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261.
Mo/HZSM-5上甲烷芳构化的诱导期钼物种的部分还原和碳物种的沉积 总被引:4,自引:0,他引:4
在无氧条件下,Mo/HZSM-5催化剂表现出良好的催化甲烷芳构化性能.采用脉冲反应,TPSR,TPR,UV Raman,XRD和BET等手段研究了反应的诱导期.BET和XRD结果表明,钼物种较好地分散于分子筛的外表面和孔道内.TPSR和TPR结果表明,在苯产生之前催化剂上至少有两种不同形式的高价钼物种被部分还原.参照MoO3/Al2O3的TPR结果,认为这两种高价钼物种可能是以多聚酸盐和微晶形式存在的MoO3.UV Raman光谱表明,催化剂表面确实存在八面体配位的多聚酸盐铝物种;而XRD没有检测到微晶铝物种的存在.脉冲反应结果表明,预还原可以缩短反应诱导期,而某种类型积碳的存在对缩短反应诱导期更为有利.根据以上结果,认为诱导期是反应活性相逐渐形成的过程,包括高价钼物种的部分还原和碳物种的沉积,而后者可能对反应更为重要. 相似文献
262.
Jian Zheng Yuan Chun Jialu Dong Qinhua Xu 《Journal of molecular catalysis. A, Chemical》1998,130(3):3085-277
Modification of non-acidic KL zeolite by chemical vapor deposition (CVD) of Si(OEt)4 and (CH3)3Si–O–Si(CH3)3 followed by Pt loading was used to study the influence of zeolite support on the aromatization of n-hexane. Deposited on the framework oxygen ions of the non-acidic zeolite, the silica layer effectively narrowed the pores of KL zeolite. But owing to the appearance of new basic sites, such as potassium oxide (K2O), the interaction between Pt metal and zeolite support was strengthened, causing Pt particles to be more electron-excess. n-Hexane pulse-flow microreactions were carried out to study the effects on the aromatization reactivity and sulfur poisoning properties. 相似文献
263.
The effect of the intermetallic compound Zr2Fe as a hydrogen acceptor in the aromatization of propane in the presence of a zeolite catalyst has been investigated. High-silica, pentasil-type zeolite ZVM was modified by Zn, Ga, or Pt. The intermetallic compound was found to remove hydrogen formed during aromatization, resulting in a 2-to 5-fold increase in the yields of aromatics and in a marked increase in selectivity for aromatization. The magnitude of this effect is shown to be dependent on the catalyst composition.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 61–63, January, 1993. 相似文献
264.
T. V. Vasina O. V. Masloboyshchikova O. V. Chetina E. G. Khelkovskaya-Sergeeva 《Russian Chemical Bulletin》1994,43(4):555-558
The catalytic properties of Pt, Zn, and Ga deposited on supports of various natures (Al2O3, SiO2, NaZSM, and HZSM) in the dehydrogenation and aromatization of ethane were investigated. Pt-containing catalysts are the most active in the conversion of ethane: the selectivity with respect to ethylene is 25–87 % depending on the nature of the support. In the presence of Zn- and Ga-containing catalysts the yield of ethylene is 2–3 times lower than with Pt-catalysts. With HZSM modified by Pt, Zn, or Ga aromatic hydrocarbons (ArH) and methane are the main products of ethane transformation. Ga/HZSM is the most efficient catalyst of the aromatization of ethane under the conditions studied (550 °C, 120 h–1).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 606–609, April, 1994. 相似文献
265.
Sulur G. Manjunatha Sreekanth BachuVasantha Krishna Kadambar Andiappan MuruganSridharan Ramasubramanian Puranik RamachandraSudhir Nambiar 《Tetrahedron letters》2014
A simple and efficient procedure for the syntheses of 4-acetamido-1-arylindazoles from corresponding 1-aryl-6,7-dihydro-5H-indazol-4-one oximes by Semmler–Wolff aromatization using acetic anhydride and sodium iodide is reported. 相似文献
266.
267.
《Green Chemistry Letters and Reviews》2013,6(2):173-177
One-pot silica promoted selective aromatization of ring-A of cholesterol using N-bromosuccinimide (NBS) has been performed. The structure of the compound has been characterized by spectral analysis (UV, FT-IR, NMR, and Mass). 相似文献
268.
A variety of Hantzsch 1,4-dihydropyridines were oxidized to the corresponding pyridines catalyzed by a catalytic amount of ferric perchlorate. The reaction was carried out in ionic liquid at room temperature, and the products were isolated in good to excellent yields. At the same time, the catalytic system was found to be reusable. 相似文献
269.