金属卟啉催化烯烃不对称环氧化反应的研究

合成了5种简单金属卟啉锰配合物，并以这5种金属卟啉作为催化剂，以手性季铵盐为手性相转移催化剂，研究催化烯烃不对称环氧化反应。结果表明：金属卟啉锰中苯环上的不同取代基对烯烃环氧化速度有较大的影响；手性相转移催化剂的加入，不仅提高了反应速度，而且对烯烃的环氧化起到了一定的不对称诱导作用；不同底物的烯烃，不对称环氧化反应对映选择性不同。     

ARGG装置催化裂化汽油降烯烃技术论述

本论文论述了ARGG装置催化裂化汽油降烯烃的几种方法,同时尽可能保持其辛烷值,实现了油品的清洁化。     

Catalytic methane coupling under periodic operation

Composition modulation strategies for improving selectivity to the C₂ products in the oxidative coupling of methane were investigated experimentally with Li₂O/MgO and CeO/Li₂O/MgO catalysts at about 100 kPa pressure and 750°C. Strategies used were 1) “methane cycling” between mixtures with different concentrations of CH₄, 2) “oxygen cycling” between mixtures with different concentrations of oxygen, 3) bang-bang cycling (air-CH₄), and 4) flushing the catalyst with an inert between exposures to reactants. Experimental C₂ yields and ethylene to total C₂ ratios showed that composition forcing is better with the Ce/Li/MgO catalyst. Methane cycling proved to be the best strategy explored.     

Catalytic olefin polymerisation at short times: Studies using specially adapted reactors

Despite the fact that the very early stages (several tens of seconds) of catalysed olefin polymerisation processes appear negligibly short with respect to the residence time of most industrial reactors, they are critical in terms of catalyst activation, obtaining good particle morphology, and avoiding irreparable problems caused by particle overheating. The different types of reactors that have been used over the course of the past few years are discussed in this feature article. It is shown that despite the difficulties encountered in finding the perfect experimental tool for this purpose, different configurations of stopped flow reactors can be used successfully to explore different aspects of what happens to the catalyst (supported and molecular) during these critical moments of polymerisation. © 2012 Canadian Society for Chemical Engineering     

Catalytic sequential reactions involving palladacycle-directed aryl coupling steps

Catalytic methods are important tools for the synthesis of C-C bonds under mild and ambient conditions. Palladium chemistry predominates in this area because it offers the opportunity to form several different types of bonds in one pot. Palladium can also tolerate a variety of functional groups. Among the many investigations of catalytic aryl-aryl couplings, the most successful technique has been the Suzuki reaction, which uses an arylboronic acid to attack an aryl-Pd bond. This Account reports our methodology, based on the cooperative action of Pd and norbornene, that achieves selective aryl-aryl coupling through C-halide and C-H activation. We are primarily interested in Pd-catalyzed sequential reactions. These reactions combine palladium as an inorganic catalyst and a strained olefin such as norbornene as an organic catalyst and can lead to biphenyl derivatives. While the palladium facilitates C-C bond formation through C-halide and C-H activation, the norbornene contributes to the construction of a palladacycle, an intermediate structure that controls and directs the subsequent reaction steps selectively. To achieve regioselective arylation at the carbon ortho to the original C-halide bond, palladacycles require an additional ortho substituent (R(1)). The palladacycle opens, giving rise to a biphenylylnorbornylpalladium complex. Because of the steric hindrance exerted by the two ortho groups, norbornene deinsertion readily occurs to form a biphenylylpalladium complex. Thus, norbornene acts as a removable scaffold. We used this biphenylylpalladium species to form C-C (with olefins, alkynes, or arylboronic acids) or C-H bonds (by hydrogenolysis). Using nonidentical aryl or heteroaryl halides, we also formed a biaryl-bonded Pd species able to undergo the final termination reaction (C-C, C-N, or C-O bond formation) either inter- or intramolecularly. We used this method to synthesize a variety of aromatic and heteroaromatic compounds. We also obtained the key metallacycle able to selectively direct the reactions by replacing norbornene with an aryl-bonded aminocarbonyl group. This method provided a diverse series of condensed heterocycles.     

Transparent cyclic olefin copolymer/silica nanocomposites

In this work, melt blending of fumed nanosilica with cyclic olefin copolymer (COC) was carried out to prepare high strength transparent composites. The effects of various loadings (1, 2, 3 and 5 wt%) of nanosilica on the physical, mechanical, dynamic mechanical, thermal, tribological and optical properties of the COC composites were investigated in detail. The tensile test results showed that the nanocomposite with 3 wt% nanosilica content provides the highest tensile strength (55.6 MPa) compared with the nanocomposite with 5 wt% nanosilica content (54.6 MPa), which is believed to be significantly dependent on better dispersion. Moreover, the glass transition temperature (from tan δ) increased from 184 °C for pure COC to 194.3 °C for the COC composite with 3 wt% nanosilica. The scratch test and nano‐indentation results showed that addition of nanosilica increased the stiffness and hardness of the composite, providing higher scratch resistance and lower frictional coefficient. UV?visible spectroscopy measurements showed that the nanocomposites have excellent optical transparency which is similar to that of the pure COC film. © 2013 Society of Chemical Industry     

Catalytic olefin epoxidation with cationic molybdenum(VI) cis-dioxo complexes and ionic liquids

The complexes [MoO₂Cl(HC(bim)₃)]Y (Y = Cl (1), BF₄ (2) and PF₆ (3)) have been prepared by reaction of MoO₂Cl₂(THF)₂ (for 1) or [MoO₂Cl(THF)₃]Y (for 2 and 3) with the tridentate ligand HC(bim)₃ = tris(benzimidazolyl)methane, and characterized by IR and Raman spectroscopy, and ¹H NMR. The turnover frequencies for the epoxidation of cis-cyclooctene at 55 °C with tert-butyl hydroperoxide (TBHP, in decane) as the oxidant and complexes 1–3 as catalysts are in the range of 70–200 mol mol_Mo^?1 h^?1. 1,2-Epoxycyclooctane is always the only reaction product for reaction times up to 24 h. With the aim of facilitating the recyclability of the complexes, the ionic liquids (ILs) [BMIM]Y and [BMPy]Y (BMIM = 1-n-butyl-3-methylimidazolium, BMPy = 1-n-butyl-3-methylpyridinium; Y = BF₄ or PF₆) were applied as ionic solvents. The catalytic performance for cyclooctene epoxidation depends strongly on the catalyst solubility in the IL. Of the 12 catalyst/IL mixtures examined, the systems 1/[BMIM]PF₆ and 1/[BMPy]PF₆ exhibit the most favorable reaction rates allied with good recyclability. The 1/[BMIM]PF₆ system was further applied using different oxidants (aqueous TBHP, aqueous H₂O₂ and urea–hydrogen peroxide adduct) and olefins (norbornene, cyclohexene, styrene, α-pinene).     

MCM-22沸石催化剂的苯与长链烯烃烷基化性能

用NH3-TPD法研究了4种不同硅铝摩尔比的MCM-22沸石的酸性质,在常压间歇式反应器中考察了它们在苯与长链烯烃烷基化反应中的催化性能,并与HY和HZSM-5沸石催化剂进行了比较。实验结果发现MCM-22的催化活性与其强酸量有一致的关系,与其硅铝摩尔比无对应关系;MCM-22的活性比HY低,但对2-P的选择性远远高于HY,这说明了MCM-22对2-P具有形状选择作用。     

A process for producing ultraclean gasoline by coupling efficient hydrodesulfurization and directional olefin conversion

To solve the contradiction between ultradeep hydrodesulfurization (HDS) and octane recovery in clean gasoline production, this article proposes a novel two‐stage fluid catalytic cracking (FCC) gasoline hydro‐upgrading process with the selective HDS catalyst in the first reactor and the complemental HDS and octane recovery catalyst in the second reactor. The process achieved the relayed removal of sulfur‐containing compounds with different natures, providing itself with excellent HDS performance, and the hydroisomerization and aromatization of olefins in the second stage endowed the process with superior octane recovery ability and high product yield while remarkably reducing the olefin content of FCC gasoline. The process was also featured by low hydrogen consumption due to the low first‐stage olefin saturation and the balanced second‐stage hydrogenation and dehydrogenation. The two‐stage process developed here sheds a light for efficiently producing ultralow sulfur gasoline from the poor‐quality FCC gasoline of high olefin and sulfur contents. © 2012 American Institute of Chemical Engineers AIChE J, 59: 571–581, 2013     

The hydrogenation of CO over molybdenum/alumina in the presence of ethylene; coupling of olefin metathesis and CO hydrogenation

Three reactions, CO hydrogenation, metathesis of C₂H₄ and CO hydrogenation in the presence of C₂H₄, have been investigated on Mo(+2)/Al₂O₃ under identical experimental conditions. The products of hydrogenation reactions were methane, ethylene and propylene. The results show that the initial rate of propylene formation for CO hydrogenation in the presence of ethylene is much larger, by a factor of 7, than the sum of the rate of propylene formation for CO hydrogenation and metathesis alone. Furthermore, it was found that¹³C labelled propylene was formed in the hydrogenation of¹³CO in the presence of ethylene. These results, taken as a whole, suggest that the same intermediate is formed in both CO hydrogenation and metathesis of ethylene, and that these intermediates can be either incorporated into ethylene and higher hydrocarbons by polymerization or incorporated into ethylene to form propylene via olefin metathesis.     

Catalytic coupling of propyne on Cu{111}

A novel analysis method of the platinum L₃ and L₂ X‐ray absorption edges of Pt/LTL catalysts indicates that chemisorbed hydrogen induces an antibonding resonance state just above the Fermi level at the Pt L₃ edge. The difference in energy of this antibonding state (E_res) with respect to the Fermi level is strongly influenced by the acidity/alkalinity of the LTL support: E_res decreases with increasing alkalinity. The decrease in E_res can also be correlated with the decrease of the neopentane hydrogenolysis turnover frequency of Pt/LTL with increasing support alkalinity. These results provide the most direct experimental evidence that the support acidity/alkalinity alters the actual chemical bond between the surface platinum atoms and the reacting molecule. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fe2O3/AC催化剂上对甲基苯硫酚的水相催化氧化偶联

以对甲基苯硫酚为模型底物，空气为氧化剂，来研究硫醇水相催化氧化偶联制备二硫醚。以活性炭为载体，采用等体积浸渍法制备了一系列负载型氧化物催化剂，并考察了其在对甲基苯硫酚氧化偶联制备对甲苯二硫醚反应中的催化性能。反应结果表明，活性炭负载的铁氧化物具有最佳催化性能。采用N₂物理吸附、X射线衍射、X射线光电子能谱和透射电镜等表征手段对活性炭负载的铁氧化物催化剂进行了表征。表征结果表明，铁氧化物为高度分散在活性炭上的Fe₂O₃物种。以Fe₂O₃/AC为催化剂，当催化剂焙烧温度为400℃，Fe负载量为5%，在50℃下反应30min时，对甲苯二硫醚的收率高达97.4%；该催化剂循环使用5次后活性无明显下降。     

烯烃/链烷烃分离工艺进展

当前开发的烯烃 /链烷烃分离技术有物理吸收法、化学吸收法、吸收分离法、萃取蒸馏法及膜分离法。其中最有发展前途的是利用π 配合作用的化学吸收法 ,现已有工业化装置。将蒸馏与吸附相结合的复合分离技术 ,是烯烃 /链烷烃分离技术的发展方向之一。     

Catalytic oxidative coupling of methane over hydroxyapatite modified with lead

Hydroxyapatite modified with lead catalyzes the oxidative dehydrogenation of methane with high selectivity to C₂ compounds at reaction temperatures as low as 700 °C. The activity is stabilized after reduction in the surface area of the catalyst during the reaction.     

Catalytic coupling boosting efficient production of 5-hydroxymethylfurfural from glucose

As a novel green chemical building block, it is of significance to increase the productivity of 5-hydroxymethylfurfural (HMF) derived from hexoses. In our work, a catalytic system efficiently converting glucose to HMF was designed, which is guided by catalytic coupling at multiple length scales. A catalyst from the sulfonated and carbonized glucose with aluminum loading containing Lewis and Brønsted acidic sites, along with tetrahydrofuran/H₂O-NaCl featuring low boiling point and biphasic solvent, was introduced to the catalytic conversion of glucose. Not only the HMF yield of 75% from glucose was achieved at 140°C for 8 h but also the purity of HMF went up to 93% by facile separation and evaporation. In the reuse of the catalysts, the selectivity of HMF was basically maintained at 81% with the conversion of glucose decreasing by ca. 20% after five runs.     

Catalytic performance of CeAPSO-34 molecular sieve with various cerium content for methanol conversion to olefin

A series of CeAPSO-34s with various cerium contents was synthesized and characterized by multiple techniques such as XRD, SEM, BET, ²⁹Si MAS NMR, NH₃-TPD and CO₂-TPD. NH₃-TPD spectra showed that a number of acid sites, especially those of strong acidity, is reduced with the increasing of Ce incorporation. Incorporation of metal ions gave rise to more silica-islands in the CeAPSO-34 framework. CO₂-TPD showed that basic sites on the surface of modified samples are due to the presence of Ce-containing species incorporation into the framework of CeAPSO-34 molecular sieves. The performance of the catalysts was studied in methanol to olefin reactions at 425 °C under the atmospheric pressure. The results showed that the incorporation of cerium ions had great effects on the structure and acidity of the molecular sieves. All SAPO-34 and MeAPSO-34 molecular sieves were the very active and selective catalyst for light olefins production. Cerium incorporation improved the catalyst lifetime and favored the ethylene and propylene generation. However, an excess Ce content resulted in an inferior catalytic performance and stability. Therefore, there existed optimal cerium content for a specific SAPO-34.     

离子液体在低碳烯烃/烷烃分离中的应用研究进展

低碳烯烃/烷烃的高效分离是石油化工领域可持续发展的关键过程之一,传统的低温精馏过程选择性低、能耗大。离子液体作为一种结构可调的绿色溶剂为低碳烃的高效分离提供了新的思路。本文综述了近年来国内外离子液体在低碳烯烃/烷烃分离中的研究进展,总结了常规离子液体、功能化离子液体以及含过渡金属的离子液体在低碳烯烃/烷烃分离中的应用,阐明了离子液体中阴阳离子、功能化基团、过渡金属与低碳烯烃相互作用的机理,着重介绍了合成金属功能化离子液体、添加金属盐、添加金属纳米粒子3种向离子液体中引入过渡金属方式的特点以及过渡金属的种类、比例,有机配体的类型对离子液体烯烃/烷烃分离性能的影响,并探讨了该方向的研究和发展趋势。     

Transformation of olefin over Ni/HZSM-5 catalyst

Olefins in the cracked naphtha can be transformed into aromatics and isoparaffin to reduce the olefin content as well as to improve the octane number. In this work, Ni/HZSM-5 bifunctional catalyst was prepared and was characterized by nitrogen adsorption, FT-IR analysis with adsorbed pyridine as well as by X-ray powder diffraction analysis. The activity of the catalyst was investigated with the transformation of 1-hexene. The experimental results show that the main reactions occurring over Ni/HZSM-5 at relatively low temperature are cracking and isomerization of 1-hexene, which results in the high concentration of olefin in the hydrotreated product. The double-bond isomerization of 1-hexene is dominant at low temperature (<220 °C) while the skeletal isomerization is elevated at high temperature, and the aromatization activity of the Ni/HZSM-5 catalyst is promoted by high temperature. The sulfided Ni/HZSM-5 catalyst shows higher aromatization activity than the reduced one and the zeolite supported Ni catalysts show comparatively better stability than that without metal components.     

Catalytic properties of various MgO catalysts for oxidative coupling of methane

A series of MgO catalysts for the oxidative coupling of methane prepared by different methods have been investigated. Specific surface area, XRD and XPS measurement results reveal that at lower temperatures catalysts with larger specific surface area, larger lattice distortion, smaller crystal dimension, and higher amount of unsaturated coordinated surface oxygen give higher catalytic activity. However, if we compare the catalytic properties of the samples in terms of unit surface area, the dependence of catalytic properties of the samples will be different.