The effect of promoter cobalt and the sequences of adding cobalt and molybdenum precursors on the performance of sulfur-resistant methanation were investigated. All these samples were prepared by impregnation method a...The effect of promoter cobalt and the sequences of adding cobalt and molybdenum precursors on the performance of sulfur-resistant methanation were investigated. All these samples were prepared by impregnation method and characterized by N2-adsorption, X-ray diffraction(XRD), temperature-programmed reduction(TPR) and laser Raman spectroscopy(LRS). The conversions of CO for Mo-Co/Al, Co-Mo/Al and CoMo/Al catalysts were 59.7%, 54.3% and 53.9%, respectively. Among these catalysts, the Mo-Co/Al catalyst prepared stepwisely by impregnating Mo precursor firstly showed the best catalytic performance. Meanwhile, the conversions of CO were 48.9% for Mo/Al catalyst and 10.5% for Co/Al catalyst. The addition of cobalt species could improve the catalytic activity of Mo/Al catalyst. The N2-adsorption results showed that Co-Mo/Al catalyst had the smallest specific surface area among these catalysts. CoMoO4species in CoMo/Al catalyst were detected with XRD, TPR and LRS. Moreover, crystal MoS2which was reported to be less active than amorphous MoS2was found in both Co-Mo/Al and CoMo/Al catalysts. Mo-Co/Al catalyst showed the best catalytic performance as it had an appropriate surface structure, i.e., no crystal MoS2and very little CoMoO4species.展开更多
As an energy-intensive industry,the chlor-alkali process has caused numerous environmental issues due to heavy electricity consumption and pollution.Chlor-alkali industry has been upgraded from mercury,diaphragm elect...As an energy-intensive industry,the chlor-alkali process has caused numerous environmental issues due to heavy electricity consumption and pollution.Chlor-alkali industry has been upgraded from mercury,diaphragm electrolytic cell,to ion exchange membrane(IEM)electrolytic cells.However,several challenges,such as the selectivity of the anodic reaction,sluggish kinetics of alkaline hydrogen evolution,degradation of membranes,the reasonable design of electrolytic cell structure,remain to be addressed.For these reasons,this paper mainly reviews the research progress of the chlor-alkali industry from materials to devices,including hydrogen evolution anode,chlorine evolution cathode,IEM,and electrolytic cell system.Finally,the research directions and prospects in the chlor-alkali industry are proposed for its further improvement.展开更多
The interaction between a promoter and an active metal crucially impacts catalytic performance.Nowadays,the influence of promoter contents and species has been intensively considered.In this study,we investigate the e...The interaction between a promoter and an active metal crucially impacts catalytic performance.Nowadays,the influence of promoter contents and species has been intensively considered.In this study,we investigate the effect of the iron(Fe)-zinc(Zn)proximity of Fe-Zn bimetallic catalysts on CO_(2)hydrogenation performance.To eliminate the size effect,Fe_(2)O_(3)and ZnO nanoparticles with uniform size are first prepared by the thermal decomposition method.By changing the loading sequence or mixing method,a series of Fe-Zn bimetallic catalysts with different Fe-Zn distances are obtained.Combined with a series of characterization techniques and catalytic performances,Fe-Zn bimetallic proximity for compositions of Fe species is discussed.Furthermore,we observe that a smaller Fe-Zn distance inhibits the reduction and carburization of the Fe species and facilitates the oxidation of carbides.Appropriate proximity of Fe and Zn(i.e.,Fe_1Zn_(1)-imp and Fe_(1)Zn_(1)-mix samples)results in a suitable ratio of the Fe_5C_(2)and Fe_(3)O_(4)phases,simultaneously promoting the reverse water-gas shift and Fischer-Tropsch synthesis reactions.This study provides insight into the proximity effect of bimetallic catalysts on CO_(2)hydrogenation performance.展开更多
Hydroformylation of formaldehyde to glycolaldehyde(GA),as a vital reaction in both direct and indirect process of syngas to ethylene glycol(EG),shows great advantages in the aspects of the process complexity and clean...Hydroformylation of formaldehyde to glycolaldehyde(GA),as a vital reaction in both direct and indirect process of syngas to ethylene glycol(EG),shows great advantages in the aspects of the process complexity and clean production.The hydroformylation of formaldehyde to GA is thermodynamically unfavourable,requiring the development of highly efficient hydroformylation catalytic systems,appropriate reaction conditions and in-depth understanding of the reaction mechanisms.In this review,we have made a detailed summary on the reaction in terms of the reaction network,thermodynamics,metal complex catalysts(including central metals and ligands),reaction conditions(e.g.,temperature,pressure,formaldehyde source and solvent)and promoters.Furthermore,the reaction mechanisms,involving neutral and anionic complex in the catalytic cycle,have been summarized and followed by a discussion on the impact of the crucial intermediates on the reaction pathways and product distribution.A brief overview of product separation and catalyst recovery has been presented in the final part.This review gives new insights into the factors that impact on the formaldehyde hydroformylation and reaction mechanisms,which helps to design more efficient catalytic systems and reaction processes for EG production via the hydroformylation route.展开更多
Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,...Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,we fabricated self-supported ultrathin NiCo layered double hydroxides(LDHs)electrodes as anode for methanol electrooxidation to achieve a high formate production rate(5.89 mmol h^(-1)cm^(-2))coupled with CO_(2)electro-reduction at the cathode.A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO_(2)reduction can reach up to 188%driven by a low cell potential of only 2.06 V at 100 mA cm^(-2)in membrane-electrode assembly(MEA).Physical characterizations demonstrated that Ni^(3+)species,formed on the electrochemical oxidation of Ni-containing hydroxide,acted as catalytically active species for the oxidation of methanol to formate.Furthermore,DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni^(3+)in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation.This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.展开更多
CeOsupports were prepared by calcination or precipitation method and 5% MoO/CeOcatalysts were prepared by incipient-wetness impregnation method. The catalytic performance of the 5% MoO/CeOcatalysts toward sulfur-resis...CeOsupports were prepared by calcination or precipitation method and 5% MoO/CeOcatalysts were prepared by incipient-wetness impregnation method. The catalytic performance of the 5% MoO/CeOcatalysts toward sulfur-resistant methanation was investigated. The results showed that the Mo/Ce-1 catalysts with CeOsupport prepared by calcination method exhibited the best sulfur-resistant methanation activity and stability with CO conversion as high as 75% while the Mo/Ce-3 catalysts the poorest. The supports and catalysts were characterized by N-adsorption–desorption, temperature-programmed reduction（TPR）, X-ray diffraction（XRD）, Raman spectroscopy（RS） and scanning electron microscope（SEM）. The results indicated that the saturated monolayer loading MoOon Ce-3 support was lower than 5% and there were some crystalline MoOparticles on the surface of the Mo/Ce-3. The preparation method of CeOhad a big influence on the specific surface area, the crystalline of CeO, and the catalytic performance of the corresponding Mo-based catalyst for sulfur-resistant methanation.展开更多
The synthesis of calcium formate by Ca(OH)_2 carbonylation was studied in a semi-batch stirred tank.The reaction mechanism was analyzed theoretically and the rate of each step was compared.The influence ofreaction con...The synthesis of calcium formate by Ca(OH)_2 carbonylation was studied in a semi-batch stirred tank.The reaction mechanism was analyzed theoretically and the rate of each step was compared.The influence ofreaction conditions on the formation of calcium formate was investigated.The results indicate that the rate-controlling step is the reaction between dissolved CO and dissolved Ca(OH)_2,and the gaseous diffusion resistance can be eliminated when the stirring speed reached 1000 r/min.Furthermore,the reaction kinetics was studied at a stirring speed of 1000 r/min,temperature of 423–453 K,pressure of 2.0–3.5 MPa and different initial concentrations of Ca(OH)_2.An effective method was proposed to measure the reaction rate of CO.A mathematical model was developed using the dual-film theory,and the parameters were obtained using regression of experimental data.The reaction rates calculated using the kinetics model were compared with experimental data.The results show that the deviations are within ±10%,proving that the established model is valid and can provide a basis for industrial amplification.展开更多
Molybdenum phosphide(MoP) catalyst has been widely applied in hydrogenation reactions, while the preparation of unsupported MoP catalysts with ultra-small size and large specific surface area(SBET) is still challengin...Molybdenum phosphide(MoP) catalyst has been widely applied in hydrogenation reactions, while the preparation of unsupported MoP catalysts with ultra-small size and large specific surface area(SBET) is still challenging. Herein, we have provided a facile method for preparing a series of MoP-x(x=P/Mo ratios ranging from 1 to 5) catalysts by pyrolyzing phytic acid(PA)-derived Mo complexes in a H2 atmosphere. The physicochemical properties and the catalytic activity of MoP catalysts were investigated. The results showed that the obtained MoP-5 catalyst had the largest SBETand exhibited ultra-small nanoparticle diameter of 3.6 nm, which ascribed to the chelation of PA and the confinement of deposited products.As the content of PA increased, the synthetic mechanism of MoP was also affected, which led to the difference in the valence of surface Mo species. The characterization results further confirmed that Moδ+ sites in MoP catalysts are active sites for methanation reaction and its content on the surface of MoP-x catalysts determines the catalytic activity.展开更多
Ethanol synthesis via dimethyl oxalate hydrogenation has garnered increasing attention in the fields of syngas utilization.Althoughε-Fe_(2)C has been identified as a promising active species for DMO hydrogenation to ...Ethanol synthesis via dimethyl oxalate hydrogenation has garnered increasing attention in the fields of syngas utilization.Althoughε-Fe_(2)C has been identified as a promising active species for DMO hydrogenation to ethanol,its formation is kinetically challenging during carbonization.In this work,a Fe_(4)N phase was first synthesized by pretreating a 30Fe/SiO_(2)catalyst in an ammonia environment,followed by carbonization in a methanol-H_(2) flow to obtain ε-Fe_(2)C as the active phase.Fe_(4)N,rather than Fe-O-Si,facilitates the transformation into iron carbide during the carbonization process.The transformation pathway of iron nitride(Fe_(x)N)is mediated by intermediate iron carbonyl species(Fe-CO),ultimately leading to the formation of iron carbide as the active phase.The resulting catalyst exhibited 40 times higher catalytic activity than the untreated catalyst in DMO hydrogenation.Combined structure properties and DFT calculation revealed that the lower energy barrier ofε-Fe_(2)C for ester hydrogenation underpins/strengthens its superior performance,while the STY of ε-Fe_(2)C is 2.8 times that ofε'-Fe_(2.2)C and 58 times that ofχ-Fe_(5)C_(2).This study provides a novel strategy for designing highly efficient iron carbide catalysts for the esters hydrogenation system.展开更多
A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assig...A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assigned to be the best catalyst,with 84%yield and exclusive3,4-selectivity.The ligand effect on both catalytic activity and regioselectivity of boracarboxylation was disclosed,which is rarely reported in any copper catalyzed boracarboxylation.The borocupration process is revealed to be a vital step for the biphosphine participated boracarboxylation of 1,3-dienes with CO_(2).The minimal substrate distortion occurring in 3,4-borocupration favors the 3,4-regioselectivity of boracarboxylation.The“pocket”confinement and suitableβ_(n)(92°–106°)of bisphosphine ligands are demonstrated to be in favour of the interaction between LCu-Bpin complex(the catalytic precursor)and1,3-diene substrate to decrease their interaction energyΔE_(int)(ζ)in 3,4-borocupration,thus promoting the 3,4-boracarboxylation.展开更多
Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework.Tailoring the acidity,particularly the distribution and location of...Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework.Tailoring the acidity,particularly the distribution and location of the Bronsted acid sites in the zeolite is effective for making it a better catalyst for these reactions.We prepared a series of H-mordenite（H-MOR） samples by varying the composition of the sol-gel,using different structure directing agents and post-treatment.NH3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Bronsted acid sites in the 8-membered ring and 12-membered ring channels.It was shown that controlled synthesis was a promising approach to improve the concentration of Bronsted acid sites in MOR,even with a low Al content.Using an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Bronsted acid sites in the 8-membered ring channels.HMI as a structure-direct agent gave an obvious enrichment of Bronsted acid sites in the 8-membered ring.Carbonylation of dimethyl ether was used as a probe reaction to examine the modification of the acid properties,especially the Bronsted acid sites in the 8-membered ring channels.There was a linear relationship between methyl acetate formation and the number of Bronsted acid sites in the 8-membered ring channels,demonstrating the successful modification of acid properties.Our results provide information for the rational design and modification of zeolites with spatial constraints.展开更多
In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high meth...In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high methanation performance. CO conversion could reach up to 90% on 25 wt% MoO3/ZrO2 catalyst, much higher than that on the conventional 25 wt% MoO3/Al2O3 catalyst. The Mo-based catalysts were characterized by XRF, XRD, Raman, BET, TEM and H2-TPR etc. It was found that MoO3 particles were highly dispersed on ZrO2 support for 25 wt% MoO3/ZrO2 catalyst prepared at 65-85℃ because of its relatively larger pore size, which contributed to a high CO conversion. Meanwhile, when MoO3 loading exceeded the monolayer coverage, the formed crystalline MoO3 and ZrM020g might block the micropores of the catalyst and make the methanation activity declined. These results are useful for preparing highly efficient catalyst for CO methanation process.展开更多
An efficient ZrO2-doped Cu/SiO2 catalyst was fabricated through hydrolysis precipitation method(HP)and used to produce ethylene glycol(EG)through dimethyl oxalate(DMO)hydrogenation.The states for zirconia on copper ca...An efficient ZrO2-doped Cu/SiO2 catalyst was fabricated through hydrolysis precipitation method(HP)and used to produce ethylene glycol(EG)through dimethyl oxalate(DMO)hydrogenation.The states for zirconia on copper catalyst and roles in DMO hydrogenation were investigated through various characterization tools,including N2 physical adsorption,XRD,H2-TPR,Methyl glycolate-TPD-MS,XPS,XAES as well.Compared with common ammonia evaporation and co-precipitation methods used in catalyst preparation,this HP method is found to effectively suppress the agglomeration and further size growth of copper nanoparticles by enhancing the interactions between copper and zirconia species.More importantly,uniform distribution of ZrO2 dopant is achieved due to the pseudo-homogeneous reactions in the mixing step of catalyst preparation.A proper amount of zirconium dopant helps achieve the desirable proportion of Cu+/(Cu++CuO)for surface copper species,especially promotes the production of Cu+species originated from Cu-ZrO2 species at the interface of copper and zirconia particles.In comparison with Cu+species formed from copper phyllosilicates reduction,the Cu+sites derived from Cu-ZrO2 species show higher adsorption ability of MG,an important intermediate species in ethylene glycol production.These adsorbed MG molecules further react with atomic hydrogen shifted from adjacent metallic copper surface,leading to a higher catalytic behavior.For the EG production via DMO hydrogenation,the turnover frequency(TOF)normalized by CuO species on CuZr/SiO2 catalyst is 1.8 times than that of traditional Cu/SiO2 counterpart.Due to the enhanced synergy effect between Cu+and Cuo active sites,a lower activation energy of ester hydrogenation on this ZrO2-doped Cu/SiO2 catalyst is believed to be responsible for the significant improvement.展开更多
The metal-support interaction is of critical importance to enhance the catalytic activity and selectivity.However,it is still challenging to construct an appropriate interaction starting from the catalyst fabrication ...The metal-support interaction is of critical importance to enhance the catalytic activity and selectivity.However,it is still challenging to construct an appropriate interaction starting from the catalyst fabrication and/or activation.We herein established low-temperature treatment of Ni^(2+)ions impregnated on ceria in reductive atmosphere and reduction-oxidation cycles as effective approachs to regulate the metal-support interaction and raise the catalytic performance in the CO_(2)methanation.The proposed construction approach yielded Ni/Ce O_(2)that displayed highly dispersed Ni nanoparticles in contact with Ce O_(2)(111)and(100)facet,higher density of surface oxygen vacancies and larger amounts of weak basic sites relative to the reference samples,which increased the capacity for H2 and CO_(2)adsorption/activation.The interaction resulted in appreciably(2-3 fold)higher activity in the CO_(2)methanation with maintaining almost full selectivity to CH4 and high stability.Coverage of Ni surface by Ce O_(2)-x thin layer as a typical structure of strong metal-support interaction resulting from high-temperature reduction,can be alleviated via reduction-oxidation cycles.We also demonstrate the activation treatment-determined metalsupport interaction effect can generally extend to(Ti O_(2)and Zr O_(2))supported Ni catalysts.展开更多
The effects of composite supports of CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 on the methanation activity of supported Co-Mo-based sulphur-resistant catalysts were investigated. The catalysts were further chara...The effects of composite supports of CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 on the methanation activity of supported Co-Mo-based sulphur-resistant catalysts were investigated. The catalysts were further characterized by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. The catalyst of 5%CoO-15%MoO3 supported on CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 composite oxides, respectively, showed different catalytic performances of syngas methanation in the presence of hydrogen sulphide as compared with that of the 5%CoO-15%MoO3/Al2O3 catalyst. The Co-Mo/CeO2-Al2O3 catalyst shows the highest methanation activity among the tested catalysts. The enhanced methanation activity may be attributed to the improvement of the dispersion of active metal species and the inhibition of the formation of S6＋.展开更多
The development of a highly efficient catalyst for CO_(2) activation and selective conversion to methanol is critical to address the issues associated with the high thermal stability of CO_(2) and controllable synthes...The development of a highly efficient catalyst for CO_(2) activation and selective conversion to methanol is critical to address the issues associated with the high thermal stability of CO_(2) and controllable synthesis of methanol.Cu-based catalysts have been widely studied because of the low cost and excellent performance in mild conditions.However,the improvement of catalytic activity and selectivity remains challenging.Herein,we prepared hollow Cu@ZrO_(2) catalysts through pyrolysis of Cu-loaded Zr-MOF for CO_(2) hydrogenation to methanol.Low-temperature pyrolysis generated highly dispersed Cu nanoparticles with balanced Cu^(0)/Cu^(+)sites,larger amounts of surface basic sites and abundant Cu-ZrO_(2) interface in the hollow structure,contributing to enhanced catalytic capacity for adsorption/activation of CO_(2) and selective hydrogenation to methanol.In situ Fourier Transform Infrared Spectroscopy revealed the methanol formation followed the formate-intermediated pathway.This work would provide a guideline for the design of high-performance catalysts and the understanding of the mechanism and active sites for CO_(2) hydrogenation to methanol.展开更多
Zeolite catalysts,such as H-mordenite(H-MOR),are readily deactivated by coke deposition in carbonylation reactions.Pyridine modification of H-MOR can improve its stability but can lead to an undesirable loss in cataly...Zeolite catalysts,such as H-mordenite(H-MOR),are readily deactivated by coke deposition in carbonylation reactions.Pyridine modification of H-MOR can improve its stability but can lead to an undesirable loss in catalytic activity.Herein,we report the intrinsic impact of the pyridine adsorption behavior on H-MOR and the spacial hindrance of the zeolite frameworks on dimethyl ether(DME)carbonylation at a molecular level.We discovered that acid sites at O2 positions,located on common walls of eight-membered ring(8-MR)side pockets and 12-MR channels,were active in DME carbonylation,but were unfortunately poisoned during pyridine modification.Density functional theory calculations revealed that the pyridine-poisoned acid sites at the O2 positions could be easily regenerated due to the spacial hindrance of the zeolite frameworks.Accordingly,they can be facilely regenerated by proper thermal treatment,which induces 60%promotion in the catalytic activity along with a high stability.Our findings demonstrate the determining role of O2 positions in H-MOR for DME carbonylation and provide a new avenue for the rational design of other efficient zeolite-relevant catalytic systems.展开更多
A series of efficient ruthenium chloride (RuCl_3)-anchored MOF catalysts,such as RuCl_3@MIL-101 (Cr)-Sal,and RuCl_3@MIL-101 (Cr)-DPPB, have been successfully synthesized by post-synthetic modification (PSM)of the term...A series of efficient ruthenium chloride (RuCl_3)-anchored MOF catalysts,such as RuCl_3@MIL-101 (Cr)-Sal,and RuCl_3@MIL-101 (Cr)-DPPB, have been successfully synthesized by post-synthetic modification (PSM)of the terminal amino of MIL-101(Cr)-NH_2 with salicylaldehyde, 2-diphenylphosphinobenzaldehyde (DPPBde) and anchoring of Ru (Ⅲ) ions. The stronger coordination electron donor interaction between Ru (Ⅲ) ions and chelating groups in the RuCl_3@MIL-101 (Cr)-DPPB enhances its catalytic performance for CO_2 hydrogenation to formic acid. The turnover number (TON) of formic acid was up to 831 in reaction time of 2 h with dimethyl sulfoxide (DMSO) and water (H_2O) as mixed solvent, trimethylamine (Et_3N) as organic base, and PPh_3 as electronic additive.展开更多
ZnO-CeO2/SBA-15 catalysts were prepared by two kinds of solid-state grinding method and used for the production of 1,3-butadiene(1,3-BD) from ethanol.A mixture of SBA-15(with or without organic template) and metal pre...ZnO-CeO2/SBA-15 catalysts were prepared by two kinds of solid-state grinding method and used for the production of 1,3-butadiene(1,3-BD) from ethanol.A mixture of SBA-15(with or without organic template) and metal precursors were ground in solid-state.The obtained catalysts were characterized by TG,N2 adsorption-desorption,TEM,XRD,Py-FTIR and NH_3-TPD techniques.Superior dispersion of metal oxides and more exposed acid sites were achieved on the catalyst lOZn_1Ce_5-AS with the presence of organic template in SBA-15 during the solid-state grinding process.The catalytic performance was evaluated in a fixed-bed reactor and a 1,3-butadiene selectivity of as high as 45% is achieved.This is attributed to the coupling effect of Zn and Ce species in the mesopores of SBA-15,in which Zn promotes ethanol dehydrogenation and Ce enhances aldol-condensation,respectively.Additionally,solvent-free method inspires new catalyst synthesis strategy for the production of 1,3-butadiene from ethanol.展开更多
文摘The effect of promoter cobalt and the sequences of adding cobalt and molybdenum precursors on the performance of sulfur-resistant methanation were investigated. All these samples were prepared by impregnation method and characterized by N2-adsorption, X-ray diffraction(XRD), temperature-programmed reduction(TPR) and laser Raman spectroscopy(LRS). The conversions of CO for Mo-Co/Al, Co-Mo/Al and CoMo/Al catalysts were 59.7%, 54.3% and 53.9%, respectively. Among these catalysts, the Mo-Co/Al catalyst prepared stepwisely by impregnating Mo precursor firstly showed the best catalytic performance. Meanwhile, the conversions of CO were 48.9% for Mo/Al catalyst and 10.5% for Co/Al catalyst. The addition of cobalt species could improve the catalytic activity of Mo/Al catalyst. The N2-adsorption results showed that Co-Mo/Al catalyst had the smallest specific surface area among these catalysts. CoMoO4species in CoMo/Al catalyst were detected with XRD, TPR and LRS. Moreover, crystal MoS2which was reported to be less active than amorphous MoS2was found in both Co-Mo/Al and CoMo/Al catalysts. Mo-Co/Al catalyst showed the best catalytic performance as it had an appropriate surface structure, i.e., no crystal MoS2and very little CoMoO4species.
基金The work was supported by the National Nature Science Foundation of China(Nos.2193800 and 22078232)the Science and Technology Major Project of Tianjin(Nos.18ZXJMTG00180 and 19ZXNCGX00030).
文摘As an energy-intensive industry,the chlor-alkali process has caused numerous environmental issues due to heavy electricity consumption and pollution.Chlor-alkali industry has been upgraded from mercury,diaphragm electrolytic cell,to ion exchange membrane(IEM)electrolytic cells.However,several challenges,such as the selectivity of the anodic reaction,sluggish kinetics of alkaline hydrogen evolution,degradation of membranes,the reasonable design of electrolytic cell structure,remain to be addressed.For these reasons,this paper mainly reviews the research progress of the chlor-alkali industry from materials to devices,including hydrogen evolution anode,chlorine evolution cathode,IEM,and electrolytic cell system.Finally,the research directions and prospects in the chlor-alkali industry are proposed for its further improvement.
基金supported by National Natural Science Foundation of China(Nos.22108200,21938008 and 22121004)Natural Science Foundation of Zhejiang Province(LQ22B060013)the Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘The interaction between a promoter and an active metal crucially impacts catalytic performance.Nowadays,the influence of promoter contents and species has been intensively considered.In this study,we investigate the effect of the iron(Fe)-zinc(Zn)proximity of Fe-Zn bimetallic catalysts on CO_(2)hydrogenation performance.To eliminate the size effect,Fe_(2)O_(3)and ZnO nanoparticles with uniform size are first prepared by the thermal decomposition method.By changing the loading sequence or mixing method,a series of Fe-Zn bimetallic catalysts with different Fe-Zn distances are obtained.Combined with a series of characterization techniques and catalytic performances,Fe-Zn bimetallic proximity for compositions of Fe species is discussed.Furthermore,we observe that a smaller Fe-Zn distance inhibits the reduction and carburization of the Fe species and facilitates the oxidation of carbides.Appropriate proximity of Fe and Zn(i.e.,Fe_1Zn_(1)-imp and Fe_(1)Zn_(1)-mix samples)results in a suitable ratio of the Fe_5C_(2)and Fe_(3)O_(4)phases,simultaneously promoting the reverse water-gas shift and Fischer-Tropsch synthesis reactions.This study provides insight into the proximity effect of bimetallic catalysts on CO_(2)hydrogenation performance.
基金supported by the National Key Research and Development Program of China(2018YFA0704501).
文摘Hydroformylation of formaldehyde to glycolaldehyde(GA),as a vital reaction in both direct and indirect process of syngas to ethylene glycol(EG),shows great advantages in the aspects of the process complexity and clean production.The hydroformylation of formaldehyde to GA is thermodynamically unfavourable,requiring the development of highly efficient hydroformylation catalytic systems,appropriate reaction conditions and in-depth understanding of the reaction mechanisms.In this review,we have made a detailed summary on the reaction in terms of the reaction network,thermodynamics,metal complex catalysts(including central metals and ligands),reaction conditions(e.g.,temperature,pressure,formaldehyde source and solvent)and promoters.Furthermore,the reaction mechanisms,involving neutral and anionic complex in the catalytic cycle,have been summarized and followed by a discussion on the impact of the crucial intermediates on the reaction pathways and product distribution.A brief overview of product separation and catalyst recovery has been presented in the final part.This review gives new insights into the factors that impact on the formaldehyde hydroformylation and reaction mechanisms,which helps to design more efficient catalytic systems and reaction processes for EG production via the hydroformylation route.
基金the financial support from the National Nature Science Foundation of China(22078232 and 21938008)the Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,we fabricated self-supported ultrathin NiCo layered double hydroxides(LDHs)electrodes as anode for methanol electrooxidation to achieve a high formate production rate(5.89 mmol h^(-1)cm^(-2))coupled with CO_(2)electro-reduction at the cathode.A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO_(2)reduction can reach up to 188%driven by a low cell potential of only 2.06 V at 100 mA cm^(-2)in membrane-electrode assembly(MEA).Physical characterizations demonstrated that Ni^(3+)species,formed on the electrochemical oxidation of Ni-containing hydroxide,acted as catalytically active species for the oxidation of methanol to formate.Furthermore,DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni^(3+)in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation.This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.
基金Financial supports from the National High Technology Research and Development Program of China(863 Project)(2015AA050504)the National Natural Science Foundation of China(21576203)
文摘CeOsupports were prepared by calcination or precipitation method and 5% MoO/CeOcatalysts were prepared by incipient-wetness impregnation method. The catalytic performance of the 5% MoO/CeOcatalysts toward sulfur-resistant methanation was investigated. The results showed that the Mo/Ce-1 catalysts with CeOsupport prepared by calcination method exhibited the best sulfur-resistant methanation activity and stability with CO conversion as high as 75% while the Mo/Ce-3 catalysts the poorest. The supports and catalysts were characterized by N-adsorption–desorption, temperature-programmed reduction（TPR）, X-ray diffraction（XRD）, Raman spectroscopy（RS） and scanning electron microscope（SEM）. The results indicated that the saturated monolayer loading MoOon Ce-3 support was lower than 5% and there were some crystalline MoOparticles on the surface of the Mo/Ce-3. The preparation method of CeOhad a big influence on the specific surface area, the crystalline of CeO, and the catalytic performance of the corresponding Mo-based catalyst for sulfur-resistant methanation.
基金supported by the National High-Tech Research and Development Program of China ("863" Program, No.2012AA06A113)
文摘The synthesis of calcium formate by Ca(OH)_2 carbonylation was studied in a semi-batch stirred tank.The reaction mechanism was analyzed theoretically and the rate of each step was compared.The influence ofreaction conditions on the formation of calcium formate was investigated.The results indicate that the rate-controlling step is the reaction between dissolved CO and dissolved Ca(OH)_2,and the gaseous diffusion resistance can be eliminated when the stirring speed reached 1000 r/min.Furthermore,the reaction kinetics was studied at a stirring speed of 1000 r/min,temperature of 423–453 K,pressure of 2.0–3.5 MPa and different initial concentrations of Ca(OH)_2.An effective method was proposed to measure the reaction rate of CO.A mathematical model was developed using the dual-film theory,and the parameters were obtained using regression of experimental data.The reaction rates calculated using the kinetics model were compared with experimental data.The results show that the deviations are within ±10%,proving that the established model is valid and can provide a basis for industrial amplification.
基金Financial supports from the National High Technology Research and Development Program of China (863 Project) (2015AA050504)。
文摘Molybdenum phosphide(MoP) catalyst has been widely applied in hydrogenation reactions, while the preparation of unsupported MoP catalysts with ultra-small size and large specific surface area(SBET) is still challenging. Herein, we have provided a facile method for preparing a series of MoP-x(x=P/Mo ratios ranging from 1 to 5) catalysts by pyrolyzing phytic acid(PA)-derived Mo complexes in a H2 atmosphere. The physicochemical properties and the catalytic activity of MoP catalysts were investigated. The results showed that the obtained MoP-5 catalyst had the largest SBETand exhibited ultra-small nanoparticle diameter of 3.6 nm, which ascribed to the chelation of PA and the confinement of deposited products.As the content of PA increased, the synthetic mechanism of MoP was also affected, which led to the difference in the valence of surface Mo species. The characterization results further confirmed that Moδ+ sites in MoP catalysts are active sites for methanation reaction and its content on the surface of MoP-x catalysts determines the catalytic activity.
基金supported by the National Natural Science Foundation of China(21878227,22278309)。
文摘Ethanol synthesis via dimethyl oxalate hydrogenation has garnered increasing attention in the fields of syngas utilization.Althoughε-Fe_(2)C has been identified as a promising active species for DMO hydrogenation to ethanol,its formation is kinetically challenging during carbonization.In this work,a Fe_(4)N phase was first synthesized by pretreating a 30Fe/SiO_(2)catalyst in an ammonia environment,followed by carbonization in a methanol-H_(2) flow to obtain ε-Fe_(2)C as the active phase.Fe_(4)N,rather than Fe-O-Si,facilitates the transformation into iron carbide during the carbonization process.The transformation pathway of iron nitride(Fe_(x)N)is mediated by intermediate iron carbonyl species(Fe-CO),ultimately leading to the formation of iron carbide as the active phase.The resulting catalyst exhibited 40 times higher catalytic activity than the untreated catalyst in DMO hydrogenation.Combined structure properties and DFT calculation revealed that the lower energy barrier ofε-Fe_(2)C for ester hydrogenation underpins/strengthens its superior performance,while the STY of ε-Fe_(2)C is 2.8 times that ofε'-Fe_(2.2)C and 58 times that ofχ-Fe_(5)C_(2).This study provides a novel strategy for designing highly efficient iron carbide catalysts for the esters hydrogenation system.
基金the National Key R&D Program of China(No.2022YFB4101900)National Natural Science Foundation of China(Nos.22278305,U21B2096)Natural Science Foundation of Tianjin City(No.23JCZDJC00040)。
文摘A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assigned to be the best catalyst,with 84%yield and exclusive3,4-selectivity.The ligand effect on both catalytic activity and regioselectivity of boracarboxylation was disclosed,which is rarely reported in any copper catalyzed boracarboxylation.The borocupration process is revealed to be a vital step for the biphosphine participated boracarboxylation of 1,3-dienes with CO_(2).The minimal substrate distortion occurring in 3,4-borocupration favors the 3,4-regioselectivity of boracarboxylation.The“pocket”confinement and suitableβ_(n)(92°–106°)of bisphosphine ligands are demonstrated to be in favour of the interaction between LCu-Bpin complex(the catalytic precursor)and1,3-diene substrate to decrease their interaction energyΔE_(int)(ζ)in 3,4-borocupration,thus promoting the 3,4-boracarboxylation.
基金supported by the National Natural Science Foundation of China(21325626,21406120)the Postdoctoral Science Foundation of China(2014M560181,2015T80214)~~
文摘Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework.Tailoring the acidity,particularly the distribution and location of the Bronsted acid sites in the zeolite is effective for making it a better catalyst for these reactions.We prepared a series of H-mordenite（H-MOR） samples by varying the composition of the sol-gel,using different structure directing agents and post-treatment.NH3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Bronsted acid sites in the 8-membered ring and 12-membered ring channels.It was shown that controlled synthesis was a promising approach to improve the concentration of Bronsted acid sites in MOR,even with a low Al content.Using an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Bronsted acid sites in the 8-membered ring channels.HMI as a structure-direct agent gave an obvious enrichment of Bronsted acid sites in the 8-membered ring.Carbonylation of dimethyl ether was used as a probe reaction to examine the modification of the acid properties,especially the Bronsted acid sites in the 8-membered ring channels.There was a linear relationship between methyl acetate formation and the number of Bronsted acid sites in the 8-membered ring channels,demonstrating the successful modification of acid properties.Our results provide information for the rational design and modification of zeolites with spatial constraints.
基金supported by the Tianjin Municipal Science and Technology Commission(14JCZDJC37500)
文摘In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high methanation performance. CO conversion could reach up to 90% on 25 wt% MoO3/ZrO2 catalyst, much higher than that on the conventional 25 wt% MoO3/Al2O3 catalyst. The Mo-based catalysts were characterized by XRF, XRD, Raman, BET, TEM and H2-TPR etc. It was found that MoO3 particles were highly dispersed on ZrO2 support for 25 wt% MoO3/ZrO2 catalyst prepared at 65-85℃ because of its relatively larger pore size, which contributed to a high CO conversion. Meanwhile, when MoO3 loading exceeded the monolayer coverage, the formed crystalline MoO3 and ZrM020g might block the micropores of the catalyst and make the methanation activity declined. These results are useful for preparing highly efficient catalyst for CO methanation process.
基金financial support from the National Natural Science Foundation of China(21878227,U1510203)。
文摘An efficient ZrO2-doped Cu/SiO2 catalyst was fabricated through hydrolysis precipitation method(HP)and used to produce ethylene glycol(EG)through dimethyl oxalate(DMO)hydrogenation.The states for zirconia on copper catalyst and roles in DMO hydrogenation were investigated through various characterization tools,including N2 physical adsorption,XRD,H2-TPR,Methyl glycolate-TPD-MS,XPS,XAES as well.Compared with common ammonia evaporation and co-precipitation methods used in catalyst preparation,this HP method is found to effectively suppress the agglomeration and further size growth of copper nanoparticles by enhancing the interactions between copper and zirconia species.More importantly,uniform distribution of ZrO2 dopant is achieved due to the pseudo-homogeneous reactions in the mixing step of catalyst preparation.A proper amount of zirconium dopant helps achieve the desirable proportion of Cu+/(Cu++CuO)for surface copper species,especially promotes the production of Cu+species originated from Cu-ZrO2 species at the interface of copper and zirconia particles.In comparison with Cu+species formed from copper phyllosilicates reduction,the Cu+sites derived from Cu-ZrO2 species show higher adsorption ability of MG,an important intermediate species in ethylene glycol production.These adsorbed MG molecules further react with atomic hydrogen shifted from adjacent metallic copper surface,leading to a higher catalytic behavior.For the EG production via DMO hydrogenation,the turnover frequency(TOF)normalized by CuO species on CuZr/SiO2 catalyst is 1.8 times than that of traditional Cu/SiO2 counterpart.Due to the enhanced synergy effect between Cu+and Cuo active sites,a lower activation energy of ester hydrogenation on this ZrO2-doped Cu/SiO2 catalyst is believed to be responsible for the significant improvement.
基金financially supported by the Tianjin Key Science and Technology Project(19ZXNCGX00030)。
文摘The metal-support interaction is of critical importance to enhance the catalytic activity and selectivity.However,it is still challenging to construct an appropriate interaction starting from the catalyst fabrication and/or activation.We herein established low-temperature treatment of Ni^(2+)ions impregnated on ceria in reductive atmosphere and reduction-oxidation cycles as effective approachs to regulate the metal-support interaction and raise the catalytic performance in the CO_(2)methanation.The proposed construction approach yielded Ni/Ce O_(2)that displayed highly dispersed Ni nanoparticles in contact with Ce O_(2)(111)and(100)facet,higher density of surface oxygen vacancies and larger amounts of weak basic sites relative to the reference samples,which increased the capacity for H2 and CO_(2)adsorption/activation.The interaction resulted in appreciably(2-3 fold)higher activity in the CO_(2)methanation with maintaining almost full selectivity to CH4 and high stability.Coverage of Ni surface by Ce O_(2)-x thin layer as a typical structure of strong metal-support interaction resulting from high-temperature reduction,can be alleviated via reduction-oxidation cycles.We also demonstrate the activation treatment-determined metalsupport interaction effect can generally extend to(Ti O_(2)and Zr O_(2))supported Ni catalysts.
文摘The effects of composite supports of CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 on the methanation activity of supported Co-Mo-based sulphur-resistant catalysts were investigated. The catalysts were further characterized by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. The catalyst of 5%CoO-15%MoO3 supported on CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 composite oxides, respectively, showed different catalytic performances of syngas methanation in the presence of hydrogen sulphide as compared with that of the 5%CoO-15%MoO3/Al2O3 catalyst. The Co-Mo/CeO2-Al2O3 catalyst shows the highest methanation activity among the tested catalysts. The enhanced methanation activity may be attributed to the improvement of the dispersion of active metal species and the inhibition of the formation of S6＋.
基金the financial support by the National Natural Science Foundation of China(22178265,U21B2096,21938008)the Tianjin Key Science and Technology Project(19ZXNCGX00030)。
文摘The development of a highly efficient catalyst for CO_(2) activation and selective conversion to methanol is critical to address the issues associated with the high thermal stability of CO_(2) and controllable synthesis of methanol.Cu-based catalysts have been widely studied because of the low cost and excellent performance in mild conditions.However,the improvement of catalytic activity and selectivity remains challenging.Herein,we prepared hollow Cu@ZrO_(2) catalysts through pyrolysis of Cu-loaded Zr-MOF for CO_(2) hydrogenation to methanol.Low-temperature pyrolysis generated highly dispersed Cu nanoparticles with balanced Cu^(0)/Cu^(+)sites,larger amounts of surface basic sites and abundant Cu-ZrO_(2) interface in the hollow structure,contributing to enhanced catalytic capacity for adsorption/activation of CO_(2) and selective hydrogenation to methanol.In situ Fourier Transform Infrared Spectroscopy revealed the methanol formation followed the formate-intermediated pathway.This work would provide a guideline for the design of high-performance catalysts and the understanding of the mechanism and active sites for CO_(2) hydrogenation to methanol.
基金supported by the National Natural Science Foundation of China(21476159,21676182)~~
文摘Zeolite catalysts,such as H-mordenite(H-MOR),are readily deactivated by coke deposition in carbonylation reactions.Pyridine modification of H-MOR can improve its stability but can lead to an undesirable loss in catalytic activity.Herein,we report the intrinsic impact of the pyridine adsorption behavior on H-MOR and the spacial hindrance of the zeolite frameworks on dimethyl ether(DME)carbonylation at a molecular level.We discovered that acid sites at O2 positions,located on common walls of eight-membered ring(8-MR)side pockets and 12-MR channels,were active in DME carbonylation,but were unfortunately poisoned during pyridine modification.Density functional theory calculations revealed that the pyridine-poisoned acid sites at the O2 positions could be easily regenerated due to the spacial hindrance of the zeolite frameworks.Accordingly,they can be facilely regenerated by proper thermal treatment,which induces 60%promotion in the catalytic activity along with a high stability.Our findings demonstrate the determining role of O2 positions in H-MOR for DME carbonylation and provide a new avenue for the rational design of other efficient zeolite-relevant catalytic systems.
基金Financial support from the National Natural Science Foundation of China(NSFC, Nos. 21776211, 21325626)the Program for New Century Excellent Talents in University(No. NCET-13-0411)the Program of Introducing Talents of Discipline to Universities(No. B06006)
文摘A series of efficient ruthenium chloride (RuCl_3)-anchored MOF catalysts,such as RuCl_3@MIL-101 (Cr)-Sal,and RuCl_3@MIL-101 (Cr)-DPPB, have been successfully synthesized by post-synthetic modification (PSM)of the terminal amino of MIL-101(Cr)-NH_2 with salicylaldehyde, 2-diphenylphosphinobenzaldehyde (DPPBde) and anchoring of Ru (Ⅲ) ions. The stronger coordination electron donor interaction between Ru (Ⅲ) ions and chelating groups in the RuCl_3@MIL-101 (Cr)-DPPB enhances its catalytic performance for CO_2 hydrogenation to formic acid. The turnover number (TON) of formic acid was up to 831 in reaction time of 2 h with dimethyl sulfoxide (DMSO) and water (H_2O) as mixed solvent, trimethylamine (Et_3N) as organic base, and PPh_3 as electronic additive.
基金financial support from the National Natural Science Foundation of China(No.21878227)。
文摘ZnO-CeO2/SBA-15 catalysts were prepared by two kinds of solid-state grinding method and used for the production of 1,3-butadiene(1,3-BD) from ethanol.A mixture of SBA-15(with or without organic template) and metal precursors were ground in solid-state.The obtained catalysts were characterized by TG,N2 adsorption-desorption,TEM,XRD,Py-FTIR and NH_3-TPD techniques.Superior dispersion of metal oxides and more exposed acid sites were achieved on the catalyst lOZn_1Ce_5-AS with the presence of organic template in SBA-15 during the solid-state grinding process.The catalytic performance was evaluated in a fixed-bed reactor and a 1,3-butadiene selectivity of as high as 45% is achieved.This is attributed to the coupling effect of Zn and Ce species in the mesopores of SBA-15,in which Zn promotes ethanol dehydrogenation and Ce enhances aldol-condensation,respectively.Additionally,solvent-free method inspires new catalyst synthesis strategy for the production of 1,3-butadiene from ethanol.
