Determination of Trace Molybdenum(VI) by Oscillographic Potentiometric Catalyzing Kinetic Method of Simplex Optimization

Under the optimum experimental conditions (i. e., pH=1.6, c KI=10.6 mmol/L, =5.4 mmol/L, =1.30 mmol/L) derived from simplex operations, trace molybdenum(VI) was determined through the agency of its catalytic effect on the reaction of H2O2 with I? in acid medium. The detection limit and linear calibration range of molybdenum were obtained as 0.5×10?6 mol/L and 0.5×10?6～120×10?6mol/L respectively. This method was applied to the examination of the industrial waste water, and the recovery ratios were found to be in the range of 101% and 107%. Key words oscillographic potentiometry - catalyzing kinetic analysis - simplex optimization - molybdenum Supported by the National Natural Science Foundation of China (Grant No. 20175013) and the Higher Education Development Foundation of Shanghai in China (Grant No. 01A17)

Effect of the catalyzing combustion of coke breeze on the energy saving in sinter process

The mechanism of additive ZC 1 for catalyzing combustion of coke breeze in sintering of iron ore fines was studied by using X ray Diffraction, TGA and GC(Gas Chromatographer), by which energy saving was achieved on sinter pot test. The results show that the distance between cleavage planes is enlarged and the π electrons are re distributed because of the insertion of cations/molecules of ZC 1 into the cleavage planes of carbon , resulting in the weakening of C-C bond, improving the adsorption of oxygen and lowering the activation energy of gasification of carbon from 25.8 kJ/mol to 18.9 kJ/mol , and the burning rate being increased and combustion residual reduced, all of which can lead to lower solid fuel consumption . Compared with the sintering test without addition of additives , the solid fuel consumption is reduced by 16.0%, meanwhile, the rate of finished sinter, the output of finished sinter and the tumbling index are increased by 2.03%, 7.0% and 3.71% , respectively, with incorporating 0.2% of additive ZC 1 in the sintering mixture, which is in agreement with the catalyzing mechanism of ZC 1.

Dechlorination of carbon tetrachloride by the catalyzed Fe-Cu process

The dectrochemical reduction characteristics of carbon tetrachlofide （CT） were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders＇ iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders＇ iron. The entire CT in 350 ml aqueous solution with 320 mg/L was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with Fe/Cu ratio of 10：1 （w/w） were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were different. The degradation rate was not significantly influenced by pH in the catalyzed Fe-Cu process; in Master Builders＇ iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders＇ iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode （Cu） and anode （Fe） compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.

Electrochemical reduction characteristics and mechanism of nitrobenzene compounds in the catalyzed Fe-Cu process

The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studied in alkaline medium（pH=11）. The catalyzed Fe-Cu process was found more effective on degradation of NBCs compared to Master Builder＇s iron. The reduction rate by the catalyzed Fe-Cu process decreased in the following order： nitrobenzene 〉4-chloro-nitrobenzene ≥m-dinitrobenzene ：〉 4-nitrophenol ≥2,4-dinitrotoluene 〉2-nitrophenol. The reduction rate by Master Builder＇s iron decreased in the following order： m-dinitrobenzene ≥4-chloro-nitrobenzene 〉4-nitrophenol 〉2,4-dinitrotoluene ≈nitrobenzene 〉2-nitrophenol. NBCs were reduced directly on the surface of copper rather than by the hydrogen produced at cathode in the catalyzed Fe-Cu process. The reduction was realized by the hydrogen produced at cathode and Fe（OH）2 in Master Builder＇s iron, It is an essential difference in reaction mechanisms between these two technologies. For this reason, the reduction by the catalyzed Fe-Cu depended greatly on NBC＇s electron withdrawing ability.

Thermal decomposition of ammonium perchlorate catalyzed with CuO nanoparticles

Ammonium perchlorate(APC)is the most common oxidizer in use for solid rocket propulsion systems.However its initial thermal decomposition is an endothermic process that requires 102.5 J·g^-1.This manner involves high activation energy and could render high burning rate regime.This study reports on the sustainable fabrication of CuO nanoparticles as a novel catalyzing agent for APC oxidizer.Colloidal CuO nanoparticles with consistent product quality were fabricated by using hydrothermal processing.TEM micrographs demonstrated mono-dispersed particles of 15 nm particle size.XRD diffractogram demonstrated highly crystalline material.The synthesized colloidal CuO particles were effectively coated with APC particles via co-precipitation by using fast-crash solvent-antisolvent technique.The impact of copper oxide particles on APC thermal behavior has been investigated using DSC and TGA techniques.APC demonstrated an initial endothermic decomposition stage at 242℃ with subsequent two exothermic decomposition stages at 297,8℃ and 452.8℃ respectively.At 1 wt%,copper oxide offered decrease in initial endothermic decomposition stage by 30%.The main outcome of this study is that the two main exothermic decomposition peaks were merged into one single peak with an increase in total heat release by 53%.These novel features can inherit copper oxide particles unique catalyzing ability for advanced highly energetic systems.

A new approach to the synthesis of diacetals(diketals) pentaerythritol catalyzed by SO_3H-functionalized ionic liquids

In this article,an efficient,simple and environmentally friendly approach to the synthesis of diacetals(diketals) pentaerythritol using SOH-functionalized ionic liquids(ILs) as catalysts was reported.The ILs show high catalytic activity and reusability with good to excellent yields of the desired products.Hammett method has been used to determine the acidity order of these ionic liquids and the results are consistent with the catalytic activities observed in acetalization reaction.Maximum product yield of 93%was observed on using[PSPy][OTf]as catalyst and it can be reused at least 8 times without obvious activity loss.

Multivariate Statistical Process Monitoring of an Industrial Polypropylene Catalyzer Reactor with Component Analysis and Kernel Density Estimation

Abstract Data-driven tools, such as principal component analysis （PCA） and independent component analysis （ICA） have been applied to different benchmarks as process monitoring methods. The difference between the two methods is that the components of PCA are still dependent while ICA has no orthogonality constraint and its latentvariables are independent. Process monitoring with PCA often supposes that process data or principal components is Gaussian distribution. However, this kind of constraint cannot be satisfied by several practical processes. To ex-tend the use of PCA, a nonparametric method is added to PCA to overcome the difficulty, and kernel density estimation （KDE） is rather a good choice. Though ICA is based on non-Gaussian distribution intormation, .KDE can help in the close monitoring of the data. Methods, such as PCA, ICA, PCA.with .KDE（KPCA）, and ICA with KDE,（KICA）, are demonstrated and. compared by applying them to a practical industnal Spheripol craft polypropylene catalyzer reactor instead of a laboratory emulator.

A Novel Palladium-Catalyzed Reaction and Its Application in Preparation of Derivatives of Stilbazols

A novel palladium-catalyzed coupling reaction for the preparation of derivatives of stilbazoles was presented. A series of stilbazoles were synthesized firstly by this highly efficient method. From this reaction it was found that reaction solvent is one of important factors in this catalytic system.

Salen-Cu(II) Complex Catalyzed <i>N</i>-Arylation of Imidazoles under Mild Conditions

Three inexpensive and air-/moisture-stable Salen-Cu complexes 1-3 were evaluated to be a novel class of catalysts for the N-arylation of imidazoles with aryl halides. A variety of aryl iodides, bromides underwent the coupling with imida-zoles, promoted by the complex 3, in moderate to excellent yields without the protection by an inert gas.

DFT Studies on Hydrogen Overfall Mechanism for Catalyzed Hydroisomerization of Pentane

The mechanism and related reaction paths in the hydroisomerization of n-pentane were studied by DFT calculations at the B3LYP/6-311＋＋G^＊＊ level. Two possible transition states were theoretically predicted and verified by the vibration frequency analysis as well as the calculations of intrinsic reaction coordinates （IRC）. Furthermore, the related reaction barriers were evaluated by single point energy at the MP2/6-311＋＋G^＊＊ level with zero point vibration correction of DFT method. Thus, it is concluded that the isomerization might go through two pathways.

Washing-off of Unfixed Reactive Dyes on Cotton Fabrics Using Fe-TAML/H_2O_2 Catalyzed Oxidation System

Unfixed reactive dyes stained on cotton fabric could be removed using Fe-tetra-amido macro-cyclic ligands( TAML) / H_2O_2 catalyzed oxidation system( COS). The colored washing-off wastewater also could be decolorized simultaneously in the same system. The decolourization kinetics showed that the decolourization ratio of reactive dyes in water could reach at least 80% at room temperature in 10 min,which followed the law of pseudo-first order reaction kinetics. The effects of the COS washing-off process parameters on the decolourization ratio,chemical oxygen demand( COD) of wastewater,K/S value,color fastness,color difference,and bursting strength were investigated in detail. The results showed that color fastness properties and final shade of fabric treated by COS were very similar to conventional soaping. The reactive dye molecules in wash-off bath were destroyed using the COS,potentially reduced COD which generated during conventional washing-off procedure.

Effect of Surfactan ton the Catalyzed Oxidation of 2,6-Dimethylphenol by Rhus Vernicifera Laccase

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Catalyst design strategy toward the efficient heterogeneously-catalyzed selective oxidation of 5-hydroxymethylfurfural

The selective oxidation of 5-hydroxymethylfurfural(HMF),a versatile bio-based platform molecule,leads to the formation of several intriguing and useful downstream chemicals,such as 2,5-diformylfuran(DFF),5-hydroxymethyl-2-furancarboxylic acid(HMFCA),formyl 2-furancarboxylic acid(FFCA),2,5-furandicarboxylic acid(FDCA) and furan-2,5-dimethylcarboxylate(FDMC).These products have been extensively employed to fabricate novel polymers,pharmaceuticals,sustainable dyes and many other value-added fine chemicals.The heart of the developed HMF oxidation processes is always the catalyst.In this regard,this review comprehensively summarized the established heterogeneous catalyst design strategy for the selective oxidation of HMF via thermo-catalysis.Particular attention has been focused on the reaction mechanism of HMF oxidation over different catalysts as well as enhancing the catalytic performance of the catalyst through manipulating the properties of the support and fabricating of multi-component metal nano-particles and oxides.The current challenges and possible research directions for the catalytic oxidation of HMF in the future are also discussed.

Oxygen pressure acid leaching of artificial sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation

The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the sintering of ZnS and FeS and used for the pressure acid leaching experiment.The variations in the potential of the pressure leaching system were investigated by using a self-designed potential autoclave.The results showed that compared to the non-iron sphalerite,there was a violent redox reaction between the 25.70%Fe-artificial sphalerite and dissolved oxygen during the process of pressure leaching;and the catalytic mechanism was attributed to the redox couple Fe^3+/Fe^2+,where Fe3+oxidizes the H2S gas film and the reduced Fe2+state is subsequently oxidized by the dissolved oxygen.Furthermore,the effect of temperature,H2SO4 concentration,and oxygen partial pressure on the artificial sphalerite with different iron contents was studied.The sphalerite samples with iron content were observed to dissolve more easily in sulfuric acid compared to the non-iron samples.Moreover,the activation energy of artificial sphalerite was observed to be lower in the sample with 25.70%iron content(22.26 kJ/mol)compared to that with no iron(32.31 kJ/mol);and the apparent reaction orders were obtained with respect to H2SO4 concentration(1.10 and 1.36)and oxygen partial pressure(1.29 and 1.41),respectively.A comprehensive kinetic model was developed on the basis of the experimental data and the fitted leaching ratio plot;and the kinetic equations for the leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation were determined.

OXIDATION OF ALKYLBENZENES CATALYZED BY IRON( Ⅱ,Ⅲ)-1,10-PHENANTHROLINE AND 2, 2'-BIPYRIDINE COMPLEXES

Oxidation of alkybenzenes PhCH_2R(R=H, CH_3, C_2H_5 and n-C_3H_7) under 1 atm. of O_2 or air catalyzed by iron(Ⅱ, Ⅲ)-2,2'-bipyridine and 1,10-phenanthroline complexes, affords the aryl-substituted ketones and alcohols with the conversion of 15.00％～34.58％ containing of 97.60％～99.80％ ketones and alcohols. The turnover numbers of these catalysts are over 3500 mol-cat. ^(-1)for 3.5 h.

Fabrication and Optical Properties of Silicon Nanowires Arrays by Electroless Ag-catalyzed Etching

In order to realize ultralow surface reflectance and broadband antireflection effects which common pyramidal textures and antireflection coatings can't achieve in photovoltaic industry,we used low-cost and easy-made Ag-catalyzed etching techniques to synthesize silicon nanowires(Si NWs) arrays on the substrate of single-crystalline silicon.The dense vertically-aligned Si NWs arrays are fabricated by local oxidation and selective dissolution of Si in etching solution containing Ag catalyst.The Si NWs arrays with 3 μm in depth make reflectance reduce to less than 3% in the range of 400 to 1000 nm while reflectance gradually reached the optimum value with the increasing of etching time.The antireflection of Si NWs arrays are based on indexgraded mechanism:Si NWs arrays on a subwavelength scale strongly scatter incident light and have graded refractive index that enhance the incidence of light in usable wavelength range.However,surface recombination of Si NWs arrays are deteriorated due to numerous dangling bonds and residual Ag particles.

Regio-and Diasteroselectivity of Rhodium-catalyzed Ring Opening Reaction of Oxabenzonorbornadienes with Heteroatom Nucleophiles

A new rhodium catalyzed ring opening reaction of oxabenzonorbornadienes and its derivatives was described. This reaction forms a new carbon-nitrogen bond via an intermolecular allylic displacement of the bridgehead oxygen with a piperazine's derivatives, which proceeds with very high regioselectivity.

Enhanced catalytic degradation process of o-nitrochlorobenzene by palladium-catalyzed Fe^0 particles

Over Pd/Fe bimetallic catalyst, o-nitrochlorobenzene（o-NCB）, at a concentration of 20 mg/L in aqueous solutions, is rapidly converted to o-chloroaniline（o-CAN） first, and then quickly dechlorinated to aniline（AN） and Cl^- , without other intermediate reaction products. The aminated and dechlorinated reactions are believed to take place on the surface site of the Pd/Fe. The o-NCB removal efficiency and the next dechlorination rate increase with an increase of bulk loading of palladium and catalysts addition due to the increase of both the surface loading of palladium and the total surface area. These results indicate that reduction, amination and dechlorination of o- NCB by palladium-catalyzed Fe^0 particles, can be designed for remediation of contaminated groundwater.

Enzyme-catalyzed Sequential Reduction of Carbon Dioxide to Formaldehyde

It has been reported that enzymatic-catalyzed reduction of CO2 is feasible. Most of literature focuses on the conversion of CO2 to methanol. Herein we put emphasis on the sequential conversion of CO2 to formaldehyde and its single reactions. It appears that CO2 pressure plays a critical role and higher pressure is greatly helpful to form more HCOOH as well as HCHO. The reverse reaction became severe in the reduction of CO2 to formaldehyde after 10 h, decreasing HCHO production. Increasing the mass ratio of formate dehydrogenase to formaldehyde dehydrogenase could promote the sequential reaction. At concentrations of nicotinamide adenine dinucleotide lower than 100 mmol·L-1, the reduction of CO2 was accelerated by increasing cofactor concentration. The optimum p H value and concentration of phosphate buffer were determined as 6.0 and 0.05 mol·L-1, respectively,for the overall reaction. It seems that thermodynamic factor such as p H is restrictive to the sequential reaction due to distinct divergence in appropriate p H range between its single reactions.