Dehydrogenation is considered as one of the most important industrial applications for renewable energy.Cubic ceria-based catalysts are known to display promising dehydrogenation performances in this area.Large partic...Dehydrogenation is considered as one of the most important industrial applications for renewable energy.Cubic ceria-based catalysts are known to display promising dehydrogenation performances in this area.Large particle size(>20 nm)and less surface defects,however,hinder further application of ceria materials.Herein,an alternative strategy involving lactic acid(LA)assisted hydrothermal method was developed to synthesize active,selective and durable cubic ceria of<6 nm for dehydrogenation reactions.Detailed studies of growth mechanism revealed that,the carboxyl and hydroxyl groups in LA molecule synergistically manipulate the morphological evolution of ceria precursors.Carboxyl groups determine the cubic shape and particle size,while hydroxyl groups promote compositional transformation of ceria precursors into CeO_(2) phases.Moreover,enhanced oxygen vacancies(Vo)on the surface of CeO_(2) were obtained owing to continuous removal of O species under reductive atmosphere.Cubic CeO_(2) catalysts synthesized by the LA-assisted method,immobilized with bimetallic PtCo clusters,exhibit a record high activity(TOF:29,241 h^(-1))and Vo-dependent synergism for dehydrogenation of bio-derived polyols at 200℃.We also found that quenching Vo defects at air atmosphere causes activity loss of PtCo/CeO_(2) catalysts.To regenerate Vo defects,a simple strategy was developed by irradiating deactivated catalysts using hernia lamp.The outcome of this work will provide new insights into manufacturing durable catalyst materials for aqueous phase dehydrogenation applications.展开更多
Catalysts with varying Fe contents were prepared using a sequential impregnation method to investigate the effects of Fe addition on the physicochemical properties of Pt/Al_(2)O_(3) and their performance in methylcycl...Catalysts with varying Fe contents were prepared using a sequential impregnation method to investigate the effects of Fe addition on the physicochemical properties of Pt/Al_(2)O_(3) and their performance in methylcyclohexane(MCH)dehydrogenation.The results demonstrated that the addition of Fe to Pt/Al_(2)O_(3) enhanced the electron density of Pt and improved catalytic activity,while exhibiting negligible influence on the catalytic selectivity for toluene.When the Fe content was 0.057%,the catalyst exhibited the highest MCH consumption rate,which was approximately two times higher than that of the catalyst without Fe.Additionally,the incorporation of Fe inhibited the formation of coke and reduced the quantity of coke deposits on the catalyst,thereby improving its catalytic durability.Overall,Fe shows promise as a prospective secondary element for Pt/Al_(2)O_(3) to enhance the MCH dehydrogenation performance.展开更多
Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added Ni...Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were investigated.Then,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle system.Brunauer-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen carriers.It was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR results.Based on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO addition.Fe_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).展开更多
Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the...Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3) dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of ethane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3) as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3) onto Ca_(2)MnO_(4) not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst.Furthermore,formation of NaNO_(3) shell on the surface of Ca_(2)MnO_(4) led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise manner.This modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO_(3)-doped Ca_(2)MnO_(4) catalyst.These findings provide compelling evidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.展开更多
Propylene is a significant basic material for petrochemicals such as polypropylene,propylene oxide,etc.With abundant propane supply from shale gas,propane dehydrogenation(PDH)becomes extensively attractive as an on-pu...Propylene is a significant basic material for petrochemicals such as polypropylene,propylene oxide,etc.With abundant propane supply from shale gas,propane dehydrogenation(PDH)becomes extensively attractive as an on-purpose propylene production route in recent years.Nitrogen-doped carbon(NC)nanopolyhedra supported cobalt catalysts were synthesized in one-step of ZIF-67 pyrolysis and investigated further in PDH.XPS,TEM and N_(2) adsorption-desorption were used to study the influence of carbonization temperature on as-prepared NC supported cobalt catalysts.The temperature is found to affect the cobalt phase and nitrogen species of the catalysts.And the positive correlation was established between Co0 proportion and space time yield of propylene,indicating that the modulation of carbonization temperature could be important for catalytic performance.展开更多
Carbon catalysts for propane oxidative dehydrogenation(PODH)can potentially replace metal oxide catalysts due to their environmental friendliness(greenness)and excellent catalytic performance.Biomass carbon materials ...Carbon catalysts for propane oxidative dehydrogenation(PODH)can potentially replace metal oxide catalysts due to their environmental friendliness(greenness)and excellent catalytic performance.Biomass carbon materials have the advantages of being abundant in variety,inexpensive,and easily available,but their catalytic selectivity is relatively poor in PODH.Therefore,we report here on a boron-doped sisal fiber carbon catalyst,which showed excellent selectivity of propylene in PODH,excluding the effect of surface-covered B2O3 on the catalytic performance by hot water washing.The carbon material exhibited the best catalytic performance with a load of 2%(mass)and a calcination temperature of 1100℃.At a reaction temperature of 400℃,the conversion rate of propane was 2.0%,and the selectivity toward propylene reached 88.6%.The new chemical bonds formed by boron on the surface of the carbon materials had an important effect on the catalytic performance,as determined by XPS characterization.The BAO groups affected the catalytic activity by inhibiting the generation of electrophilic oxygen species,while the BAC content improved the selectivity toward propylene by changing the electron cloud density.展开更多
The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic re...The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic reaction is constrained by thermodynamic equilibrium and involves a complex reaction network, leading to a heightened focus on catalysts and process design. Copper-based catalysts have been extensively studied and exhibit exceptional low-temperature catalytic performance in cyclohexanol dehydrogenation, with some being commercially used in the industry. This paper specifically concentrates on research advancement concerning active species, reaction mechanisms, factors influencing product selectivity, and the deactivation behaviors of copper-based catalysts. Moreover, a brief introduction to the new processes that break thermodynamic equilibrium via reaction coupling and their corresponding catalysts is summarized here as well. These reviews may off er guidance and potential avenues for further investigations into catalysts and processes for cyclohexanol dehydrogenation.展开更多
Oxidative dehydrogenation of propane is an attractive route for the synthesis of propylene due to its favorable thermodynamic and kinetic characteristics, however, it is challenging to realize high selectivity towards...Oxidative dehydrogenation of propane is an attractive route for the synthesis of propylene due to its favorable thermodynamic and kinetic characteristics, however, it is challenging to realize high selectivity towards propylene. Recently, it has been discovered that boron nitride (BN) is a promising catalyst that affords superior selectivity towards propylene in oxidative dehydrogenation of propane. Summarizing the progress and unravelling the reaction mechanism of BN in oxidative dehydrogenation of propane are of great significance for the rational design of efficient catalysts in the future. Herein, in this review, the underlying reaction mechanisms of oxidative dehydrogenation of propane over BN are extracted;the developed BN catalysts are classified into pristine BN, functionalized BN, supported BN and others, and the applications of each category of BN catalysts in oxidative dehydrogenation of propane are summarized;the challenges and opportunities on oxidative dehydrogenation of propane over BN are pointed out, aiming to inspire more studies and advance this research field.展开更多
Developing high-performing non-noble transition metal catalysts for H_(2) evolution from chemical hydrogen storage materials is of great significance for the hydrogen economy system, yet challenging. Herein,we present...Developing high-performing non-noble transition metal catalysts for H_(2) evolution from chemical hydrogen storage materials is of great significance for the hydrogen economy system, yet challenging. Herein,we present for the first time that anomalous metastable hexagonal close-packed Ni nanoparticles induced by heteroatom N doping encapsulated in carbon(N-hcp-Ni/C) can exhibit admirable catalytic performance for ammonia borane(AB) dehydrogenation, prominently outperforming conventional fcc Ni counterpart with similar morphology and favorably presenting the state-of-the-art level.Comprehensive experimental and theoretical studies unravel that unusual hcp phase engineering of Ni together with N doping could induce charge redistribution and modulate electronic structure, thereby facilitating H_(2)O adsorption and expediting H_(2)O dissociation(rate-determining step). As a result, AB dehydrogenation can be substantially boosted with the assistance of N-hcp-Ni/C. Our proposed strategy highlights that unconventional crystal phase engineering coupled with non-metal heteroatom doping is a promising avenue to construct advanced transition metal catalysts for future renewable energy technologies.展开更多
Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existin...Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existing catalyst is limited due to the poor activity and stability,which hinders its industrialization.Herein,we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI)for CO_(2)-ODP.Characterization results reveal that the Zn2+species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt,Rh,or Rh Pt are highly dispersed in the zeolite crystals.The isolated Zn2+cations are very effective for activating the propane and the small NPs are favorable for activating the CO_(2),which synergistically promote the selective transformation of propane and CO_(2)to propylene and CO.As a result,the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield,satisfactory CO_(2)conversion,and long-term stability.Moreover,considering the tunable synergetic effects between the isolated cations and NPs,the developed approach offers a general guideline to design more efficient CO_(2)-ODP catalysts,which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+cations for Zn2+cations in the MFI zeolite matrix.展开更多
Borocarbonitride(BCN) materials are newly developed metal-free catalytic materials exhibiting high selectivity in oxidative dehydrogenation(ODH) of alkanes. However, the in-depth understandings on the role of boron(B)...Borocarbonitride(BCN) materials are newly developed metal-free catalytic materials exhibiting high selectivity in oxidative dehydrogenation(ODH) of alkanes. However, the in-depth understandings on the role of boron(B) dopants and the intrinsic activities of –C=O and –B–OH still remain unknown.Herein, we report a series of BCN materials with regulable B content and surface oxygen functional groups via self-assembly and pyrolysis of guanine and boric acid. We found that the B/C ratio is the key parameter to determine the activity of ODH and product distribution. Among them, the high ethylbenzene conversion(~57%) and styrene selectivity(~83%) are achieved in ODH for B_(1)CN. The styrene selectivity can be improved by increasing of B/C ratio and this value reaches near 100% for B_5CN.Structural characterizations and kinetic measurements indicate that –C=O and –B–OH dual sites on BCN are real active sites of ODH reaction. The intrinsic activity of –C=O(5.556 × 10^(-4)s^(-1)) is found to be 23.7 times higher than –B–OH(0.234 × 10^(-4)s^(-1)) site. More importantly, we reveal that the deep oxidation to undesirable CO_(2) occurs on –C=O rather than –B–OH site, and B dopant in BCN materials can reduce the nucleophilicity of –C=O site to eliminate the CO_(2) emission. Overall, the present work provides a new insight on the structure–function relationship of the BCN catalytic systems.展开更多
Pt-based catalysts are the typical industrial catalysts for propane dehydrogenation(PDH),which still suffer from insufficient lo ng-term durability due to the structu ral instability and coke deposition.A commercial ...Pt-based catalysts are the typical industrial catalysts for propane dehydrogenation(PDH),which still suffer from insufficient lo ng-term durability due to the structu ral instability and coke deposition.A commercial γ-Al_(2)O_(3) supported thermally robust sub-nanometer Pt2In3intermetallic catalyst with atomically ordered structure and rigorously separated Pt single atoms was fabricated,which showed outstanding robustness in 240 h long-term operation at 600℃ with the deactivation rate constant kdas low as0.00078 h^(-1), ranking among the lowest reported values.Based on various in situ characterizations and theoretical calculations,it was proved that the catalyst stability not only resulted from the separated Pt single-atom sites but also significantly affected by the distance of adjacent Pt atoms.An increasing distance to 3.25 A in the Pt_(2)In_(3)could induce a weak π-adsorption configuration of propylene on Pt sites,which facilitated the desorption of propylene and restrained the side reactions like coking.展开更多
High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was...High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was treated by oxygen plasma to further enhance catalyst performance.The results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO_(2) capture active oxygen species in gas and transform V^(4+)to V^(5+)without damage to M1 structure.The space-time yield of ethylene of the plasma-treated catalyst was significantly increased,in which the catalyst shows an enhancement near~100% than that of phase-pure M1 at 400℃ for ODHE process.Plasma treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst materials.Energy conversion is achieved by using the catalyst as a medium.展开更多
Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot matc...Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot match, acoustic holograms pursue the realization of high-resolution complex acoustic fields and gradually tend to high-frequency ultrasound applications. However, conventional continuous phase holograms are limited by three-dimensional(3D) printing size, and the presence of unavoidable small printing errors makes it difficult to achieve acoustic field reconstruction at high frequency accuracy. Here, we present an optimized discrete multi-step phase hologram. It can ensure the reconstruction quality of image with high robustness, and properly lower the requirement for the 3D printing accuracy. Meanwhile, the concept of reconstruction similarity is proposed to refine a measure of acoustic field quality. In addition, the realized complex acoustic field at 20 MHz promotes the application of acoustic holograms at high frequencies and provides a new way to generate high-fidelity acoustic fields.展开更多
Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has ...Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has been investigated by changing the content of Sn.It was found that with the presence of potassium,suitable addition of Sn could not only increase the metal dispersion,but also reduce the catalyst acidity.In these cases,the synergistic effect could also strengthen the interactions between the metal and support,which resulted in an increase in both catalytic activity and stability.In our experiments,Pt-0.6SnK/Al catalyst exhibited the lowest deactivation rate (12.4%) and showed a selectivity to isobutene higher than 94% at the isobutane conversion of about 45.3% after running the reaction for 6 h.However,with the excessive loading of Sn,surface property of active sites and the interactions between metal and support were changed.As a result,the initial optimal ratio between the metallic function and acid function would be destroyed,which was disadvantageous to the reaction.展开更多
Deactivation mechanism of Cr-Al2O3catalyst and the interaction of Cr-A1 in the dehydrogenation of isobutane, as well as the nature of the catalytic active center, were studied using XRD, SEM, XPS, H2-TPR, isobutane-TP...Deactivation mechanism of Cr-Al2O3catalyst and the interaction of Cr-A1 in the dehydrogenation of isobutane, as well as the nature of the catalytic active center, were studied using XRD, SEM, XPS, H2-TPR, isobutane-TPR and TPO techniques. The results revealed that the deactivation of Cr-Al2O3 catalyst was mainly caused by carbon deposition on its surface. The Cr3+ ion could not be reduced by hydrogen but could be reduced to Cr2+ by hydrocarbons and monoxide carbon. The active center for isobutane dehydrogenation could be Cr2+/Cr3+ produced from Cr6+ by the on line reduction of hydrocarbon and carbon monoxide. The binding energy of Al3+ was strongly affected by the state of chromium cations in the catalysts.展开更多
The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNaIZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD, BET, TEM,...The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNaIZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD, BET, TEM, XPS, NH3-TPD, H2 chemisorption, TPR and TPO techniques. It has been found that with suitable amount of cerium addition, the platinum dispersion increased, while the carbon deposition tended to be eliminated easily. In these cases, the presence of cerium could not only realize the better distribution of metallic particles on the support, but also strengthen the interactions between Sn species and the support. Additionally, XPS spectra confirmed that more amounts of tin could exist in oxidized form, which was advantageous to the reaction. In our experiments, PtSnNaCe (1.1 wt%)/ZSM-5 catalyst exhibited the best catalytic performance. After running the reaction for 750 h, propane conversion was maintained higher than 30% with the corresponding selectivity to propylene of about 97%.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
VOx/SiO2 catalysts prepared by impregnation method were used for catalytic dehydrogenation of n-butane to butenes and characterized by X-ray diffraction, FT-IR, UV-vis, Raman, and BET measurements. The effects of VOx ...VOx/SiO2 catalysts prepared by impregnation method were used for catalytic dehydrogenation of n-butane to butenes and characterized by X-ray diffraction, FT-IR, UV-vis, Raman, and BET measurements. The effects of VOx loading and the reaction temperature on the VOx/SiO2 catalysts and their catalytic performances for the dehydrogenation of n-butane were studied. When the VOx loading was 12% g/gcat and reaction temperature was between 590 ℃ and 600℃, n-butane conversion and butenes yields reached the highest value under H2 flux of 10 ml/min and n-butane flux of 10 ml/min. Product distribution, such as the ratio of 2-butene to 1-butene and the ratio of cis-2-butene to trans-2-butene, was mainly influenced by the reaction temperature.展开更多
A series of mesoporous Cu-Zn-Al2O3 materials have been synthesized at ambient temperature and their structure was characterized by XRD, N2 physical adsorption and TPR techniques. Their catalytic applications for the d...A series of mesoporous Cu-Zn-Al2O3 materials have been synthesized at ambient temperature and their structure was characterized by XRD, N2 physical adsorption and TPR techniques. Their catalytic applications for the dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were evaluated in a fixed-bed flow reactor at atmospheric pressure. It is demonstrated from the XRD patterns that both the as-synthesized samples and calcined samples have the typical XRD patterns of meso-structured materials and the results of N20 chemical adsorption showed that Cu was embedded in the framework of the mesoporous materials and homogeneously dispersed in the mesoporous Cu-Zn-Al2O3 materials. The catalytic activity of 2-butanol dehydrogenation was varied in the order of CZA(10) 〈 CZA(CP) 〈 CZA(20) 〈 CZA(30); while the selectivity of MEK was increased in the order of CZA(CP) 〈 CZA(10) 〈 CZA(20) 〈CZA(30).展开更多
基金financial supports National Natural Science Foundation of China(22078365,21706290)Natural Science Foundation of Shandong Province(ZR2017MB004)+2 种基金Innovative Research Funding from Qingdao City,Shandong Province(17-1-1-80-jch)“Fundamental Research Funds for the Central Universities”and“the Development Fund of State Key Laboratory of Heavy Oil Processing”(17CX02017A,20CX02204A)Postgraduate Innovation Project(YCX2021057)from China University of Petroleum.
文摘Dehydrogenation is considered as one of the most important industrial applications for renewable energy.Cubic ceria-based catalysts are known to display promising dehydrogenation performances in this area.Large particle size(>20 nm)and less surface defects,however,hinder further application of ceria materials.Herein,an alternative strategy involving lactic acid(LA)assisted hydrothermal method was developed to synthesize active,selective and durable cubic ceria of<6 nm for dehydrogenation reactions.Detailed studies of growth mechanism revealed that,the carboxyl and hydroxyl groups in LA molecule synergistically manipulate the morphological evolution of ceria precursors.Carboxyl groups determine the cubic shape and particle size,while hydroxyl groups promote compositional transformation of ceria precursors into CeO_(2) phases.Moreover,enhanced oxygen vacancies(Vo)on the surface of CeO_(2) were obtained owing to continuous removal of O species under reductive atmosphere.Cubic CeO_(2) catalysts synthesized by the LA-assisted method,immobilized with bimetallic PtCo clusters,exhibit a record high activity(TOF:29,241 h^(-1))and Vo-dependent synergism for dehydrogenation of bio-derived polyols at 200℃.We also found that quenching Vo defects at air atmosphere causes activity loss of PtCo/CeO_(2) catalysts.To regenerate Vo defects,a simple strategy was developed by irradiating deactivated catalysts using hernia lamp.The outcome of this work will provide new insights into manufacturing durable catalyst materials for aqueous phase dehydrogenation applications.
文摘Catalysts with varying Fe contents were prepared using a sequential impregnation method to investigate the effects of Fe addition on the physicochemical properties of Pt/Al_(2)O_(3) and their performance in methylcyclohexane(MCH)dehydrogenation.The results demonstrated that the addition of Fe to Pt/Al_(2)O_(3) enhanced the electron density of Pt and improved catalytic activity,while exhibiting negligible influence on the catalytic selectivity for toluene.When the Fe content was 0.057%,the catalyst exhibited the highest MCH consumption rate,which was approximately two times higher than that of the catalyst without Fe.Additionally,the incorporation of Fe inhibited the formation of coke and reduced the quantity of coke deposits on the catalyst,thereby improving its catalytic durability.Overall,Fe shows promise as a prospective secondary element for Pt/Al_(2)O_(3) to enhance the MCH dehydrogenation performance.
文摘Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were investigated.Then,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle system.Brunauer-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen carriers.It was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR results.Based on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO addition.Fe_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).
基金support of National Natural Science Foundation of China(22179027)gratefully acknowledged.This work was also supported by the Natural Science Foundation of Guangxi Province(2021GXNSFAA075063,2018GXNSFDA281005)+1 种基金the National Key Research and Development Program of China(2017YFE0105500)Science&Technology Research Project of Guangdong Province(2017A020216009).
文摘Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3) dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of ethane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3) as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3) onto Ca_(2)MnO_(4) not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst.Furthermore,formation of NaNO_(3) shell on the surface of Ca_(2)MnO_(4) led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise manner.This modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO_(3)-doped Ca_(2)MnO_(4) catalyst.These findings provide compelling evidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.21802167,21961132026,92034302,21878331,91645108)the National Key Research and Development Program Nanotechnology Specific Project(No.2020YFA0210903).
文摘Propylene is a significant basic material for petrochemicals such as polypropylene,propylene oxide,etc.With abundant propane supply from shale gas,propane dehydrogenation(PDH)becomes extensively attractive as an on-purpose propylene production route in recent years.Nitrogen-doped carbon(NC)nanopolyhedra supported cobalt catalysts were synthesized in one-step of ZIF-67 pyrolysis and investigated further in PDH.XPS,TEM and N_(2) adsorption-desorption were used to study the influence of carbonization temperature on as-prepared NC supported cobalt catalysts.The temperature is found to affect the cobalt phase and nitrogen species of the catalysts.And the positive correlation was established between Co0 proportion and space time yield of propylene,indicating that the modulation of carbonization temperature could be important for catalytic performance.
基金supported by the Taishan Scholars Program of Shandong Province(tsqn202103051).
文摘Carbon catalysts for propane oxidative dehydrogenation(PODH)can potentially replace metal oxide catalysts due to their environmental friendliness(greenness)and excellent catalytic performance.Biomass carbon materials have the advantages of being abundant in variety,inexpensive,and easily available,but their catalytic selectivity is relatively poor in PODH.Therefore,we report here on a boron-doped sisal fiber carbon catalyst,which showed excellent selectivity of propylene in PODH,excluding the effect of surface-covered B2O3 on the catalytic performance by hot water washing.The carbon material exhibited the best catalytic performance with a load of 2%(mass)and a calcination temperature of 1100℃.At a reaction temperature of 400℃,the conversion rate of propane was 2.0%,and the selectivity toward propylene reached 88.6%.The new chemical bonds formed by boron on the surface of the carbon materials had an important effect on the catalytic performance,as determined by XPS characterization.The BAO groups affected the catalytic activity by inhibiting the generation of electrophilic oxygen species,while the BAC content improved the selectivity toward propylene by changing the electron cloud density.
基金the support from Clariant International Ltd.the National Natural Science Foundation of China (Nos.22022811,21938008,and U21B2096)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic reaction is constrained by thermodynamic equilibrium and involves a complex reaction network, leading to a heightened focus on catalysts and process design. Copper-based catalysts have been extensively studied and exhibit exceptional low-temperature catalytic performance in cyclohexanol dehydrogenation, with some being commercially used in the industry. This paper specifically concentrates on research advancement concerning active species, reaction mechanisms, factors influencing product selectivity, and the deactivation behaviors of copper-based catalysts. Moreover, a brief introduction to the new processes that break thermodynamic equilibrium via reaction coupling and their corresponding catalysts is summarized here as well. These reviews may off er guidance and potential avenues for further investigations into catalysts and processes for cyclohexanol dehydrogenation.
基金This work received financial support from the National Natural Science Foundation of China(21902116)Scientific Research Foundation of Technology Department of Liaoning province of China(2022-MS-379)Liaoning Revitalization Talents Program(XLYC1902070).
文摘Oxidative dehydrogenation of propane is an attractive route for the synthesis of propylene due to its favorable thermodynamic and kinetic characteristics, however, it is challenging to realize high selectivity towards propylene. Recently, it has been discovered that boron nitride (BN) is a promising catalyst that affords superior selectivity towards propylene in oxidative dehydrogenation of propane. Summarizing the progress and unravelling the reaction mechanism of BN in oxidative dehydrogenation of propane are of great significance for the rational design of efficient catalysts in the future. Herein, in this review, the underlying reaction mechanisms of oxidative dehydrogenation of propane over BN are extracted;the developed BN catalysts are classified into pristine BN, functionalized BN, supported BN and others, and the applications of each category of BN catalysts in oxidative dehydrogenation of propane are summarized;the challenges and opportunities on oxidative dehydrogenation of propane over BN are pointed out, aiming to inspire more studies and advance this research field.
基金supported by the National Natural Science Foundation of China (52002412 and 22072186)the Natural Science Foundation of Guangdong Province (2021A1515010575)the Guangzhou Science and Technology Plan General Project (202102020862)。
文摘Developing high-performing non-noble transition metal catalysts for H_(2) evolution from chemical hydrogen storage materials is of great significance for the hydrogen economy system, yet challenging. Herein,we present for the first time that anomalous metastable hexagonal close-packed Ni nanoparticles induced by heteroatom N doping encapsulated in carbon(N-hcp-Ni/C) can exhibit admirable catalytic performance for ammonia borane(AB) dehydrogenation, prominently outperforming conventional fcc Ni counterpart with similar morphology and favorably presenting the state-of-the-art level.Comprehensive experimental and theoretical studies unravel that unusual hcp phase engineering of Ni together with N doping could induce charge redistribution and modulate electronic structure, thereby facilitating H_(2)O adsorption and expediting H_(2)O dissociation(rate-determining step). As a result, AB dehydrogenation can be substantially boosted with the assistance of N-hcp-Ni/C. Our proposed strategy highlights that unconventional crystal phase engineering coupled with non-metal heteroatom doping is a promising avenue to construct advanced transition metal catalysts for future renewable energy technologies.
基金supported by the National Natural Science Foundation of China(21902097,21636006 and 21761132025)the China Postdoctoral Science Foundation(2019M653861XB)+1 种基金the Natural Science Foundation of Shaanxi Province(2020JQ-409)the Fundamental Research Funds for the Central Universities(GK201901001 and GK202003035)。
文摘Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existing catalyst is limited due to the poor activity and stability,which hinders its industrialization.Herein,we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI)for CO_(2)-ODP.Characterization results reveal that the Zn2+species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt,Rh,or Rh Pt are highly dispersed in the zeolite crystals.The isolated Zn2+cations are very effective for activating the propane and the small NPs are favorable for activating the CO_(2),which synergistically promote the selective transformation of propane and CO_(2)to propylene and CO.As a result,the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield,satisfactory CO_(2)conversion,and long-term stability.Moreover,considering the tunable synergetic effects between the isolated cations and NPs,the developed approach offers a general guideline to design more efficient CO_(2)-ODP catalysts,which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+cations for Zn2+cations in the MFI zeolite matrix.
基金financial support from the National Natural Science Foundation of China (22072018)the Natural Science Foundation of Fujian Province of China (2021J06010)。
文摘Borocarbonitride(BCN) materials are newly developed metal-free catalytic materials exhibiting high selectivity in oxidative dehydrogenation(ODH) of alkanes. However, the in-depth understandings on the role of boron(B) dopants and the intrinsic activities of –C=O and –B–OH still remain unknown.Herein, we report a series of BCN materials with regulable B content and surface oxygen functional groups via self-assembly and pyrolysis of guanine and boric acid. We found that the B/C ratio is the key parameter to determine the activity of ODH and product distribution. Among them, the high ethylbenzene conversion(~57%) and styrene selectivity(~83%) are achieved in ODH for B_(1)CN. The styrene selectivity can be improved by increasing of B/C ratio and this value reaches near 100% for B_5CN.Structural characterizations and kinetic measurements indicate that –C=O and –B–OH dual sites on BCN are real active sites of ODH reaction. The intrinsic activity of –C=O(5.556 × 10^(-4)s^(-1)) is found to be 23.7 times higher than –B–OH(0.234 × 10^(-4)s^(-1)) site. More importantly, we reveal that the deep oxidation to undesirable CO_(2) occurs on –C=O rather than –B–OH site, and B dopant in BCN materials can reduce the nucleophilicity of –C=O site to eliminate the CO_(2) emission. Overall, the present work provides a new insight on the structure–function relationship of the BCN catalytic systems.
基金financially supported by the DNL Cooperation Fund,CAS (DNL202002)the National Natural Science Foundation of China (22102180)+3 种基金the CAS Project for Young Scientists in Basic Research,(YSBR-022)the Key Research Program of Frontier Sciences,CAS (ZDBS-LY-7012)Liao Ning Revitalization Talents Program (XLYC2007070)the Fundamental Research Funds for the Central Universities (20720220009)。
文摘Pt-based catalysts are the typical industrial catalysts for propane dehydrogenation(PDH),which still suffer from insufficient lo ng-term durability due to the structu ral instability and coke deposition.A commercial γ-Al_(2)O_(3) supported thermally robust sub-nanometer Pt2In3intermetallic catalyst with atomically ordered structure and rigorously separated Pt single atoms was fabricated,which showed outstanding robustness in 240 h long-term operation at 600℃ with the deactivation rate constant kdas low as0.00078 h^(-1), ranking among the lowest reported values.Based on various in situ characterizations and theoretical calculations,it was proved that the catalyst stability not only resulted from the separated Pt single-atom sites but also significantly affected by the distance of adjacent Pt atoms.An increasing distance to 3.25 A in the Pt_(2)In_(3)could induce a weak π-adsorption configuration of propylene on Pt sites,which facilitated the desorption of propylene and restrained the side reactions like coking.
基金supported by the National Natural Science Foundation of China (No.21776156).
文摘High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was treated by oxygen plasma to further enhance catalyst performance.The results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO_(2) capture active oxygen species in gas and transform V^(4+)to V^(5+)without damage to M1 structure.The space-time yield of ethylene of the plasma-treated catalyst was significantly increased,in which the catalyst shows an enhancement near~100% than that of phase-pure M1 at 400℃ for ODHE process.Plasma treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst materials.Energy conversion is achieved by using the catalyst as a medium.
基金Project supported by the China Postdoctoral Science Foundation (Grant No.2023M732745)the National Natural Science Foundations of China (Grant Nos.61974110 and 62104177)+1 种基金the Fundamental Research Funds for the Central Universities,China (Grant Nos.QTZX23022 and JBF211103)the Cooperation Program of XDU– Chongqing IC Innovation Research Institute (Grant No.CQ IRI-2022CXY-Z07)。
文摘Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot match, acoustic holograms pursue the realization of high-resolution complex acoustic fields and gradually tend to high-frequency ultrasound applications. However, conventional continuous phase holograms are limited by three-dimensional(3D) printing size, and the presence of unavoidable small printing errors makes it difficult to achieve acoustic field reconstruction at high frequency accuracy. Here, we present an optimized discrete multi-step phase hologram. It can ensure the reconstruction quality of image with high robustness, and properly lower the requirement for the 3D printing accuracy. Meanwhile, the concept of reconstruction similarity is proposed to refine a measure of acoustic field quality. In addition, the realized complex acoustic field at 20 MHz promotes the application of acoustic holograms at high frequencies and provides a new way to generate high-fidelity acoustic fields.
基金supported by the National Natural Science Foundation of China (21106017 and 50873026)Specialized Research Fund for the Doctoral Program of Higher Education of China (20100092120047)Production and Research Prospective Joint Research Project of Jiangsu Province of China (Grant No.BY2009153)
文摘Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has been investigated by changing the content of Sn.It was found that with the presence of potassium,suitable addition of Sn could not only increase the metal dispersion,but also reduce the catalyst acidity.In these cases,the synergistic effect could also strengthen the interactions between the metal and support,which resulted in an increase in both catalytic activity and stability.In our experiments,Pt-0.6SnK/Al catalyst exhibited the lowest deactivation rate (12.4%) and showed a selectivity to isobutene higher than 94% at the isobutane conversion of about 45.3% after running the reaction for 6 h.However,with the excessive loading of Sn,surface property of active sites and the interactions between metal and support were changed.As a result,the initial optimal ratio between the metallic function and acid function would be destroyed,which was disadvantageous to the reaction.
基金supported by the Natural Science Foundation of Shandong Provence of China(ZR2013BM008)
文摘Deactivation mechanism of Cr-Al2O3catalyst and the interaction of Cr-A1 in the dehydrogenation of isobutane, as well as the nature of the catalytic active center, were studied using XRD, SEM, XPS, H2-TPR, isobutane-TPR and TPO techniques. The results revealed that the deactivation of Cr-Al2O3 catalyst was mainly caused by carbon deposition on its surface. The Cr3+ ion could not be reduced by hydrogen but could be reduced to Cr2+ by hydrocarbons and monoxide carbon. The active center for isobutane dehydrogenation could be Cr2+/Cr3+ produced from Cr6+ by the on line reduction of hydrocarbon and carbon monoxide. The binding energy of Al3+ was strongly affected by the state of chromium cations in the catalysts.
基金supported by the National Natural Science Foundation of China (Grant No. 50873026 and 21106017)the Production and Research Prospective Joint Research Project of Jiangsu Province of China (Grant No. BY2009153)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100092120047)
文摘The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNaIZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD, BET, TEM, XPS, NH3-TPD, H2 chemisorption, TPR and TPO techniques. It has been found that with suitable amount of cerium addition, the platinum dispersion increased, while the carbon deposition tended to be eliminated easily. In these cases, the presence of cerium could not only realize the better distribution of metallic particles on the support, but also strengthen the interactions between Sn species and the support. Additionally, XPS spectra confirmed that more amounts of tin could exist in oxidized form, which was advantageous to the reaction. In our experiments, PtSnNaCe (1.1 wt%)/ZSM-5 catalyst exhibited the best catalytic performance. After running the reaction for 750 h, propane conversion was maintained higher than 30% with the corresponding selectivity to propylene of about 97%.
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The project was supported by Program for New Century Excellent Talents in University (Grant No. NCET-04-0987)Doctor Fund of Science Research of Xinjiang University (Grant No. BS060101).
文摘VOx/SiO2 catalysts prepared by impregnation method were used for catalytic dehydrogenation of n-butane to butenes and characterized by X-ray diffraction, FT-IR, UV-vis, Raman, and BET measurements. The effects of VOx loading and the reaction temperature on the VOx/SiO2 catalysts and their catalytic performances for the dehydrogenation of n-butane were studied. When the VOx loading was 12% g/gcat and reaction temperature was between 590 ℃ and 600℃, n-butane conversion and butenes yields reached the highest value under H2 flux of 10 ml/min and n-butane flux of 10 ml/min. Product distribution, such as the ratio of 2-butene to 1-butene and the ratio of cis-2-butene to trans-2-butene, was mainly influenced by the reaction temperature.
基金supported by Science and Technology Development Project of Shandong Province. 2007GG3 WZ03018
文摘A series of mesoporous Cu-Zn-Al2O3 materials have been synthesized at ambient temperature and their structure was characterized by XRD, N2 physical adsorption and TPR techniques. Their catalytic applications for the dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were evaluated in a fixed-bed flow reactor at atmospheric pressure. It is demonstrated from the XRD patterns that both the as-synthesized samples and calcined samples have the typical XRD patterns of meso-structured materials and the results of N20 chemical adsorption showed that Cu was embedded in the framework of the mesoporous materials and homogeneously dispersed in the mesoporous Cu-Zn-Al2O3 materials. The catalytic activity of 2-butanol dehydrogenation was varied in the order of CZA(10) 〈 CZA(CP) 〈 CZA(20) 〈 CZA(30); while the selectivity of MEK was increased in the order of CZA(CP) 〈 CZA(10) 〈 CZA(20) 〈CZA(30).