Cobalt molybdenum oxide catalysts for selective oxidation of cyclohexane

Oxidation of cyclohexane has been carried out using molecular oxygen over cobalt molybdenum oxide (CoMoO₄) catalysts in solvent free conditions. The catalysts were prepared using citrate method with three different molar ratios of Co:Mo, 1:1, 1:2, and 2:1 along with individual oxides for comparative studies. While all the catalysts showed significant activity and selectivity, CoMoO₄ with 1:1 ratio showed the best performance compared to the others with a conversion of 7.38%, with selectivity to cyclohexanol and cyclohexanone (KA oil) of 94.3%, in 1 h. The performance of the catalyst, has been studied as a function of oxygen pressure, reaction temperature, and catalyst loading. It was observed that the catalyst deactivates during the course of the reaction. The reasons for deactivation and methods for restoring the activity have been studied. A kinetic model is presented that captures the complex kinetics and matches well with the experimental data. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4384–4402, 2016     

脂肪醇制脂肪叔胺胺化催化剂的研究与开发

综述了近20年醇法胺化制脂肪叔胺催化剂的发展概况,介绍了催化剂的作用机理、制备方法、性能评价及影响因素等,其中以铜镍和铜铬系列的多元催化剂性能较好。稀土元素和锌的加入提高了铜镍催化剂的选择性,从微观上阐述了催化胺化反应中锌对铜镍价态的影响,并讨论了影响催化剂稳定性的因素。     

用于低碳混合醇合成的Fe/CuZnSi催化剂研究

采用沉淀-浸渍方法制备了Fe/CuZnSi催化剂,发现在浸渍Fe过程中生成FeZn2 Cu3 O6.5晶体,它在焙烧过程中分解形成CuO晶体,有利于Cu和Fe相互均匀分布,提高催化剂的CO加氢反应活性,CO转化率主要决定于催化剂中的Fe含量,催化剂中的Cu与Zn质量相等时,液态产物中的醇含量明显增加,C2+醇约占总醇质量的50％.     

Oxidation of alcohols using RuMnCe catalysts

The combination of ruthenium, manganese as well as cerium oxides formed an active catalytic system for the oxidation of 2-octanol and other alcohols. The addition of manganese species as promotors resulted in more active catalysts than comparable cobalt-doped oxidic materials. The application of RuMnCe oxides on redox-active supports, such as TiO₂ or CeO₂, by deposition–precipitation caused a further improvement of catalytic activity. A tolerance to nitrogen-containing substrates was observed.     

F—T合成技术进展

Ｆ－Ｔ合成技术分高温与低温技术两类。高温技术包括早期的疏相流化床反应器技术和后开发的密相流化床反应器技术,低温技术则包括早期的Ａｒｇｅ管式固定床反应器技术和新开发的浆态床反应器技术。本文分别介绍了上述技术的最新进展。     

About the nature of the Co-Cu interaction in Co-based catalysts for higher alcohols synthesis

As evidenced from magnetic measurements and FTIR spectroscopy of CO, the interaction of cobalt and copper in CoCu-based catalysts results in a surface CoCu alloy. It is proposed that this alloy is responsible for the orientation of the CO + H₂ reaction towards higher alcohols, probably via a dual-site mechanism which involves both Co and Cu of the alloy.     

Cyanoethylation of alcohols over solid base catalysts

Cyanoethylation of alcohols with acrylonitrile to form 3-alkoxypropanenitriles proceeds effectively over solid base catalysts such as alkaline metal oxides and hydroxides, lanthanum oxide, and alumina supported potassium fluoride and hydroxide at a reaction temperature below 323 K. The order of the reactivity of alcohols varied with the types of catalyst. With magnesium hydroxide and calcium hydroxide, the reactivity of alcohol decreased: methanol>ethanol>2-propanol, while with the alkaline earth oxides, lanthanum oxide, and alumina supported KOH and KF, the reactivity order was opposite. The reactivity orders are interpreted by the acidity of alcohol combined with the basic strength of the catalysts. The catalytic activity of solid base catalysts were scarcely affected by exposure of the catalyst to air before use for the reaction.     

Synthesis of higher alcohols with cobalt and copper based model catalysts: effect of the alkaline metals

The synthesis of higher alcohols, obtained from CO hydrogenation over transition metals, is an alternative for the production of chemical commodities and less pollutant renewable fuels nowadays. In this work, the influence of different alkali metals (Li, Na, K, Cs) over the formation of active phases of supported catalysts, based on cobalt and copper, as well as the performance of these solids in the reaction of CO hydrogenation under a 50 bar pressure were studied. The solids were prepared by continuous coprecipitation of sodium carbonate with metal nitrate solutions (Al–Co, Al–Cu or Al–Co–Cu) promoted with the alkali metals with dry impregnation. Characterization studies by atomic absorption spectrophotometry, BET, XPS and also the results of catalytic tests show that physico-chemical properties of the obtained catalyst are similar to those of the industrial catalyst used as reference (I).     

CaO基催化剂在制备生物柴油中的应用进展

CaO无毒性,廉价易得,在反应体系中溶解度较低,具有很高的催化酯交换反应活性,被普遍认为是最具潜力的制备生物柴油的固体催化剂。为进一步提高其催化活性,将其复合、负载、掺杂,制备了各种各样的CaO基催化剂。本文从催化剂的制备、物理性质、化学性质以及酯交换反应的活性等方面对本征态、复合型、负载型、掺杂型CaO催化剂进行了综述。     

Cobalt catalysts in selective catalytic reduction of NO by methane

Impregnated cobalt-containing catalysts are studied in the selective catalytic reduction of NO by methane. The active component of all the impregnated cobalt-containing catalysts is Co₃O₄. The role of O₂ seems to maintain the surface stoichiometry of Co₃O₄. The main reason of decrease of catalytic activity of samples based on MgO, SiO₂, Al₂O₃ in selective catalytic reduction of NO is due to oxide-oxide interaction promoted by water. Catalysts based on montmorillonite (HMM) are stable in the presence of water. All the carriers can be placed by the capability for oxide–oxide interaction in the following order: SiO₂ ≫ MgO > Al₂O₃ ≫ HMM. This revised version was published online in August 2006 with corrections to the Cover Date.     

固体酸催化制备生物柴油研究进展

生物柴油是一种具有优良燃烧性能的石化替代燃料,开发可用于通过酯交换反应制备生物柴油的固体酸催化剂已成为国内外研究热点。本文综述了固体酸在催化合成生物柴油方面的研究进展,介绍了以纳米材料、磁性材料作为载体以及掺杂稀土元素等固体酸改性方法,并对固体酸催化制备生物柴油的发展前景进行了展望。     

固体酸催化剂制备生物柴油研究进展

生物柴油是一种可再生的生物能源,近年来得到广泛关注.固体酸催化剂可同时催化油脂和脂肪酸制备生物柴油,同时还具有环境友好、易于和产物分离等优点.本文综述了沸石分子筛、杂多酸、离子交换树脂、固体超强酸等同体酸在催化合成生物柴油方面的研究进展.     

Synthesis of mixed alcohols from CO2 contained syngas on supported molybdenum sulfide catalysts

The performances of active carbon supported molybdenum sulfide catalysts prepared by different procedures or promoted by different elements in the synthesis of mixed alcohols from CO₂ containing syngas were examined. The results showed that high alcohol activity and selectivity could be obtained by employing a rapid drying procedure and employing a H₂S---H₂ stream for (NH₄)₂MoS₄ decomposition. Addition of Co, Cr and Cl to K---Mo/C catalyst led to an increase in the alcohol activity or selectivity. The presence of CO₂ in the feed caused a greater amount of water to be produced but reduced the formation of CO₂. The product distribution was also strongly influenced by the presence of either CO₂ or H₂S in the feed. Addition of CO₂ reduces the formation of higher alcohols while H₂S increases higher alcohol formation.     

Homogeneous catalysts of redox reactions based on heteropoly acid solutions. II. Synthesis of catalyst for pilot industrial production of methylethylketone

The homogeneous catalyst used in the 2005–2006 scale-up of the oxidation of n-butylenes into methylethylketone to the industrial level is a chloride-free aqueous solution of palladium complexes in a modified 0.25 M solution of Mo-V-P heteropoly acid with the molecular formula H₁₂P₃Mo₁₈V₇O₈₅ (HPA-7′). Its advantages are increased oxidative capacity in the primary oxidation of n-C₄H₈ and increased thermal stability, which allows quick catalyst regeneration with atmospheric oxygen at 160–170°C. The paper describes the preparation of a pilot lot of the catalyst with a total volume of 50 L; the starting substances were V₂O₅, MoO₃, and H₃PO₄. The key point of the synthesis was dissolving V₂O₅ while stirring in a dilute and cooled H₂O₂ solution. This formed V(V) peroxide complexes, which decompose at elevated temperature to give a 0.0175 M H₆V₁₀O₂₈ solution. This solution was stabilized by adding a calculated amount of H₃PO₄ to give a more stable 0.0125 M H₉PV₁₄O₄₂ solution. Since the H₉PV₁₄O₄₂ solution occupied a large volume, its synthesis was performed three times in a 300-L reactor. In the main 500-L reactor, MoO₃ was dissolved in water with stirring, while adding the remaining portion of H₃PO₄. The resulting mixture was evaporated, gradually introducing all of the previously obtained portions of the dilute H₉PV₁₄O₄₂ solution. The resulting HPA-7′ solution was evaporated to ～100 L and filtered twice, separating the insignificant amount of the precipitate. The filtered solution was again evaporated to 50 L, and a calculated amount of PdCl₂ was added to it while stirring at 70–80°C. A total of 27 lots of the (Pd + 0.25 M HPA-7′) catalyst with a total volume of 1350 L were obtained. All apparatuses of the pilot industrial unit for MEK synthesis were filled with this catalyst.     

Application of metal triflate catalysts for the trans-esterification of Jatropha curcas L. oil with methanol and higher alcohols

This paper describes an experimental study on the application of metal triflate salts for the (trans‐) esterification of fatty esters (triolein, methyl oleate, methyl linoleate), fatty acid (oleic acid), as well as Jatropha curcas L. oil with methanol and higher alcohols (ethanol, n‐propanol, iso‐propanol, iso‐butanol, tert‐butanol). The effect of the metal type (scandium, bismuth, aluminium, lanthanum, copper, zinc) and process conditions on reaction performance were evaluated. Highest conversions were obtained with Al(OTf)₃. Reaction of triolein with methanol gave 99 mol% conversion at 165 °C for 1 h and the main product was the methyl ester. In addition, partial methoxylation of the carbon–carbon double bonds in the fatty acid chains was observed, though their fraction in the mixture was less than 20 mol%. The trans‐esterification reaction was also successfully performed using higher alcohols, giving >95 % conversions for ethanol, n‐propanol, iso‐propanol and iso‐butanol, whereas tert‐butanol was not reactive. For the reaction of oleic acid with methanol, quantitative esterification, partial methoxylation of the carbon–carbon double bonds and the formation of small amounts of a lactone was observed. The methodology using Al(OTf)₃ was successfully performed on the trans‐esterification reaction of JO (FFA content of 2.1 wt%) with various alcohols. Key properties (viscosity, pour point and cloud points) of the (branched) Jatropha esters were determined. The best cold‐flow properties were obtained for the iso‐propyl esters of JO, with cloud point and pour point of ?3 and ?24 °C, respectively.     

Comparison of different heterogeneous catalysts and different alcohols for the esterification reaction of oleic acid

Oils with high amount of free fatty acid (FFA) are becoming one of the most promising alternatives to produced biodiesel; due, principally, to it low cost. However, because of the presence of FFA, the conventional basic homogenous catalyst should not be used with the aim to avoid the production of soaps.In this work, different catalysts, such as solid resins, zeolite and enzymes, as well as different alcohols: ethanol anhydrous, ethanol 96°, 1-propanol, 2-propanol and butanol, were tested for the direct esterification reaction of pure oleic acid.The influence of several variables, such as alcohol’s carbon chain length, the presence of water, which has a negative effect on the final conversion shifting the final conversion to a lower level, and the location of the OH group were studied.The enzymatic catalyst, Lipozyme CALB, turned out to be the best one, achieving a final conversion of 98% after three days reaction.