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1.
利用小型固定流化床实验装置,对C4烃类在催化裂化催化剂上催化转化反应规律进行了实验研究,考察了不同反应温度及空速对C4烃类催化转化反应的产物分布和组成的影响。实验结果表明,催化裂化催化剂对C4烃类具有一定芳构化和裂化性能,在适宜的反应条件下,可增产芳烃和丙烯;在C4烃类催化转化过程中,丁烯是主要的反应物,而丁烷几乎不反应;低反应温度有利于增产芳烃,高反应温度有利于增产丙烯。较低的空速对增产芳烃和丙烯都有利。根据双分子反应机理和反应结果,建立了C4烃类在催化裂化催化剂上催化转化过程的反应网络。对C4烃类催化转化历程分析表明,中间产物碳五和碳六烯烃较弱的二次裂化性能是C4烃类在催化裂化催化剂上催化转化过程中乙烯和丙烯产率较低的主要原因。  相似文献   

2.
通过对Cu/HZSM-5分子筛上乙醇的无氧芳构化反应主要产物的在线定量分析,评价了催化剂组成、反应温度、气体空速对芳构化活性的影响。结果表明:Cu/HZSM-5分子筛具有良好的芳构化性能。当金属Cu含量为5%,催化温度为300℃,乙醇气体空速为167h-1时,催化剂具有最好的芳构化效果,乙醇的转化率为35.41%,苯的选择性达到了27.59%。对不同催化温度下反应产物中乙烯生成量的变化情况的研究,证实了乙烯是此催化反应过程的一种最初产物。  相似文献   

3.
Zn/HZSM-5分子筛催化剂对丙烷芳构化反应中芳烃分布的影响   总被引:5,自引:0,他引:5  
采用浸渍法,制备了Zn/HZSM-5分子筛催化剂,考察了锌含量、反应温度对丙烷芳构化反应的影响,根据产物分布情况,讨论了锌物种在丙烷芳构化反应中的作用,并以氮气作载气,带入烷基芳烃乙苯、二甲苯、甲苯,考察了温度对催化剂脱烷基反应的影响。结果表明,锌物种不公能够催化丙烷的脱氢活化,提高其转化率,而且能促进随后进行的齐聚、脱氢芳构化第一系列反应,提高芳烃的选择性,并进一步催化烷基芳烃的脱烷基反应,导致  相似文献   

4.
水热处理Zn/HZSM-5催化剂对丙烷芳构化反应的影响   总被引:7,自引:0,他引:7  
解红娟  王军威 《分子催化》2000,14(4):289-293
考察了水热处理对Zn/HZSM-5催化剂丙烷芳构化反应的影响,并采用FT-IR手段,研究了处理温度对催化剂表面酸性的影响,结果表明,随着水热处理温度的升高,单位晶胞中的B酸中心数减少,而上酸中心数增加,丙烷的转化率和芳烃选择性升高,水热处理温度为400℃时达到最大值,此时催化剂的脱氢中心Zn^2+与聚合,环化的B酸中心为最佳匹配状态,随着处理温度的进一步升高、B酸中心数显著下降,丙烷的转化率和芳烃  相似文献   

5.
 采用水蒸气和碱性氨水蒸气在500℃下对纳米HZSM-5沸石催化剂进行了水热处理改性,并用XRD,IR,NH3-TPD和XRF对催化剂进行了表征.以降低FCC汽油(≤70℃馏分)烯烃含量为探针反应,考察了不同水热处理介质对催化剂酸性质和催化性能的影响.结果表明,经不同介质水热处理后,纳米HZSM-5沸石中约10%的Al2O3被脱除,总酸量降低,导致积炭失活的强酸中心明显减少;不同水热处理介质对催化剂的总酸量没有明显影响,而对酸中心类型分布的影响较大.水热处理改性使催化剂活性的稳定性明显改善,初始活性降低.同时,水热处理改性降低了催化剂对芳构化反应的催化活性,提高了对异构化反应的催化活性.采用氨水(0.5mol/L)蒸气处理的纳米HZSM-5催化剂其降烯烃催化活性更为稳定.在给定的反应条件下,FCC汽油的烯烃含量(φ)由65.9%降低到约26%,产物中烯烃、芳烃(主要是C7~C9芳烃)和烷烃含量分别保持在25%,19%和55%左右,辛烷值基本不变.  相似文献   

6.
在脉冲微反装置上考察了不同的预处理条件对Zn/Al-CLM催化剂的丙烷芳构化反应的影响。结果表明,丙烷在Zn/Al-CLM催化剂上具有一定的的反应活性和芳烃选择性,而且芳构化主要转化为苯;载体Al-CLM的焙烧温度、金属锌负载量、活化温度等对Zn/Al-CLM催化剂的丙烷芳构化性能具有重要影响。载体经500℃预焙烧制备的Zn/Al-CLM催化剂具有最好的柱结构保留度,从而表现出最佳的芳构化性能;随着锌含量的增加,Zn/Al-CLM催化剂的酸量增大,从而使丙烷转化率增大,而选择性则是锌含量质量分数为5.8%时具有极大值;400℃活化处理可使Zn与Al-CLM之间具有适中的相互作用,从而使得Zn/Al-CLM具有较高的芳烃收率。  相似文献   

7.
 考察了 H-ZSM-5 和 Zn/H-ZSM-5 催化剂的二甲醚芳构化性能. 结果表明, H-ZSM-5 分子筛催化剂酸性的增强和酸中心的增多有利于二甲醚芳构化. 当在 H-ZSM-5 催化剂中加入 2% Zn 时, 在 360 oC 下反应时总芳烃收率从 50.0% 增加至 66.2%, C8 芳烃收率从 28.6% 增加到 39.0%. 反应温度升高到 480 oC 时, 总芳烃收率增加至 78.0%.  相似文献   

8.
研究了反应温度、空速、Mo担载量和焙烧温度对MoO3/HZSM-5催化剂上甲烷的芳构化反应的影响.HZSM-5分子筛的Bronsted酸性、孔道结构和Mo在分子筛中的分布是影响催化性能的重要因素.HZSM-5上Mo担载量为2~3%时活性最佳,在1013K反应温度下甲烷转化率可达9%,芳烃选择性大于90%.空速影响的实验表明乙烯是反应的初始产物.在此基础上提出了"甲烷酸助异裂活化"的新概念、"金属钼类碳烯中间物"的新观点和甲烷芳构化的可能机理.  相似文献   

9.
以HZSM-5(SiO2/Al2O3=38)为载体,偏钨酸铵为钨源制备了双功能催化剂WC/HZSM-5,考察了其催化正己烷芳构化反应性能,并采用X射线衍射、扫描电子显微镜、X射线能量散射谱和程序升温氨脱附等手段对催化剂进行了表征,探讨了制备方法和WC含量对WC/HZSM-5催化剂性能的影响.结果表明,采用原位还原碳化法制备的WC/HZSM-5(RC)催化剂上正己烷芳构化反应性能优于浸渍法制备的WC/HZSM-5(IP).5%WC/HZSM-5(RC)样品在反应初始阶段芳烃选择性为10.28%,而HZSM-5上的仅为2.56%.WC/HZSM-5(RC)催化剂上反应产物中轻质芳烃(苯、甲苯和二甲苯)含量增加,重质芳烃C9+含量降低,其催化性能优于Pt/HZSM-5催化剂.产物分布的变化可能是由于WC与分子筛间的协同作用所致.  相似文献   

10.
研究了催化剂制备方法、Mo含量、预处理条件和反应条件对在无氧条件下HZSM-5负载的Mo基催化剂上甲烷直接芳构化反应的影响,及积炭和烧炭再生对催化剂性能的影响.发现Mo含量为3.5~4%时催化剂活性最高,生成苯的速率高达1.2×10-3mol·g-1·s-1.降低空速和提高反应温度均有利于甲烷的直接芳构化.随着反应的进行,乙烯的选择性不断提高,苯的选择性则不断降低.XPS结果表明,反应后催化剂表面积炭,且研磨法制备的催化剂中Mo6+被还原成不具活性的金属态Mo0.卡宾中间体(Mo=CH2)可能是甲烷芳构化反应的起始物.  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

15.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

16.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

17.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

18.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

19.
20.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).  相似文献   

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