谈化工工艺乙烯催化氧化制环氧乙烷过程

在催化剂存在下,乙烷与气态氧作用生成环氧乙烷。是典型的非均相催化氧化反应过程。本文对乙烯催化氧化制环氧乙烷过程进行简要的分析。

新型氧化铝基制硫催化剂的研制

介绍了LS-02新型氧化铝制硫催化剂的研制、表征及活性评价。该催化剂以氧化铝为主要原料,采用转动成型工艺制备。该催化剂较LS-300催化剂具有更高的比表面积、更大的孔体积、更合理的孔分布及更高的克劳斯活性和水解活性,综合性能达到国外同类催化剂水平。

二氧化硫氧化制硫酸催化剂起燃温度的测试及应用

针对目前缺少二氧化硫氧化制硫酸催化剂起燃温度的标准方法和文献报道的现状,对催化剂最低起燃温度进行了测试与评价,结果表明,非含铯催化剂试样最低起燃温度在360℃以上;含铯催化剂试样最低起燃温度在340℃以上;催化剂最低起燃温度与催化剂化学组成、相态结构和孔道结构等因素有关。

环氧乙烷化工工艺的制作过程

环氧乙烷是最简单也是最重要的环氧化合物，在常温下为气体，沸点10．5℃。环氧乙烷是以乙烯为原料产品中的第三大品种，仅次于聚乙烯和苯乙烯。在催化剂存在下，乙烷与气态氧作用生成环氧乙烷。本文对环氧乙烷化工工艺的制作过程进行分析。

脱硫脱碳装置尾气硫回收方案比较

在合成氨生产系统中,脱硫脱碳装置的尾气排放至硫回收装置后可制硫磺或硫酸。针对CLAUS催化氧化制硫磺工艺和湿法制硫酸工艺2种硫回收方案,从尾气达标、工艺设备和占地、工艺能耗等方面进行对比分析,结论是湿法制硫酸工艺更加环保,且设备集成化程度高、占地小、能耗低,是最佳的硫回收产品方案。同时,对浓硫酸市场进行了预测。

脱硫脱碳装置尾气硫回收方案比较

在合成氨生产系统中，脱硫脱碳装置的尾气排放至硫回收装置后可制硫磺或硫酸。针对CLAUS催化氧化制硫磺工艺和湿法制硫酸工艺2种硫回收方案，从尾气达标、工艺设备和占地、工艺能耗等方面进行对比分析，结论是湿法制硫酸工艺更加环保，且设备集成化程度高、占地小、能耗低，是最佳的硫回收产品方案。同时，对浓硫酸市场进行了预测。

Numerical simulation of diffusion process for oxidative dehydrogenation of butene to butadiene

A comprehensive single particle model which includes the mesoscale and microscale models was developed to study the influence of particle diameter on mass and heat transfer occurring within a ferrite catalyst during the oxidative dehydrogenation of butene to butadiene process. The verified model can be used to investigate the influence of catalyst diameter on the flow distribution inside the particle. The simulation results demonstrate that the mass fraction gradients of all species, temperature gradient and pressure gradient increase with the increase of the particle diameter. It means that there is a high intraparticle transfer resistance and strong diffusion when applying the large catalysts. The external particle mass transfer resistance is nearly constant under different particle diameters so that the effect of particle diameter at external diffusion can be ignored. A large particle diameter can lead to a high surface temperature, which indicates the external heat transfer resistance. Moreover, the selectivity of reaction may be changed with a variety of particle diameters so that choosing appropriate particle size can enhance the production of butadiene and optimize the reaction process.

Importance, features and uses of metal oxide catalysts in heterogeneous catalysis

This short review paper aims at assembling the present state of the art of the multiuses of metal oxides in heterogeneous catalysis, concerning liquid and gaseous phases of the reactant mixtures on solid catalysts. It includes the description of the main types of metal oxide catalysts, of their various preparation procedures and of the main reactions catalysed by them (acid-base type, selective and total oxidations, bi-functional catalysis, photocatalysis, biomass treatments, environmental catalysis and some of the numerous industrial applications). Challenges and prospectives are also discussed.

Atomic layer deposition: Catalytic preparation and modification technique for the next generation

Atomic layer deposition(ALD)attracts great attention nowadays due to its ability for designing and modifying catalytic systems at the molecular level.There are several reported review papers published recently discussing this technique in catalysis.However,the mechanism on how the deposited materials improve the catalyst stability and tune the reaction selectivity is still unclear.Herein,catalytic systems created via ALD on stepwise preparation and/or modification under self-limiting reaction conditions are summarized.The effects of deposited materials in terms of electronic/geometry modification over the catalytic nanoparticles(NPs)are discussed.These effects explain the mechanism of the catalytic stability improvement and the selectivity modification.The unique properties of ALD for designing new catalytic systems are further investigated for building up photocatalytic reaction nanobowls,tandem catalyst and bi-active-component metallic catalytic systems.

Preparation of nitric humic acid by catalytic oxidation from Guizhou coal with catalysts

Nitric humic acid was prepared by catalytic oxidation between nitric acid and Guizhou coal, with added catalysts. We investigated catalytic oxidation processes and the factors that affect the reactions. The effects of different catalysts, including NiSO4 support on active carbon （AC-NiS04）, NiS04 support on sil- icon dioxide （SiO2-NiSO4）, composites of SO42-1Fe203, Zr-iron and vanadium-iron composite were stud- ied. As well, we investigated nitric humic acid yields and the chemical structure of products by element analysis, FT-IR and E4/E6 （an absorbance ratio at wavelengths of 465 and 665 nm of humic acid alkaline extraction solutions）. The results show that the catalytic oxidation reaction with added catalysts can increase humic acid yields by 18.7%, 16.36% 12.94%, 5.61% and 8.59%, respectively. The highest yield of humic acid, i.e., 36.0%, was obtained with AC-NiSO4 as the catalyst. The amounts of C and H decreased with the amount of nitrogen. The increase in the E4/E6 ratio in catalytic oxidation of （Guizhou） coal shows that small molecular weights and high yields of nitric humic acid can be obtained by catalytic oxidation reactions.

Preparation of Cu-BiVO_4 and Its Photocatalytic Properties for Desulfurization of Model Oil

A photocatalyst Cu-BiVO4 was synthesized by the hydrothermal method and was characterized by XRD, UV-vis DRS, and N2 adsorption-desorption measurement. The catalytic activity of the Cu-BiVO4 samples was studied on desulfurization of thiophene dissolved in n-octane, which was used as a model light oil, via photocatalytic oxidation reaction under illumination by visible light. The catalyst characterization results indicated that the loading of Cu on the catalyst did not change the crystal phase of BiVO4, and the crystallinity of the Cu-BiVO4 sample was found to be better at pH=7. The Cu-BiVO4 samples presented a significant bathochromic shift of the absorption band in the visible region, and the absorption intensity increased for the composite catalyst. The desulfurization experiments showed that the Cu-BiVO4 sample prepared at a pH value of 7 had a better catalytic activity. Under proper operating conditions, the desulfurization rate of the model compound achieved by Cu-BiVO4 sample prepared at pH=7 could reach as high as 90%.

Preparation and application of perovskite-type oxides for electrocatalysis in oxygen/air electrodes

Recent advances in the preparation and application of perovskite-type oxides as bifunctional electrocatalysts for oxygen reaction and oxygen evolution reaction in rechargeable metal-air batteries are presented in this review.Various fabrication methods of these oxides are introduced in detail,and their advantages and disadvantages are analyzed.Different preparation methods adopted have great influence on the morphologies and physicochemical properties of perovskite-type oxides.As a bifunctional electrocatalyst,perovskite-type oxides are widely used in rechargeable metal-air batteries.The relationship between the preparation methods and the performances of oxygen/air electrodes are summarized.This work is concentrated on the structural stability,the phase compositions,and catalytic performance of perovskite-type oxides in oxygen/air electrodes.The main problems existing in the practical application of perovskite-type oxides as bifunctional electrocatalysts are pointed out and possible research directions in the future are recommended.

Influence of preparation methods on the physicochemical properties and catalytic performance of MnO_x-CeO_2 catalysts for NH_3-SCR at low temperature

This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation,hydrothermal treatment, co‐precipitation, and a sol‐gel technique, were used to synthesizeMnOx‐CeO2 catalysts. The catalysts were characterized in detail, and an NH3‐SCR model reaction waschosen to evaluate the catalytic performance. The results showed that the preparation methodsaffected the catalytic performance in the order: hydrothermal treatment > sol‐gel > co‐precipitation> impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content,oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sitesand acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalystformed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal catalyticperformance, and good H2O resistance in NH3‐SCR reaction. This was attributed to incorporationof Mnn+ into the CeO2 lattice to form a uniform ceria‐based solid solution (containing Mn‐O‐Cestructures). Strengthening of the electronic interactions between MnOx and CeO2, driven by thehigh‐temperature and high‐pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environment‐friendly route to synthesizing low‐temperature denitrification (deNOx) catalysts.

Immobilization of metalloporphyrins on CeO_2@SiO_2 with a core-shell structure prepared via microemulsion method for catalytic oxidation of ethylbenzene

Ce O2@Si O2 core-shell nanoparticles were prepared by microemulsion method, and metalloporphyrins were immobilized on the Ce O2@Si O2 core-shell nanoparticles surface via amide bond. The supported metalloporphyrin catalysts were characterized by N2 adsorption-desorption isotherm(BET), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), ultraviolet and visible spectroscopy(UV-Vis), and Fourier transform infrared spectroscopy(FT-IR). The results show that the morphology of Ce O2@Si O2 nanoparticles is core-shell microspheres with about 30 nm in diameter, and metalloporphyrins are immobilized on the Ce O2@Si O2 core-shell nanoparticles via amide bond. Especially, the core-shell structure contains multi Ce O2 core and thin Si O2 shell, which may benefit the synergistic effect between the Ce O2 core and the porphyrin anchored on the very thin Si O2 shell. As a result, this supported metalloporphyrin catalysts present comparably high catalytic activity and stability for oxidation of ethylbenzene with molecular oxygen, namely, ethylbenzene conversion remains around 12% with identical selectivity of about 80% for acetophenone even after six-times reuse of the catalyst.

Effects of Oxygen Transfer Limitation and Kinetic Control on Biomimetic Catalytic Oxidation of Toluene

Under oxygen transfer limitation and kinetic control, liquid-phase catalytic oxidation of toluene over metalloporphyrin was studied. An improved technique of measuring dissolved oxygen levels for gas-liquid reaction at the elevated temperature and pressure was used to take the sequential data in the oxidation of toluene catalyzed by metalloporphyrin. By this technique the corresponding control step of toluene oxidation could be obtained by varying reaction conditions. When the partial pressure of oxygen in the feed is lower than or equal to 0.070 MPa at463 K, the oxidation of toluene would be controlled by oxygen transfer, otherwise the reaction would be controlled by kinetics. The effects of both oxygen transfer and kinetic control on the toluene conversion and the selectivity of benzaldehyde and benzyl alcohol in biomimetic catalytic oxidation of toluene were systematically investigated.Three conclusions have been made from the experimental results. Firstly, under the oxygen transfer limitation the toluene conversion is lower than that under kinetic control at the same oxidation conditions. Secondly, under the oxygen transfer limitation the total selectivity of benzaldehyde and benzyl alcohol is lower than that under kinetic control with the same conversion of toluene. Finally, under the kinetics control the oxidation rate of toluene is zero-order with respect to oxygen. The experimental results are identical with the biomimetic catalytic mechanism of toluene oxidation over metalloporphyrins.

Preparation of Alumina Abrasion-Resistant Ceramic Grinding Ball with Spent FCC Equilibrium Catalyst

The chemical composition, structure and thermal stability of the spent FCC equilibrium catalyst from an oil refinery were characterized by XRD, FT-IR, DTA-TG, BET, complete chemical analysis, SEM, and XRF. The spent FCC equilibrium catalyst, clay, barium carbonate, and talc were used as the main raw materials to prepare the alumina abrasion-resistant ceramic balls to be used in the powder grinding mill for manufacture of architecture tiles. The results showed that after proper formulation study, the spent FCC equilibrium catalyst could replace industrial alumina to prepare high performance grinding balls. Meanwhile, the various performance indices of the grinding ball could meet the quality standard for similar products, and additionally, the energy saving effect was achieved in the operation of the grinding section, resulting in a successful comprehensive utilization of solid wastes.

Robust cobalt oxide catalysts for controllable hydrogenation of carboxylic acids to alcohols

The selective catalytic hydrogenation of carboxylic acids is an important process for alcohol production,while efficient heterogeneous catalyst systems are still being explored.Here,we report the selective hydrogenation of carboxylic acids using earth‐abundant cobalt oxides through a reaction‐controlled catalysis process.The further reaction of the alcohols is completely hindered by the presence of carboxylic acids in the reaction system.The partial reduction of cobalt oxides by hydrogen at designated temperatures can dramatically enhance the catalytic activity of pristine samples.A wide range of carboxylic acids with a variety of functional groups can be converted to the corresponding alcohols at a yield level applicable to large‐scale production.Cobalt monoxide was established as the preferred active phase for the selective hydrogenation of carboxylic acids.

Fundamental aspects in CO_(2) electroreduction reaction and solutions from in situ vibrational spectroscopies

Using renewable energy to drive carbon dioxide reduction reaction(CO_(2)RR)electrochemically into chemicals with high energy density is an efficient way to achieve carbon neutrality,where the effective utilization of CO_(2) and the storage of renewable energy are realized.The reactivity and selectivity of CO_(2)RR depend on the structure and composition of the catalyst,applied potential,electrolyte,and pH of the solution.Besides,multiple electron and proton transfer steps are involved in CO_(2)RR,making the reaction pathways even more complicated.In pursuit of molecular-level insights into the CO_(2)RR processes,in situ vibrational methods including infrared,Raman and sum frequency generation spectroscopies have been deployed to monitor the dynamic evolution of catalyst structure,to identify reactive intermediates as well as to investigate the effect of local reaction environment on CO_(2)RR performance.This review summarizes key findings from recent electrochemical vibrational spectrosopic studies of CO_(2)RR in addressing the following issues:the CO_(2)RR mechanisms of different pathways,the role of surface-bound CO species,the compositional and structural effects of catalysts and electrolytes on CO_(2)RR activity and selectivity.Our perspectives on developing high sensitivity wide-frequency infrared spectroscopy,coupling different spectroelectrochemical methods and implementing operando vibrational spectroscopies to tackle the CO_(2)RR process in pilot reactors are offered at the end.

Effect of Preparation Method on the Physicochemical Properties of MoVNbTe Catalyst for Propane Ammoxidation to Acrylonitrile

MoVNbTe catalyst has been found to be the most active and selective catalyst in the ammoxidation of propane to ACN, the selective oxidation of propane to acrylic acid and in the oxidative dehydrogenation of ethane to ethylene. However, in our previous work, when 0.5 mL of MoVNbTe catalyst prepared using slurry method was tested in the propane ammoxidation to ACN, it only shows 1% conversion of propane with about 55% selectivity to CAN, thus giving only 0.6% yields to ACN. The poor catalyst activity is attributed to insufficient formation of crystalline phases essential for the propane activation process. In an attempt to improve the physicochemical properties of this catalyst, several preparation methods have been used, namely hydrothermal, reflux, changing the solvent and changing the calcinations temperature. The modified catalysts have been characterized using X-Ray Diffraction （XRD） and N2 physisorption （BET）. The MoVNbTe catalyst prepared by hydrothermal method shows a remarkable improvement in the formation of crystalline phases.