采用单因素法,以2-氯-4,6-二(N-丁基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪、环己烷、叔丁基过氧化氢为原料,三氧化钼为催化剂合成2-氯-4,6-二(N-丁基-1-环己氧基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪。结果表明,最佳工艺条件为反...采用单因素法,以2-氯-4,6-二(N-丁基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪、环己烷、叔丁基过氧化氢为原料,三氧化钼为催化剂合成2-氯-4,6-二(N-丁基-1-环己氧基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪。结果表明,最佳工艺条件为反应温度95℃,反应时间14 h,原料物质的量比n(2-氯-4,6-二(N-丁基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪)∶n(环己烷)∶n(叔丁基过氧化氢)为0.01∶0.45∶0.2,催化剂三氧化钼用量为0.4 g (相对0.01 mol2-氯-4,6-二(N-丁基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪),产品收率为93.50%。展开更多
Tailoring the Ti coordination states in titanosilicate zeolites to simultaneously improve feedstock conversion and maximize the target product selectivity remains a challenge in the pursuit of high-performance catalys...Tailoring the Ti coordination states in titanosilicate zeolites to simultaneously improve feedstock conversion and maximize the target product selectivity remains a challenge in the pursuit of high-performance catalysts for selective oxidation reactions.Herein,we provide a facile strategy to synthesize hierarchical anatase-free TS-1(MFI-type)zeolites with tetrahedrally coordinated(TiO_(4))and octahedrally coordinated Ti species(TiO_(6)).The TiO_(4)species provide high epoxide selectivity,while the TiO_(6)species afford improved alkene conversion.This strategy is achieved by synergistically using an L-lysine-assisted approach and a two-step crystallization;the two-step crystallization approach prevents the formation of anatase TiO_(2),while L-lysine stabilizes the TiO_(6)species and ensures efficient incorporation of TiO_(6)into the anatase-free TS-1 zeolites.Compared with their conventional counterparts,which only contain TiO_(4)species,the as-prepared TS-1 zeolites(Si/Ti=36.9)result in a higher 1-hexene conversion(33%),higher TON value(153),and comparable epoxide selectivity(95%).This synthetic strategy provides avenues to tailor the amount and distribution of Ti species in titanosilicate zeolites to achieve high catalytic performances in various processes.展开更多
Hydroxy-phenyl)-5-(2-methyl-phenyl)-6-ethoxycarbonyl-cyclohexen-2-one has been synthesized and characterized by elemental analysis, IR, UV, H NMR and MS, and its crystal 1 structure was determined by X-ray single-crys...Hydroxy-phenyl)-5-(2-methyl-phenyl)-6-ethoxycarbonyl-cyclohexen-2-one has been synthesized and characterized by elemental analysis, IR, UV, H NMR and MS, and its crystal 1 structure was determined by X-ray single-crystal diffraction method. The crystal belongs to the monoclinic system, space group P21/c with a = 14.6298(13), b = 5.8623(5), c = 22.255(2) ?, β = 105.855(2)o, V = 1836.0(3) ?3, Mr = 350.40, Z = 4, Dc = 1.268 g/cm3, F(000) = 744, μ(MoKα) = 0.086 mm-1, R = 0.0680 and wR = 0.1498. The crystal analysis results show that the cyclohexene unit of the title compound has a quasi-chair conformation, and a centrosymmetric dimer with a 16-membered ring is produced by the intermolecular hydrogen bonds.展开更多
Hollow titanium silicalite （HTS） molecular sieve has been synthesized, and information on its structure, physico- chemical characterization, as well as surface property was investigated by a host of analytical metho...Hollow titanium silicalite （HTS） molecular sieve has been synthesized, and information on its structure, physico- chemical characterization, as well as surface property was investigated by a host of analytical methods, such as XRF, XRD, low-temperature N2 adsorption/desorption, TEM, FT-IR, UV-Vis, 29Si MAS NIVIR, and XPS techniques. The characterization results suggest that HTS zeolite has a special hollow crystal structure and its mesopore volume is larger than that of TS-1 zeolite. The titanium species in this zeolite are composed of the framework tetrahedral Ti （IV） ions and extra-framework octahedral Ti （IV） ions, which tend to disperse into its bulk phase. This zeolite material also has been applied to catalyze the cyclohexanone oxidation process, and the products are not completely consistent with those results obtained by using TS-1 zeolite, which might be caused by their difference in pore structure and pore volume, especially the mesopore volume. Cy- clohexanone oxidation catalyzed by HTS zeolite is a representative consecutive reaction, the main target products of which are e-caprolactone, 6-hydroxyhexanoic acid and adipic acid. The effect of H202/cyclohexanone mole ratio on the cyclohexa- none conversion, the total target product selectivity, the distribution of three target products selectivity and their variations along with reaction time is also researched and analyzed, which indicate that HTS zeolite shows a high performance for the Baeyer-Villiger reaction of cyclohexanone and catalytic oxidation of 6-hydroxyhexanoic acid under mild conditions, and the quantity of active surface titanium species as well as the pore structure and mesopore volume controlling the mass diffusion rate are the key factors determining the catalytic activity of HTS zeolite and product selectivity.展开更多
A method for oxidative degradation of 1,4-dioxane （1,4-D） in waste water using a combination of ozone oxidation with UV irradiation （ozone/UV） treatment was investigated. The results showed that 1,4-D was degraded...A method for oxidative degradation of 1,4-dioxane （1,4-D） in waste water using a combination of ozone oxidation with UV irradiation （ozone/UV） treatment was investigated. The results showed that 1,4-D was degraded by ozone/UV treatment up to 90 min. The optimum concentration for the injected ozone gas was about 40 g·m^3 under a constant level of UV irradiation. Furthermore, solid phase extraction and GC-MS analysis showed no specific or reproducible peaks due to by-products of 1,4-D. It was therefore concluded that 1,4-D was completely degraded by ozone/UV treatment. In contrast, the amount of 1,4-D remaining decreased slowly in the presence of HCOf or CI. It was suggested that the degradation of 1,4-D, which results from .OH oxidation, was retarded by the presence of HCO3 or CI, which act as radical scavengers.展开更多
Ti/BMMs （Ti supported bimodal mesoporous silica） catalysts have been prepared via self-assembly route com- bined with ship-in-a-bottle method. The recovery and recycling performances of Ti/BMMs were investigated in ...Ti/BMMs （Ti supported bimodal mesoporous silica） catalysts have been prepared via self-assembly route com- bined with ship-in-a-bottle method. The recovery and recycling performances of Ti/BMMs were investigated in the epoxidation of cyclohexene. In order to the evaluate the regeneration methods and to examine the deactivation behaviors, the deactivated Ti/BMMs catalysts were washed in chloroform or calcinated at 450 ℃ for 6 h and then activity of the recovery catalysts were examined. Meanwhile, the structure features and surface properties of the regenerated catalysts were characterized by X-ray diffraction, N2-sorption analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravi- metric analysis, UV visible spectroscopy and X-ray photoelectron spectroscopy. The results showed that the typical bimodal mesoporous structure of recycled Ti/BMMs catalysts was still maintained, and the phenomenon of Ti leaching during the catalytic process and recovery was negligible. In particular, spectroscopic observations indicated that the effects of the regeneration methods on the tetrahedrally-coordinated Ti species and catalytic deactivation were remarkable. The main reasons were related to the polarities of used solvents during recovery tests, the environment medium of adsorbed water inside mesopore channels and the deposition of bulky mole- cules of by-products on the mesoporous surface.展开更多
Heterogeneous oxidation of cyclohexane by tert-butyl hydroperoxide (TBHP) was carried out over ZSM-5 catalysts with different Si/Al ratios in ionic liquids and organic molecular solvents. Higher yield and selec-tivity...Heterogeneous oxidation of cyclohexane by tert-butyl hydroperoxide (TBHP) was carried out over ZSM-5 catalysts with different Si/Al ratios in ionic liquids and organic molecular solvents. Higher yield and selec-tivity of the desired products were found in ionic liquids than in molecular solvents. The conversion of cyclohexane exhibits a decrease from 15.8% to 10.8% with the increase of Si/Al ratio of the HZSM-5 catalyst, and all the cata-lysts exhibit good selectivity of monofunctional oxidation products at around 97%. The activity of catalyst is found strongly dependent on the alkyl chain length of ionic liquid.展开更多
文摘采用单因素法,以2-氯-4,6-二(N-丁基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪、环己烷、叔丁基过氧化氢为原料,三氧化钼为催化剂合成2-氯-4,6-二(N-丁基-1-环己氧基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪。结果表明,最佳工艺条件为反应温度95℃,反应时间14 h,原料物质的量比n(2-氯-4,6-二(N-丁基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪)∶n(环己烷)∶n(叔丁基过氧化氢)为0.01∶0.45∶0.2,催化剂三氧化钼用量为0.4 g (相对0.01 mol2-氯-4,6-二(N-丁基-2,2,6,6-四甲基-4-哌啶胺基)-1,3,5-三嗪),产品收率为93.50%。
文摘Tailoring the Ti coordination states in titanosilicate zeolites to simultaneously improve feedstock conversion and maximize the target product selectivity remains a challenge in the pursuit of high-performance catalysts for selective oxidation reactions.Herein,we provide a facile strategy to synthesize hierarchical anatase-free TS-1(MFI-type)zeolites with tetrahedrally coordinated(TiO_(4))and octahedrally coordinated Ti species(TiO_(6)).The TiO_(4)species provide high epoxide selectivity,while the TiO_(6)species afford improved alkene conversion.This strategy is achieved by synergistically using an L-lysine-assisted approach and a two-step crystallization;the two-step crystallization approach prevents the formation of anatase TiO_(2),while L-lysine stabilizes the TiO_(6)species and ensures efficient incorporation of TiO_(6)into the anatase-free TS-1 zeolites.Compared with their conventional counterparts,which only contain TiO_(4)species,the as-prepared TS-1 zeolites(Si/Ti=36.9)result in a higher 1-hexene conversion(33%),higher TON value(153),and comparable epoxide selectivity(95%).This synthetic strategy provides avenues to tailor the amount and distribution of Ti species in titanosilicate zeolites to achieve high catalytic performances in various processes.
基金This work was financially supported by the Education Committee of Hunan Province (02C465)Hunan Provincial Key Discipline and Hunan Provincial General College Leader of Learning
文摘Hydroxy-phenyl)-5-(2-methyl-phenyl)-6-ethoxycarbonyl-cyclohexen-2-one has been synthesized and characterized by elemental analysis, IR, UV, H NMR and MS, and its crystal 1 structure was determined by X-ray single-crystal diffraction method. The crystal belongs to the monoclinic system, space group P21/c with a = 14.6298(13), b = 5.8623(5), c = 22.255(2) ?, β = 105.855(2)o, V = 1836.0(3) ?3, Mr = 350.40, Z = 4, Dc = 1.268 g/cm3, F(000) = 744, μ(MoKα) = 0.086 mm-1, R = 0.0680 and wR = 0.1498. The crystal analysis results show that the cyclohexene unit of the title compound has a quasi-chair conformation, and a centrosymmetric dimer with a 16-membered ring is produced by the intermolecular hydrogen bonds.
基金the financial support of the State Basic Research Project ‘‘973’’ by the Ministry of Science and Technology of People’s Republic of China (2006CB202508)
文摘Hollow titanium silicalite （HTS） molecular sieve has been synthesized, and information on its structure, physico- chemical characterization, as well as surface property was investigated by a host of analytical methods, such as XRF, XRD, low-temperature N2 adsorption/desorption, TEM, FT-IR, UV-Vis, 29Si MAS NIVIR, and XPS techniques. The characterization results suggest that HTS zeolite has a special hollow crystal structure and its mesopore volume is larger than that of TS-1 zeolite. The titanium species in this zeolite are composed of the framework tetrahedral Ti （IV） ions and extra-framework octahedral Ti （IV） ions, which tend to disperse into its bulk phase. This zeolite material also has been applied to catalyze the cyclohexanone oxidation process, and the products are not completely consistent with those results obtained by using TS-1 zeolite, which might be caused by their difference in pore structure and pore volume, especially the mesopore volume. Cy- clohexanone oxidation catalyzed by HTS zeolite is a representative consecutive reaction, the main target products of which are e-caprolactone, 6-hydroxyhexanoic acid and adipic acid. The effect of H202/cyclohexanone mole ratio on the cyclohexa- none conversion, the total target product selectivity, the distribution of three target products selectivity and their variations along with reaction time is also researched and analyzed, which indicate that HTS zeolite shows a high performance for the Baeyer-Villiger reaction of cyclohexanone and catalytic oxidation of 6-hydroxyhexanoic acid under mild conditions, and the quantity of active surface titanium species as well as the pore structure and mesopore volume controlling the mass diffusion rate are the key factors determining the catalytic activity of HTS zeolite and product selectivity.
文摘A method for oxidative degradation of 1,4-dioxane （1,4-D） in waste water using a combination of ozone oxidation with UV irradiation （ozone/UV） treatment was investigated. The results showed that 1,4-D was degraded by ozone/UV treatment up to 90 min. The optimum concentration for the injected ozone gas was about 40 g·m^3 under a constant level of UV irradiation. Furthermore, solid phase extraction and GC-MS analysis showed no specific or reproducible peaks due to by-products of 1,4-D. It was therefore concluded that 1,4-D was completely degraded by ozone/UV treatment. In contrast, the amount of 1,4-D remaining decreased slowly in the presence of HCOf or CI. It was suggested that the degradation of 1,4-D, which results from .OH oxidation, was retarded by the presence of HCO3 or CI, which act as radical scavengers.
基金Supported by the National Natural Science Foundation of China(21076003,21272005)the Funding Project for the Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of the Beijing Municipality(PHR201107104,005000541211019/20,005000543111517)
文摘Ti/BMMs （Ti supported bimodal mesoporous silica） catalysts have been prepared via self-assembly route com- bined with ship-in-a-bottle method. The recovery and recycling performances of Ti/BMMs were investigated in the epoxidation of cyclohexene. In order to the evaluate the regeneration methods and to examine the deactivation behaviors, the deactivated Ti/BMMs catalysts were washed in chloroform or calcinated at 450 ℃ for 6 h and then activity of the recovery catalysts were examined. Meanwhile, the structure features and surface properties of the regenerated catalysts were characterized by X-ray diffraction, N2-sorption analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravi- metric analysis, UV visible spectroscopy and X-ray photoelectron spectroscopy. The results showed that the typical bimodal mesoporous structure of recycled Ti/BMMs catalysts was still maintained, and the phenomenon of Ti leaching during the catalytic process and recovery was negligible. In particular, spectroscopic observations indicated that the effects of the regeneration methods on the tetrahedrally-coordinated Ti species and catalytic deactivation were remarkable. The main reasons were related to the polarities of used solvents during recovery tests, the environment medium of adsorbed water inside mesopore channels and the deposition of bulky mole- cules of by-products on the mesoporous surface.
基金Supported by the National Natural Science Foundation of China (20776037, 20425619)the Program for Changjiang Scholars and Innovative Research Teams in Universities (IRT0641)the Research Foundation of Hebei University of Science and Technology (XL200716)
文摘Heterogeneous oxidation of cyclohexane by tert-butyl hydroperoxide (TBHP) was carried out over ZSM-5 catalysts with different Si/Al ratios in ionic liquids and organic molecular solvents. Higher yield and selec-tivity of the desired products were found in ionic liquids than in molecular solvents. The conversion of cyclohexane exhibits a decrease from 15.8% to 10.8% with the increase of Si/Al ratio of the HZSM-5 catalyst, and all the cata-lysts exhibit good selectivity of monofunctional oxidation products at around 97%. The activity of catalyst is found strongly dependent on the alkyl chain length of ionic liquid.
