Fe(2-EHA)(3)/Al(i-Bu)(3)/hydrogen phosphite catalyst for preparing syndiotactic 1,2-polybutadiene

Polymerizing 1,3-butadiene into syndiotactic 1,2-polybutadiene with art iron(III) catalyst system has been investigated. Activity of the catalyst was affected by the type of cocatalyst alkylaluminum and the phosphorus compound as an electron donor, molar ratio of catalyst components, and their aging sequence and aging time of the catalyst. The microstructure and configuration of the polymer was decided by the catalyst components, the higher [Al]/[Fe] molar ratio tending to yield syndiotactic 1,2-polybutadiene, while the higher [P]/[Fe] molar ratio favors the formation of amorphous 1,2-polybutadiene.

La对Pd/Al/蜂窝陶瓷催化剂高温活性与耐热稳定作用的研究

中国科学院山西煤炭化学研究所

Fe改性工业Cu/Zn/Al催化剂甲醇水蒸气重整反应制氢的研究

中国科学院山西煤炭化学研究所

Preparation of W-Al alloys by mechanical alloying

W1-xAlx (x=0-0.86) alloys were synthesized by mechanically alloying the pure metal powder mixtures at designated compositions by conventional high-energy ball milling. The W-Al alloys were stable under high pressure and high temperature. The alloys were lighter than W. The hardness and oxidation resistance of the alloys was greatly improved compared to both W and Al. (C) 2002 Elsevier Science B.V. All rights reserved.

Carbon ceramic electrodes bulk-modified with nanoparticles of ferrocenebutyrate-intercalated Mg-Al layered double hydroxide

Ferrocenebutyrate-intercalated layered double hydroxide (FcLDH) was prepared by the coprecipitation method and characterized by PXRD, FTIR, TEM and elemental analysis. FcLDH nanoparticles in deionized water were deposited onto the surface of graphite powder to yield graphite powder-supported FcLDH, which was subsequently dispersed into methyltrimethoxysilane-derived gels to fabricate surface-renewable, stable, rigid carbon ceramic electrodes containing the electroactive ferrocenyl group. Cyclic voltammetric study revealed that peak currents of the FcLDH-modified electrode were diffusion-con trolled in 0.1 mol l(-1) KCl aqueous solution. In addition, the formal potential of the modified electrode is related to the activity of chloride ion with a Nernst slope of 56 mV per decade.

Cyclization in situ of isoprene polymerization catalyzed by Nd-Al bimetallic complex

Function of chloride and effect of various alkylaluminiums, C1/A1 molar ratio, solvents on cyclization in situ of isoprene polymerization catalyzed by Nd-Al bimetallic complex were studied. The structure of cyclized products was characterized by means of IR and H-1 NMR, The results indicated that in the course of isoprene polymerization with rare earth catalytic system, the function of alkylchloride introduced is terminating cis-polymerization and generating cationic species with alkyl-aluminums to initiate cyclization in situ. Soluble cyclized polyisoprene was obtained with fragments of cyclopolyisoprene.

Co-Cu-Al mixed oxides derived from hydrotalcite-like compound for NO reduction by CO

Various hydrotalcite based catalysts were prepared for catalytic removal of NO (NO reduction by CO). The general formula of hydrotalcite compounds (HTLc) was Co-Cu-Al-HTLc. Precalcination of these materials at 450 degrees C for NO reduction by CO, was necessary for catalytic activity. All catalysts except Co-A1 and Cu-Al have very good activity at lower temperature for NO reduction by CO. All samples were characterized by XRD and BET. The tentative reaction mechanism was also proposed.

Preparation, charactreization, and catalytic properties of Co-M-Al (M = transition metal) mixed oxides derived from hydrotalcite-like compound

Hydrotalcite-like compounds (HTLcs) CoMAlCO3, where M stands for Cr, Mn, Ni, Cu, or Fe, were synthesized by coprecipitation. After calcination at 450 degrees C, they became mixed oxides with spinel-like structure. The mixed oxides were characterized by XRD, BET, chemical analysis and the adsorption of NO. The catalytic decomposition of NO and its reduction by CO were studied over these mixed oxides. The study showed that the catalytic activity for removal of NO, was very high. The reaction mechanism is proposed and the effects of d-electrons of the transition metals on catalytic activity are elucidated.

The effect of preparation conditions on the catalyst Nd(P-507)(3)/H2O/Al(i-Bu)(3) for the polymerization of styrene

The catalyst system neodymium phosphonate Nd(P-507)(3)/H2O/Al(i-Bu)(3) for the polymerization of styrene was examined. Effects of the addition order of the catalyst components, catalyst aging time and aging temperature on the catalyst activity and the polymer characteristics were investigated. The catalyst activity for isospecific polymerization of styrene increases with aging time and reaches the maximum with a catalyst aged for 45 min at 70 degrees C. The aging time that the catalyst needs to reach the highest activity for isospecific polymerization decreases with increasing aging temperature. The preformed catalyst and the in situ catalyst were compared with respect to the kinetic behavior of the styrene polymerization and the polymer characteristics.

Ti-Al系金属间化合物的价电子结构及其合金化行为

由固体和分子经验电子理论(EET)分析了Ti-Al系金属间化合物合金化前后的价电子结构,再计算了该系合金各相的均匀变形因子α和解理能Gc 值,据此分析了合金化对该系金属间化合物脆性的影响。结果表明,常量合金化元素Nb使Ti3Al基合金的α2相无序化,增加了韧的第二相,减弱了Ti-Ti共价键,综合导致α和Gc 值增大,使Ti3Al的脆性有本质改善;微量合金化元素Mn减弱了TiAl基合金的Al-Al共价键,并诱发孪生,使α和Gc 有所提高,在一定程度上降低了TiAl的脆性;TiAl3极低的α和Gc导致恶劣的本征脆性,Mn也难以改变其脆性本质

Nd-Al双金属配合物催化双烯聚合反应动力学

以Nd-Al双金属配合物为催化剂，考察了丁二烯和异戊二烯聚合反应的动力学，得到稳态聚合速率方程式为RP＝K［M］[ND］ｎ（ｎ＝１）；丁二烯比异戊二烯有更大的表观增长速率常数ｋ．这些与聚合体系中是否存在过量的烷基铝无关．对多组分稀土催化剂作用下异戊二烯聚合反应动力学方程中出现较高ｎ值的现象进行了初步的探讨