Understanding the Pt-like Catalytic Activity of Transition Metal Carbide Ta4C_(3) for I_(3)^(-) Reduction

This paper attempts to understand the Pt-like catalytic activity of transition metal carbide Ta4C_(3) for IRR(I_(3)^(-)reduction reaction)based on the correlation of adsorption energy to d-band center(εd).Ta4C_(3) was prepared by carbothermal reduction method with a template.Its photoelectrochemical properties were investigated as a CE(counter electrode)in DSSC(dye-sensitized solar cell).Its surface electronic structures,including DOS(density of state)andεd,and adsorption energy were computed by first-principle DFT(density functional theory).In TMC(transition metal carbide)Ta4C_(3),the interaction between Ta and C atoms makes the d-band of Ta broaden and results in the downward shift of itsεd.A moderate absorption energy corresponding to theεd is achieved,which is the nature of the Pt-like catalytic activity of Ta4C_(3).Appropriate change of adsorption energy by adjustingεd is a promising strategy to improve catalytic activity.This work is of great significance to the fundamental and application researches.

Preparation and Electrochemical Performance Study of Catalytic Cracking Oil Slurry-based Porous Carbon Materials

Catalytic cracking oil slurry is a by-product of catalytic cracking projects,and the efficient conversion and sustainable utilization of this material are issues of continuous concern in the petroleum refining industry.In this study,oxygen-enriched activated carbon is prepared using a one-step KOH activation method with catalytic cracking oil slurry as the raw material.The as-prepared oil slurry-based activated carbon exhibits a high specific surface area of 2102 m^(2)/g,welldefined micropores with an average diameter of 2 nm,and a rich oxygen doping content of 32.97%.The electrochemical performance of the nitrogen-doped porous carbon is tested in a three-electrode system using a 6 mol/L KOH solution as the electrolyte.It achieves a specific capacitance of up to 230 F/g at a current density of 1 A/g.Moreover,the capacitance retention rate exceeds 89%after 10000 charge and discharge cycles,demonstrating excellent cycle stability.This method not only improves the utilization efficiency of industrial fuel waste but also reduces the production cost of supercapacitor electrode materials,thereby providing a simple and effective strategy for the resource utilization of catalytic cracking oil slurries.

Biocatalytic enhancement of laccase immobilized on ZnFe_(2)O_(4) nanoparticles and its application for degradation of textile dyes

Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on amino-functionalized ZnFe_(2)O_(4) nanoparticles(ZnFe_(2)O_(4)-laccase)and its application for the degradation of textile dyes.Due to the existence of a large number of oxygen vacancies on the surface of the ZnFe_(2)O_(4) nanoparticles,negative ions accumulated on the magnetic carriers,which resulted in a harsh optimal pH value of the ZnFe_(2)O_(4)-laccase.Laccase activity assays revealed that the ZnFe_(2)O_(4)-laccase possessed superior pH and thermal stabilities,excellent reusability,and noticeable organic solvent tolerance.Meanwhile,the ZnFe_(2)O_(4) laccase presented efficient and sustainable degradation of high concentrations of textile dyes.The initial decoloration efficiencies of malachite green(MG),brilliant green(BG),azophloxine,crystal violet(CV),reactive blue 19(RB19),and procion red MX-5B were approximately 99.1%,95.0%,93.3%,87.4%,86.1%,and 85.3%,respectively.After 10 consecutive reuses,the degradation rates of the textile dyes still maintained about 98.2%,92.5%,83.2%,81.5%,79.8%and 65.9%,respectively.The excellent dye degradation properties indicate that the ZnFe_(2)O_(4)-laccase has a technical application in high concentrations of dyestuff treatment.

The catalytic activity of transition metal oxide nanoparticles on thermal decomposition of ammonium perchlorate

The catalytic proficiency of three MONs for AP thermal decomposition was studied in this work.A chemical co-precipitation method was used for synthesis of MONs(CuZnO,CoZnO,and NiZnO)and their characterization carried out by utilizing XRD,FTIR,and SEM.The TGA/DSC technique was employed for the investigation of the catalytic proficiency of MONs on the AP.The DSC data were used for measuring activation energy of catalyzed AP by using Ozawa,Kissinger,and Starink method.The MONs were much sensitive for AP decomposition,and the performance of AP decomposition was further improved.Among all the MONs,the CuZnO exhibits higher catalytic action than others and decomposition temperature of AP is descending around 117℃ by CuZnO.The reduction in the activation energy was noticed after the incorporation of MONs in AP.

Preparation of SO_4^(2-)/TiO_2-WO_3 solid superacid and its catalytic activity in acetalation and ketaltion

SO_4^(2-)/TiO_2-WO_3 was prepared and its catalytic activity under differentsynthetic conditions was discussed with esterification of n-butanoic acid and n-butyl alcohol asprobing reaction. The optimum conditions are found that the mass fraction of H_2WO_4 used in thecompound is 12.5 percent, the calcination temperature is 580 deg C, the calcination time is 3 h, andthe soaked consistency of H_2SO_4 is 1.0 mol centre dot L^(-1). Then SO_4^(2-)/TiO_2-WO_3 wasapplied as the catalyst in the catalytic synthesis of eight similar important ketals and acetalsunder the optimum conditions and revealed high catalytic activity. On condition that the molar ratioof aldehyde/ketone to glycol is 1:1.5, the mass fraction of the catalyst used in the reactants is0.5 percent, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 64.2percent-95.1 percent. Moreover, it can be easily recovered and reused.

Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

Theoretical Study on the Catalytic Activity and Sulfur Resistibility of Amorphous Alloy Ni-B-P

In the present paper, one hundred cluster models NinBP （n = 1-6） have been designed and studied by density functional theory （DFT） to get an insight into the local structure, catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found： that as the content of Ni in the clusters increases, the value of Fermi level in clusters fluctuated, which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS, we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP （n = 1 -6）, we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity, strong sulfur resistibility appears in clusters Ni3BP, and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future.

Phospholipase C from Pseudomonas aeruginosa and Bacillus cereus:characterization of catalytic activity

Objective:To study characteristics of phospholipases C(PLCs),their importance for producing microorganisms us well us the potential of their use for industrial purposes.Methods:PLC from Bacillus cereus(B.cereus) D101 was selected as an example of Gram-positive PLCs and PLC from Pseudomanas aeruginosa(P.aeruginosa) D183 of Gram-negative ones.Enzymes were partially purified by ammonium sulfate precipitation followed by membrane dialysis.Partially purified preparations were used to study effect of different factors on activities as well as in substrate specificity tests which were conducted using a turbidimetric assay method.Results:Maximum activity was at pH 7 and 8 and 40 ℃ for P.aeruginosa PLC,and pH 8-10 and 37 ℃ for B.cereus PLC.Both PLCs were inhibited by Pi at 5 mM or higher,whereas,PLC from B.cereus only was inhibited by EDTA.Activity of P.aeruginosa PLC was not affected by removing Zn^(2+) ions from reaction mixture or their replacement with Ca^(2+),Ba^(2+),Mg^(2+) or Mn^(2+)ions.Vis-a-vis,activity of B.cereus PLC was found to be metal ion dependent PLCs from both isolates were relatively thermostable and showed maximum affinity toward phosphatidylcholine.Sphingomyelin and phosphatidylethanolamine were not good substrates and phosphatidylinositol,phosphatidylserine,phosphatidylglycerol and cardiolipin could be considered nonsubstrates.Conclusions:Human body physiological conditions could favor activity of P.aeruginosa and B.cereus PLCs.These enzymes may participate in phosphate scavenging and virulence of producing isolates but not in autolysis.PLCs from both isolates are potential candidates for industrial use.

A new method to improve surface morphology of Ni-Fe-Mo-Co alloy electrode and its catalytic activity for HER

A new pretreatment method has been developed to improve the catalytic activity of the Ni-Fe-Mo-Co alloy electrode for hydrogen evolution reaction （HER）. The procedure involves pre-electrolyzing the Ni-Fe-Mo-Co alloy electrode in 30% KOH solution containing 10% potassium sodium tartrate at 70℃ for 2 h, until some of the Mo and Fe elements are leached out. The surface morphology of the Ni-Fe-Mo-Co alloy demonstrates a unique hive-like structure after the pre- treatment, which has the pore size in a nanometer range （about 50 nm）, a very large real surface area, and good stability. The results of the electrochemical studies show that compared to other similar electrode materials and the treated Ni-Fe-Mo-Co electrode by leaching method, the pre-treated Ni-Fe-Mo-Co electrode has a much lower overpotential and much higher exchange current density for HER. In addition, a long-term continuous electrolysis test with a current interruption shows that the Ni-Fe-Mo-Co alloy has excellent catalytic stability.

Synthesis, Crystal Structure and Catalytic Activity of a Pd-PEPPSI Complex Bearing Bromine Group

A new Pd-PEPPSI complex(2) with the bromo groups on the para-positions of N-aryl moieties of NHC has been synthesized and characterized by NMR and X-ray single-crystal diffraction. Complex 2 crystallizes in monoclinic, space group P2_1/c with a = 11.8790(8), b = 14.3038(10), c = 15.9905(11) ?, β = 101.291(2)°, V = 2664.4(3) ?3, Z = 4, D_c = 1.722 Mg/m^3, μ = 3.913 mm^(-1), F(000) = 1352, the final R = 0.0682 and wR = 0.1914 for 15113 observed reflections(I > 2σ(I)), R(all data) = 0.0970, w R(all data) = 0.2115, completeness to theta of 25.00 is 100.0% and GOOF = 1.035. Influenced by the electron-withdrawing bromo groups, the Pd-PEPPSI complex(2) showed high catalytic activity for the Suzuki-Miyaura cross-coupling reactions of aryl chlorides and arylboronic acids with a low catalyst loading(0.05 mol%) at room temperature in air.

Size-dependent peroxidase-like catalytic activity of Fe_3O_4 nanoparticles

有三种不同尺寸的 Fe3O4 nanoparticles (NP ) 的象 Peroxidase 一样催化性质，由化学一起沉淀和大音阶的第五音鈥揼e l 方法综合了，被紫外鈥搗i s 光谱分析调查。由把 Fe3O4 NP 与 11， 20，和 150 nm 的平均直径作比较，我们发现催化活动与减少的 nanoparticle 尺寸增加。用反应产品和底层的反应水流描绘 Fe3O4 NP 的催化活动的电气化学的方法也被开发。

Study on Hydrothermal Stability and Catalytic Activity of Al-SBA-15 Mesoporous Materials Prepared by Impregnation Method

The mesoporous Al-SBA-15 zeolite was obtained via impregnation of pure silica-based SBA-15 zeolite with aluminum nitrate.The Al-SBA-15 sample was calcined in air at 800 ℃ for 6 h and hydrothermally treated at near 100 ℃ for 120 h,respectively,and then the thermal and hydrothermal stability of Al-SBA-15 sample was investigated by X-ray diffractometry (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM) and nitrogen adsorption and desorption techniques.The Al-SBA-15 sample was also studied by 27 Al nuclear magnetic resonance (27 Al NMR) and ammonia temperature programmed desorption (NH 3-TPD) techniques.In addition,the catalytic activity of Al-SBA-15 zeolite was investigated by the Friedel-Crafts reactions of 2,4-di-tert-butylphenol with cinnamyl alcohol.The test results showed that the thermal and hydrothermal stability of Al-SBA-15 zeolite was better than that of SBA-15 zeo-lite.The Al-SBA-15 zeolite sample prepared by impregnation method exhibits more framework aluminum species and Al-O-Si units.Therefore,the number of the surface hydroxyl groups was reduced,resulting in the stabilization of framework structure ofAl-SBA-15 zeolite.The aluminum species can form weak and medium-strong acid sites with catalytic activity.

Synthesis,Characterization and Catalytic Activity of Propionamide Complexes of Rare Earth Chlorides

Propionamide complexes of rare earth chlorides were synthesized. Formula of the complexes is LnCl 3·3PA. The ligand is shown to behave as a normal amide donor with the oxygen of the carbonyl group coordinated to the metal ions. Binary system composed of propionamide and aluminum alkyl shows higher activity and stereospecificity for butadiene polymerization. The cis 1,4 content of polybutadiene is more than 98%.

Synthesis,Characterization and Catalytic Activity of ZnAl Anionic Clay Pillared by α-Na6[GaW11O39Fe（H2O）]·18H2O

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅａｎｉｏｎｉｃｃｌａｙｉｓａｌｓｏｃａｌｅｄｌａｙｅｒｅｄｄｏｕｂｌｅｈｙｄｒｏｘｉｄｅ（ｎｏｔｅｄａｓＬＤＨ），ｉｔｓｕｎｉｑｕｅｂａｓｉｃｃａｔａｌｙｔｉｃｆｕｎｃｔｉｏｎ，ｉｎｔｅｒｅｓｔｉｎｇ“ｍｅｍｏｒｙｅｆｅ...

Pretreatment of Polymer-Supported Pd-Co and Its Catalytic Activity

Various pretreatments of poly (N-vinyl-2-pyrrolidone) (PVP) protected palladium-cobalt system result in different catalytic activities in the hydrodechlorination of chlorobenzene.

Density Functional Theory for the Investigation of Catalytic Activity of X@Cu_(12)(X = Cu, Ni, Co, or Fe) for N_2O Decomposition

We have investigated the reaction mechanism for N20 decomposition on Cu13 via density functional theory. It is found that N20 decomposition on the cluster is more prone to be along the Eley-Rideal （ER） pathway in comparison with the Langmuir-Hinshelwood （LH） channel. There exists structural relaxation for Cu13 cluster in the reaction, which may influence the catalytic activity of cluster for the subsequent N2O decomposition. The core atom in the Cu13 cluster is substituted with the Fe, Co, or Ni to enhance structural stability and prevent from the obvious configuration relaxation in the reaction. Note that these bimetallic clusters are of icosahedra as the Cu13. They have activities for N2O dissociation along ER pathway and the heteroatorn in the cluster can prevent configuration from relaxation. Finally, the Ni@Cu12 cluster can be as a superior catalyst in a complete catalytic cycle via comparison in this study.

SURFACE STATE AND CATALYTIC ACTIVITY OF ACTIVATED AMORPHOUS Fe_(80)Zr_(12)B_8 ALLOY

The depth profile of composition,chemical state of elements and morphology of as- received and activated amorphous Fe_(80)Zr_(12)B_8 alloy ribbons have been studied by means of Auger electron spectroscopy,X-ray photoelectron spectroscopy and scanning Auger microprobe combined with Ar ion bombardment.Both dull and free sides of the as- received ribbons were covered with an iron oxide layer.While a pronounced surface segregation and oxidation of B and precipitation of microcrystalline α-Fe particles were observed on both sides of activated ribbons,B and Zr were oxidized selectively in subsurface layer.On both sides of ribbons,a porous surface structure formed. The BET surface area was measured to be increasing from 0.11 to 2.68 m^2/g.The principal mechanism of in situ activation has been discussed.

Synthesis,Characterization and Catalytic Activity of Polyoxometalates Derived from α-P2W15O56(12

Ｓｙｎｔｈｅｓｉｓ，ＣｈａｒａｃｔｅｒｉｚａｔｉｏｎａｎｄＣａｔａｌｙｔｉｃＡｃｔｉｖｉｔｙｏｆＰｏｌｙｏｘｏｍｅｔａｌａｔｅｓＤｅｒｉｖｅｄｆｒｏｍα－Ｐ;Ｗ;Ｏ;６;ＬｉｇａｎｄＭＥＮＧＬｕ，ａｎｄＬＩＵＪｉｎｇ－ｆｕ(Ｄｅｐａ...

Catalytic Activity of Nanodiamonds in Azocoupling Reaction

The catalytic efficiency of modified nanodiamonds (MND) in reactions of interaction between organic compounds was demonstrated on the example of azocoupling reaction (hydrogen peroxide-4-aminoantipyrine-phenol). It was found that catalytic action of MND was caused by redox active metal ions of Fe and Cu located on the MND surface. The neutralization of the ions significantly decreased catalytic properties of MND.

Role of amino acid residues involved in the active cavity of proline iminopeptidase in catalytic activity

The proline iminopeptidase (PchPiPA) of the white-rot fungi Phanerochaete chrysosporium is an exopeptidase specific to catalyze hydrolysis of the N-terminal proline of peptides or proteins. Its catalytic cavity is comprised of a catalytic triad (Ser107, Asp264 and His292) and an oxyanion hole (His38, Gly39, Gly40 and Pro41). In this work, several amino acid residues involved in the catalytic cavity were selected for investigation of their influences on the catalytic activity by site-directed mutagenesis. It was shown that mutation of residues (Gly39 and Gly40) involved in oxyanion hole resulted in almost complete loss of catalytic activity largely due to changes in kcat. The other residues (Gly42 and Cys45) lined at the entrance of the active cavity also yielded a profound negative effect on the activity. Mutation of the other two residues Arg130 and Gly131 which were flanked spatially by the nucleophilic attacking active site of Ser107, caused different effects on the activity. R130Aincreased catalytic efficiency due to changes in both kcat and Km;while G131V decreased the value of kcat/Km mainly due to changes in kcat. And T111Aalso caused a negative effect on the kcat. Conclusively, these amino acid residues involved in active cavity were more susceptible to be negatively affected by mutation, suggested that the active cavity of proline iminopeptidase might evolve to be less plausible.