Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Ethylene (C2H4) and propylene (C3H6) are primarily synthesized via two routes:the cracking of light alkanes and the methanol-to-olefins(MTO) process.CO2 is an inevitable byproduct in the industrial production of olefins,it not only corrodes the reactors but also reduces the activity of the olefin polymerization catalyst.Consequently,even trace amounts of CO2 necessitate its removal during olefin polymerization.This paper reviews the major technologies for CO2 removal and separation,including absorption,low-temperature distillation,membrane separation and selective adsorption.Among these approaches,selective adsorption technology stands out with the advantages of low energy consumption,simple adsorbent preparation procedures,low operating costs and controllable environmental pollution,rendering it a prominent research hotspot in CO2 removal and separation.This work also summarizes the research progress on various adsorbent types and their modification.It is proposed that the core direction for the future development of CO2 adsorption removal technology in olefin lies in developing environmentally friendly adsorbent materials featuring high CO2 adsorption capacity,high precision,superior selectivity,low energy consumption and low cost.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Glycolic acid,as an important organic chemical raw material,is widely used in fields such as chemical cleaning,daily chemical products,biodegradable new materials,and pharmaceuticals and pesticides.The traditional production process of glycolic acid has problems such as severe equipment corrosion,significant environmental pollution,and high costs.The methylester hydrolysis method,as a green and environmentally friendly process route,has received extensive attention in recent years.This paper systematically reviews the research progress in the reaction mechanism,catalyst system,laboratory purification, product separation,and technical and economic aspects of the methylester hydrolysis reaction of glycolic acid.It analyzes the current technical challenges and looks forward to future development directions.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Propylene oxide (PO) is a crucially important basic chemical raw material,and the development of its green synthesis processes is a focus of current research.The gas-phase epoxidation route using hydrogen and oxygen as direct oxidants,with the advantages of 100% atom economy and solvent-free operation,is regarded as the most promising next-generation PO production technology.This review summarizes the latest research progress on catalysts with titanium silicalite-1(TS-1) as the core support in this reaction system.Emphasis is placed on the Au/TS-1 catalyst system,providing an in-depth analysis of the effects of the active site structure(Au nanoparticle size,coordination environment of Ti species),support properties(pore structure,surface characteristics,Si/Ti ratio),and preparation methods on catalytic performance.The reaction mechanism under the H2/O2 pathway and the competitive reaction network are discussed in detail,and a comparative analysis with auxiliary catalytic systems such as Pt-Pd/TS-1 is conducted.Finally,future research directions and prospects are proposed.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
To address the increasingly serious issue of CO2 emissions,it is necessary to develop efficient catalysts for the hydrogenation of CO2 to produce olefins.By adjusting the amount of reducing solvent ethylene glycol,the degree of reduction of the Fe-based catalyst precursor can be precisely controlled;Na additives are introduced for modification,and the synergistic effects of reduction degree and Na additives on the structure and performance of the catalyst are systematically studied.The results show that increasing the reduction degree can significantly increase the content of Fe monomer in the catalyst,thereby promoting the formation of the key active phase Fe5C2 during the reaction.The introduction of Na additives not only enhanced the adsorption and activation of CO2,further accelerated the formation of Fe5C2,but also effectively inhibited the secondary hydrogenation of olefins,successfully shifting the product distribution from being dominated by alkanes to being dominated by olefins.The optimal catalyst EG-40-Na,under the conditions of 300 ℃ and normal pressure,achieved a CO2 conversion rate of 22.1%,a C2+ hydrocarbon selectivity of 74.4%,and the main product was low-carbon olefins.This collaborative strategy optimizes the entire process from the surface properties,phase composition to the microscopic structure of the catalyst,providing a new idea for rational design of high-performance CO2 conversion catalysts.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Using Ru/Al2O3 as the catalyst,the selective hydrogenation reaction of p-phenylenediamine to prepare 1,5-cyclohexanediamine was carried out in a fixed-bed reactor.The catalytic activity,selectivity and stability of the catalyst were systematically investigated.Regarding the phenomenon of catalyst activity decline during the reaction,the regeneration pathway was explored.Various characterization techniques such as XRD,N2 adsorption-desorption,XRF,ICP and TG-DSC were employed to compare and analyze the phase structure,pore characteristics,elemental composition,dispersion degree of active components and surface species of the fresh catalyst and the deactivated catalyst.The results showed that the main reasons for catalyst deactivation included the coverage of active components,the minor loss of active components,and the high-temperature sintering of active metals.After regeneration treatment,the dispersion degree of active components and the number of active sites on the surface of the deactivated catalyst were significantly restored,and the catalytic activity was greatly enhanced,which could meet the process requirements for the hydrogenation reaction of p-phenylenediamine again.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Hydroformylation reaction is one of the most important homogeneous catalytic reactions in chemical production.Its products are widely used in the production of high-value-added chemicals such as plasticizers,surfactants,and solvents.The main product obtained from the hydroformylation reaction of vinyl acetate can be used to produce key industrial products such as 1,2-propanediol,1,3-propanediol,lactic acid,and 3-hydroxypropionic acid.Five different structural phosphorus ligands(monodentate,conventional bidentate,ferrocenyl bidentate) were designed and constructed for the rhodium-based catalytic system.The effects of ligand electron effect and steric hindrance on the regioselectivity of the vinyl acetate hydroformylation reaction were investigated,and the reaction mechanism was clarified by density functional theory(DFT) calculations.The results showed that all catalytic systems achieved 100% substrate conversion rate and over 90% aldehyde selectivity,with excellent catalytic performance.Electron-withdrawing ligands are conducive to the formation of linear aldehydes,while electron-donating ligands favor the formation of branched aldehydes.DFT calculations indicated that there were two coordination isomers,ae and ee,at the catalytic active center,clarifying the mechanism of region selectivity regulation dominated by electron effect and assisted by steric hindrance,providing an important reference for the design of highly selective hydroformylation catalytic systems.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
NaY molecular sieves were prepared using high-concentration water glass,and the influence of four types of directing agents on the synthesis was investigated.The results showed that the low n(Na2O)∶n(Al2O3) directing agent SDA-1 prepared by using high-concentration water glass did not achieve satisfactory synthesis results for the molecular sieves.After using a formula close to the edge of the synthesis phase region of NaY molecular sieves,the relative crystallinity of the synthesized samples could only reach 62%.However,the high-silicon-type directing agent SDA-4 prepared by using high-concentration water glass achieved the best synthesis effect,and NaY molecular sieves with a relative crystallinity greater than 90% could be synthesized under different formulas.The total surface area of NaY molecular sieves synthesized by using high-concentration water glass was 18.4 m2/g higher than that of NaY molecular sieves synthesized by ordinary water glass,and the mesoporous specific surface area increased by 24.6 m2/g.The NaY molecular sieves synthesized by using high-concentration water glass had smaller grain sizes and presented more sheet-like morphologies of crystals.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Three Ba-CuZrO2 catalysts were synthesized by the co-precipitation method,with the precipitation pH values being 8,10,and 12 respectively.The performance of the catalysts in the production of ketone compounds from ethanol was investigated.The catalysts were characterized by N2-physical adsorption,XRD,H2-TPR,XPS,CO2-TPD,ethanol-TPSR,and in situ DRIFTS.The results showed that the structural properties of the catalysts prepared by the co-precipitation method were greatly affected by the precipitation pH value.Compared with CZ-8 and CZ-12,the CZ-10 catalyst had a larger specific surface area,abundant basic sites,and multiple adsorption intermediates on the surface,which promoted the ethanol dehydrogenation process.Acetaldehyde further underwent a condensation reaction under the action of the basic sites to form ketone products.Using the CZ-10 catalyst,the ketone selectivity reached 71.2%,with a 2-pentanone selectivity of 29.4%.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
To address the insufficient isobutyraldehyde yield in existing propylene hydroformylation processes,a novel composite ligand catalytic system was constructed by combining phosphite ligand DC-22 with triphenylphosphine.The application research on increasing isobutyraldehyde output via propylene hydroformylation was carried out.Process conditions were optimized in a batch reactor,and long-term stability evaluation was performed using a continuous stirred-tank reactor unit.The results show that the composite ligand combined with rhodium precursor presents favorable synergistic catalytic effect,with the optimal molar ratio of Rh to P being 1∶6.Under the conditions of reaction pressure 1.8 MPa,temperature 80 ℃ and rhodium concentration of 80 mg/kg,after 600 h continuous operation,propylene conversion remains steadily above 90%.The n/i ratio of mixed butyraldehyde is approximately 1.3,which greatly improves the selectivity toward isobutyraldehyde.In addition,this catalytic system possesses better stability than single phosphite ligand system,showing promising prospects for industrial application.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Different carrier-loaded palladium catalysts were prepared by the co-precipitation method for the hydrogenation reaction of tetrachlorosilane.It was found that the carrier had a significant impact on the catalyst performance.Among them,carbon nanotubes showed the best catalytic activity due to their structural characteristics,good electrical conductivity and corrosion resistance.The conversion rate could reach 97.02%.Using carbon nanotubes as the carrier,the influence of different reduction methods of palladium and the modification of metal additives on the comprehensive performance of the catalyst was further investigated.The results showed that when sodium borohydride was used as the reducing agent,a high conversion rate could be maintained while the loss rate of metal palladium was the lowest.After modifying with Mg,the loss rate of metal palladium was further the lowest,and the conversion rate was further increased to 99.88%,achieving the optimal comprehensive performance of the catalyst.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
The ethane decarbonization unit of the Total Gas Treatment Plant of Changqing Oilfield selected a new decarbonization process flow of two-stage absorption with lean liquid and semi-lean liquid,combined with two-stage flash vaporization regeneration.It used activated N-methyl diethanolamine+piperazine(MDEA+PZ) as the adsorbent.Since its commissioning,problems such as low efficiency and high energy consumption have occurred in the decarbonization unit.Through process simulation analysis software HYSYS,the process flow was simulated and calculated to optimize the semi-lean liquid circulation process and the amine liquid circulation volume.This effectively solved the problems existing in the operation of the decarbonization unit,further improving the operation efficiency of the device and reducing energy consumption.The total savings in annual electricity consumption and the increased production of ethane amounted to CNY 2 274 700,demonstrating great practicality and promotion potential.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
To evaluate the catalytic performance of different hydrolytic catalysts in organic sulfur hydrolysis reactions and investigate the effect of reaction temperature on hydrolysis performance,hydrolytic catalysts from various manufacturers were selected,and their hydrolysis performances were compared at different temperatures.The experimental results showed that above 60 ℃,all three hydrolytic catalysts met the efficiency requirements for carbonyl sulfide(COS) hydrolysis in the fine desulfurization process of coke oven gas,and the hydrolysis efficiency increased with rising temperature.When the reaction temperature exceeded 120 ℃,only two of the carbon disulfide(CS2) hydrolytic catalysts satisfied the efficiency requirements for CS2 hydrolysis in coke oven gas.The hydrolysis performance of organic sulfur was related to the content of the active component Al2O3 in the hydrolytic catalyst:a lower Al2O3 content led to poor CS2 hydrolysis performance.Therefore,rapid preliminary evaluation and screening of catalysts could be achieved by detecting the Al2O3 content in the hydrolytic catalysts.
Abstract (
)
Download PDF (
)
Rich HTML
(
)
Knowledge map
Save
Select representative wastewater samples from a certain chemical industrial park and adopt ozone catalytic oxidation pretreatment combined with hydrolysis acidification technology for in-depth treatment.Firstly,it undergoes sedimentation treatment,and then the ozone catalytic oxidation pretreatment unit is introduced.By setting different ozone concentrations and ozone flow rates as test conditions,the wastewater is preliminarily treated.Then,the hydrolysis acidification deep treatment unit is applied to decompose the organic matter in the wastewater.Subsequently,multiple treatment units such as anoxic tank,aerobic tank,and sedimentation tank are successively applied to comprehensively treat the wastewater.The results show that under the conditions of ozone concentration of 100 mg/L and flow rate of 60 mL/min,the chemical oxygen demand concentration in the S05 group wastewater is 25.36 mg/L,the biological oxygen demand concentration is 10 mg/L,the ammonia nitrogen concentration is 2.5 mg/L,the suspended solids concentration is 8.26 mg/L with a removal rate of 75.36%;the total phosphorus concentration is 0.25 mg/L,with a removal rate of 85.15%.All indicators meet the discharge standards,providing a reliable solution for wastewater treatment in the chemical industrial park.
