The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an e...The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1(MFI)zeolites by replacing tetrabutyl orthotitanate(TBOT)with tetrabutyl orthotitanate tetramer(TBOT-tetramer)as the titanium source.The introduced TBOT-tetramer slowed down the zeolite crystallization process,and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species.Notably,the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40.The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area.It also impeded the formation of anatase species,resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.展开更多
With the increasingly stringent standards for limiting sulfide content in liquid fuels,oxidative desulfurization(ODS)has become a promising ultra-deep desulfurization process in fuel desulfurization.TS-1 zeolites show...With the increasingly stringent standards for limiting sulfide content in liquid fuels,oxidative desulfurization(ODS)has become a promising ultra-deep desulfurization process in fuel desulfurization.TS-1 zeolites show great potential as catalysts for ODS reactions,due to its remarkable oxidation activity at low temperatures and pressure.However,the inherent microporous structure of conventional TS-1 zeolites restricts the mass transportation and renders the active sites in the microporous space of TS-1 zeolites inaccessible for bulky aromatic organosulfur compounds.Fabrication of hierarchical TS-1 zeolites by incorporating meso-/macropores into microporous TS-1 zeolites is an effective strategy to improve mass transportability.In recent years,abundant efforts have been dedicated to developing synthetic strategies of hierarchical TS-1 zeolite,thereby improving its catalytic performance in the ODS process.This mini-review addresses the synthetic methods of hierarchical TS-1 catalysts and their catalytic performance in the ODS reactions.In addition,some current problems and prospects of synthesis routes for constructing hierarchical TS-1 catalysts have also been revised.We expect this mini-review to shed light on the more efficient preparation strategies of hierarchical TS-1 zeolites for the ODS process.展开更多
Simultaneous achievement of constructing mesopores and eliminating anatase is a long-term pursuit for enhancing the catalytic performance of TS-1.Here,we developed an aromatic compounds-mediated synthesis method to pr...Simultaneous achievement of constructing mesopores and eliminating anatase is a long-term pursuit for enhancing the catalytic performance of TS-1.Here,we developed an aromatic compounds-mediated synthesis method to prepare anatase-free and hierarchical TS-1 for olefin epoxidation.A series of hierarchical TS-1 zeolites were prepared by introducing aromatic compounds containing different functional groups via the crystallization process.The formation of intercrystalline mesopores and insertion of titanium into framework were facilitated at different extent.The synergistic coordination of carboxyl and hydroxyl in aromatic compounds with Ti(OH)4 realizes the uniform distribution of titanium species and eliminates the generation of anatase.Noteworthily,eight machine learning models were trained to reveal the mechanism of additive functional groups and preparation conditions on anatase formation and microstructure optimization.The prediction accuracy of most models can reach more than 80%.Benefiting from the larger mesopore volumes(0.37 cm3⋅g−1)and higher content of framework Ti species,TS-DHBDC-48h samples exhibit a higher catalytic performance than other zeolites,giving 1-hexene conversion of 49.3%and 1,2-epoxyhenane selectivity of 99.9%.The paper provides a facile aromatic compounds-mediated synthesis strategy and promotes the application of machine learning toward the design and optimization of new zeolites.展开更多
The catalytic performances over propylene epoxidation with H_(2)and O_(2)(HOPO process)are significantly affected by the properties(e.g.,surface properties,Ti coordination,morphology)of titanosilicate zeolite.Introduc...The catalytic performances over propylene epoxidation with H_(2)and O_(2)(HOPO process)are significantly affected by the properties(e.g.,surface properties,Ti coordination,morphology)of titanosilicate zeolite.Introducing urea into zeolite synthesis is a simple and convenient method to modify these properties of titanosilicate zeolite.Uncalcined pore-blocked titanium silicalite-1(TS-1,i.e.,TS-1-B)with the lower urea dosage possesses more defective structure and unsaturated coordinated Ti sites verified by 29Si nuclear magnetic resonance(NMR)and X-ray photoelectron spectroscopy(XPS)analysis,which results in a high initial activity and hydrogen efficiency;while the high surface acidity generated by these Ti species leads to a continuous decrease in the activity and the propylene oxide(PO)selectivity during the reaction.As the amount of urea gradually increases,the TS-1-B samples present the reduced surface defects and defective and unsaturated Ti species.Specially,TS-1-B-0.30U presents the weaker PO adsorption on PO-diffusion reflectance infrared Fourier transform spectra(DRIFTS),thus results in the high stable PO formation rate and selectivity over its Au catalyst.Furthermore,a flat-plate-like shape with a shorter thickness of 100 nm along the b-axis direction is observed on the urea-modified TS-1.Compared with the conventional ellipsoidal TS-1 with crystal sizes of 200 and 500 nm,the flat-plate-like TS-1-0.30U displays the less surface defects,unsaturated Ti species,the weaker Lewis acid,which is favorable for the desorption and intracrystalline diffusion of PO,thus reduces the occurrence of side reactions for the improved selectivity and stability.This work may provide a reference for developing titanium-containing materials with high activity and stability over HOPO reaction.展开更多
In the present work, the effect of oxides on the alkylation of benzene with 1-dodecene was comprehensively investigated over MCM-49 n-heptanol, n-heptaldehyde and n-heptanoic acid were selected as the model oxides her...In the present work, the effect of oxides on the alkylation of benzene with 1-dodecene was comprehensively investigated over MCM-49 n-heptanol, n-heptaldehyde and n-heptanoic acid were selected as the model oxides herein, and obvious decrease of lifetime could be caused by only trace amount of oxides added in the feedstocks. However, the deactivated catalysts were difficult to be regenerated by extraction with hot benzene. Additionally, coke-burning was also proved to be incapable to regenerate the deactivated catalysts mainly for the dealumination during calcination. Further characterizations complementary with DFT calculations were conducted to demonstrate that the deactivation was mainly due to the firm adsorption of oxides on the acid sites.展开更多
The exploration of high-efficient catalysts based on hierarchical Ti-containing zeolites with optimized active titanium species distribution is of great value in enhancing the epoxidation of bulky olefins. Herein, hie...The exploration of high-efficient catalysts based on hierarchical Ti-containing zeolites with optimized active titanium species distribution is of great value in enhancing the epoxidation of bulky olefins. Herein, hierarchical TS-1(MFI) zeolite with an extra-large external surface area(210 m2/g) and highly active octahedral- coordinated Ti species was prepared via organic base-assisted sequential post-treatment. Such a catalyst afforded a high turnover number value(TON, 114) in 1-octene epoxidation reaction, which was over twice than that(53) of the untreated conventional microporous TS-1 parent. According to the detailed characterization results, we revealed the hierarchical porosity construction effect of tetrapropylamonium hydroxide(TPAOH) treatment(first step) and the octahedral-coordinated Ti species fabrication effect of ethylamine(EA) treatment(second step) under hydrothermal condition. Such a facile post-treatment strategy reported in this work may provide guidance for the rational synthesis of TS-1 zeolite with enhanced catalytic activity.展开更多
Platinum(Pt)supported on Zinc(Zn)modified silicalite-1(S-1)zeolite(denoted as Pt-Zn/S-1)was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time.Both Le...Platinum(Pt)supported on Zinc(Zn)modified silicalite-1(S-1)zeolite(denoted as Pt-Zn/S-1)was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time.Both Lewis and Bronsted acid sites were detected in Pt-Zn/S-1 catalyst by means of FT-IR adsorption of NH3 experiment,which were identified as mostly weak and medium ones.Besides,Pt and Zn species showed strong interaction,as revealed by the TPR(Temperature-programmed reduction)and XPS(X-ray photoelectron spectroscopy)experiments.Pt-Zn/S-1 catalyst exhibited excellent aromatization function rather than isomerization and cracking side reactions in the conversion of n-hexane.Pulse experimental study showed that 75.6%of n-hexane conversion and 76.8%of benzene selectivity were obtained over Pt0.1-Zn60/S-l catalyst at 550℃ and under atmospheric pressure.By spectroscopy tests and pulse experimental results,it was concluded that the n-hexane aromatization over Pt-Zn/S-1 catalyst follows a metal-acid bifunctional mechanism.Furthermore,with the assistance of Zn,the electron-deficient Pt species in Pt-Zn/S-1 showed good sulfur tolerance performance.展开更多
In this study,EU-1 zeolite was successfully synthesized via a quasi-solid state approach and assembled to catalyst for the C 8 aromatics isomerization process.The catalytic properties were tuned through careful modifi...In this study,EU-1 zeolite was successfully synthesized via a quasi-solid state approach and assembled to catalyst for the C 8 aromatics isomerization process.The catalytic properties were tuned through careful modification of the acidity of EU-1 zeolites and metal-doping of the catalyst.It was shown that EU-1 was an excellent candidate for the C 8 aromatics isomerization process due to its unique structure.In addition,steam treatment of EU-1 at 450-500 ℃ could optimize the acidic properties of the catalyst,hence enhance its catalytic performance.The effect of the amount of Pt on ethylbenzene conversion was studied and the optimum amount was determined to be about 0.3-0.4 wt%.It was confirmed that EU-1 zeolite prepared via a quasi-solid state approach and then dealuminated by steam treatment had better activity and selectivity than conventional mordenite(MOR) zeolite and could be an excellent candidate for C 8 aromatics isomerization.展开更多
A novel composite material(TD)composed of TS-1 microcrystalline and dendritic mesoporous silica nanospheres(DMSNs)was successfully prepared.The TD composite material had open pore structure and large specific surface ...A novel composite material(TD)composed of TS-1 microcrystalline and dendritic mesoporous silica nanospheres(DMSNs)was successfully prepared.The TD composite material had open pore structure and large specific surface area,which was conducive to the mass transfer of reactants and products.The Ti element in TS-1 could be used as an electron assistant,and the spillover d-electrons were conducive to the improvement of the sulfidation and dispersion of MoS_(2),thereby forming more type II MoS_(2) active phases.The incorporation of Ti could bring more Brønsted(B)and Lewis(L)acid,which was conducive to the hydrogenation pathway(HYD)selectivity(41.2%)of dibenzothiophene(DBT)hydrodesulfurization(HDS)and isomerization(ISO)route selectivity(21.9%)of 4,6-dimethyldibenzothiophene(4,6-DMDBT)HDS,thus improve the HDS activity of DBT and 4,6-DMDBT.NiMo/TD-70(Aging temperature=70℃)had the best HDS activities of DBT(99.0%)and 4,6-DMDBT(93.7%)due to its large open pore structure,good acidity,suitable metal-support interaction(MSI)and perfect dispersion of the metallic active sites.展开更多
Adsorption properties of an adsorbent or a catalyst towards adsorbates are crucial in the process of adsorption separation or catalytic reaction. Surface morphology and structure of adsorbents have a significant impac...Adsorption properties of an adsorbent or a catalyst towards adsorbates are crucial in the process of adsorption separation or catalytic reaction. Surface morphology and structure of adsorbents have a significant impact on the adsorption properties. In this study, a novel acidic ionic liquid, 1-butyl-3-(triethoxysilylpropyl)imidazolium hydrogen sulfate(i.e., [BTPIm][HSO_4]), was synthesized and subsequently grafted onto the MCM-36 zeolite for the regulation of its adsorption properties towards isobutane and 1-butene. The resultant [BTPIm][HSO_4]-immobilized MCM-36(i.e., MCM-36-IL) was characterized by FT-IR, XPS, XRD, SEM, TG/DTG and N_2 adsorption–desorption measurement. It was found that the specific surface area, micropore volume and mesopore volume of the MCM-36 support underwent a reduction upon the immobilization of ionic liquid,while the surface density of acid increased from 0.0014 to 0.0035 mmol·m^(-2). The adsorption capacity of isobutane and 1-butene on the MCM-36-IL was determined by a static volumetric method. Results demonstrated that the interaction between isobutane and MCM-36-IL was enhanced and the interaction between 1-butene and MCM-36-IL was reduced. As a result, a tunable adsorption ratio of isobutane/1-butene on MCM-36 was achieved.With the increase in surface density of acid and the tunable adsorption ratio of isobutane and 1-butene on the functionalized MCM-36, the acidic ionic liquid-immobilized zeolites are beneficial to obtain an improved reaction yield and a prolonged catalyst life in the reactions catalyzed by solid acid.展开更多
Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-...Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-glycidoxy propyl trimethoxy silane(GPTMS), N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxyl silane(APAEDMS),and N-(β-aminoethyl)-γ-aminopropyl dimethoxyl(ethyoxyl) silane(TMPED). The hierarchical EU-1 samples were characterized by XRD, SEM, N_2 adsorption, FT-IR and NH_3-TPD to analyze the crystallinity, morphology, surface area, pore size distribution and acidity. The results showed that hierarchical EU-1 zeolites were successfully synthesized; organosilanes have great influence on crystal morphology of EU-1 zeolites; the exterior surface area of hierarchical EU-1 zeolite, which synthesized with organosilanes(APAEDMS) adding into synthesis system, increased by 62.1% and mesopore volume increased by 129.1% compared with conventional EU-1 zeolites, thus can reduce the diffusional restriction markedly in catalytic reaction. The catalytic performance of hierarchical EU-1zeolites were evaluated in m-xylene isomerization on fixed bed reactor. The catalytic data showed that the isomerization activity PX/X of the hierarchical EU-1 zeolites reached around 24.09% in theoretical thermodynamic equilibrium from 23.83%, and the selectivity of C_8 aromatic hydrocarbon increased from 75.16% to 84.87%. The conversion of p-xylene increased from 16.30% to 18.41%.展开更多
Four ZSM-5 zeolite catalysts with different Si/Al ratios for the catalytic cracking of C4 fractions to produce ethylene and propylene were prepared in this study.First,the adsorption isotherms of pure n-butane and but...Four ZSM-5 zeolite catalysts with different Si/Al ratios for the catalytic cracking of C4 fractions to produce ethylene and propylene were prepared in this study.First,the adsorption isotherms of pure n-butane and butene-1 and their mixtures on these catalysts at 300K and p=0—100kPa were measured using the intelligent gra- vimetric analyzer.The experimental results indicate that the presence of Al can significantly affect the adsorption of butene-1 than that of n-butane on ZSM-5 zeolites.Then,the double Langmuir(DL)model was applied to study the pure gas adsorption on ZSM-5 zeolites for pure n-butane and butene-1.By combining the DL model with the ideal adsorbed solution theory(IAST),the IAST-DL model was applied to model the butene-1(1)/n-butane(2)binary mixture adsorption on ZSM-5 zeolites with different Si/Al ratios.The calculated results are in good agreement with the experimental data,indicating that the IAST-DL model is effective for the present systems.Finally,the adsorp- tion over a wide range of variables was predicted at low pressure and 300K by the model proposed.It is found that the selectivity of butene-1 over n-butane increases linearly with the decrease of Si/Al ratio.A correlation between the selectivity and Si/Al ratio of the sample was proposed at 300K and p=0.08MPa.展开更多
A facile and convenient protocol was developed for the synthesis of 1,5-diarylpyrazoles using Baylis-Hillman adducts in the presence of HY-zeolite as an efficient recyclable heterogeneous catalyst in reasonable reacti...A facile and convenient protocol was developed for the synthesis of 1,5-diarylpyrazoles using Baylis-Hillman adducts in the presence of HY-zeolite as an efficient recyclable heterogeneous catalyst in reasonable reaction times(1.5-2.5 h) and high yields (78-90%).展开更多
The catalytic oxidation processes for cyclohexane/H2O2/acetone system over the TS-1 zeolite was studied. Study results have revealed that the cyclohexane conversion was 27% after the reaction proceeded at 100C for 2 h...The catalytic oxidation processes for cyclohexane/H2O2/acetone system over the TS-1 zeolite was studied. Study results have revealed that the cyclohexane conversion was 27% after the reaction proceeded at 100C for 2 hours at a cyclohexane/H2O2 molar ratio of 0.8. The cyclohexanol/cyclohexanone molar ratio was 1.3along with a certain amount of organic acids and esters, the formation of which was closely associated with the oxidation of reaction solvent and deep oxidation of cyclohexanone and cyclohexanol contained in the reaction products. With respect to the catalytic oxidation of cyclohexane/H2O2 system the selection of appropriate solvent was critically important.展开更多
基金the National Natural Science Foundation of China, China (Grant 21920102005, 22288101, and 21835002)the 111 Project, China (B17020)+2 种基金the European Union through the European Research Council, European Union (grant ERC-AdG-2014-671093, SynCatMatch)the Spanish Government through “Severo Ochoa”, Spain (SEV2016-0683, MINECO) for supporting this workthe financial support from China Scholarship Council, China
文摘The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1(MFI)zeolites by replacing tetrabutyl orthotitanate(TBOT)with tetrabutyl orthotitanate tetramer(TBOT-tetramer)as the titanium source.The introduced TBOT-tetramer slowed down the zeolite crystallization process,and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species.Notably,the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40.The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area.It also impeded the formation of anatase species,resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.
基金supported by the National Natural Science Foundation of China(21971082)the Jilin Province Science and Technology Development Plan(20200201096JC and 20190201229JC)+1 种基金the China Postdoctoral Science Foundation(2019T120235 and 2018M640280)for supporting this workthe 111 Project(B17020)。
文摘With the increasingly stringent standards for limiting sulfide content in liquid fuels,oxidative desulfurization(ODS)has become a promising ultra-deep desulfurization process in fuel desulfurization.TS-1 zeolites show great potential as catalysts for ODS reactions,due to its remarkable oxidation activity at low temperatures and pressure.However,the inherent microporous structure of conventional TS-1 zeolites restricts the mass transportation and renders the active sites in the microporous space of TS-1 zeolites inaccessible for bulky aromatic organosulfur compounds.Fabrication of hierarchical TS-1 zeolites by incorporating meso-/macropores into microporous TS-1 zeolites is an effective strategy to improve mass transportability.In recent years,abundant efforts have been dedicated to developing synthetic strategies of hierarchical TS-1 zeolite,thereby improving its catalytic performance in the ODS process.This mini-review addresses the synthetic methods of hierarchical TS-1 catalysts and their catalytic performance in the ODS reactions.In addition,some current problems and prospects of synthesis routes for constructing hierarchical TS-1 catalysts have also been revised.We expect this mini-review to shed light on the more efficient preparation strategies of hierarchical TS-1 zeolites for the ODS process.
基金National Key Research and Development Program of China,Grant/Award Number:2021YFB3500700SINOPEC Research Institute of Petroleum Processing+3 种基金Natural Science Foundation of Guangdong Province of China,Grant/Award Number:2022A1515011918Scientific and Technological Innovation Foundation of Shunde Graduate SchoolUniversity of Science and Technology Beijing,Grant/Award Number:BK20AE003Fundamental Research Funds for the Central Universities,Grant/Award Number:FRF-IDRY-20-004。
文摘Simultaneous achievement of constructing mesopores and eliminating anatase is a long-term pursuit for enhancing the catalytic performance of TS-1.Here,we developed an aromatic compounds-mediated synthesis method to prepare anatase-free and hierarchical TS-1 for olefin epoxidation.A series of hierarchical TS-1 zeolites were prepared by introducing aromatic compounds containing different functional groups via the crystallization process.The formation of intercrystalline mesopores and insertion of titanium into framework were facilitated at different extent.The synergistic coordination of carboxyl and hydroxyl in aromatic compounds with Ti(OH)4 realizes the uniform distribution of titanium species and eliminates the generation of anatase.Noteworthily,eight machine learning models were trained to reveal the mechanism of additive functional groups and preparation conditions on anatase formation and microstructure optimization.The prediction accuracy of most models can reach more than 80%.Benefiting from the larger mesopore volumes(0.37 cm3⋅g−1)and higher content of framework Ti species,TS-DHBDC-48h samples exhibit a higher catalytic performance than other zeolites,giving 1-hexene conversion of 49.3%and 1,2-epoxyhenane selectivity of 99.9%.The paper provides a facile aromatic compounds-mediated synthesis strategy and promotes the application of machine learning toward the design and optimization of new zeolites.
基金the funds from the Research Fund for National Key Research and Development Program of China(No.2021YFA1501403)the National Natural Science Foundation of China(Nos.21922803 and 22038003)+1 种基金Shanghai Rising-Star Program(No.17QA1401200)the Innovation Program of the Shanghai Municipal Education Commission(No.17ZR1407300).
文摘The catalytic performances over propylene epoxidation with H_(2)and O_(2)(HOPO process)are significantly affected by the properties(e.g.,surface properties,Ti coordination,morphology)of titanosilicate zeolite.Introducing urea into zeolite synthesis is a simple and convenient method to modify these properties of titanosilicate zeolite.Uncalcined pore-blocked titanium silicalite-1(TS-1,i.e.,TS-1-B)with the lower urea dosage possesses more defective structure and unsaturated coordinated Ti sites verified by 29Si nuclear magnetic resonance(NMR)and X-ray photoelectron spectroscopy(XPS)analysis,which results in a high initial activity and hydrogen efficiency;while the high surface acidity generated by these Ti species leads to a continuous decrease in the activity and the propylene oxide(PO)selectivity during the reaction.As the amount of urea gradually increases,the TS-1-B samples present the reduced surface defects and defective and unsaturated Ti species.Specially,TS-1-B-0.30U presents the weaker PO adsorption on PO-diffusion reflectance infrared Fourier transform spectra(DRIFTS),thus results in the high stable PO formation rate and selectivity over its Au catalyst.Furthermore,a flat-plate-like shape with a shorter thickness of 100 nm along the b-axis direction is observed on the urea-modified TS-1.Compared with the conventional ellipsoidal TS-1 with crystal sizes of 200 and 500 nm,the flat-plate-like TS-1-0.30U displays the less surface defects,unsaturated Ti species,the weaker Lewis acid,which is favorable for the desorption and intracrystalline diffusion of PO,thus reduces the occurrence of side reactions for the improved selectivity and stability.This work may provide a reference for developing titanium-containing materials with high activity and stability over HOPO reaction.
文摘In the present work, the effect of oxides on the alkylation of benzene with 1-dodecene was comprehensively investigated over MCM-49 n-heptanol, n-heptaldehyde and n-heptanoic acid were selected as the model oxides herein, and obvious decrease of lifetime could be caused by only trace amount of oxides added in the feedstocks. However, the deactivated catalysts were difficult to be regenerated by extraction with hot benzene. Additionally, coke-burning was also proved to be incapable to regenerate the deactivated catalysts mainly for the dealumination during calcination. Further characterizations complementary with DFT calculations were conducted to demonstrate that the deactivation was mainly due to the firm adsorption of oxides on the acid sites.
基金This work was supported by the National Natural Science Foundation of China (Nos.21835002,21621001,22001090)the "111" Project of China(No.B17020)the China Postdoctoral Science Foundation(No.2021T140259).
文摘The exploration of high-efficient catalysts based on hierarchical Ti-containing zeolites with optimized active titanium species distribution is of great value in enhancing the epoxidation of bulky olefins. Herein, hierarchical TS-1(MFI) zeolite with an extra-large external surface area(210 m2/g) and highly active octahedral- coordinated Ti species was prepared via organic base-assisted sequential post-treatment. Such a catalyst afforded a high turnover number value(TON, 114) in 1-octene epoxidation reaction, which was over twice than that(53) of the untreated conventional microporous TS-1 parent. According to the detailed characterization results, we revealed the hierarchical porosity construction effect of tetrapropylamonium hydroxide(TPAOH) treatment(first step) and the octahedral-coordinated Ti species fabrication effect of ethylamine(EA) treatment(second step) under hydrothermal condition. Such a facile post-treatment strategy reported in this work may provide guidance for the rational synthesis of TS-1 zeolite with enhanced catalytic activity.
基金financially supported by the National Natural Science Foundation of China (21603023)
文摘Platinum(Pt)supported on Zinc(Zn)modified silicalite-1(S-1)zeolite(denoted as Pt-Zn/S-1)was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time.Both Lewis and Bronsted acid sites were detected in Pt-Zn/S-1 catalyst by means of FT-IR adsorption of NH3 experiment,which were identified as mostly weak and medium ones.Besides,Pt and Zn species showed strong interaction,as revealed by the TPR(Temperature-programmed reduction)and XPS(X-ray photoelectron spectroscopy)experiments.Pt-Zn/S-1 catalyst exhibited excellent aromatization function rather than isomerization and cracking side reactions in the conversion of n-hexane.Pulse experimental study showed that 75.6%of n-hexane conversion and 76.8%of benzene selectivity were obtained over Pt0.1-Zn60/S-l catalyst at 550℃ and under atmospheric pressure.By spectroscopy tests and pulse experimental results,it was concluded that the n-hexane aromatization over Pt-Zn/S-1 catalyst follows a metal-acid bifunctional mechanism.Furthermore,with the assistance of Zn,the electron-deficient Pt species in Pt-Zn/S-1 showed good sulfur tolerance performance.
基金supported by the National Natural Science Foundation of China (No. 20973123)the National Basic Research Program of China (Grant No.2012CB215002)
文摘In this study,EU-1 zeolite was successfully synthesized via a quasi-solid state approach and assembled to catalyst for the C 8 aromatics isomerization process.The catalytic properties were tuned through careful modification of the acidity of EU-1 zeolites and metal-doping of the catalyst.It was shown that EU-1 was an excellent candidate for the C 8 aromatics isomerization process due to its unique structure.In addition,steam treatment of EU-1 at 450-500 ℃ could optimize the acidic properties of the catalyst,hence enhance its catalytic performance.The effect of the amount of Pt on ethylbenzene conversion was studied and the optimum amount was determined to be about 0.3-0.4 wt%.It was confirmed that EU-1 zeolite prepared via a quasi-solid state approach and then dealuminated by steam treatment had better activity and selectivity than conventional mordenite(MOR) zeolite and could be an excellent candidate for C 8 aromatics isomerization.
基金This research was supported by the Science Foundation of China University of Petroleum-Beijing(No.2462023QNXZ002)the National Key R&D Program of China(2021YFA1501201)+2 种基金the National Natural Science Foundation of China(No.22278174)Independent research project of State Key Laboratory of heavy oil(2021–01)Shandong Excellent Young Scientists Fund Program(Overseas,2022HWYQ-082).
文摘A novel composite material(TD)composed of TS-1 microcrystalline and dendritic mesoporous silica nanospheres(DMSNs)was successfully prepared.The TD composite material had open pore structure and large specific surface area,which was conducive to the mass transfer of reactants and products.The Ti element in TS-1 could be used as an electron assistant,and the spillover d-electrons were conducive to the improvement of the sulfidation and dispersion of MoS_(2),thereby forming more type II MoS_(2) active phases.The incorporation of Ti could bring more Brønsted(B)and Lewis(L)acid,which was conducive to the hydrogenation pathway(HYD)selectivity(41.2%)of dibenzothiophene(DBT)hydrodesulfurization(HDS)and isomerization(ISO)route selectivity(21.9%)of 4,6-dimethyldibenzothiophene(4,6-DMDBT)HDS,thus improve the HDS activity of DBT and 4,6-DMDBT.NiMo/TD-70(Aging temperature=70℃)had the best HDS activities of DBT(99.0%)and 4,6-DMDBT(93.7%)due to its large open pore structure,good acidity,suitable metal-support interaction(MSI)and perfect dispersion of the metallic active sites.
基金Supported by the National Natural Science Foundation of China(No.21276163,and No.21576168)
文摘Adsorption properties of an adsorbent or a catalyst towards adsorbates are crucial in the process of adsorption separation or catalytic reaction. Surface morphology and structure of adsorbents have a significant impact on the adsorption properties. In this study, a novel acidic ionic liquid, 1-butyl-3-(triethoxysilylpropyl)imidazolium hydrogen sulfate(i.e., [BTPIm][HSO_4]), was synthesized and subsequently grafted onto the MCM-36 zeolite for the regulation of its adsorption properties towards isobutane and 1-butene. The resultant [BTPIm][HSO_4]-immobilized MCM-36(i.e., MCM-36-IL) was characterized by FT-IR, XPS, XRD, SEM, TG/DTG and N_2 adsorption–desorption measurement. It was found that the specific surface area, micropore volume and mesopore volume of the MCM-36 support underwent a reduction upon the immobilization of ionic liquid,while the surface density of acid increased from 0.0014 to 0.0035 mmol·m^(-2). The adsorption capacity of isobutane and 1-butene on the MCM-36-IL was determined by a static volumetric method. Results demonstrated that the interaction between isobutane and MCM-36-IL was enhanced and the interaction between 1-butene and MCM-36-IL was reduced. As a result, a tunable adsorption ratio of isobutane/1-butene on MCM-36 was achieved.With the increase in surface density of acid and the tunable adsorption ratio of isobutane and 1-butene on the functionalized MCM-36, the acidic ionic liquid-immobilized zeolites are beneficial to obtain an improved reaction yield and a prolonged catalyst life in the reactions catalyzed by solid acid.
基金Supported by the National Innovation Fund for Small and Medium-sized Technology-based Firms(14C26211400552)
文摘Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-glycidoxy propyl trimethoxy silane(GPTMS), N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxyl silane(APAEDMS),and N-(β-aminoethyl)-γ-aminopropyl dimethoxyl(ethyoxyl) silane(TMPED). The hierarchical EU-1 samples were characterized by XRD, SEM, N_2 adsorption, FT-IR and NH_3-TPD to analyze the crystallinity, morphology, surface area, pore size distribution and acidity. The results showed that hierarchical EU-1 zeolites were successfully synthesized; organosilanes have great influence on crystal morphology of EU-1 zeolites; the exterior surface area of hierarchical EU-1 zeolite, which synthesized with organosilanes(APAEDMS) adding into synthesis system, increased by 62.1% and mesopore volume increased by 129.1% compared with conventional EU-1 zeolites, thus can reduce the diffusional restriction markedly in catalytic reaction. The catalytic performance of hierarchical EU-1zeolites were evaluated in m-xylene isomerization on fixed bed reactor. The catalytic data showed that the isomerization activity PX/X of the hierarchical EU-1 zeolites reached around 24.09% in theoretical thermodynamic equilibrium from 23.83%, and the selectivity of C_8 aromatic hydrocarbon increased from 75.16% to 84.87%. The conversion of p-xylene increased from 16.30% to 18.41%.
基金Supported by the National Natural Science Foundation of China (Nos.20236010,20476004) and China Petroleum & Chemical Corporation (No.X504023).
文摘Four ZSM-5 zeolite catalysts with different Si/Al ratios for the catalytic cracking of C4 fractions to produce ethylene and propylene were prepared in this study.First,the adsorption isotherms of pure n-butane and butene-1 and their mixtures on these catalysts at 300K and p=0—100kPa were measured using the intelligent gra- vimetric analyzer.The experimental results indicate that the presence of Al can significantly affect the adsorption of butene-1 than that of n-butane on ZSM-5 zeolites.Then,the double Langmuir(DL)model was applied to study the pure gas adsorption on ZSM-5 zeolites for pure n-butane and butene-1.By combining the DL model with the ideal adsorbed solution theory(IAST),the IAST-DL model was applied to model the butene-1(1)/n-butane(2)binary mixture adsorption on ZSM-5 zeolites with different Si/Al ratios.The calculated results are in good agreement with the experimental data,indicating that the IAST-DL model is effective for the present systems.Finally,the adsorp- tion over a wide range of variables was predicted at low pressure and 300K by the model proposed.It is found that the selectivity of butene-1 over n-butane increases linearly with the decrease of Si/Al ratio.A correlation between the selectivity and Si/Al ratio of the sample was proposed at 300K and p=0.08MPa.
基金support from the Research Council of University of Guilan
文摘A facile and convenient protocol was developed for the synthesis of 1,5-diarylpyrazoles using Baylis-Hillman adducts in the presence of HY-zeolite as an efficient recyclable heterogeneous catalyst in reasonable reaction times(1.5-2.5 h) and high yields (78-90%).
文摘The catalytic oxidation processes for cyclohexane/H2O2/acetone system over the TS-1 zeolite was studied. Study results have revealed that the cyclohexane conversion was 27% after the reaction proceeded at 100C for 2 hours at a cyclohexane/H2O2 molar ratio of 0.8. The cyclohexanol/cyclohexanone molar ratio was 1.3along with a certain amount of organic acids and esters, the formation of which was closely associated with the oxidation of reaction solvent and deep oxidation of cyclohexanone and cyclohexanol contained in the reaction products. With respect to the catalytic oxidation of cyclohexane/H2O2 system the selection of appropriate solvent was critically important.