首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
An investigation has been conducted into the staged synthesis of 2-methylimidazole from ethylenediamine and acetic acid in the presence of a bifunctional aluminoplatinum catalyst. It has been shown that the formation stage of 2-methylimidazoline occurs more quickly on -Al2O3 than its dehydrogenation on the Pt centers. From a comparison of the processes of dehydrogenation of 2-methylimidazoline in the molten phase and in aqueous solution it follows that the water eliminated in the imidazoline formation stage could cause the decrease in activity during the dehydrogenation on the Pt centers. The structures of the secondary and intermediate products have been established for each stage of the process and their formation routes are discussed.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 1997–2002, September, 1992.  相似文献   

2.
The formation of 1-ethyl-2-methylimidazole (1-Et-2-MI) and 1-ethyl-2-methylimidazoline (1-Et-2-MIN), intermediates in the synthesis of 2-methylimidazole (2-MI) from ethylenediamine (EDA) and AcOH in the presence of a platinum-on-alumina catalyst, was studied. Using CH3 14COOH the incorporation of two acetate units into 1-Et-2-MI and 1-Et-2-MIN molecules was demonstrated. The same products were also obtained on dehydrogenation of 2-methylimidazoline (2-MIN) under mild conditions (220–230 °C). A part of the latter is transformed to N-ethyl ethylendiamine (EEDA) and EDA. These facts indicate that both 1-Et-2-MI and 1-Et-2-MIN result from hydrogenolysis of the imidazoline ring with subsequent ethylation. A reverse reaction, the C5-cyclization of EEDA, was also observed. The formation of 2-MI is favored by increasing temperature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 937–940, May, 1993.  相似文献   

3.
利用热力学基础数据和相关软件对F-T合成催化剂COS中毒的热力学进行了计算。在热力学上,Ru、Fe、Co的COS中毒在F-T合成反应可以发生的条件下均是自发过程。F-T合成反应体系中10-9级的COS即可使Ru基催化剂中的金属Ru生成RuS2而中毒。Fe和Co毒化后生成的硫化物种类较多,对反应的热力学计算结果表明,对于不同的反应,其平衡常数的差异很大,对应中毒反应发生时,所需COS的浓度也不同。由于Fe基F-T合成催化剂活性相的复杂性,利用对催化剂相关性质的修饰开发具有一定抗硫性的铁基F-T合成催化剂是可行的;对于Co催化剂,利用F-T合成的反应特点和催化剂改性开发具有一定抗硫性催化剂也是可能的。  相似文献   

4.
The reduction process and the surface properties of industrial prereduced triply and doubly promoted iron catalyst for ammonia synthesis have been studied using thermogravimetry, thermal desorption of N2 and X-ray diffraction. The properties of both catalysts have been discussed on the basis of the double layer model of iron catalyst. A concept of facet formation on the active surface of the catalysts has been proposed. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

5.
采用并流沉淀法分别制备了CuO-CeO2(物质的量比为5:1)、CuO-ZnO(物质的量比为5:4)、CuO-ZnO-CeO2(物质的量比为5:4:1)三组目标催化剂,通过X射线衍射(XRD)、氢气升温还原(H2-TPR)、CO2程序升温脱附(CO2-TPD)、氮气吸附-脱附、X射线光电子能谱(XPS)、N2O滴定表征技术对催化剂的物化性能进行了测试,并在高温高压微催化反应器中对催化剂进行活性评价。研究了CuO-ZnO-CeO2组成对CO2加氢合成甲醇的影响。结果表明,与二组分催化剂相比较,三组分CuO-ZnO-CeO2催化剂物化性能及催化活性发生了很大变化,催化剂表面碱性位增强,热稳定性增强,CuO颗粒粒径变小,铜分散度以及氧空位浓度提高,最终催化活性显著提高。其中,CuO-ZnO-CeO2催化剂中,CuO颗粒粒径为8.2nm,铜的比表面积为68.4m2/g,铜分散度为7.19%,甲醇的选择性和收率分别为48.6%和0.057mmol/(g·min),催化剂活性较好。  相似文献   

6.
A new thermal‐latent hydrosilylation catalyst consisting of H2PtCl6 and polymers bearing amine moieties is described. In the presence of aminated polymers, the catalytic activity of H2PtCl6 was suppressed remarkably in the model reaction of triethylsilane with trimethylvinylsilane, whose effect was remarkably higher in comparison with monomeric amines. On heating, however, sufficient catalytic activity was attained where the activation temperature was dependent on the amine content in the polymer and polymer structure. Furthermore, this catalyst system was applied to the curing process of silicone resin to confirm the thermal‐latent character of the catalyst. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 804–809, 2000  相似文献   

7.
采用完全液相法以不同的铜源和锌源为原料制备了CuZnAl催化剂,在浆态床反应器中考察了其催化合成气合成乙醇的性能,并采用XRD、H2-TPR、NH3-TPD-MS及BET技术对催化剂进行表征。结果表明,以乙酸铜替换硝酸铜,抑制了热处理过程中Cu2O的还原,提高了催化剂的比表面积,为催化剂具有较高的乙醇选择性提供了适宜的酸中心和孔径,其总醇选择性达45.6%,总醇中乙醇所占比例达28.7%。  相似文献   

8.
[reaction: see text] A novel amino alcohol-based Ir bifunctional complex acts as an efficient catalyst for oxidative lactonization of 1,4- or 1,5-diols with a substrate-to-catalyst molar ratio of 200-1000 in acetone or butanone. The reaction proceeds with broad functional group tolerance to give lactone in high yield at room temperature. The catalyst precursor Cp*IrCl[OCH(2)C(C(6)H(5))(2)NH(2)] is isolated and characterized by a single-crystal X-ray analysis.  相似文献   

9.
考察了不同助剂(Mn、Zn、Co)对CuFeZr催化剂用于合成气制混合醇的影响。借助BET、XRD、H2-TPR等对其物化性质进行了表征,结果表明,加入助剂可减小颗粒粒径并且增强对CO的吸附能力以及催化剂表面碱性,其中,加入Zn可以增强CuFe间的相互作用,改善CuFeZr催化剂的还原性质,提高对CO的吸附能力,以及提供最强的表面碱性。用固定床反应器对催化剂的反应性能进行了评价,反应结果表明,加入Zn可以显著提高CuFeZr催化剂用于合成气制混合醇的反应活性及醇选择性,使醇时空收率从0.026 g/(gcat·h)提高至0.071 g/(gcat·h)。由于循环条件下,反应产物CO2同时也是原料气的组成成分,进一步地探究了原料气中CO2浓度对催化剂反应性能的影响。结果表明,加入CO2可提高CO转化率和醇以及烃的收率,但阻碍链增长反应并使得产物烯烷比降低。其中,在所考察浓度范围内,原料气中含有2.5%的CO2最有利于醇和烃的生成尤其是低碳醇和低碳烃的生成。  相似文献   

10.
研究了煅烧温度对ZnCr基催化剂合成异丁醇性能的影响。结果表明,随着煅烧温度的升高,催化剂的活性和产物分布都发生了较大的变化。催化剂在较低的温度下煅烧,液相产物中醇主要是甲醇和异丁醇;在较高的温度下煅烧,液相产物醇的分布符合A-S-F方程。用BET、XRD、H2-TPR、XPS等技术手段对催化剂织构参数、体相结构、还原性能、表面组成进行表征。结果表明,在300℃煅烧时,催化剂中的ZnO和Cr2O3未完全形成非计量尖晶石ZnxCr2/3(1-x)O;400℃煅烧时,催化剂中形成了最多量非计量尖晶石ZnxCr2/3(1-x)O;当煅烧温度高于400℃时,随着煅烧温度进一步升高,非计量尖晶石ZnxCr2/3(1-x)O逐步发生了分解,生成了更多量的ZnO和Cr2O3,导致催化剂的活性随之下降。进一步证明了非计量尖晶石ZnxCr2/3(1-x)O是该催化反应活性相。  相似文献   

11.
The synthesized supported undecatungstophosphate has been proven to be successful for acid catalyzed as well as oxidation reactions, especially, in obtaining 98.5% conversion of styrene and 100% selectivity for benzaldehyde.  相似文献   

12.
13.
An addition-cure liquid silicone rubber (ALSR) with ureido-containing MQ silicone resin (U-MTQ) was prepared by hydrosilylation with platinum catalyst (Pt). ALSR samples were characterized by thermogravimetric analysis (TGA) and thermogravimetry coupled with infrared spectroscopy (TG-FTIR), and the char layers of ALSR samples after inclined plate tracking and erosion test (IPT) were characterized by X-ray photoelectron spectroscopy (XPS). The effects of Pt content (5–100 ppm) on the curing characteristics, mechanical properties and tracking and erosion resistance of ALSR were investigated. It was found that the cure rate increased with increase of Pt content. When the Pt content was 10 ppm or 15 ppm, the ALSR had excellent tracking and erosion resistance, all specimens could pass the 4.5 kV level in IPT, and the erosion rate was only 0.13% and 0.15%, respectively. ALSR samples possessed optimum mechanical properties and thermal stability when the Pt content was 15 ppm. TG-FTIR results showed that ALSR generated less carbonyl compounds (CH2O) and cyclic oligomers but more methane (CH4) when the Pt content was 15 ppm. This demonstrated that there were lower levels of the oxidation of methyl groups and the main chain unzipping degradation of ALSR, and more homolysis of Si-CH3 during the degradation. The XPS results also showed that the macromolecular radicals would further cross-link to form a firm Si-C ceramic barrier to protect ALSR samples under Pt catalysis and high temperature, thus the tracking and erosion resistance of ALSR could be improved.  相似文献   

14.
15.
浸渍溶液pH值对Co/TiO2催化剂F-T反应性能的影响   总被引:2,自引:2,他引:2  
Fischer—Tropsch合成(简称F—T合成)是煤和天然气转化制取液体燃料的重要途径,催化剂的研制与开发是该过程实现工业化的关键步骤。钻基催化剂以其较高的加氢反应活性、较高的长链烃选择性和较低的水煤气变换活性而成为F—T合成中最有前途的催化体系之一。钴基催化剂的制备通常采用浸渍法。除了能够提高催化剂的比表面积和分散度,载体可以与金属发生相互作用而改变活性金属组分的结构组成、电子状态等,从而影响催化剂的催化反应性能。TiO2作为F—T合成的载体近年来受到普遍的关注。文献[7,8]是针对TiO2载体的低表面有针对性地添加无机氧化物黏接剂,提高金属钴的负载量,从而改进催化剂的反应性能;或者是添加助剂及第二金属组分以提高催化剂分散与还原性能。本文通过调节浸渍液pH值控制钻钛的相互作用并与催化剂反应性能关联,以期为催化剂制备条件的选择提供参考。  相似文献   

16.
17.
采用连续流动微反装置和原位漫反射红外光谱法考察了Ni/SiO2及添加ZrO2助剂的Ni/ZrO2-SiO2催化剂CO甲烷化催化活性和吸附性能。结果表明,在CO体积分数 1%、空速 5000h-1、常压的反应条件下,200℃时Ni/ZrO2-SiO2催化剂可将CO完全转化。而相同反应条件下Ni/SiO2催化剂上CO的转化率仅为35%,直至270℃时方可将CO完全转化。由此可见,ZrO2助剂的添加明显提高了Ni/ZrO2-SiO2催化剂的CO甲烷化催化活性。同时,ZrO2助剂的添加显著提高了Ni/ZrO2-SiO2催化剂对CO的吸附能力,H2存在时可通过在较低温度时形成较多的桥式羰基氢化物来提高Ni/ZrO2-SiO2催化剂的CO甲烷化催化活性;CO甲烷化反应条件下,Ni/SiO2和Ni/ZrO2-SiO2催化剂上C-O键的削弱和断裂是经由羰基氢化物 多氢羰基氢化物的途径,而不是经由C-O键的直接断裂途径。  相似文献   

18.
The Cu/SiO2 catalyst prepared by incipient wetness method exhibited very high activity and selectivity for the vapor-phase synthesis of JV-butylaniline from aniline and 1-butanol. When Cu loading was 0.70 mmol/g-SiO2 and the catalyst precursor was calcined at 500 ℃, 1-butanol conversion reached 99%, and the selectivity of JV-butylaniline exceeded 97%.  相似文献   

19.
The Cu/SiO2 catalyst prepared by incipient wetness method exhibited very high activity and selectivity for the vapor-phase synthesis of N-butylaniline from aniline and 1-butanol. When Cu loading was 0.70 mmol/g-SiO2 and the catalyst precursor was calcined at 500 ℃, 1-butanol conversion reached 99%, and the selectivity of N-butylaniline exceeded 97%.  相似文献   

20.
The kinetic behavior of deuteriation of nitrobenzoic acids has been studied at 130 °C in the presence of homogenous platinum salt catalyst in a medium containing deuteriated acetic acid in heavy water. The quasiunimolecular H/D exchange rate constants for particular position of aromatic ring hydrogens were determined by proton NMR integration signal. The difference in the kinetics patterns of H/D exchange has been shown for the 2-nitro-, 3-nitro- and 4-nitrobenzoic acid.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号