γ?Al2O3 is commonly used as a carrier for catalysts, and the physicochemical properties of its surface greatly influence the catalytic reaction. The exposed Al coordination environment can be regulated by adjusting the morphology of γ?Al2O3 carriers by changing the synthesis method and synthesis conditions. The energy of the exposed crystal lattice of carriers with different morphologies is different, which will directly affect the acidity of the carrier and the interaction between active metals, and active metals and carriers, thus creating different loading sites of active metals. Carrier morphology control is an effective way to regulate the structure of the active components. The regulation of the support morphology of the propane dehydrogenation catalyst will affect the catalytic performance. The research progress of γ?Al2O3 support was reviewed from the aspects of preparation method, morphology control, and its influence on propane dehydrogenation catalyst.
For the deep removal of CO from hydrogen?rich gas,the preparation of catalysts with better CO?Prox catalytic performance is a current research hotspot.CuO/NiO?CeO2 catalysts were prepared by stepwise impregnation method,and the catalysts were characterized by XRD,BET,H2?TPR and HR?TEM to investigate the effects of molar loading of metal Cu+Ni (metal loading) on the catalysts' structure,reduction properties and their CO?Prox performance.The results showed that Cu/Ni?O?Ce solid solutions were all formed in CuO/NiO?CeO2 catalysts.The catalytic activity is mainly related to the content of Cu species highly dispersed on the carrier surface as well as to the content of the solid solution.Among them,the catalyst with a metal loading of 8% had a higher content of Cu species highly dispersed on the carrier surface and a higher content of solid solutions,and the catalyst exhibited better catalytic activity.Under the CO/H2/CO2/O2/Ar atmosphere,a reaction temperature of 130 °C,an oxygen excess coefficient of 1.2,and a mass?air velocity of 20 266 mL/（g·h）,the CO conversion was 95.9%,and the CO oxidation selectivity was 86.3%.
Cu0.7Mn0.3Al2.5 ternary solid solution spinel catalysts were prepared by ball milling method using copper nitrate as the copper source, proposed thin alumina as the aluminium source, citric acid as the additive, and manganese acetate as the third component to partially replace copper. With the help of characterisation techniques such as XRD, BET, H2?TPR and XPS, the crystalline phase structure, weaving properties, reducing properties and surface cation states and distributions of Cu0.7Mn0.3Al2.5 were investigated. The catalytic performance of Cu0.7Mn0.3Al2.5 in methanol steam reforming (MSR) for hydrogen production with a sustained release feature was scrutinized, and a comparison was made with CuAl2.5 binary spinel and Cu0.7Zn0.3Al2.5 ternary spinel catalysts. The results showed that compared with CuAl2.5 and Cu0.7Zn0.3Al2.5, the Cu0.7Mn0.3Al2.5 exhibited the maximum contraction of the unit cell, resulting in a smaller unit cell constant. The catalyst had smaller crystalline size and higher specific surface area. The catalyst showed an aluminium?rich state, but with a higher percentage of Cu in the surface spinel phase, which made the reduction under H2 atmosphere more difficult, and exhibited a better slow?release catalytic performance in MSR hydrogen production. Under the conditions of a reaction temperature of 265 °C, n（H2O）/n（CH3OH） =2, and mass flow rate of 2.25 h-1, a stable conversion rate of 84% was achieved for 40 hours. The study provided valuable data reference for the development of efficient copper?based sustained?release catalysts.
Cobalt?based catalyst is regarded as a suitable choice for Fischer?Tropsch synthesis (FTS) due to its high activity and strong C—C bond formation ability. FTS reaction mechanism of Co?based catalysts was summarised, and the structure of the active phase as well as the conformational relationship between additives and catalytic performance were analysed. For clarifying the role of catalyst supports, the promotion of FTS reaction via regulating metal?carrier interaction was also summarized. Specially, the direct synthesis of liquid fuel by coupling metal Co with zeolite catalyst was discussed, and the reaction route for liquid fuel and the character of as?used bifunctional catalyst were focused.
Graphite phase carbon nitride(g?C3N4), as an environmentally benign semiconductor material, has good application prospects in photocatalysis. However, the disadvantages of pure g?C3N4 such as small specific surface area and difficult separation of photogenerated carriers will limit its photocatalytic performance, which will restrict its large?scale application.From the synthetic methods and modification strategies, the research progress of g?C3N4 photocatalysts by researchers in recent years is reviewed, and the development of g?C3N4 photocatalysts in the fields of degradation of pollutants in water treatment, H2 and H2O2 production is summarised, and it can be found that the performance of the modified g?C3N4 photocatalysts has been greatly improved.Finally,the development direction of g?C3N4 photocatalyst is prospected.
A series of B?MFI zeolites were synthesized using a solvent?free method using tetrapropylammonium hydroxide (TPAOH) as a template. XRD, SEM, N2 adsorption desorption, in situ infrared spectroscopy, and pyridine adsorption infrared spectroscopy were used to characterize the effect of template agent addition on the physicochemical properties of B?MFI zeolites, and the performance of 1?butene double bond isomerization reaction was investigated. The results showed that the addition of template significantly affected the grain size and skeleton boron species content of B?MFI zeolites. When the template agent addition was 4.500 g (n（SiO2）/n（TPAOH)=11.6）, the B?MFI zeolites obtained had the smallest particle size and the largest number of silicon boron hydroxyl pits, providing more highly active reaction sites. The reaction evaluation results confirmed that when using B?MFI molecular sieve catalyst for the double bond isomerization of 1?butene, the conversion rate of 1?butene was as high as 70.00%, and the selectivity of 2?butene was greater than 99%. The catalyst had excellent stability and showed no signs of deactivation during the evaluation period.
Different morphology CeO2 was used as a catalyst to catalyse the synthesis of trimethylene carbonate from CO2 and 1,3?propanediol.The structure and composition of cerium oxides were characterized by SEM, TEM, XPS and XRD. The results showed that the yield of trimethylene carbonate was up to 72.5% at 130 ℃ for 4 h when using the rod?shaped cerium oxide as catalyst and 2?cyanopyridine as dehydrating agent. R?CeO2 has a higher number of defect sites and an suitable specific surface area, The average particle size is small and it has moderate number of Lewis acidic sites. Based on this, the substrate range was expanded, and the experimental results showed that both five?membered cyclic carbonates and six?membered cyclic carbonates could be obtained in good yields.
As a classic non?metallic semiconductor photocatalyst, graphite phase carbon nitride material （g?C3N4） has attracted widespread attention in recent years due to its stable physical and chemical properties, reasonable band structure, low cost, easy availability, safety, and pollution?free advantages. It has good application and development prospects in the fields of environmental protection, purification and energy catalysis. However, the utilization of g?C3N4 in studies is significantly hampered by its tiny specific surface area, limited absorption of visible light, and high rate of recombination of photogenerated electrons and holes. The basic structure, characteristics and main modifications of g?C3N4 are reviewed, covering modification means such as elemental doping, morphological modulation, noble metal deposition and the practical applications of g?C3N4 in recent years at home and abroad.
Under the hydrothermal synthesis,an organic?inorganic hybrid compound was prepared through the self?assembly process by using phosphomolybdic acid as a polyoxometallate (polyacid for short) building block and triphenylphosphine as an organic ligand.Its molecular formula was determined by X?ray single?crystal diffraction technique as H15{(PMo12O40)2[MoO4?(PPh3)4]2?[NaO3?(PPh3)3][(H2O?PPh3)3]（compound 1),which is a novel inorganic?organic hybrid material formed by electrostatic interactions between [PMo12O40]3-,[MoO4?(PPh3)4]2-,[NaO3?(PPh3)3]5- and H2O?PPh3 building blocks.The IR spectrum,luminescence spectra and cyclic voltammetric characteristic curves of compound 1 were also tested,focusing on the photocatalytic degradation of methylene blue(MB).The good ability of compound 1 to degrade organic dyes was demonstrated by photodegradation analysis experiments.
A new method for the synthesis of esters by C=C bond breaking in olefins has been realised using cobalt nanoparticles (Co?NC?900) as catalysts and oxygen as oxidant.The catalytic system has a wide range of substrate applications and functional group compatibility.A diverse set of mono? and multi?substituted aromatic and aliphatic alkenes could be effectively cleaved and converted into the corresponding esters by C=C bond cleavage. In addition, the catalyst can be recycled up to six times without significant loss of activity.Characterization analysis revealed nanostructured nitrogen?doped graphene?layer coated cobalt nanoparticleis possibly responsible for excellent catalytic activity.Mechanistic studies revealed that alcohols or ketones derived from olefins under oxidative conditions are formed as intermediates,which subsequently are converted to esters through a tandem sequential process.
Pt0.5?Snx/γ?Al2O3 catalysts with different Sn loads were prepared by constant volume sequential impregnation method and ultrasonic shock method to improve metal dispersion. The catalysts were characterized by XRD, BET, H2?TPR, CO?IR and TG, and the effects of Sn content on the active center structure and propane dehydrogenation performance of Pt0.5?Snx/γ?Al2O3 catalysts were investigated. The results showed that adjusting the n（Pt）/n（Sn） by changing the Sn content in the samples would lead to the difference in the spatial distribution of Pt and Sn species, and thus affect the mode of action between Pt and Sn. With the increase of Sn, the interaction between Pt?Sn helps to increase the dispersion of Pt, the number of active sites, the improvement of the reaction activity of the catalyst. However, when excessive Sn is introduced, a Pt?Sn alloy is formed, resulting in the coating of Pt, resulting in a decrease in the number of active sites and a decline in the reactivity.
While fossil energy is being exhausted day by day,and the problem of environmental pollution needs to be solved urgently.However,the social demand for energy is growing,so the development of green energy has received extensive attention from many scientific researchers.As an efficient energy conversion device,fuel cell has many advantages such as high efficiency, high performance and environmental friendliness.In the choice of fuel cell catalyst,Pt?based catalysts are the preferred materials because of their unique catalytic properties,but their high preparation cost and unstable catalytic properties have hindered the commercialisation of Pt?based catalysts.The working principle of Pt?based catalysts for cathode oxygen reduction reaction of proton exchange membrane fuel cells and the influencing mechanism of catalyst activity are briefly introduced.The research direction of Pt?based catalysts is summarized.Finally,the development direction of future research is prospected.
Plasma modification is an effective way to improve the catalytic activities of materials.Firstly,Co2(OH)2CO3 precursor was synthesized by a hydrothermal method.Then,the precursor was subjected to the oxygen atmosphere low?temperature plasma, and the surface modified Co3O4 catalyst (Co3O4?P) was obtained,which was further characterized the XRD,SEM,H2?TPR,O2?TPD,TEM,XPS,FTIR,Raman spectrum and UV?visible spectrum.The results demonstrate that plasma treatment could reduce the average valence state of Co elements in Co3O4 to form more defective sites on the catalyst surface,and lower the Co-O bond energy of Co3O4 to improve its low temperature reduction performance.Under the irradiation of full solar spectrum light with intensity of 776 mW/cm2,reaction space velocity of 30 000 mL/（g·h）and toluene concentration of 500 μg/g，the toluene degradation performance of the Co3O4?P catalyst could reach 100.0%，which was approximately twice that of the Co3O4 catalyst (Co3O4?T) prepared by thermal calcination.
Hydroisomerization reactions are widely adopted in octane upgrading,diesel fuel coagulation reduction and lubricant base oil dewaxing and viscosity reduction.One?dimensional pore zeolites have unique pore?selective effects on straight?chain alkanes,and thus server as the most suitable acidic carrier and active component for isomerization in hydroisomerization reactions. Its isomerization performance is mainly depended on the topologic structure,acid properties and crystal size of zeolite.This paper mainly summarizes the research progress of synthesis,modification and application of one?dimensional pore zeolites with different topologies in recent years as well as the development trend and application prospect of these zeolites for hydroisomerization.
CeO2?X (X is the hydrothermal synthesis time, X=3, 6, 12, 24 h) carriers were prepared by varying the hydrothermal synthesis time using Ce(NO3)3·6H2O and urea as raw materials, and CuO/CeO2?X catalysts were obtained by isovolumetric impregnation with active component Cu, which were applied to methanol steam reforming (MSR) reaction. The effects of hydrothermal synthesis time on the structure and physicochemical properties of the prepared CeO2?X carriers and CuO/CeO2?X catalysts were explored by XRD, BET, H2?TPR.The performances of the CuO/CeO2?X catalyst samples were evaluated in methanol steam reforming(MSR) reaction.The results show that the CuO/CeO2?6 has good catalytic activity. At the reaction temperature of 280 °C, when the molar ratio of water to methanol was 1.2, and the space velocity of methanol vapor (GHSV) was 800 h-1, the methanol conversion rate could reach 92.8%.
The properties of alumina supports are the key factors affecting the propane dehydrogenation performance of Pt?Sn/γ?Al2O3 catalysts.In this paper,γ?Al2O3 supports were prepared at three calcination temperatures of 450,650,850 ℃,and the structures and properties of the supports and supported catalysts were systematically studied by XRD,XRF,NH3?TPD,Py?FTIR, CO?FTIR,OH?FTIR,and other characterization methods.The properties of the propane dehydrogenation reaction were evaluated by a fixed?bed micro?reaction evaluation device with online analysis,and the gas?phase product distribution and coking properties were analyzed.The results show that with the increase in calcination temperature,the surface acid content of γ?Al2O3 supports decreases,and calcination at 850 ℃ almost eliminates the weak L acid centers on the surface.This indicates that the number of coordinated unsaturated Al sites on the surface of γ?Al2O3 and surface hydroxyl groups decreases as the calcination temperature grows,which is not conducive to the high dispersion of metal active centers.Both CO?FTIR and TEM results confirm the formation of larger Pt clusters on Pt?Sn/γ?Al2O3?850,and more Pt active phase structure with saturated coordination can promote the occurrence of side reactions such as deep dehydrogenation and reduce the selectivity of propylene products.
Organic sulfides widely exist in natural resources such as petroleum and coal,which have abundant resource reserves.In the petroleum refining industry,the cleavage of C-S bonds is usually required for the desulfurization of petroleum fractions. Among them,the transition metal?catalyzed cleavage reactions of C-S bonds have attracted the attention of researchers owing to the advantages of high efficiency,mild conditions,and low pollution.This review summarizes the progress in transition metal?catalyzed C-S bond cleavage reactions of different types of organic sulfides,and provides insights into Pd,Cu,Ni and Fe catalytic systems and mechanisms.Moreover,the development of such reactions is proposed.
