THE CRYSTAL STRUCTURE AND SPECTROSCOPIC PROPERTIES OF THE COMPLEXES FORMED BY TiCl_4 AND MgCl_2 WITH ESTERS——A RESEARCH ON THE STRUCTURE OF HIGHLY EFFICIENT CATALYSTS FOR POLYPROPYLENE

The complexes of TiCl_4, MgCl_2 and esters which are significant in industry have beenstudied by X-ray diffraction, IR and uv spectra. Their single crystal structures have also beendetermined. TiCl_4 and PhCOOEt can form two complexes, TiCl_4·L and TiCl_4·2L·MgGl_2, CH_3COOEtand H_2O form complex MgCl_2·2CH_3COOEt·2H_2O. All of them are molecular crystals. Theirspacial groups are C_(2h)~5-P2_1/c, C_(2h)~5-P2_1/n and C_(2h)~6-C_2/c respectively. From the XRD powderpattern, it has been ascertained that TiCl_4·L is formed in the process of the catalyst prepara-tion with milling-soaking method. Comparison between the IR spectra of the catalyst and Mgcomplex indicates that the coordinative bonds of the surface complex of the catalyst are verysimilar to that of the complex.     

CuCl等在γ-Al_2O_3表面的分散及其对乙烯吸附的研究

本文研究了CuCl在γAl_20_3表面上的分散和乙烯在CuCl/γ-Al_2O_3上的吸附和程序升温脱附情况.X射线相定量法和紫外漫反射法都表明用烘烤法或浸渍法制备的CuCl/γ-Al_2O_3中CuCl在γ-Al_2O_3表面可达单层分散.X射线相定量法测得CuCl在γ-Al_2O_3表面上的最大分散量为0.095克CuCl/100米~2γ-Al_2O_3表面.吸附和程序升温脱附研究表明,分散在γ-Al_2O_3表面上的CuCl在室温常压下便可吸附乙烯,比纯CuCl吸附乙烯的能力提高千倍以上,分散后的CuCl吸附乙烯的分子比可高达0.19C_2H_4分子/Cu~ 离子.分散在γ-Al_2O_3表面上的CuCl可与C_2H_4,C_3H_6等形成表面π络合物,但要求有合适的几何环境.这些结果可供利用CuCl/γ-Al_2O_3分离含不饱和键分子时参考。     

具有优异热稳定性的磷修饰氧化钛及其对水中污染物的降解

通过水热法制得磷修饰氧化钛,它在亚甲基蓝和对氯苯酚的降解以及消除大肠杆菌的实验中都表现出高于纯氧化钛的优异活性,甚至优于商品化催化剂P25.在捕获剂中降解亚甲基蓝的实验证实羟基自由基是最主要的活性氧物种,并且磷修饰氧化钛在光照下拥有较强的产生羟基自由基的能力,同时,磷修饰氧化钛具有非常高的热稳定性,直到950℃才会发生...     

蔗糖辅助制备大比表面积氧化铝

The preparation of alumina with large surface area, certain phase and porosimetry has always been one of important researches. A new method using much less sucrose (the molar ratio of sucrose to Al^3 =0.5) was developed to prepare γ-Al2O3 with large surface area and high thermal stability. Firstly, ammonium hydroxide was dropped to aqueous solution of aluminum nitrate and sucrose. The resulted precipitate in suspension washeated until a homogeneous gel was ohtained. Then the gel was dehydrated at 110℃ to get a fluffy black precursor. Finally, γ-Al2O3 with A=345m^2/g was prepared by calcining the preeursor at 600℃ for 24h. The precursor and the obtained γ-Al2O3 were characterized by DTA-TG, N2 adsorption-desorption isotherms, XRD and TEM, According to the dispersion behaviors of organic compounds on supports, the related mechanism was discussed.     

一氧化碳中选择氧化除氢催化剂的研究

Several supported Pd catalysts were prepared and their catalytic activity for selective oxidation of hydrogen was studied. The results show that the variety of the supports has great effect on the catalytic activity. The space velocity and the Pd loading show also certain influence. The most active catalyst Pd/C A can selectively remove H 2 at 170～200℃ and 1?800 h -1 from a feed gas consisting of H 2 (0 197%), O 2 (0 103%), CO (40%) and N 2 (balance). When CO content in the feed gas increases to 78%, the activity of the catalyst only decreases a little, indicating that the results obtained here seems applicable to the removal of H 2 from pure CO.     

氧气氛下固溶体Sn1-xZrxO2选择催化还原一氧化氮的增强效应

Reduction of NO by hydrocarbons in an oxidizing atmosphere is an attractive way to substitute the traditional NOx abatement technology from a viewpoint of practical application to the deNOx systems of diesel and lean-burn gasoline engine exhausts[1～3]. In this study, a series of novel catalysts Sn1 - xZrxO2 solid solutions were prepared by substituting some of the Sn4 + ions in a cassiterite lattice with Zr4+ ions.These solid solutions performed significantly higher activity than pure SnO2 presented on the selective reduction of NO with propene in the poresence of O2.     

水对氩气中催化法分解甲烷制备单壁碳纳米管的影响

用"柠檬酸法"制备W-Fe-MgO和Mo-Fe-MgO催化剂,以Ar为载气,在1273 K催化分解CH₄制单壁碳纳米管(SWCNTs),发现原料气中加水和不加水对产物的影响极大.不加水时,产物中SWCNTs含量极低,以无定形碳和多壁碳纳米管(MWCNTs)为主;加少量水时,产物绝大部分是直径在1～3 nm左右SWCNTs形成的管束.在1273 K下,H₂O分压在0.67～2.0 kPa时得到SWCNTs含量较高的产物,100 mg催化剂上的碳产量为40～52 mg.进一步增加原料气中的水分压到2.7 kPa,则无碳产物生成.通过对比实验、粗产物XRD分析和对反应尾气质谱检测,可得如下结论:在Mo-Fe-MgO和W-Fe-MgO催化剂中的金属氧化物和碳化物是CH₄分解为无定形碳的活性相,Fe-Mo合金相是CH₄分解得SWCNTs的主要活性相.当反应气中无水时,CH₄在催化剂中的氧化物和碳化物上生成的无定形碳起决定作用,而Fe-Mo合金上生成SWCNTs的反应相对减少,使产物中SWCNTs含量很低;反应气中有少量水时,水抑制了催化剂中氧化物和碳化物上无定形碳的生成,使CH₄在Fe-Mo合金上分解生成SWCNTs成为主反应,此时产物中SWCNTs含量较高;水量过大时,催化剂中氧化物不能被还原为金属,故无SWCNTs生成,而此时水也抑制了无定形碳的生成,因而无任何碳产物生成.     

镁-钛系聚乙烯高效催化剂的机理研究

本文对一种典型的反应法制聚乙烯高效催化剂的各步反应产物进行了研完:第一步氯化镁加乙醇反应,生成醇合物MgCl₂·nC₂H₅OH,其作用是将氯化镁晶格破坏;第二步加烷基铝,第三步加四氯化钛,其作用是与醇合物中的醇反应使之溶解,重新生成高分散的氯化镁微晶,活性组份钛化合物高度分散在氯化镁微晶表面上,故催化剂具有高活性。用这种反应法制得的高效催化剂,载体分散度高,内部孔隙多,有利于传质,因而比一般研磨法制得的高效催化剂聚合收率高。X光衍射发现在其他一些聚乙烯高效催化剂中也存在微晶MgCl₂,说明它们的高活性机理是类似的。     

低温固相法制备高比表面积的纳米MgO

 以草酸和乙酸镁为原料,采用低温固相化学反应合成出前体MgC2O4·2H2O, 再通过焙烧得到纳米MgO. 采用X射线衍射、 N2物理吸附、透射电镜和热重-差热技术对前体和MgO样品进行了表征,并考察了焙烧气氛的影响. 结果表明,在流动干燥的氮气中520 ℃焙烧4 h后制得了比表面积高达412 m2/g的纳米MgO; 此MgO为面心立方结构,晶粒尺寸为4～5 nm, 粒子堆积成在一定程度上长程有序的介孔结构,并具有十分优良的抗高温烧结性能, 600和800 ℃焙烧2 h后,其比表面积仍分别高达357和153 m2/g.