Effect of Surfactants on Catalytic Activity of Diastase α-Amylase

The enzyme amylase is one of the hydrolyzing enzymes used in detergent formulation in order to remove soil based on polysaccharides. The effectiveness of the enzyme depends on its compatibility with other ingredients of the formulation. Among the studied additives, comprising anionic surfactants sodium dodecyl hydrogen sulfate (SDS) and dioctyl sodium sulfosuccinate, the cationic surfactant cetyl trimethyl ammonium bromide (CTAB), nonionic surfactants polyoxyethylene sorbitan monooleate and polyoxyethylene octyl phenyl ether, carboxy methyl cellulose and sodium sulfate, only the anionic surfactant SDS and cationic surfactant CTAB showed catalytic enhancement of α-amylase. The kinetic parameters, K _m and k _cat, showed an increase in catalytic activity in the micellar pseudophase. The decrease in optimum temperature from 55 to 30 °C and the shift in optimum pH from 5.5 to 7 on the addition of SDS and CTAB for the hydrolysis of starch are very favorable to enhance the washing characteristics.     

Kinetic Study of Co-b-Zeolite for Selective Catalytic Reduction

The effects of grain size, space velocity, temperature and reactant concentration on the kinetics of NOx reduction with propane over Co-b-zeolite catalyst were investigated. The external mass transfer phenomenon was examined by varying the space velocity. The results show that the transfer can be negligible when the space velocity is greater than 60000 h-1 in low temperature range. However, the transfer exists at high temperatures even when the space velocity reaches a high level. Variation of the catalyst grain size from 0.05 to 0.125 mm does not change the conversion rate of NOx. The concentrations of components, NOx, C3H8 and O2, were also investigated to have a better understanding of mechanism. Based on the experimental data, the selectivity formula was proposed. The results shows that lower temperature is helpful to get higher selectivity as the activation energy of hydrocarbon oxidation, Ea,2, is greater than that of NOx reduction, Ea,1, (Ea,2>Ea,1). High NOx concentration and low C3H8 concentration are beneficial to high selectivity. However in order to maintain high activity simultaneously, the temperature and C3H8 concentration should be high enough to promote NOx reduction. 10%(j) H2O and 75′10-6(j) SO2 were introduced into the reaction system, and Co-b-zeolite shows strong resistance to water and SO2.     

Catalytic Wet Air Oxidation of oChlorophenol in Wastewater

Catalytic wet air oxidation (CWAO) was investigated in laboratory-scale experiments for the treatment of o-chlorophenol in wastewater. Experimental results showed that wet air oxidation (WAO) process in the absence of catalyst was also effective for o-chlorophenol in wastewater treatment. Up to 80% of the initial CODcr was removed by wet air oxidation at 270℃ with twice amount of the required stoichiometric oxygen supply. At temperature of 150℃, the removal rate of CODCr was only 30%. Fe2(SO4)3, CuSO4, Cu(NO3)2 and MnSO4 exhibited high catalytic activity. Higher removal rate of CODcr was obtained by CWAO. More than 96% of the initial CODcr was removed at 270℃ and 84.6%-93.6% of the initial COD Cr was removed at 150℃. Mixed catalysts had better catalytic activity for the degradation of o-chlorophenol in wastewater.     

Simulation of Catalytic Combustion of Methane in a Monolith Honeycomb Reactor

1 INTRODUCTION Monolith honeycomb reactor plays an important role in catalytic combustion[1] such as combustion chambers for gas turbines used in power generation where methane is the main reactant. It contains hun-dreds of parallel channels that are often of the order of 1—2mm in diameter. The catalyst may be dispersed within a washcoat that is coated onto the surface of the channels[2] where catalytic combustion occurs. Com-pared to conventional gas-phase combustion, catalytic combusti…     

Multiobjective Optimization of the Industrial Naphtha Catalytic Re-forming Process

1 INTRODUCTION Petroleum refining and petrochemical industries aim at maximizing one prime product while simulta-neously minimizing another accessory product to im-prove the quality of the prime product. Unfortunately, the two requirements are often conflicting or incon-sistent. It is necessary to determine the trade-off com-promises to balance the two objectives[1,2]. As the core of aromatics complex unit, catalytic reforming is a very important process for transforming naphtha into arom…     

Catalytic activity of mesoporous catalysts in Friedel–Crafts benzylation of benzene

Different samples of metal-incorporated MCM-41 were prepared and used as catalysts in Friedel–Craft’s benzylation of benzene. The catalytic performance was evaluated by off-line GC analysis. Fe-MCM-41 exhibited excellent activity, the sample with Si/Fe ratio = 10 showed 90% conversion with 95% selectivity towards diphenylmethane within a few minutes. Generally, the activity per Fe-site was an order of magnitude higher for the samples containing a combination of Fe₂O₃ nano-particles and isolated Fe³⁺ sites. A synergy of two catalytic centers (particles and isolated sites) is proposed to explain the high performance of the highly loaded samples. The catalytic performance of Fe-MCM-41 was superior to other metal-containing MCM-41 (e.g. Ga, Sn, and Ti) catalysts, or other Fe-containing mesoporous materials (e.g. Fe-HMS).     

Catalytic Production of Liquid Fuels from Biomass‐Derived Oxygenated Hydrocarbons: Catalytic Coupling at Multiple Length Scales

The catalytic processing of biomass‐derived feedstocks to liquid fuels and chemical intermediates is complex and expensive. Therefore, conversion processes involving a limited number of reaction, separation, and purification steps are necessary. Coupling of catalytic processes has the potential to lead to the development of new processes, thereby improving the overall economics of biomass conversion. Functional coupling at the molecular scale has the potential to produce novel catalytic materials to replace homogeneous catalysts. Active site coupling of different sites within the same reactor can help reduce operating costs by combining sequential reactions in a single reactor. Chemical reaction coupling of heterogeneous and homogeneous reactions may lead to improvements in overall catalytic performance for liquid phase processes by enhancing surface reactions with liquid phase reactions. Finally, phase coupling leads to improvements in overall yield by improving the equilibrium conversion or by suppressing undesired side reactions.     

Catalytic performance of sulfonic acid functionalized ionic liquids on preparation of biodiesel

通过1-烯丙基咪唑与1,4-丁基磺酸内酯反应制备的两性离子分别与硫酸、三氟甲基磺酸、磷钨酸、磷钼酸和硅钨酸直接反应制备了5种磺酸功能化离子液体。采用¹H NMR、FTIR、TG/DTA等技术手段对其结构及热稳定性进行了表征。最后通过催化油酸与甲醇酯化反应制生物柴油过程对催化剂的催化活性和重复使用性进行了评价。结果表明,5种离子液体均具有高催化活性（高于浓硫酸）,并且重复使用4次后,催化活性基本保持不变。3种杂多酸离子液体不溶于产物,以固态形式与产物混合,为其回收和重复利用提供了有利条件。     

Kinetic Study of Co-β-Zeolite for Selective Catalytic Reduction of NOx with Propane

The effects of grain size, space velocity, temperature and reactant concentration on the kinetics of NOx reduction with propane over Co-β-zeolite catalyst were investigated. The external mass transfer phenomenon was examined by varying the space velocity. The results show that the transfer can be negligible when the space velocity is greater than 60000 h-1 in low temperature range. However, the transfer exists at high temperatures even when the space velocity reaches a high level.Variation of the catalyst grain size from 0.05 to 0.125 mm does not change the conversion rate of NOx. The concentrations of components, NOx, C3H8 and O2, were also investigated to have a better understanding of mechanism. Based on the experimental data, the selectivity formula was proposed. The results shows that lower temperature is helpful to get higher selectivity as the activation energy of hydrocarbon oxidation, Ea,2, is greater than that of NOx reduction, Ea,1, (Ea,2＞Ea,1). High NOx concentration and low C3H8 concentration are beneficial to high selectivity. However in order to maintain high activity simultaneously, the temperature and C3H8 concentration should be high enough to promote NOx reduction. 10%(ψ) H2O and 75×10-6(ψ) SO2 were introduced into the reaction system, and Co-β-zeolite shows strong resistance to water and SO2.     

Catalytic performance of advanced titanosilicate selective oxidation catalysts – a review

This review article aims to cover the state-of-the-art of titanosilicate catalysts for selective oxidations developed within past seven years. Many elaborated materials (e.g., layered and pillared titanosilicates, hierarchical composite materials, and others) have been prepared and thoroughly characterized; however, their catalytic properties have been usually investigated only using a single or few model substrates and compared with a benchmarking material. The main goal of this article is to summarize the novel catalysts and compare their catalytic performance with each other. The comparison is focused on epoxidation. In addition, phenol hydroxylation and sulphide oxidation are briefly covered.     

Catalytic properties of SrSn1−xSbxO3 in methanol oxidation

Ceramic model catalyst materials of general formula SrSn_1–x Sb _x O₃ are synthesised by solid state reaction. X-ray diffraction shows the materials to be single phase over the composition range 0 x0.085, with a second phase, identified as SrSb₂O₅, being produced at higher antimony doping levels. XPS, Auger electron spectroscopy and valence band photoemission show strong segregation of Sb to the surface of the material even within the single phase regime. The catalytic properties of the materials are examined using methanol oxidation as a test reaction. The activity and selectivity to formaldehyde production shown by these materials is found to be strongly correlated with the attainment of the bulk solubility limit of Sb in the SrSnO₃ perovskite host.     

CO Oxidation of Au–Pt Nanostructures: Enhancement of Catalytic Activity of Pt Nanoparticles by Au

The CO oxidation activity of Pt deposited on Ta₂O₅/Ta was studied with various amounts of Au post-deposited on Pt/Ta₂O₅/Ta. For Pt nanoparticles with a mean size of 2–4 nm, an enhancement in the CO oxidation activity with increasing amount of post-deposited Au was found. The mixed Au–Pt nanoparticles with sizes in the range of 2–4 nm exhibited higher stability than the bare Au nanoparticles with a similar size range. In contrast to the results obtained with the Pt nanoparticles, the catalytic activity of a thicker Pt film gradually decreased with increasing amount of Au deposited. Based on the CO desorption experiments, it is suggested that the surface of the catalytically active Au–Pt bimetallic structures consists of both Au and Pt sites.     

Catalytic Cracking of Gas-Oils in Electromagnetic Fields: I—Dielectric Properties of Zeolitic Catalysts

Three different zeolitic catalytic systems (13X, 5A and Ammonium Y) were tested for their dielectric properties, surface area and pore-size distribution. The 13X catalyst conductance is higher than other catalysts. The activation energies for 13X, 5A and Ammonium Y are 100, 80, and 50 kJ/mole respectively. The capacitances of 13X catalyst increase with increasing temperature causing a complex behaviour at higher temperatures and frequencies while the capacitances of 5A catalyst are usually less than 10 pF and those of Ammonium Y catalyst are erratic at low temperature. The 13X catalyst is the most suitable catalyst for its dielectric properties and proves to have a good potential to be heated by a RF dielectric reactor. The BET surface area in m²/g are 524 ± 2, 353 ± 1 and 684 ± 3 while the average pore diameters (in ) by the BET technique are 33, 22, 26 and the micropore volumes in cm³/g are 0.187, 0.125 and 0.220 for 13X, 5A and Ammonium Y respectively.     

Catalytic application of mesoporous molecular sieves to vapor‐phase Beckmann rearrangement of cyclohexanone oxime

The vapor‐phase Beckmann rearrangement of cyclohexanone oxime to ɛ‐caprolactam catalyzed by mesoporous molecular sieves was studied. The proton‐form mesoporous molecular sieves, H‐MCM‐41 and H‐FSM‐16, exhibited extremely high activity, selectivity and stability for ɛ‐caprolactam formation when 1‐hexanol was used as diluent. The weak acid sites and/or surface silanol groups of mesoporous molecular sieves play an important role in the selective ɛ‐caprolactam formation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Catalytic synthesis of hematite–mica pearlescent pigments using a low-temperature method

A novel low-temperature method is described for the direct synthesis of Fe₂O₃/mica pearlescent pigments with ferric chloride as a precursor and trace Fe(II) as a catalyst which does not require any calcination step. The as-synthesized pigments are characterized in detail by means of different techniques including X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, and colorimetry. The influence of various factors on the transformation from Fe(OH)₃ coating layer to crystalline hematite coating layer is investigated, respectively. Furthermore, this paper studies several critical technological parameters pertaining to the influences on morphology and color properties of the pigments such as the coating temperature and the pH value.     

Catalytic Combustion of Methane over Cobalt–Magnesium Oxide Solid Solution Catalysts

A series of cobalt–magnesium oxide solid solution catalysts (CoMgO) have been prepared using urea combustion methods, and characterised by X-ray diffraction (XRD) and laser Raman (LR). The catalytic activities for methane combustion have been tested in a continuous-flow microreactor. The Co content has a significant effect on the activity of the cobalt–magnesium oxide solid solution catalysts. The catalysts containing 5 and 10% Co have the lowest light-off temperature in methane combustion. In the preparation of cobalt–magnesium oxide solid solution catalysts, higher urea to metal ratio favors the formation of the catalysts with smaller crystal particles and leads to a better catalytic performance for methane combustion. Addition of lanthanum nitrate to the solution of Co and Mg nitrate depressed the formation of the cobalt–magnesium oxide solid solution and decreased the activity of the catalysts for methane combustion. The cobalt–magnesium oxide solid solution catalysts are very stable when the calcination or reaction temperature is no more than 900°C. However, the catalytic activity decreases rapidly after high temperature (>1000°C) calcination, possibly due to sintering of the catalyst and thus decrease of the surface area.     

Catalytic monoepoxidation of butadiene over titanium silicate molecular sieves TS‐1

Titanium silicate molecular sieves TS‐1 have been prepared under hydrothermal conditions with tetrapropylammonium hydroxide as structure‐directing agent. The structures of TS‐1 were characterized by means of XRD, TEM, FT‐IR, DR UV‐Vis, ICP‐AES, and N₂ adsorption/desorption techniques. Its catalytic performances in the epoxidation of butadiene with hydrogen peroxide were investigated; 3,4‐epoxy‐1‐butene was obtained with high selectivity. The influences of various parameters such as temperature, solvent, and titanium content on the activities of the catalysts were studied systematically. This revised version was published online in July 2006 with corrections to the Cover Date.     

Catalytic dehydrogenation of isopropanol on La2−xSrxNiO4±y

The series of compounds La_2–xSr_xNiO_4±y (0.0 x 1.0) crystallising in tetragonal K₂NiF₄ structure were prepared and catalytic activity have been investigated using isopropanol decomposition as model reaction. All the catalyst compositions catalyse only the dehydrogenation of isopropanol reaction. The composition La_1.5Sr_0.5NiO₄ showed high activity compared to other compositions in the series. The composition is unique not only in catalytic property but also in other physical properties like structural characteristics, electrical resistivity and metal to semiconductor transition.     

Catalytic potency of zeolite Y immobilized copper-2,2′-bipyridine hybrid complex in oxidation of olefins

Journal of Porous Materials - A zeolite immobilized hybrid catalyst [Cu(bpy)2]2+NaY [bpy?=?2,2′-bipyridine](1) was prepared by immobilizing Cu(II)-bipyridine complex onto NaY...