Dehydration of Ethanol to Ethylene on Ring- and Trilobe-Shaped Catalysts

The indicators of ethanol to ethylene catalytic dehydration process on trilobe- and ring-shaped samples of an alumina catalyst were compared at the fixed parameters: thermal agent temperature and catalyst load. Experiments were performed in a flow-through reactor of a laboratory setup and in a tubular reactor of a pilot installation. The use of the less active ring-shaped catalyst ensures higher values of ethanol conversion, ethylene yield, and catalyst performance and significantly lower hydraulic resistance, compared to the more active trilobe-shaped catalyst. This is caused by lower intensity of the heat absorption on the less active catalyst and, correspondingly, to the higher temperature in the ring bed due to higher bed porosity.     

用于苯选择加氢制环己烯的非晶态合金Ru-La-B/ZrO2催化剂的失活与再生

 研究了在中试装置上经长期运转后的非晶态合金Ru-La-B/ZrO2催化剂的失活原因与再生方法. 结果表明: 催化剂失活不是由微孔堵塞、比表面积减小、晶粒长大或催化剂中毒而引起的,而是由于在长期运转过程中催化剂吸附了反应浆液中的Zn2+ 和反应器壁引入的Fe2+ , 通过酸洗的方法可以使催化剂的活性和选择性基本恢复.     

Composition and structure of pyrophoric nickel catalysts according to X-ray diffraction data

The properties of a nickel catalyst obtained by treatment of nickel–aluminum alloy with sodium hydroxide in the presence of H₂O₂ and additionally stabilized with increased pressure were studied. Additional stabilization decreased the catalyst activity by 25%, but gave a more distinct picture for an XRD analysis of the active catalyst surface and decreased the time of deactivation of the dehydrated catalyst with air oxygen. The catalyst stabilization was explained by the displacement of water, decrease in the pore size, and surface inhomogeneity.     

Effect of Support and Acidity of Catalyst on the Direct Oxidation of Ethylene to Acetic Acid

The selective oxidation of ethylene to acetic acid was investigated on Pd-acid/ support catalyst system. The catalytic activity is influenced strongly by the acidity of the catalyst. The stronger the catalyst acidity the higher the catalytic activity. The nature of the support also influences the activity of the catalyst substantially. The catalyst has highest activity when it exhibits highest acidity on silica.     

纳米金催化剂的抗水性能和抗硫中毒性能

与Au/Al2O3相比,复合载体负载的Au/FeOx/Al2O3具有更高的催化CO氧化的低温活性和稳定性,且表现出湿度增强效果,水分压为550~1 600 Pa时催化剂活性较高.在完全无水的环境中,催化剂发生快速不可逆失活;在饱和水汽的环境中,催化剂发生缓慢可逆失活.在水汽作用下的失活与纳米金粒子的粒径长大有关.助剂对催化剂抗水性能影响不大,但对抗硫中毒性能的影响较大.Au/CeO2/Al2O3催化剂显示有最佳的抗硫中毒性能.催化剂表面硫化物和硫酸盐的生成是导致催化剂不可逆硫中毒失活的主要原因.     

MoO3催化碳酸二甲酯与乙酸苯酯合成碳酸二苯酯

采用焙烧法制备了MoO3催化剂并将其用于碳酸二甲酯(DMC)与乙酸苯酯(PA)合成碳酸二苯酯(DPC)反应,考察了焙烧温度对催化荆性能的影响,并用X射线衍射(XRD)对催化剂结构进行了表征.结果发现,在400或500℃焙烧的催化剂具有良好的催化性能,DMC转化率为73.9%,DPC和甲基苯基碳酸酯的选择性分别为39.5%和56.5%.XRD结果表明,该催化剂物相组成为正交晶系MoO3,且(021)或/和(110)晶面有利于酯交换反应.催化剂使用5次后DMC转化率从73.9%降至10.2%,多次重复使用后的催化剂在窄气气氛中于400或500℃焙烧即可再生,再生后催化剂的性能几乎和新鲜催化剂相当.     

Effects of Temperature and Catalyst to Oil Weight Ratio on the Catalytic Conversion of Heavy Oil to Propylene Using ZSM-5 and USY Catalysts

It is useful for practical operation to study the rules of production of propylene by the catalytic conversion of heavy oil in FCC (fluid catalytic cracking). The effects of temperature and C/O ratio (catalyst to oil weight ratio) on the distribution of the product and the yield of propylene were investigated on a micro reactor unit with two model catalysts, namely ZSM-5/Al2O3 and USY/Al2O3, and Fushun vacuum gas oil (VGO) was used as the feedstock. The conversion of heavy oil over ZSM-5 catalyst can be comparable to that of USY catalyst at high temperature and high C/O ratio. The rate of conversion of heavy oil using the ZSM-5 equilibrium catalyst is lower compared with the USY equilibrium catalyst under the general FCC conditions and this can be attributed to the poor steam ability of the ZSM-5 equilibrium catalyst. The difference in pore topologies of USY and ZSM-5 is the reason why the principal products for the above two catalysts is different, namely gasoline and liquid petroleum gas (LPG), repspectively. So the LPG selectivity, especially the propylene selectivity, may decline if USY is added into the FCC catalyst for maximizing the production of propylene. Increasing the C/O ratio is the most economical method for the increase of LPG yield than the increase of the temperature of the two model catalysts, because the loss of light oil is less in the former case. There is an inverse correlation between HTC (hydrogen transfer coefficient) and the yield of propylene, and restricting the hydrogen transfer reaction is the more important measure in increasing the yield of propylene of the ZSM-5 catalyst. The ethylene yield of ZSM-5/Al2O3 is higher, but the gaseous side products with low value are not enhanced when ZSM-5 catalyst is used. Moreover, for LPG and the end products, dry gas and coke, their ranges of reaction conditions to which their yields are dependent are different, and that of end products is more severe than that of LPG. So it is clear that maximizing LPG and propylene and restricting dry gas and coke can be both achieved via increasing the severity of reaction conditions among the range of reaction conditions which LPG yield is sensitive to.     

Highly active, immobilized ruthenium catalysts for oxidation of alcohols to aldehydes and ketones. Preparation and use in both batch and flow systems

A novel, highly active immobilized ruthenium catalyst, which can be successfully used in oxidation of alcohols to aldehydes and ketones, has been developed. In contrast to most immobilized catalysts, the Ru catalyst has activity that is higher than that of the original non-immobilized catalyst. In a batch system, the Ru catalyst was recovered and reused several times without loss of activity. The catalyst was also applied to a flow system, in which excellent conversions and yields were demonstrated. No leaching of Ru was observed in both cases.     

甲基丙烯醛氧化酯化制甲基丙烯酸甲酯催化剂的制备与应用

甲基丙烯醛氧化酯化制甲基丙烯酸甲酯催化剂的制备与应用;催化剂; 甲基丙烯酸甲酯; 甲基丙烯醛; 氧化-酯化反应     

新型苯选择加氢制环己烯非晶态催化剂Ru-Fe-B/ZrO2的制备及其可调变性

采用化学还原法制备了一种新型高活性和高选择性苯选择加氢制环己烯的Ru-Fe-B/ZrO2纳米非晶态合金催化剂,并利用透射电镜、选区电子衍射、X射线衍射和N2物理吸附仪等手段对催化剂进行了表征.重点研究了Ru-Fe-B/ZrO2催化剂活性和选择性的可调变性,及还原剂NaBH4浓度和洗涤后滤液的pH值对其催化性能的影响.结果表明,在新型Ru-Fe-B/ZrO2催化剂上,当苯转化54%时,环己烯选择性高达80%,同时环己烯选择性随苯转化率升高而缓慢下降.向反应浆液中添加酸性或碱性物质可以调变催化剂的活性和选择性,同时催化剂制备工艺和性能具有很好的可重复性.Ru-Fe-B/ZrO2催化剂融合了纳米和非晶材料的特性,这是其对苯选择加氢制环己烯表现出高活性和高选择性的主要原因.     

Ferrofluid catalyzed water gas shift reaction to give carbon-dioxide and hydrogen

A ferrofluid consisting of colloidally dispersed magnetite particles in water was found to be an efficient selective catalyst for water gas shift reaction at 15–25 atmosphere of CO pressure in the temperature range of 423–553 K where the products obtained were only CO₂ and H₂. The reaction was studied as a function of variation of the concentration of catalyst, pressure of CO gas and temperature. Kinetic parameters suggested a mechanism involving first order dependence in CO and catalyst concentrations.     

Zinc-catalyzed aerobic oxidation of benzoins and its extension to enantioselective oxidation

Zn(II)-DABCO complex is used as an efficient catalyst for the aerobic oxidation of benzoins to benzils in the presence of molecular oxygen. Usage of chiral zinc complex as catalyst resulted in enantioselective oxidative kinetic resolution of racemic benzoin to yield enantiomerically enriched benzoins.     

Preparation of modified Ce-SAPO-34 catalysts and their catalytic performances of methanol to olefins

The modified Ce-SAPO-34 catalysts were prepared with three methods, i.e., the liquid ion exchange with air calcination, impregnation with air calcination and impregnation with steam calcination methods. The catalytic performances of the catalysts for methanol to olefins were investigated. The properties of the catalysts were characterized using XRD, BET, XRF, FT-IR and NH₃-TPD. The results indicated that compared to the SAPO-34 catalyst the catalyst prepared with the impregnation and air calcination prolonged the lifetime by 40 min and improved the selectivity to ethylene by 5% (mol) and the catalyst prepared with the impregnation and steam calcination showed the best modification effect, prolonging the lifetime by 70 min and improving the ethylene selectivity by 10% (mol). The catalyst prepared with the liquid ion exchange showed similar behaviour as the SAPO-34 catalyst. It was verified that the porous structure and surface acidity of these catalysts determined their catalytic behaviors.     

Short synthesis of bis-NHC-Pd catalyst derived from caffeine and its applications to Suzuki, Heck, and Sonogashira reactions in aqueous solution

A short and efficient synthesis of a bis-NHC-palladium catalyst simply prepared from caffeine in two steps was reported. The air and moisture stable Pd catalyst can be used as a good catalyst in running Suzuki-Miyaura, Mizoroki-Heck, and Sonogashira reactions in aqueous solution.     

Single Particle Assays to Determine Heterogeneities within Fluid Catalytic Cracking Catalysts

Fluid catalytic cracking (FCC) is an important process in oil refinery industry to produce gasoline and propylene. Due to harsh reaction conditions, FCC catalysts are subject to deactivation through for example, metal accumulation and zeolite framework collapse. Here, we perform a screening of the influence of metal poisons on the acidity and accessibility of an industrial FCC catalyst material using laboratory-based single particle characterization that is, μ-XRF and fluorescence microscopy in combination with probe molecules. These methods have been performed on density-separated FCC catalyst fractions, allowing to determine interparticle heterogeneities in the catalyst under study. It was found that with increasing catalyst density and metal content, the acidity and accessibility of the catalyst particles decreased, while their distribution narrowed with catalyst age. For example, particles containing high Ni level possessed very low acidity and were hardly accessible by a Nile Blue dye. Single catalyst particle mapping identifies minority species like the presence of a phosphated zeolite ZSM-5-containing FCC additive for selective propylene formation, catalyst particles without any zeolite phase and catalyst particles, which act as a trap for SO_x.     

Partial oxidation of methane to syngas catalyzed by a nickel nanowire catalyst

A nickel nanowire catalyst was prepared by a hard template method,and characterized by transmission electron microscopy (TEM),N2 physical adsorption,X-ray photoelectron spectrometry (XPS),X-ray diffraction (XRD) and H2 temperature-programmed reduction (H2-TPR).The catalytic properties of the nanowire catalyst in the partial oxidation of methane to syngas were compared with a metallic Ni catalyst which was prepared with nickel sponge.The characterization results showed that the nickel nanowire catalyst had high specific surface area and there was more NiO phase in the nickel nanowire catalyst than in the metallic Ni catalyst.The reaction results showed that the nickel nanowire catalyst had high CH4 conversion and selectivities for H2 and CO under low space velocity.     

In an attempt to provide a user's guide to the galaxy of benzylidene, alkoxybenzylidene, and indenylidene ruthenium olefin metathesis catalysts

The data reported in this paper demonstrate that great care must be taken when choosing an appropriate catalyst for a given metathesis reaction. First-generation catalysts were found to be useful in the metathesis of sterically unhindered substrates. Second-generation catalysts (under optimised conditions) showed good to excellent activities toward sterically hindered and electron-withdrawing group (EWG)-substituted alkenes that do not react using the first-generation complexes. A strong temperature effect was noted on all of the reactions tested. Interestingly, attempts to force a reaction by increasing the catalyst loading were much less effective. Therefore, when possible, it is suggested that metathesis transformations should be carried out with a second-generation catalyst at 70 degrees C in toluene. However, different second-generation catalysts proved to be optimal for different applications and no single catalyst outperformed all others in all cases. Nevertheless, some empirical rules can be deduced from the model experiments, providing preliminary hints for the selection of the optimal catalysts.     

Reinforced nickel catalysts for steam reforming of methane to synthesis gas

XRD, mercury porosimetry, low-temperature nitrogen adsorption and electron microscopy were used to study peculiarities of the formation of reinforced composite nickel catalysts. The catalysts were prepared by sintering powdered metallic nickel with a supported nickel catalyst (GIAP-3 or NIAP-18) applied to a reinforcing stainless steel gauze. It was found that a metal matrix, in the pores of which supported catalyst particles were distributed, was formed in the composite catalysts. The NIAP-18-based catalyst exceeded the GIAP-3-based catalyst in activity toward the methane steam reforming. The NIAP-18-based catalyst was as active as the Cr₂O₃-doped NIAP-18-based catalyst, but showed a worse coke-resistance. A chromium oxide additive increased the activity of the GIAP-3-based catalyst.     

苯氧乙酰基四羰基钴催化亚胺与一氧化碳交替共聚反应合成多肽类聚合物简

报道了一种新的苯氧乙酰基四羰基钴催化剂,并将其用于催化亚胺与一氧化碳的交替共聚反应. 1H NMR分析结果表明,该催化剂在1个大气压的CO气氛下以烷基钴和酰基钴平衡的形式存在. 催化反应结果表明,该催化剂具有良好的催化性能,可以得到具有较高分子量、N端为苯氧乙酰基的多肽类聚合物,且具有较窄的分子量分布. 利用核磁共振\,红外光谱和质谱等对多肽聚合物的结构进行了表征,结果表明,聚合物链终止端除了具有慕尼黑酮类结构的端基以外,还存在酰胺类的端基,并对后者的生成机制进行了解释.     

LaFeO3催化剂在木质素湿法氧化合成芳香醛反应中的活性与稳定性

利用溶胶-凝胶法制备了钙钛矿型复合氧化物LaFeO3, 利用X射线衍射、扫描电子显微镜、 X射线光电子能谱和N2吸附等表征手段考察了所制备样品的结构、形貌、表面物种和比表面积,并将其作为催化剂用于木质素湿法氧化合成芳香醛的反应中. 结果表明,该催化剂具有较高的活性和稳定性. 在适当的反应条件下, LaFeO3催化剂能显著提高木质素的转化率以及各芳香醛的产率,紫丁香醛的产率提高幅度大于香草醛和对羟基苯甲醛,紫丁香醛的最大产率是无催化剂反应时的1.85倍. 催化剂连续使用5次后仍能保持较高的活性,且体相结构没有发生明显的变化.