Dehydrogenation of n-butane over vanadia catalysts supported on silica gel

VOx/SiO2 catalysts prepared by impregnation method were used for catalytic dehydrogenation of n-butane to butenes and characterized by X-ray diffraction,FT-IR,UV-vis,Raman,and BET measurements.The effects of VOx loading and the reaction temperature on the VOx/SiO2 catalysts and their catalytic performances for the dehydrogenation of n-butane were studied.When the VOx loading was 12% g/gcat and reaction temperature was between 590 ℃ and 600 ℃,n-butane conversion and butenes yields reached the highest value under H2 flux of 10 ml/min and n-butane flux of 10 ml/min.Product distribution,such as the ratio of 2-butene to 1-butene and the ratio of cis-2-butene to trans-2-butene,was mainly influenced by the reaction temperature.     

Skeletal isomerization of butene over natural ferrierite

The conversion of butenes to isobutene was compared on chemically modified natural and synthetic H-ferrierite catalysts. The proper balance of extra-framework species together with properly chosen reaction conditions allowed 100% isobutene selectivity.     

Synthesis and characterization of high molecular weight atactic polybutene‐1 with a monotitanocene/methylaluminoxane catalyst system

A novel catalyst precursor, the monotitanocene (η⁵‐pentamethylcyclopentadienyl) titanium tricinnamyloxide [Cp*Ti(OCH₂? CH?CHC₆H₅)₃], was synthesized and employed for butene‐1 polymerization in the presence of methylaluminoxane. The effects of the polymerization conditions on the catalytic activity, molecular weight, stereoregularity, and regioregularity of the polymer so obtained were investigated in detail. The results show that the monotitanocene is desirable for the production of atactic polybutene‐1 coupled with good yields under typical polymerization conditions, high molecular weight (weight‐average molecular weight = 5.3–9.6 × 10⁵), and stereoirregularity with the Bernoullian factor B equal to 0.95, which indicates that chain‐end control is predominant. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4068–4073, 2001     

Coke precursor as an intermediate during the alkylation of isobutene/butene over a solid superacid

~~Coke precursor as an intermediate during the alkylation of isobutene/butene over a solid superacid~~     

Poly(1‐butene)/clay nanocomposites: Preparation and properties

The preparation and properties of poly(1‐butene) (PB)/clay nanocomposites are described for the first time. Nanocomposites were prepared with the melt‐intercalation technique, using organically modified clay. The X‐ray diffraction patterns portrayed well‐defined diffraction peaks at higher d‐spacing than pristine clay, confirming the intercalation of polymer in silicate layers. Because PB exhibits time‐dependent polymorphism, the effect of clay on the phase transformation of PB was examined with thermal analysis. The phase transformation from a metastable tetragonal form to a stable hexagonal form was enhanced because of incorporation of layered silicates in the polymer matrix. The nanocomposites exhibited about a 40–140% increase in storage modulus depending on the clay content and significantly lower coefficient of thermal expansion. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1014–1021, 2003     

Sn—Mo混合氧化物的结构与催化性能

Sn－Mo混合氧化物是一种较好的催化剂，它对低碳烯烃氧化制饱和酮［1］，丁烯氧化脱氢制丁二烯和丁二烯氧化制顺丁烯二酸酐[2]等选择氧化反应都有很好的催化活性．但是，由于其结晶度差，人们对Sn－Mo混合氧化物的形成过程研究较少，我们曾研究过不同配比的Sn－Mo混合氧化物的结构与催化活性的关系[3]．本文用XPS、XRD、ESR等方法研究了不同焙烧温度的Sn0.8Mo0.2混合氧化物的催化活性与结构，目的是进一步研究Sn－Mo混合氧化物的形成过程．称取45．2gSnCl2·2H2O溶于蒸馏水中，滴加氨水生成Sn（OH）2·xH2O白色沉淀，用NH4OH和…     

Estimation of Polymerization Conditions Needed to Make Ethylene/1‐olefin Copolymers with Specific Microstructures Using Artificial Neural Networks

Two artificial neural network models (forward and inverse) are developed to describe ethylene/1‐olefin copolymerization with a catalyst having two site types using training and testing datasets obtained from a polymerization kinetic model. The forward model is applied to predict the molecular weight and chemical composition distributions of the polymer from a set of polymerization conditions, such as ethylene concentration, 1‐olefin concentration, cocatalyst concentration, hydrogen concentration, and polymerization temperature. The results of the forward model agree well with those from the kinetic model. The inverse model is applied to determine the polymerization conditions to produce polymers with desired microstructures. Although the inverse model generates multiple solutions for the general case, unique solutions are obtained when one of the three key process parameters (ethylene concentration, 1‐olefin concentration, and polymerization temperature) is kept constant. The proposed model can be used as an efficient tool to design materials from a set of polymerization conditions.

     

Coke precursor as an intermediate during the alkylation of isobutane/butene over a solid superacid

Alkylation of isobutane/butene was conducted on a Brønsted-Lewis conjugated solid superacid. It is found that some hydrocarbons accumulated on the catalyst surface. These hydrocarbons, as called coke precursor, played an intermediate role at the initial stage of the alkylation before they lead the catalyst to lose its activity. The presence of the intermediate is beneficial to the alkylation between isobutane and butene, while increase the TMP content and TMP/DMH ratio in the products     

1－丁烯齐聚反应 X．羧酸镍／有机铝体系催化性能的调变

１－丁烯齐聚反应　Ｘ．羧酸镍／有机铝体系催化性能的调变高占先，李文忠，林青松，周科衍（大连理工大学化工学院，大连１１６０１２）关键词Ｚｉｅｇｌｅｒ催化剂，丁烯齐聚，卤代乙酸镍，有机铝，催化性能调变在［（η３Ｃ３Ｈ５）ＮｉＸ］２／ＡｌＥｔ１．５Ｃｌ１．...     

在H3PO4存在下2,3-二甲基-2-丁烯与乙酐的酰化反应

在H3PO4存在下进行了2，3－二甲基－2－丁烯与乙酐的酰化反应，结果表明，H3PO4是室温下催化2，3－二甲基－2－丁烯与乙酐酰化反应的有效催化剂，在H3PO4存在下，酰化产物的收率主要取决于：（a)H3PO4的用量，（b)乙酐的用量；（c)反应温度和（d)反应时间，在适宜反应条件下，所得3，3，4－三甲基－4－戊烯－2－酮（TMP）约为99％，另外还发现，反应体系中加入少量乙酸，不会明显减少酰化产物的收率，乙酐的纯度，反应物的加入顺序对该反应几乎没有任何影响，在有和没有溶剂CH2Cl2的条件下所得酰化产物的收率是可比的。