, Ce, or La） promoted catalysts. The prepared materials were characterized by inductively coupled plasma atomic emission spectroscopy（ICP-AES）, X-ray powder diffraction（XRD）, hydrogen temperatureprogramed reduction（H;-TPR）, ammonia temperature-programed desorption（NH;-TPD）, nitrogen physisorption analysis（N;-BET）, transmission electron microscopy（TEM） and thermogravimetric analysis（TGA）. The incorporation of promoters like Zr, Ce and La on SBA-15 support and successive Co impregnation leaded to smaller cobalt crystallites improving metaldispersion. Besides, stronger metal-support interactions between Co species and M/SBA-15 supports were observed. Thanks to the incorporation of Zr, La and mainly Ce, promoted catalysts present higher glycerol conversion than Co/SBA-15 along 5 h of time on stream. Besides, at 600 oC, Co/M/SBA-15（M: Zr, Ce, or La） catalysts produce higher hydrogen amounts than Co/SBA-15.展开更多
Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of ...Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio,temperature,catalyst amount by using TBHP as an oxidizing agent.Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion(97.3%) was observed at styrene to TBHP mole ratio of 1:4,temperature at 80 °C and 20 mg of catalyst.Further,the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.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
Highly dispersed palladium nanoparticles were synthesized in the presence of immobilized ionic liquid on mesoporous silica SBA-15.PdNPs(2.4 nm)_me-Im@SBA-15 catalyst was prepared by the reduction using NaBH_4 as the r...Highly dispersed palladium nanoparticles were synthesized in the presence of immobilized ionic liquid on mesoporous silica SBA-15.PdNPs(2.4 nm)_me-Im@SBA-15 catalyst was prepared by the reduction using NaBH_4 as the reducing agent with controlled feed rate and has been investigated as ligand-free catalyst for Suzuki–Miyaura cross-coupling reaction at room temperature in aqueous solution under air.PdNPs catalyst was also prepared in situ from PdCl4_me-Im@SBA-15 during the reaction and demonstrated high activity and stability towards nitrobenzene hydrogenation at high temperature. Both catalysts were reusable at least for four recycle processes without significant loss in activity with simple procedure. The catalysts were characterized by TEM, EXAFS, FTIR and XPS.展开更多
Recently,cyclic(alkyl)(amino)carbenes(CAACs)have been widely used as ligands to enhance the catalytic reactivity of center metal,but the problem of recycling this expensive ligand remains to be solved.In this work,the...Recently,cyclic(alkyl)(amino)carbenes(CAACs)have been widely used as ligands to enhance the catalytic reactivity of center metal,but the problem of recycling this expensive ligand remains to be solved.In this work,the heterogeneous SBA-15-CAAC-Ir catalyst was prepared by a covalent attachment method.and using SBA-15 as the carrier.It shows high reactivity for the hydrogenation of CO_(2) to formate.After immobilization,the ordered mesoporous structure and the overall rod-like morphology of the original SBA-15 have been preserved very well.Using SBA-15-CAAC-Ir as catalyst,up to 21050 TON can be obtained at 60℃.In addition,the catalyst can be separated easily by centrifugation,and the catalytic activity of SBA-15-CAAC-Ir can still remain very high after multiple cycles.展开更多
基金National Natural Science Foundation of China(No.20603005)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20090041110012) for their financial support
文摘A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh_3-Pd） exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.
基金supported by the National Nature Science Foundation of China (Nos.21377016 and 21577014)Programme of Introducing Talents of Discipline to Universities (No.B13012)Program for Changjiang Scholars and Innovative Research Team in University (No.IRT_13R05)
文摘Rod-like, hexagonal and fiber-like SBA-15 mesoporous silicas were synthesized to support MnO_x for toluene oxidation. This study showed that the morphology of the supports greatly influenced the catalytic activity in toluene oxidation. MnO_x supported on rod-like SBA-15(R-SBA-15) displayed the best catalytic activity and the conversion at 230°C reached more than 90%, which was higher than the other two catalysts. MnO_x species consisted of coexisting MnO_2 and Mn_2O_3 on the three kinds of SBA-15 samples. Large amounts of Mn_2O_3 species were formed on the surface and high oxygen mobility was obtained on MnO_x supported on R-SBA-15, according to the H_2 temperature programmed reduction(H_2-TPR)and X-ray photoelectron spectroscopy(XPS) results. The Mn/R-SBA-15 catalyst with greater amounts of Mn_2O_3 species possessed a large amount of surface lattice oxygen, which accelerated the catalytic reaction rate. Therefore, the surface lattice oxygen and high oxygen mobility were critical factors on the catalytic activity of the Mn/R-SBA-15 catalyst.
基金supported by the National Nature Science Foundation of China (50873026, 21106017)the Production and Research Prospective Joint Research Project (BY2009153)+1 种基金the Science and Technology Support Program (BE2008129) of Jiangsu Province of ChinaSpecialized Research Fund for the Doctoral Program of Higher Education of China (20100092120047)
文摘The catalytic properties of PtSn-based catalysts supported on siliceous SBA-15 and Al-modified SBA-15, such as Al-incorporated SBA-15 （AlSBA-15） and alumina-modified SBA-15 （Al2O3/SBA-15）, for propane dehydrogenation were investigated. Al2O3/SBA-15 was prepared either by an impregnation method using aluminum nitrate aqueous solution, or by the treatment of SBA-15 with a Al（OC3H7）3 solution in anhydrous toluene. N2-physisorption, FT-IR spectroscopy, solid-state 27Al MAS NMR spectroscopy, hydrogen chemisorption, XRF, NH3 temperature-programmed desorption, X-ray photoelectron spectroscopy and TPO were used to characterize these samples. Among these catalysts, the PtSn-based catalyst supported on Al2O3/SBA-15, which was grafted with Al（OC3H7）3, exhibited the best catalytic performance in terms of activity and stability The possible reason was due to the high Pt metal dispersion and/or the strong interactions among Pt, Sn, and the support.
基金supported by the National Nature Science Foundation of China (21073184 and 21103175)One Hundred Person Project of the Chinese Academy of Sciences
文摘Preparation of dispersed transition metal oxides catalyst with low oxidation state still remains a challenging task in heterogeneous catalysis.In this study,vanadium oxides supported on zeolite SBA-15 have been prepared under hydrothermal condition using V 2 O 5 and oxalic acid as sources of vanadium and reductant,respectively.The structures of samples,especially the oxidation state of vanadium,and the surface distribution of vanadium oxide species,have been thoroughly characterized using various techniques,including N 2-physisorption,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,UV-visible spectra（UV-Vis） and UV-visible-near infrared spectra（UV-Vis-NIR）.It is found that the majority of supported vanadium was in the form of vanadium（IV） oxide species with the low valence of vanadium.By adjusting hydrothermal treatment time,the surface distribution of vanadium（IV） oxide species can be tuned from vanadium（IV） oxide cluster to crystallites.These materials have been tested in the hydroxylation of benzene to phenol in liquid-phase with molecular oxygen in the absence of reductant.The catalyst exhibits high selectivity for phenol（61%） at benzene conversion of 4.6%,which is a relatively good result in comparison with other studies employing molecular oxygen as the oxidant.
基金Supported by the Key Program of the National Natural Science Foundation of China(21036007)the National High-Tech Project of China(2012AA062903)
文摘Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The Mg O–SBA-15 supports and Pd–Pb/Mg O–SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of Mg O improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3 Pb particles on magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts was smaller than that on the pure silica-based Pd–Pb/SBA-15 catalysts. The experiments on catalyst performance showed that the magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts had higher activity than pure silica-based Pd–Pb/SBA-15 catalysts, showing the strong dependence of catalytic activity on the average size of active particles. The difference of activity between Pd–Pb/SBA-15 catalysts and Pd–Pb/Mg O–SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by Mg O, which led to the different Pd3 Pb particle sizes and then resulted in the different number of active sites. Besides magnesia loadings, other factors, such as hydrochloric acid molar concentration and magnesium precursors, had considerable influences on the catalytic activity.
文摘Dehydrogenation of propane on Pt or Pt Sn catalyst over Al2O3 or SBA-15 support was investigated. The catalysts were characterized by CO-pulse chemisorption, thermogravimetry, temperature-programmed-reduction of H2,and diffuse reflectance infrared Fourier transform spectroscopy of absorbed CO. The results show that the platinum species is in oxidation state in the catalyst on Al2O3 support, so the catalyst must be reduced in H2 before dehydrogenation reaction. Addition of Sn improves the Pt dispersion, but the catalyst deactivates rapidly because of the coke formation. The interaction of Pt and Al2O3 is strong. On SBA-15 support, the platinum species is completely reduced to Pt0 in the calcination process, so the reduction is not needed. Addition of Sn improves the activity and selectivity of the catalyst. The interaction of Pt and SBA-15 is weak, so it is easy for Pt particles to sinter.
基金supported by NSFC(21376261,21173270,21177160)Beijing Natural Science Foundation(2142027)+1 种基金863 Program of China(2013AA065302)the Doctor Select Foundation(20130007110007)
文摘SBA-15 supported Mo catalysts （Moy/SBA-15） were prepared by an ultrasonic assisted incipient-wetness impregnation method. The physical and chemical properties of the catalysts were characterized by means of N2-adsorption-desorption, XRD, TEM, UV-Vis, Raman, XANES and H2-TPR. The results showed that a trace amount of MoO3 was produced on high Mo content samples. Tum-over frequency （TOF） and product selectivity are dependent on the molybdenum content. Both Mo0.75/SBA-15 and Mo1.75/SBA-15 catalysts give the higher catalytic activity and the selectivity to the total aldehydes for the selective oxidation of C2H6. At the reaction temperature of 625℃, the maximum yield of aldehydes reached 4.2% over Mo0.75/SBA-15 catalyst. The improvement of the activity and selectivity was related with the state of MoOx species.
基金the financial support from the“Comunidad Autónoma de Madrid”through the RESTOENE2 project(S2013/MAE-2882)the“Ministerio de Economía y Competitividad”through the project CTQ2013-44447-R
文摘The steam reforming of glycerol has been studied at 500 and 600 oC using Co/SBA-15 and Co/M/SBA-15（M: Zr, Ce, or La） promoted catalysts. The prepared materials were characterized by inductively coupled plasma atomic emission spectroscopy（ICP-AES）, X-ray powder diffraction（XRD）, hydrogen temperatureprogramed reduction（H;-TPR）, ammonia temperature-programed desorption（NH;-TPD）, nitrogen physisorption analysis（N;-BET）, transmission electron microscopy（TEM） and thermogravimetric analysis（TGA）. The incorporation of promoters like Zr, Ce and La on SBA-15 support and successive Co impregnation leaded to smaller cobalt crystallites improving metaldispersion. Besides, stronger metal-support interactions between Co species and M/SBA-15 supports were observed. Thanks to the incorporation of Zr, La and mainly Ce, promoted catalysts present higher glycerol conversion than Co/SBA-15 along 5 h of time on stream. Besides, at 600 oC, Co/M/SBA-15（M: Zr, Ce, or La） catalysts produce higher hydrogen amounts than Co/SBA-15.
文摘Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio,temperature,catalyst amount by using TBHP as an oxidizing agent.Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion(97.3%) was observed at styrene to TBHP mole ratio of 1:4,temperature at 80 °C and 20 mg of catalyst.Further,the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.
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.
基金the financial support from the Institute for Quantum Chemical Exploration(IQCE)
文摘Highly dispersed palladium nanoparticles were synthesized in the presence of immobilized ionic liquid on mesoporous silica SBA-15.PdNPs(2.4 nm)_me-Im@SBA-15 catalyst was prepared by the reduction using NaBH_4 as the reducing agent with controlled feed rate and has been investigated as ligand-free catalyst for Suzuki–Miyaura cross-coupling reaction at room temperature in aqueous solution under air.PdNPs catalyst was also prepared in situ from PdCl4_me-Im@SBA-15 during the reaction and demonstrated high activity and stability towards nitrobenzene hydrogenation at high temperature. Both catalysts were reusable at least for four recycle processes without significant loss in activity with simple procedure. The catalysts were characterized by TEM, EXAFS, FTIR and XPS.
基金supported by the National Natural Science Foundation of China(Nos.22178159,21878141)Key Research&Development Plan of Jiangsu Province(BE2019095)。
文摘Recently,cyclic(alkyl)(amino)carbenes(CAACs)have been widely used as ligands to enhance the catalytic reactivity of center metal,but the problem of recycling this expensive ligand remains to be solved.In this work,the heterogeneous SBA-15-CAAC-Ir catalyst was prepared by a covalent attachment method.and using SBA-15 as the carrier.It shows high reactivity for the hydrogenation of CO_(2) to formate.After immobilization,the ordered mesoporous structure and the overall rod-like morphology of the original SBA-15 have been preserved very well.Using SBA-15-CAAC-Ir as catalyst,up to 21050 TON can be obtained at 60℃.In addition,the catalyst can be separated easily by centrifugation,and the catalytic activity of SBA-15-CAAC-Ir can still remain very high after multiple cycles.
