Excessive nitrogen oxides (NO_x) in the atmosphere will directly harm human health and damage the ecological environment.Ammonia-selective catalytic reduction (NH₃-SCR) technology can effectively reduce NO_x emissions,but the vanadium-based catalysts are susceptible to SO₂,alkaline (earth) metals,etc. in the flue gas,and vanadium species are biologically toxic,so non-vanadium based denitration catalysts gradually entered the vision of researchers.In addition,some low-temperature flue gas denitration has gradually been paid attention to.Hence,the research of green and efficient low-temperature NH₃-SCR catalyst is urgent.Manganese-based catalysts have become important research objects due to their excellent denitration activity at low-temperature.This paper summarizes the important research status of manganese-based denitration catalysts,especially single and composite MnO_xcatalysts,modification of supported MnO_xcatalysts,and denitration mechanism,which can provide a reference for the development of practical and efficient manganese-based low-temperature denitration catalysts.

The technological research progress on isophthalonitrile hydrogenation to m-xylylenediamine in recent years is reviewed.Through the in-depth exploration of the reaction mechanism,the discussion focuses on the active site,promoter,support,preparation method of the supported hydrogenation catalyst,and the reaction process including regeneration technology.And the feasible strategies to effectively inhibit the side reactions and improve the long-term operation of the catalyst are summarized.Finally,the focus and difficulty of future research in this field are still the development of the supported catalysts with high-selectivity and high-stability,and the optimization of the green process for the efficient hydrogenation of nitriles to amines.

Na-modified Pt/SAPO-11 catalyst was prepared by ultrasonic-assistant impregnation method.The temperature-programmed desorption of ammonia,pyridine-FT-IR and solid-state magic-angle-spinning NMR results reveals that the Na-modification reduces the amount of medium-strong strength Brønsted acid sites and total acid sites on Pt/SAPO-11 catalysts.The results of the n-dodecane hydroisomerization show that the selectivity of the i-dodecane increased significantly with the modification of Na promoter as compared with the unmodified Pt/SAPO-11 catalyst.An i-dodecane yield of 89% has been obtained on the Pt5Na/SAPO-11 catalyst.Combined with the results of the reaction and characterization,it was demonstrated that the Na promoter could affect the reaction pathway of n-alkane hydroisomerization on the catalyst.

Using alumina and modified Y zeolite as carriers,ammonium thiomolybdate and nickel nitrate as active component precursors,sulfur-containing precursor hydrocracking catalysts with different additives were prepared by equal volume impregnation method.The catalysts were characterized by BET,FT-IR,XRD and HRTEM.The results showed that the addition of different additives has a certain effect on the surface physicochemical properties of the catalyst.The total acid content and medium strong acid content on the catalyst surface increased with the addition of acid additives.At the same time,the active phase,crystal length and number of layers of the catalyst were well improved,more reaction centers were generated,and the service performance of the catalyst was improved.With the addition of basic additives,the acid content of the catalyst was reduced,and the length and number of lamellae were reduced,which was not conducive to the performance of the catalyst.The evaluation results showed that the conversion and selectivity of the catalyst reached the best state by adding additive of ethylenediamine tetraacetic acid.

Develop a heterogeneous catalytic system for the efficient and selective oxidation of benzyl alcohol to benzaldehyde under closed conditions to replace the chlorinated hydrolysis of toluene and the liquid-phase oxidation of toluene can provide theoretical support for the establishment of an environmentally friendly green synthesis process.In this study,a series of SBA-15 zeolite supported copper-based composite oxides,namely CuO/SBA-15 and CuCoO_x/SBA-15,were designed and synthesized by nano-casting method,and applied to catalyze the selective oxidation of benzyl alcohol to benzaldehyde.The prepared oxides were characterized by SAXS,XRD,SEM,TEM,BET,XPS,IR,TG,etc.The results show that the copper-cobalt composite oxides have spinel structure.Cu is the active site for CuCoO_x/SBA-15 catalyst to catalyze the oxidation of benzyl alcohol to benzaldehyde.The addition of cobalt can reduce the electronic binding energy of divalent copper.The efficient catalytic performance of CuCoO_x/SBA-15 catalyst is derived from the synergistic catalytic effect of CuO and CuCo₂O₄.When n(Cu):n(Co)=2:1,the synergistic effect is best.

The safe storage and controlled release of hydrogen is one of the key factors affecting the development of hydrogen energy.Formic acid is considered as a promising chemical hydrogen storage material due to its nontoxic,high energy density and easy storage/transportation.In this paper,Pd/C catalyst were prepared with carbon black(XC-72) as carrier and palladium chloride as precursor,and characterized by XRD,FT-IR and XPS.The catalytic decomposition of formic acid to hydrogen over the as-synthesized catalysts was evaluated,and the influence of preparation conditions on its catalytic performance was studied.The results showed that catalysts calcined at 650 ℃ for 2 h with 3.5 g carbon black(XC-72) in 50 mL crucible had high catalytic activity and good stability,over which TOF of formic acid to hydrogen reached 7 257 h^-1 at 60 ℃.

Au/CeO₂ catalysts with Au mass fraction of 2% were prepared by deposition-precipitation method using flower-like CeO₂ as support.The effects of calcination temperature on the catalytic activity for CO oxidation reaction were studied by means of ICP-AES,XRD,TEM,XPS and H₂-TPR techniques.The results showed that the low-temperature catalytic activity was significantly improved after calcination.The catalyst calcined at 300 ℃ exhibited the highest low-temperature catalytic activity,and the CO volume fraction of 1% could be reduced to 1.84 mg·m^-3 at 18 ℃.It is suggested that the redox capacity of the catalyst is closely related to the calcination temperature and plays a crucial role in the CO oxidation over the flower-like Au/CeO₂ catalyst.

The catalytic performance of three methanol synthesis catalysts was investigated under different technological conditions in this paper,and the catalysts were characterized by XRD,TPR,TG-DTG and N₂ adsorption-desorption at low temperature.The experimental results show that cat-1 with stronger synergistic effect of CuO and ZnO,smaller grain size of CuO,higher dispersion has the best catalytic activity and thermal stability,as well as a wider range of airspeeds.The optimum reaction conditions of cat-1 in this experiment were temperature 240 ℃,pressure 8 MPa and GHSV 10 000 h^-1,under which the methanol spatial and temporal yield was 2.02 g·(h·mL)^-1 and 1.74 g·(h·mL)^-1 after aging.

In this work, montmorillonite pillared with Fe-Ni-Al was synthesized by ion exchange method. The effect of active metal percentage, active metal ratio (Fe/Ni) and calcination temperature on the catalyst activity was studied, and the catalyst was characterized by XRD, BET, ICP, and the stability of the catalyst was also investigated. The results show that the catalyst prepared with active metal molar fraction of 6%,active metal ratio n_(Fe):n_(Ni)=4:6,and calcination temperature of 500 ℃ had a layer spacing d₀₀₁ of 1.770 nm and a specific surface area of 151.9 m²·g^-1.The COD removal efficiency of degraded dye wastewater was 88.9%.The component dissolution was very low and the catalyst showed good stability.

Active carbon adsorption catalytic oxidation is an important development direction of flue gas desulfurization technology.We studied the effects of pore structure and water vapor content on desulfurization performance.The results show that the pore structure of activated carbon with microporous and mesoporous is an important factor affecting desulfurization effect.When the moisture content is about volume fraction of 8%-11%,the desulfurization efficiency is high.The oxygen volume fraction in flue gas is as high as 3%-8%,it is enough to convert SO₂ into sulfuric acid,therefore,there is no need to supplement additional oxygen,which solves the problem of SO₂ removal under the condition of oxygen enrichment.Under the same experimental conditions,the desulfurization effect and stability of the self-made activated carbon are better than those of foreign products.

With the increasing scale of the aromatics unit,the composition of fresh C₈ aromatics feedstock changes greatly,and the catalyst of ethylbenzene conversion type xylene isomerization tends to have higher temperature rise and lower purity of circulating hydrogen when it is put into operation,it is easy to cause problems such as interlock of compressor,risk of heat exchanger leakage,shut down in start-up process and long time in adjusting process parameters of isomerization.Based on the analysis of the difficulties in the process of catalyst feeding,combined with the characteristics of the RIC-270 series of xylene isomerization catalyst for conversion of ethylbenzene and large-scale aromatics unit,the method of catalyst feed-in and start-up process was optimized and carried out in an industrial plant.The results show that by optimizing the composition of feed,increasing the flow of make-up hydrogen gas,reducing the feeding pressure and lowering the pressure in time,the starting process of feeding can be stable,and the problems such as over-temperature and interlock of compressors can be avoided,the method can be applied to the starting of similar catalyst system.

The stability and deactivation mechanism of the vanadium phosphorus oxide catalyst for n-butane oxidation to maleic anhydride (MA) were studied.The stability test of the catalyst for nearly 6 000 h was performed using a fixed-bed reactor.The fresh and spent catalysts were characterized by XRD,FT-IR,N₂ adsorption-desorption,XPS and redox titration.The results suggested that without phosphorus addition,the catalytic performance gradually decreased,along with the decrease of the phase of V⁵⁺ and the average vanadium valence of the catalysts.The phase of V⁴⁺ stably exists over the fresh and spent catalysts.The surface phosphorus was firstly volatilized followed by the diffusion of the bulk phosphorous to the surface,and as the reaction progress the catalysts underwent further loss of surface phosphorus.Meanwhile,the specific surface area of the deactivated catalyst increased significantly.The phosphorus loss and the increased specific surface area are the main reasons for the catalyst deactivation.

Effects of different influencing factors (initial concentration,pH value,current density,electrolyte concentration) on the electro catalytic oxidation and degradation of diclofenac(DCF) in water were studied using titanium oxide(Ti₄O₇) as anode.The active substances that played a major role in the degr-adation process were explored by quenching experiment.The results showed that the optimal degradation was obtained when the initial concentration of diclofenac was 10 mg·L^-1,pH was 3,current density was 15 mA·cm^-2 and electrolyte concentration was 0.05mol·L^-1.·OH and $\mathrm {SO^{-}_{4}}$· play a major role in the electro catalytic oxidation of DCF by titanium oxide electrode.Ti₄O₇ electrode can effectively treat diclofenac in water.