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Propylene oxide (PO) is an important chemical intermediate mainly used in the production of various organic raw materials such as polyether polyols and propylene glycol,and is widely used in fields such as food and tobacco.The use of titanium silicon molecular sieve (TS-1) as a carrier to load metal gold as a catalyst for gas-phase epoxidation of propylene has broad industrial application prospects.This article mainly introduces the main factors and catalytic mechanism that affect Au/TS-1 catalyst,including the preparation method of the catalyst,gold particle size,and additives.The main preparation methods include immersion method,sedimentation precipitation method,solid grinding method,ionic liquid method,and colloid method,among which sedimentation precipitation method is currently the mainstream laboratory preparation method for catalysts.The main influence of gold particle size is reflected in the 2 nm gold catalytic effect,which is most favorable for the occurrence of propylene epoxidation reaction.The main additives are alkali metals Na and Cs,which can improve the catalytic performance of the catalyst.The Au/TS-1 catalyzed epoxidation of propylene mainly relies on the dual site synergistic catalysis of Au and Ti sites.How to prepare high-performance Au/TS-1 on a large scale is currently the main difficulty in the industrial application of propylene hydrogen phase epoxidation to produce propene oxide.
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Excessive emissions of carbon dioxide have caused serious environmental problems,especially global warming and ocean acidification.The electrocatalytic CO2 reduction reaction (CO2RR) is one of the most promising methods for converting CO2 into high-energy-density fuels or high-value chemicals. Because of their low cost and high selectivity for C3 products,copper-based catalysts have garnered a lot of attention as efficient electrocatalysts for the reduction of carbon dioxide to multi-carbon compounds.This paper summarizes the research progress of copper-based catalysts for CO2RR to generate C3 products in recent years,including the reaction mechanism of CO2RR to generate C3 products,and improving the electroreduction performance of copper-based catalysts through structural regulation,surface regulation,bimetallic and other strategies.Finally,the key challenges and future research directions in this field are outlined to provide ideas for further development of highly active CO2RR catalysts to generate C3 products.
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Taking ExxonMobil for example,this paper examined the patent application trends and technical routes for the related patents of metallocene polyethylene as cataloged in the Derwent patent database.By February 29,2024,ExxonMobil has submitted 175 patent applications related to metallocene polyethylene,including 59 in China.The analysis revealed that ExxonMobil has a comprehensive patent layout,including metallocene catalyst designs,polymerization processes,applications and modifications of metallocene polyethylene.The patent layout of ExxonMobil in China was basically consistent with that in the world.However,ExxonMobil emphasized catalyst design in its global layout,and payed more attention to application technology in its patent layout in China.Combined with the analyzed results above,some suggestions were given for domestic relevant enterprises and research institutions to deploy technical forces.
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This paper discusses the reaction mechanism of methane dry reforming (DRM),including the microscopic mechanism of the key steps and the main factors affecting the reaction path.The properties and characteristics of various catalysts used for DRM,including metal oxide and metal carbide as support catalysts,and precious metal and Fe,Co,Ni as active component,are comprehensively evaluated,and their advantages and disadvantages in catalytic activity,selectivity and stability are analyzed.In addition,this paper also focuses on the mechanism of additives in improving catalytic performance,and how to optimize the overall performance of catalysts by regulating the type and dosage of additives.Finally,the application status of methane dry reforming technology in industrial production is summarized,and the future development direction is proposed.
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Research progress on catalysts of 4-tertbutylphenol via alkylation of phenol was outlined,and solid acid catalyst,supported solid acid catalysts,resin catalysts and molecular sieve catalysts in the application of 4-tertbutylphenol alkylation were introduced.It was pointed out that the development of catalytic performance and environment friendly alkylation catalysts was the future of 4-tertbutylphenol industrialization research direction.
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The catalytic hydrogenation of p-chloronitrobenzene to synthesize p-chloroaniline is an important organic chemical reaction,and the key to this catalytic reaction is to realize nitro hydrogenation and reduction without dechlorination.N-doped modified Pt0.3/NxC catalysts were prepared by an impregnation method,which showed that the metal-carrier interactions induced by N-doped activated carbon carriers improved the activity,selectivity and stability of the catalysts,while inhibiting the C—Cl bond breakage.Among them,the average particle size of Pt nanoparticles on the surface of the Pt0.3/N0.2C catalyst prepared by using a mass ratio of urea to activated carbon of 0.2 was the smallest and uniformly dispersed.The catalyst exhibited excellent conversion (100%),selectivity (99.0%) and reusability for the catalytic synthesis of p-chloroaniline from p-chloronitrobenzene hydrogenation at 50 ℃,0.5 MPa,and a reaction time of 90 min.
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In this paper,TiO2 powder and UiO-66 were obtained by sol-gel method and solvothermal method respectively.Then UiO-66@TiO2 composite photocatalyst was synthesized.Composite nano-photocatalyst UiO-66-NH2@TiO2 was prepared by solvothermal method using titanate(C16H36O4Ti) as the Ti source,2-amino benzoic acid as the -NH2 source,benzoic acid as crosslinker,and UiO-66 as the carrie.By in situ infrared spectroscopy (FT-IR),ultraviolet diffuse reflection (DRS),field emission scanning electron microscope (SEM),energy spectrum (EDS),N2 adsorption-desorption,X-ray photoelectron energy spectrum (XPS) and X-ray diffraction (XRD),the structure,morphologe,shape of prepared TiO2,UiO-66,UiO-66@TiO2,UiO-66-NH2 and UiO-66-NH2@TiO2 were characterized.Catalytic performance test was applied in photocatalytic degradation of methyl orange (MO) solutions.The test results showed that the degradation of 50 mL 5 mg·L-1 MO solution in 160 min was 92.35% under the condition of 0.800 g UiO-66-NH2@TiO2,and pH=1.Therefore,it can be proved that UiO-66-NH2@TiO2 has high photocatalytic activity.
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A series of tungstovanadophosphoric heteropolyacid catalysts H4PW11VO40,H5PW10V2O40,H6PW9V3O40 and H6P2W18O62 were prepared by conventional aqueous solution and ether extraction methods.And the structures of tungstovanadophosphoric heteropolyacid catalysts were characterized by powder X-ray diffraction (PXRD) and infrared spectroscopy (FT-IR).The tungstovanadophosphoric heteropolyacid catalysts were used in the catalytic synthesis of tributyl citrate,and the effects of different heteropolyacid structures,reaction temperature,alcohol/acid molar ratio,catalyst dosage on the esterification of tributyl citrate were investigated.The results showed that H6P2W18O62 had the highest catalytic activity,and the average esterification of tributyl citrate could reach up to 95.9% when reaction temperature was 150 ℃,alcohol/acid molar ratio was 4∶1,and catalyst dosage was 0.15 g.
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By adding silane reagent to intervene in the crystallization process of TS-1,the directional aggregation of nanocrystalline grains was achieved,and thus continuous and dense titanium-silicon molecular sieve membranes were prepared by bridging on micrometer-sized spherical carriers.Its structure was characterized by various analytical methods(SEM,XRD,FT-IR and UV-Vis),and its catalytic activity for the direct epoxidation reaction of chloropropene was examined.The experimental results showed that the TS-1 titanium-silicon molecular sieve spherical membranes prepared by the bridging method had higher homogeneity and densification,which improved the stability of the membrane layer during the epoxidation reaction.The selectivity of chloropropylene oxide,the yield of chloropropylene oxide,the conversion of H2O2,and the effective utilization efficiency of H2O2 reached 95.61%,86.93%,97.54%,and 93.21%,respectively.And there was no obvious decrease in the reaction activity after three cycle experiments.The TS-1 titanium-silicon molecular sieve membrane prepared by the bridging method is easy to be recycled and can be reused while maintaining its catalytic performance.
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A series of catalysts with different metal and support were synthesized by chemical fluid deposition (CFD) method using supercritical CO2 as solvent.In this work,hydrodeoxygenation of 2-methoxyl-4-allyl phenol was applied for investigating the performance of different catalysts.The effect of support (SBA-15, SO42-/ZrO2,HY) and content of different metal (Pd,Pt) on conversion and selectivity were investigated.While the effects of reaction condition on the conversion of reactant and selectivity of product were also evaluated.It was shown that the conversion of 2-methoxyl-4-allyl phenol and selectivity of high carbon number aromatic hydrocarbons could reach 98.0% and 94.2% respectively when SO42-/ZrO2 was support,m(Pd)∶m(Pt)=3∶1,total mass fraction of 3%,reaction temperature was 300 ℃.
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Using waste lubricating oil as the feedstock,the effects of reaction temperatures on the hydroconversion characteristics,product distributions and properties were investigated with oil-soluble Mo-based catalysts and solid Fe-based catalysts.The results showed that the hydroconversion products of waste lubricating oil with reaction temperature are similar under two different catalysts.As the reaction temperature increased,the heavy oil conversion in waste lubricating oil significantly improved,primarily generating C6-C12 naphtha fractions and C12-C25 diesel fractions.At a reaction temperature of 450 ℃,the heavy oil was completely converted,with the combined yield of light oil reaching 92.35%.The content of impurity elements S,N,and O in the liquid products significantly decreased,while the H/C atomic ratio increased.The content of aliphatic hydrocarbons decreased,and the content of aromatic hydrocarbons slightly increased.Additionally,macromolecular hydrocarbons underwent polycondensation reactions on the surface of the solid products,forming micron to submicron spherical particles.
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In order to improve the phenomenon of micro-pores caused by water evaporation in the film forming process of epoxy acrylate emulsion,four different oxidized polyethylene waxes XW-17,XE-16,PED522 and 629A were used to modify the epoxy emulsion.Due to the high melting point of oxidized polyethylene wax,it was used as a functional monomer to modify epoxy acrylate,and its optimal amount was studied.Finally,epoxy emulsion was prepared by soap-free core-shell emulsion polymerization.Fourier transform infrared spectroscopy (FT-IR) confirmed that oxidized polyethylene wax was successfully introduced into epoxy acrylate.The optimum addition amount of oxidized polyethylene wax was determined by cross-linking degree and water absorption.The microstructure of emulsion before and after modification was characterized by transmission electron microscopy (TEM).Thermal weight (TGA),static water contact angle and atomic force microscopy (AFM) were used to test the emulsion dry film before and after modification.The results showed that the addition of oxidized polyethylene wax could improve the thermal properties and roughness of the emulsion dry film,but did not change the hydrophilicity of the emulsion dry film.The optimum addition amount of oxidized polyethylene wax to modified epoxy acrylate was mass fraction of 0.3%,and the modified emulsion with 629A had the best performance.
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Ethylene oxide (EO) is a pivotal derivative in the ethylene industry,which is next to polyethylene in importance.Silver (Ag)-based catalysts exhibit exceptional performance in the epoxidation of ethylene to EO.The RS-891 catalyst,synthesized via the impregnation method,was characterized using X-ray diffraction (XRD),scanning electron microscopy (SEM),mercury intrusion porosimetry,X-ray photoelectron spectroscopy (XPS),and oxygen temperature-programmed desorption (O2-TPD) to elucidate its structural and chemical properties.The catalytic performance of RS-891 in the epoxidation of ethylene to produce EO was systematically evaluated.The results demonstrate that the α-Al2O3 support utilized in the RS-891 catalyst possesses a lamellar structure with an interlocking configuration,which enhances the mechanical strength of the support and promotes the uniform dispersion of silver nanoparticles.This structural feature effectively mitigates nanoparticle aggregation,thereby extending the operational lifespan of the catalyst.Laboratory evaluations conducted over 1 500 h,corroborated by industrial operational data,indicate that the RS-891 catalyst achieves an EO selectivity exceeding 88% after 100 h of operation,with a consistent upward trend in selectivity thereafter.Once selectivity surpasses 88%,the catalyst maintains stable and reliable performance,ensuring high catalytic efficiency.The close alignment between industrial application data and laboratory results underscores the exceptional stability of the RS-891 catalyst,highlighting its significant potential for industrial applications and substantial economic value.
