催化裂化汽油催化氧化及萃取脱硫的研究

以分子氧为氧化剂,将催化氧化与萃取分离相结合,开展催化汽油氧化萃取脱硫研究。结果表明,与直接萃取相比,汽油经过氧化及溶剂萃取,汽油脱硫率有所提高,并且随着氧化温度的提高而增大,氧化过程对催化汽油脱硫有贡献。催化剂能够加速硫化物氧化反应,几种催化剂的汽油脱硫率从大到小顺序为：氧化铈＞碳酸锰或四硼酸钠或氧化锌＞硼酸或过硼酸钠。使用氧化锌或碳酸锰催化剂时,随着催化剂用量的增加,汽油脱硫率总体呈现降低的变化趋势。以硼酸为催化剂时,脱硫率随着催化剂用量的增加先增加后降低,认为催化汽油中硫化物的氧化反应符合连串反应机制。     

新型催化热分解脱酸催化剂研究

催化热分解脱酸是一种方便且成本低廉的脱酸方法，但脱酸率较低，限制了工业化。通过采用氧化镁、氧化锌、镁铝水滑石和H-ZSM-5作为催化剂活性组分进行脱酸实验，发现镁铝水滑石对催化热分解脱酸具有较高的活性，可作为催化剂的活性组分，从机理方面证明具有催化石油酸分解的作用。对不同制备工艺制备的催化剂进行评价，得出最佳的催化剂制备工艺为：采用机械混合制球法，镁铝水滑石用量为催化剂质量的30%，活性氧化铝为载体，焙烧温度500 ℃。将中海油减二线馏分油与脱酸后油品进行红外分析，表明脱酸后油品中的环烷酸消失，证明镁铝水滑石催化剂具有良好的脱酸效果。     

ZnO和金属单质催化尿素醇解法制备碳酸二甲酯的研究

使用不同方法制备ZnO催化剂并对其催化活性进行了比较,选出了高催化活性的催化剂,找到了合成碳酸二甲酯(DMC)的最佳工艺条件并且对催化剂进行了XRD和SEM表征.同时对3种金属单质进行了活性比较,得到镁粉有高的催化活性,并提出了镁粉催化反应的机理.同时,本实验还优化了通气方式.     

Chemical Fixation of Carbon Dioxide to Propylene Carbonate Using Smectite Catalysts with High Activity and Selectivity

The reaction of propylene oxide and carbon dioxide to propylene carbonate was carried out using Mg-, Ni- and Mg-Ni-containing smectite catalysts which contain different amounts of alkali atoms such as sodium, potassium and lithium. These catalysts are highly active and selective for this reaction. The catalytic activity strongly depends on the elemental composition of the catalyst used. Particularly the amount of alkali atoms incorporated in the catalyst is the most important factor governing the catalytic performance. The most active catalyst among those prepared in the present study shows a turnover number of 105 mmol/g for the propylene carbonate formation, which is the highest turnover number compared with those reported so far (10 mmol/g) for the title reaction.     

氧化锌的制备及其对碳酸二甲酯合成的催化作用

通过焙烧醋酸锌法、微波活化ZnO法、溶胶-凝胶法和沉淀法制备得到四种ZnO催化剂,并对其进行尿素与甲醇反应制碳酸二甲酯(DMC)活性测定以及XRD和SEM表征。结果表明,溶胶-凝胶法制备得到的ZnO催化剂颗粒大小均匀,催化活性好,DMC收率为8.17％。还提出ZnO催化尿素与甲醇反应制DMC的反应机理。     

On the junction effect theory of activity in methanol synthesis catalysts

The junction effect theory which has been propounded to account for the activity in methanol synthesis of oxide supported copper catalysts has been examined in the light of published data on the mechanism of methanol synthesis on copper/zinc oxide/alumina catalysts. The absence of a formate species on the surface of the zinc oxide component of the catalyst after methanol synthesis (the formate species has been shown to be the pivotal intermediate in methanol synthesis on zinc oxide) precludes its involvement in the reaction and negates the applicability of the theory to the copper/zinc oxide/alumina system.     

THE ROLE OF LATTICE OXYGEN IN THE DYNAMIC BEHAVIOR OF OXIDE CATALYSTS

The lattice of an oxide catalyst used for oxidation reactions can act as a reservoir for oxygen, storing and releasing it for reactions at the catalyst surface under appropriate conditions. The implication of this oxygen storage property of an oxide catalyst on its dynamic response characteristics has been investigated through an experimental study of 2-butene oxidation over vanadium oxide as a model reaction. Isothermal reaction rate measurements in a differential reactor and nonisothermal studies in a single pellet reactor have been carried out. Following a step increase in the feed butene concentration, isothermal reaction rate overshoot and pellet temperature overshoot were observed. These observations could be modelled in a qualitatively correct way by a very simple model accounting for the participation of lattice oxygen in the catalytic reactions under dynamic conditions. It is demonstrated through model simulations that the ignition characteristics of a catalyst pellet are significantly affected by the participation of the lattice oxygen, when steady state multiplicity is present.     

Catalytic performance of sulfate-grafted graphene oxide for esterification of acetic acid with methanol

Graphene oxide possesses tremendous mechanical and electronic properties in combination with large surface area and accessible active sites leading to the development of novel innovative heterogeneous catalysts. The present study elaborates the catalytic activity of graphene oxide, enhanced by grafting active sulfate groups on its surface to result as a superior catalyst. The catalyst was evaluated in the model acetic acid esterification reaction with methanol in terms of acid conversion. Catalysts consisting of varied sulfate concentrations and calcination time were synthesized and optimized for its best catalytic activity. The prepared catalysts (GO-SO₄) were characterized using XRD, FT-IR, SEM-EDS, XPS, and BET. A 44% enhancement in catalyst activity was observed using sulfate-grafted graphene oxide (GO-SO₄) catalyst over bare GO due to the synergistic effect of sulfate ions. The catalyst can be separated out by simple filtration. Further, the influence of operating process parameters including catalyst loading, and the reaction temperature was evaluated toward the maximum acid conversion. In addition, the detailed kinetic study was also done in this system using Pseudo-homogeneous model.     

Microspherical chromium oxide/alumina catalyst KDM for fluidized-bed isobutane dehydrogenation: Development and industrial application experience

A microspherical chromium oxide/alumina catalyst (KDM) has been developed for fluidized-bed isobutane dehydrogenation. This catalyst shows a high catalytic activity, selectivity, and thermal stability. The KDM preparation technology involves an alumina support produced by centrifugal thermal activation (CTA) of gibbsite-CEFLAR? technology. This technology makes it possible to regulate the phase composition of the CTA product in a wide range and to synthesize, from this product, supports with preset structural and textural properties. The support and catalyst production technologies have been commercialized by Altailyuminofor Co. Since 2008, the KDM catalyst has been employed by SIBUR Holding Co. and Ekooil Co. (Omsk). Industrial-scale application of the catalyst has demonstrated that isobutane dehydrogenation over an IM-2201 + KDM mixture reduces the catalyst consumption (kg/(t isobutylene)) from 22–23 for pure IM-2201 to 8-9.5 for the IM-2201 + KDM mixture. For further improvement of the KDM catalyst, fundamental studies of the nature of the active component of this catalyst have been carried out: the role of different states of supported chromium oxide species in dehydrogenation has been elucidated and approaches to controlling the proportion of active and selective chromium oxide species have been devised. These studies have culminated in the development of a catalyst modification whose activity and selectivity exceeds the same characteristics of the original KDM catalyst by 2–4 wt %.     

Characterization of Cure Profile of Anaerobic Adhesives by Real-Time FT-IR Spectroscopy. I. Effect of Transition Metal Dithiolate Complexes

A model acrylic adhesive formulation consisting of triethylene glycol dimethacrylate (TRIEGMA) monomer, cumene hydroperoxide (CHP), o-benzoic sulfimide (saccharin or BS) and with or without a metal dithiolate catalyst has been made to study kinetics and mechanism of the anaerobic polymerization. In these studies, a real-time FT-IR spectroscopic (RT/FT-IR) technique has been used to study anaerobic cure profiles at room temperature. The catalytic effect of several transition metal dithio complexes for redox-initiated acrylate polymerization has been studied. The dithiolates used in these studies include the dithiocarbamate, xanthate dithiophosphate complexes of copper, nickel and zinc systems. Copper diacetylacetonate was also studied for comparison of its catalytic reactivity. A syner-gistic effect of copper dithiolate catalyst and saccharin was observed. The effects of catalyst concentration, metal and ligand type, and co-initiator on cure profiles have been monitored in a real-time mode.     

锌、镓改性HZSM-5分子筛催化烷烃芳构化工艺研究

用浸渍法把Ga、Zn以氧化物的形式负载于HZSM－5上制得催化剂,用于催化C3－4烷烃芳构化反应,确定了添加剂的含量,研究了反应条件对催化剂活性的影响,实验结果表明：分别加入2％Ga和2％Zn的HASM-5后,反应转化率为92％,芳烃选择性达78.6％,二甲苯中对二甲苯含量大于995,反应进行了100h,催化活性无明显降低,显示出良好的催化活性和稳定性。     

Selective oxidation and ammoxidation of propane on a Mo–V–Te–Nb–O mixed metal oxide catalyst: a comparative study

A comparative study on the selective oxidation and the ammoxidation of propane on a Mo–V–Te–Nb–O mixed oxide catalyst is presented. The catalyst has been prepared hydrothermally at 175 °C and heat-treated in N₂ at 600 °C for 2 h. Catalyst characterization results suggest the presence mainly of the orthorhombic Te₂M₂₀O₅₇ (M = Mo, V and Nb) bronze in samples before and after use in oxidation and ammoxidation, although some little modifications have been observed after its use in ammoxidation reaction. Propane has been selectively oxidized to acrylic acid (AA) in the 340–380 °C temperature range while the ammoxidation of propane to acrylonitrile (ACN) has been carried out in the 360–420 °C temperature interval. The steam/propane and the ammonia/propane molar ratios have an important influence on the activity and the selectivity to acrylic acid and acrylonitrile, respectively. The reaction network in both oxidation and ammoxidation reactions as well as the nature of active and selective sites is also discussed. The catalytic results presented here show that the formation of both ACN and AA goes through the intermediate formation of propene.     

天然气催化燃烧催化剂的研究(Ⅱ）

介绍了天然气催化燃烧钙钛矿型氧化物催化剂、六铝酸盐型催化剂以及负载型非贵金属催化剂的研究现状。对于钙钛矿型氧化物催化剂,利用A位取代或调整B位元素的种类及配比、新的技术和方法制备高比表面积或具有纳米结构的钙钛矿型氧化物,是提高其甲烷催化燃烧活性的重要手段。六铝酸盐型催化剂具有很高的热稳定性和甲烷燃烧活性,但起燃温度较高,通过采用将金属Pd负载到六铝酸盐上或改变制备方法,提高其比表面积,以提高其低温反应活性。负载型非贵金属催化剂研究最多的是过渡族金属,其氧化活性、抗毒性能和耐久性都存在问题,需进一步研究。     

Effects of morphology and composition on catalytic performance of double metal cyanide complex catalyst

Double metal cyanide (DMC) complexes based on Zn₃[Co(CN)₆]₂ were prepared using different zinc salts and complexing agents and They were characterized by elemental analysis, IR and XRD. The catalytic properties of DMC complexes were determined in polymerization of propylene oxide. Great differences in morphology of DMC complexes was were correlated with preparation route as well as with the kind of zinc salts employed. The catalytic activity was strongly dependent on the morphology of DMC complexes and composition of catalysts. The study revealed that the amorphous catalyst made from ZnCl₂ and t-BuOH had the highest activity (up to 26 kg polymer/g catalyst). The DMC catalyst was non-stoichiometric. Polymerization of propylene oxide (PO) catalyzed by DMC proceeded in a controlled manner. The molecular weight of each polymer was controlled by the monomer/initiator ratio, the values of molecular weight distribution (MWD) were in the range of 1.23–1.48. The polymer has an atactic structure and a head-to-tail regiosequance.     

Gold, silver and copper catalysts supported on TiO2 for pure hydrogen production

A catalytic study of the hydrogen production by CO water gas shift reaction (WGSR) on gold, silver and copper particles supported on TiO₂ has been carried out. A deep characterisation of the catalysts by TPR and FTIR has been performed. Silver catalyst exhibits no catalytic activity, copper and gold catalysts show intermediate and very high performances, respectively. These strong differences have been interpreted on the basis of FTIR data of CO adsorption at 90 K and on the effect of coadsorbed species. Gold and copper catalysts, either oxidised or reduced, are able to adsorb CO. Reduced silver catalyst does not adsorb CO at all, while oxidised silver catalyst does quite strongly.     

酸催化山梨醇脱水制异山梨醇的研究进展

异山梨醇是一种生物基功能性二元醇,近年来因其在聚合物工业中的潜在应用价值而备受关注。山梨醇脱水反应是生物质转化合成异山梨醇的关键步骤,目前普遍采用酸催化体系,且在酸性催化剂开发及工艺研究方面均取得了良好进展。本工作主要介绍了已报道的酸性催化剂结构与性质对催化活性及选择性的影响,指出强酸性均相催化剂具有高催化活性,但腐蚀性强,且不易循环利用;多相催化剂催化活性与酸性位点、酸度、酸容量、孔结构、表面性质和结构等都有关系,且这些性质随催化剂组成和结构改变而相互影响。针对目前山梨醇脱水反应催化剂均相催化腐蚀性强、催化剂循环性差,多相催化剂催化活性不高的现状,高催化活性可循环使用的离子液体催化剂是一种具有发展潜力的均相催化剂,对多相催化剂构效关系还应进行更多的研究以指导新型催化剂的开发。     

Soybean oil transesterification over zinc oxide modified with alkali earth metals

Fatty acid methyl esters, derived from vegetable oils or animal fats and better known as biodiesel, have received considerable attention because of their environmental benefits and the limited resources of fossil fuels. Most biodiesel is usually produced by the transesterification of vegetable oils with methanol in the presence of a catalyst. This study reports on the preliminary results of using alkaline earth metal-doped zinc oxide as a heterogeneous catalyst for transesterification of soybean oil. The highest catalytic activity was obtained with ZnO loaded with 2.5 mmol Sr(NO₃)₂/g, followed by calcination at 873 K for 5 h. When the transesterification reaction was carried out at reflux of methanol (338 K), with a 12:1 molar ratio of methanol to soybean oil and a catalyst amount of 5 wt.%, the conversion of soybean oil was 94.7%. Besides, tetrahydrofuran (THF), when used as a co-solvent, could increase the conversion up to 96.8%. However, the recovered catalyst exhibited the lower catalytic activity with a conversion of soybean oil of 15.4%. Furthermore, DTA-TG, IR and the Hammett indicator method were employed for the catalyst characterizations.     

A highly efficient polymer‐anchored palladium(II) complex catalyst for hydrogenation,Heck cross‐coupling and cyanation reactions

BACKGROUND: Precise architectures of steric and electronic properties of palladium species play a crucial role in designing highly functionalized catalyst systems responsible for target organic transformations. Pd catalysts supported on polymer materials have been employed extensively as catalysts not only for hydrogenation but also for coupling reactions in the production of fine chemicals. RESULTS: A new polymer‐anchored Pd(II) complex has been synthesized and characterized. The catalyst shows high catalytic activity in the hydrogenation of styrene oxide, Heck cross‐coupling and cyanation reactions of aryl halides. The effect of various reaction parameters were investigated to optimize reaction conditions. The catalytic system shows good activity in the hydrogenation of styrene oxide (conversion 98%) with a selectivity to 2‐phenylethanol (93%) which is higher than its homogeneous analogues. The catalyst also exhibits excellent catalytic activity for the Heck cross‐coupling and cyanation reactions of various substituted and non‐substituted aryl halides. CONCLUSIONS: Results demonstrate that the catalyst is robust and stable and can be recovered quantitatively by simple filtration and reused several times without loss of activity. Copyright © 2010 Society of Chemical Industry     

Synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification: Catalyst screening and reaction optimization

The synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification is reported. Firstly, a catalyst screening has been performed by studying the influence of different basic and acid homogeneous and heterogeneous catalysts on reaction results. Catalytic activity is extremely low for acidic catalysts indicating that reaction rate is very slow. On the contrary, high conversions and yields are obtained for basic catalysts. Catalytic activity increases with catalyst basic strength. The best heterogeneous catalyst is CaO. Calcination of CaO increases dramatically its activity due to calcium hydroxide removal from its surface. A reaction optimization study has been carried out with CaO as catalyst by using a factorial design of experiments leading to operation conditions for achieving a 100% conversion and a >95% yield at 1.5 h reaction time: 95 °C, catalyst/glycerol molar ratio = 0.06 and dimethyl carbonate/glycerol molar ratio = 3.5. Carbonate glycerol can be easily isolated by filtering the catalyst out and evaporating the filtrate at vacuum. Leaching of catalyst in reaction medium was lower than 0.34%. Catalyst recycling leads to a quick decrease in both conversions and yields probably due to a combination of catalyst deactivation by CaO exposure to air between catalytic runs, and a decrease in the catalyst surface area available for reaction due to particle agglomeration.     

Hydrolytic decomposition of CF4 over alumina-based binary metal oxide catalysts: high catalytic activity of gallia-alumina catalyst

The hydrolytic decomposition of CF₄ has been conducted on gallia promoted alumina (Ga-Al oxide) catalysts at 803–903 K and 0.1 MPa. Steady state activity on 20% Ga-Al oxide was 15 times of that on Ce10%-AlPO₄ catalyst, on which the highest activity has been reported. The catalytic activity was further improved by incorporation of sulfate anion in Ga-Al oxide and by applying sol–gel method in preparation of the catalyst. XRD spectra of Ga-Al oxides showed a shift of diffraction peaks assigned to γ-alumina toward lower angles, indicating the formation of gallia-alumina solid solution. In situ FT-IR of pyridine adsorption spectra of Ga-Al oxides showed peaks solely attributable to Lewis acid (L-acid) sites at 1445–1455, ca. 1495, 1577, ca. 1594, and ca. 1622 cm⁻¹. The steady state catalytic activities increased with increasing peak areas at 1446 or 1622 cm⁻¹ of Ga-Al oxides with various Ga%, suggesting participation of Lewis acid sites into the reaction. It is demonstrate from surface area measurements of Ga-Al oxide catalyst before and after the reaction that not only higher catalytic activity but also higher catalyst stability were observed on Ga-Al oxide, Ga-Al oxide with sulfate, and Ga-Al oxide prepared by sol–gel method than on their parent oxides of alumina, Ga-Al oxide, and Ga-Al oxide prepared by incipient wetness method, respectively.