Study on the Catalyst for Catalytic Air Wet Oxidation on Highly Organic Wastewater

The industrial effluents are as varied as the industries themselves, in terms of nature of contaminants, their concentration treatment, and disposal methods required. For the highly organic wastewater, the technique of wet air oxidation (WAO) is more available. Currently more than 200 full scale WAO plants are in operation for the treatment of a wide variety of effluent streams. In the recent years, the use of homogeneous and heterogeneous catalysts has received a great attention. The homogeneous catalysts are in general more effective oxidation catalysts for increasing the rates of oxidation. But it is necessary to make precipitation step to recover/remove the toxic catalyst from the final effluent In view of this, heterogeneous catalyst systems are preferable. So we investigated on the way of preparation of copper oxide on a spinel support of Al₂O₃) and its effects on the catalytic wet air oxidation (CWAO) on highly organic wastewater.     

Minireview: Silver-Doped Titanium Dioxide and Silver-Doped Zinc Oxide Photocatalysts

The catalytic oxidation of organic dyes using various systems has been widely reported during the past decade. Photocatalytic methods, heterogeneous processes for the degradation of dyes, are one of the best and efficient oxidation processes to treat industrial wastewater with minimal residual waste. This review describes the improvement in catalytic activity of silver-doped titanium dioxide and silver-doped zinc oxide. The degradation of dyes provides information about the catalytic performance of silver-doped metal oxide. The effects of pH, catalyst concentration, dye concentration, hydrogen peroxide, dissolved oxygen, temperature, irradiation time, and light source have been reviewed along with the degradation mechanism and reaction methodology of organic dyes.     

湿式催化氧化技术研究进展

现代化学工业的迅速发展促进了经济的快速发展,但与此同时进入水体的化学物质的种类和数量也急剧增加,给环境带来了很大的危害.因此,发展高浓度、有毒、有害的有机工业废水的高效处理技术,就显得日趋紧迫和十分重要,得到了人们的广泛关注.     

甲烷催化氧化制含氧化合物的研究*

本文对甲烷催化氧化制含氧化合物的研究, 从多相催化和液相催化两个方面进行了综述; 对多相催化的研究从催化剂的选择、反应温度、反应压力、氧源、反应添加物、反应器及反应机理等方面进行了总结, 液相氧化的研究则对不同的研究体系进行了详细的综述。     

CeO2掺杂RuO2/γ-Al2O3催化剂结构与湿式氧化降解苯酚的活性研究

采用浸渍法制备了RuO2/γ-Al2O3和RuO2-CeO2/γ-Al2O3催化剂,利用XRD,XPS和ESR分析了催化剂的结构,并研究了湿式氧化降解苯酚的活性.结果表明,两种催化剂表面RuO2均有良好的分散性,并且催化剂表面存在氧空位和化学吸附氧,CeO2的掺杂使催化剂表面氧空位和化学吸附氧数量增加.两种催化剂对湿式氧化降解苯酚具有良好的催化活性,当苯酚质量浓度为4200mg/L,在150℃和3MPa下,RuO2/γ-Al2O3催化剂湿式氧化降解苯酚反应150min后,苯酚全部被去除,RuO2-CeO2/γ-Al2O3催化剂反应60min后,苯酚的去除率为96%.     

Recent Advances in Facile Liquid Phase Epoxidation of Light Olefins over Heterogeneous Molybdenum Catalysts

Molybdenum complexes are versatile and efficient for liquid phase olefin epoxidation reactions. Rational design of catalysts is critical to achieve high atom efficiency during epoxidation processes. Although liquid phase epoxidation has been a popular topic for decades, three key issues, (a) rational control of morphology of molybdenum nanoparticles, (b) manipulating metal‐support interaction and (c) altering electronic configuration at molybdenum center remains unsolved in this area. Therefore, in this paper, we have critically revised recent research progress on heterogeneous molybdenum catalysts for facile liquid phase olefin epoxidation in terms of catalyst synthesis, surface characterization, catalytic performance and structure‐function relationship. Furthermore, plausible reaction mechanisms will be systematically discussed with the aim to provide insights into fundamental understanding on novel epoxidation chemistry.     

温和条件下液态醇催化氧化制醛、酮

本文对温和条件下液态醇催化氧化制醛或酮的研究进展进行了全面评述,介绍了均相催化剂、液固多相催化剂、有机相-水相两相催化剂、氟两相催化剂和离子液相催化剂,着重讨论了以O_2为氧源的催化体系.     

Electrochemical oxygen transfer reactions: electrode materials,surface processes,kinetic models,linear free energy correlations,and perspectives

This work summarizes progresses achieved in electrochemical oxygen transfer reactions from water to organic pollutant molecules on metal oxide electrodes during the past two decades. Fundamental understanding of the dynamics of the electrochemical oxygen transfer reaction is of crucial importance for the development of key concepts of electrocatalytic processes, leading to the implementation of environmental electrochemistry wastewater treatment schemes with rational design of the suitable electrocatalytic systems. We discuss the current knowledge on the electrochemical oxygen transfer reaction, emphasizing the importance of surface processes in order to generalize mechanistically the experimental results obtained on different electrode materials, describing also the practical kinetic models developed and their implications. From the information gathered in this review, it is apparent that explanations for the kinetics of the reactions in relation to the structure of the organic compounds involved is lacking, hence that new information about structure-reactivity relationships is needed. We show in particular that the open circuit decay of the concentration of radical cations, obtained from spectroelectrochemical data, allows correlating the structure of adsorbed states with reactivity during oxygen transfer reactions, pointing as well to research efforts required to understand the catalytic performance of metal oxide electrodes in decomposing organic compounds strongly adsorbed on their surfaces. Finally, some perspectives for future research in this area are briefly commented.     

The Schenck Ene Reaction: Diastereoselective Oxyfunctionalization with Singlet Oxygen in Synthetic Applications

Oxyfunctionalized molecules are principal building blocks in organic synthesis. In cellular processes highly efficient enzymes serve as selective catalysts for the formation of such synthetic units, for example the oxygenases oxyfunctionalize substrates by activating molecular oxygen. To date no comparable effective chemical oxidation system has been found. A useful photochemical process is the oxyfunctionalization of allylic substrates by sensitized photooxygenation, for which molecular oxygen and light serve as natural sources. This allylic oxidation of olefins by the ene reaction with singlet oxygen (Schenck reaction) figures as a highly versatile synthetic method. While the regioselectivity of this transformation has been studied for decades, only during the last years has attention focused on stereocontrol. Through these recent efforts it has become possible to control high stereoselectivity in the photooxygenation of organic substrates. This breakthrough has enhanced substantially the utility of singlet oxygen in diastereoselective synthesis.     

Carbohydrate-based nanostructured catalysts: applications in organic transformations

The requirement of green and sustainable materials to prepare heterogeneous catalysts has intensified for practical reasons over the past few decades. Carbohydrates are possibly the most plentiful and renewable organic materials in nature with inimitable physiochemical properties, plausible low-cost and large-scale production, and sustainability features could be exploited in the generation of nanostructured heterogeneous catalysts. This review article outlines the organic transformations catalyzed by diverse carbohydrate-based nanostructured catalysts in greener and environmentally friendly processes. Selected examples are highlighted for a variety of organic reactions exploiting the proposed catalysts’ reactivity and reusability, and interactions with the intrinsic nature of the applied carbohydrate supports; advantages and speculated challenges of the introduced catalysts are deliberated as well.