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The study of carbon dioxide(CO2) hydrogenation to methanol is significant for China to alleviate the energy pressure and achieve carbon peaking and carbon neutrality goals.In this reaction,the design and optimization of the catalyst are the essential elements in determining the CO2 conversion and methanol selectivity.Alloy catalysts show extraordinary potential in promoting CO2 activation and hydrogenation process due to their unique electronic structure and geometrical configuration.This review comprehensively surveys the advancements in solid-solution alloys and intermetallics,particularly Cu-based,In-based,Ga-based,and other emerging alloy systems,for heterogeneous catalysis of CO2 hydrogenation to methanol.This paper also analyzes the current research strategies and ideas.It looks forward to the potential future directions and applications of alloy catalysts,aiming to provide valuable insights for researchers in related fields.
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The large amount of waste plastics produced by human activities has brought serious pollution to the air,soil and sea in all fields.And even microplastics in the environment enter the human body through biological circulation,causing great harm to human health.According to the current recycling status of waste plastics,the research progress on several chemical recycling methods and new recycling processes for chemical recycling of waste plastics with sustainable development prospects were reviewed, mainly including solvolysis,hydrogenolysis,photocatalytic degradation.The catalytic degradation methods adapted to different types of waste plastics and the important role of various catalysts in the catalytic degradation reaction were summarized.And the catalytic efficiency of the main current catalysts was compared to provides a theoretical basis for the selection of effective catalysts and methods for the efficient degradation of waste plastics.
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Polyoxometalates(POMs),as a type of multinuclear coordination polymer,have found extensive applications in catalysis,adsorption,and electrochemistry due to their unique structures and excellent physicochemical properties.However,the solubility of POMs in polar solvents has limited their application scope.To address this issue,researchers have developed POM-based composites.This review summarizes the latest research progress of POMs-based composites in the fields of biomass conversion,pollutant treatment,and electrochemistry.Studies have shown that these composites exhibit significant advantages in enhancing catalyst stability,promoting the transformation of biomass macromolecules,improving the efficiency of wastewater treatment and gas purification,and improving electrochemical performance.These achievements not only overcome the problem of POMs’ solubility but also provide new ideas and directions for technological innovation and applications in related fields.
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On the basis of ZrO2 catalyst doped with Si and La,this article introduces the pore forming agent polymethyl methacrylate(PMMA) in different ways to regulate the acidity,alkalinity and pore properties of the catalyst,and improve the conversion and selectivity of the gas-phase selective dehydration of 1,4-butanediol(BDO) to prepare 3-buten-1-ol.Through X-ray diffraction(XRD) for phase analysis,and characterization results such as Fourier transform infrared spectroscopy(FT-IR),NH3 temperature programmed adsorption(NH3-TPD),and CO2 temperature programmed adsorption(CO2-TPD),it can be seen that the pore forming agent PMMA can significantly improve the dispersion of Si and La elements,thereby enhancing the acidity and alkalinity of the corresponding catalyst.At the same time,characterization results such as N2 physical adsorption-desorption curves and scanning electron microscopy(SEM) showed that the pore forming agent PMMA changed the microstructure of the catalyst,improved its performance,especially ZrO2-DPM catalyst,and ultimately achieved a conversion of 85.36% for 1,4-butanediol and a selectivity of 64.56% for 3-buten-1-ol.
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Cu-SAPO-34 molecular sieve catalyst was synthesized by one-step hydrothermal method.The Cu-SAPO-34 molecular sieve catalyst was modified by loading cerium element using low-cost morpholine as the template,and new complex Cu-TEPA as the copper source and co-template.Effects of calcination temperature,heating rate and Ce/Al ratio on catalytic performance of Cu-SAPO-34 molecular sieve in NOx removal from diesel engine exhaust were studied,and the catalyst was characterized by XRD and N2 adsorption-desorption.The results show that the loading of cerium element can effectively improve the catalytic performance of Cu-SAPO-34 molecular sieve catalyst.When the calcination temperature is 700 ℃,the heating rate is 5 ℃·min-1,and the Ce/Al molar ratio is 0.06,the Cu/Ce-SAPO-34 catalyst has the highest NOx removal efficiency of 89.6%.The structure,crystallinity,specific surface area and pore volume of the catalyst at this time are also relatively best.
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Proton exchange membrane fuel cell,as a new type of energy conversion device with high energy density,friendly environment,fast starting speed rate at room temperature and long life,is the first choice of automobile power new energy battery.The catalyst is the key factor affecting the activation polarization of proton exchange membrane fuel cells.In this study,mass fraction of 50%Pt/C catalyst was prepared by using acetophenone semicarbazone as modifier and tetrammineplatinum chloride as active component.The preferred catalyst has a specific mass activity of 217.64 mA·mg-1 and an electrochemical active area of 87.63 m2·g-1 for electrochemical activity test.After 30 000 cycles of durability test,the specific mass activity and the electrochemical active area have only declined by 11.57% and 15.63%,respectively.
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MoS2/ZnO composite photocatalyst was synthesized by hydrothermal method.The composition and morphology of as-prepared photocatalyst were tested by infrared spectroscopy,X-ray powder diffraction,scanning electron microscopy and UV diffuse reflectance spectroscopy.The results show that the lamellar MoS2 is attached to the rod-like ZnO surface,and the light absorption capacity of the composite is enhanced to a certain extent in the visible region.For light irradiation of 120 min and the mass fraction amount of MoS2 was 1.5%,the degradation efficiency of MoS2/ZnO(MZ-3) for 15 mg·L-1 tetracycline was up to 90.01%,which was higher than that of pure ZnO.Five cycle stability test experiments showed the stable photodegradation performance of the composite catalyst.
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In this paper,the effect of Al2O3 carriers calcinated at different temperatures on Cr2O3/Al2O3 catalysts was investigated.The carriers and catalysts were analyzed and characterized by XRD,nitrogen adsorption and NH3-TPD.The results show that the pore structure and surface acidity of the carriers were different when the calcination temperature of the carriers were different,which led to the different conversion,selectivity and stability of the catalysts.When the calcination temperature of the carrier was lower,the specific surface of the carrier was larger,the number of surface hydroxyl groups was higher,and the catalyst had higher conversion,lower selectivity and better stability for the isobutane reaction.When the calcination temperature of the carrier was higher,the specific surface of the carrier was smaller,and the number of surface hydroxyl groups was lower,and the catalyst had lower conversion,higher selectivity and worse stability for the isobutane reaction.
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Three oxidizing catalysts were prepared by using Al2O3 as the carrier and regulating the content ratio of active components Co and Mo.On this basis,pre-sulfurized hydrotreating catalysts were prepared by introducing sulfurizing agent.At the same time,the desulfurization performance of the 2-4# catalyst with good performance in coke oven gas was investigated under different reaction conditions.The results showed that the best organic sulfur conversion was achieved at the CoO/MoO3 mass ratio of 0.4,the reaction pressure of 2 MPa and the temperature of 350 ℃.Under the same preparation conditions,the organosulfur conversion of the ex-situ presulfurization catalyst was 1.69% higher than the in-situ presulfurization catalyst,and the catalyst was stable in long-term use,which is promising for market application.
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Methanation of carbon dioxide is an effective way to convert and utilize carbon dioxide.In response to the low activity of carbon dioxide methanation catalysts,this article uses nickel as the active component and in-situ growth method to prepare a multi metal component high activity carbon dioxide methanation catalyst La2NiCoO6.Through SEM and BET characterization,it was found that adding La element can improve the dispersion and pore structure of nickel based catalysts,which is beneficial for enhancing their activity.The catalyst La2NiCoO6 was investigated under different process conditions,and it was found that the conversion of carbon dioxide was 91.21% and methane selectivity was 97.63% under the process conditions of reaction temperature 400 ℃,atmospheric pressure,gas space velocity 12 000 mL·(g·h)-1,and n(H2)∶n(CO2)=4,indicating that the catalyst has high activity at low temperature.And the catalyst La2NiCoO6 still maintains relatively high activity and stability within a 300 hour activity cycle.
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In order to broaden the source of ethylene cracking feedstock and reduce the diesel to gasoline ratio,hydro-upgrading of straight-run diesel to use it as ethylene cracking feedstock is one of the important ways.The hydro-upgrading catalyst of diesel is the key factor affecting the yield and properties of diesel.The catalysts with different active metal content were prepared,and the effects of catalysts at diffe-rent reaction temperatures on the yield and properties of upgraded diesel were investigated.The results show that the matching between the hydrogenation ability and ring opening ability of the catalyst can be increased while increasing the metal content of the catalyst.At the BMCI value ≤10,the yield of diesel upgraded by catalyst B can reach 57.3%,and the reaction temperature is 4 ℃ lower than that of catalyst A with low metal content.
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A series of copper-silicon nanotubular catalysts(Cu-Si-NT) with different copper-silicon ratios were prepared by hydrothermal method and used in the biomass-based hydrogenation of 5-hydroxymethylfurfural(HMF) to 2,5-dimethylfuran(DMF),and the effect of copper-silicon ratio on the structure and hydrogenation performance of the catalyst was explored.The results of catalyst activity test showed that when molar ratio of Cu/Si was 1∶1,the highest catalytic activity was obtained with HMF conversion of 100%,DMF selectivity of 74.7% under the conditions of reaction temperature of 180 ℃,reaction time of 1 h,nitrogen pressure of 2 MPa,and isopropanol as solvent and hydrogen source.After 5 cycles,the reactivity of Cu-Si-NT catalyst did not decrease significantly,indicating that the catalyst had good catalyst stability.Through a series of characterization methods such as XRD,SEM/TEM and XPS,it was found that the catalyst had a nanotubular structure,and the precursor copper silicate was reduced to form a composite structure of Cu0/Cu+,which had high hydrogen transfer hydrogenation activity and stability.
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The process flow and reaction mechanism of the MTBE unit of Sinopec Quanzhou Petrochemical Co.,Ltd.were presented briefly.The process parameters of the MTBE unit were studied using orthogonal experiments.The results showed that the optimal process parameters for the MTBE unit were etherification tower pressure of 0.52 MPa,reactor space velocity of 1.26 h-1,and alcohol to olefin ratio of 1.30.Through experimental verification,the content of MSBE in MTBE products decreased from about mass fraction of 1.5% to below 0.6% after the optimization of process parameters.Replacing the original catalyst in etherification distillation column with CDM catalytic distillation module could effectively reduce the generation of MSBE.
