共查询到19条相似文献,搜索用时 46 毫秒
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甲烷在钼/含磷五元环沸石催化剂上的无氧芳构化 总被引:2,自引:0,他引:2
报道甲烷在无氧条件下,在一种不同于Mo/HZSM-5催化剂的钼/含磷五元环沸石催化剂上催化转化制高级烃类(苯等)的新反应,实验表明,在钼/含磷五元环沸石催化刘,当Mo浸渍的重分数为20%时,甲烷具有最佳反应活性,其转化率为9.23%,工选择怀为92.745,用BET、XRD、NH3-TPD和TPRcMo 相似文献
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负载型钼基催化剂上甲烷,乙烷无氧芳构化反应研究 总被引:1,自引:0,他引:1
研究了不同载体钼基催化剂上甲烷,乙烷的无氧芳构化反应。在所采用的载体中,HZSM-5具有最佳性能,对甲烷的芳构化反应,Mo/HZSM-5催化剂表现出较高的活性和芳烃选择性;而Mo/Al2O3或Mo/SiO2催化剂则相对较差。对于乙烷的反应,钼物种的存在更有利于甲烷或乙烯的生成,芳烃选择性相对较低。钼物种较强的断键能力可能是使甲烷C-H键活化的原因。 相似文献
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以含硼杂原子分子筛HBZSM-5为载体,考察了其担载MoO3后催化甲烷无氧芳构化反应的性能,并结合XRD,IR,TG和SEM等手段对催化剂进行了表征。实验结果表明,MoO3/HBZSM-5催化剂具有较高的甲烷芳构化活性,但稳定性较差,随着引入分子筛骨架中硼量的增大,甲烷的极值转化率增高;随着反应温度的升高,MoO3/HBZSM-5催化剂的甲烷芳构化活性升高。从产物分布的变化来看,硼的引入对于催化剂 相似文献
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钼基分子筛催化剂,由于不同分子筛的孔道大小及孔道形状不同,对甲烷芳构化反应表现出不同的催化性能,具有8元环孔道结构的小孔ERS-7分子筛没有催化活性,说明甲烷的芳构化反应离不开分子筛孔道作用,较小的孔道中不能生成苯等芳烃,具有10元环孔道结构的ZSM-5,ZSM-11和ZRP-1三种分子筛具有较好的催化性能,但由于其孔道大小及孔道形状的差别在催化行为上表现出一定的差异,具有10元环和12元环孔道结构的MCM-22分子筛,尤其对对苯等轻芳烃而言,催化性能最佳,具有12元环孔道结构的JQX-1以及中孔分子筛SBA-15,虽然上有一定的催化性能,但活性较低,研究结果表明,孔道大小,与苯分子动态直径相近或孔道稍大的分子筛是催化甲烷芳构化反应的良好载体,孔道过大或过小都不利于苯和萘等烃的生成。 相似文献
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Non-oxidative aromatization of C1 to C3 hydrocarbons over Pd-promoted Ga/HZSM-5 catalyst under mild conditions 总被引:1,自引:0,他引:1
Xiao Chun Shen Hui Lou Kai Hu Xiao Ming Zheng 《中国化学快报》2007,18(4):479-482
The Pd-promoted Ga/HZSM-5 catalyst was prepared by impregnation method and its catalytic activity for non-oxidativearomatization of C1 to C3 hydrocarbons was assessed using a microreactor-GC system operated with temperature at 823 K andspace velocity at 410 h1.The catalyst is more catalytically active for methane conversion than Ga/HZSM-5.The massspectroscopy analyses confirmed that13CH4 was converted to aromatic products. 相似文献
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Meera A. Shah Samuel Raynes Dr. David C. Apperley Dr. Russell A. Taylor 《Chemphyschem》2020,21(7):673-679
The first selective oxidation of methane to methanol is reported herein for zinc-exchanged MOR (Zn/MOR). Under identical conditions, Zn/FER and Zn/ZSM-5 both form zinc formate and methanol. Selective methane activation to form [Zn-CH3]+ species was confirmed by 13C MAS NMR spectroscopy for all three frameworks. The percentage of active zinc sites, measured through quantitative NMR spectroscopy studies, varied with the zeolite framework and was found to be ZSM-5 (5.7 %), MOR (1.2 %) and FER (0.5 %). For Zn/MOR, two signals were observed in the 13C MAS NMR spectrum, resulting from two distinct [Zn-CH3]+ species present in the 12 MR and 8 MR side pockets, as supported by additional NMR experiments. The observed products of oxidation of the [Zn-CH3]+ species are shown to depend on the zeolite framework type and the oxidative conditions used. These results lay the foundation for developing structure–function correlations for methane conversion over zinc-exchanged zeolites. 相似文献
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Hao Zhang Aleksei Bolshakov Raghavendra Meena Gustavo A. Garcia A. Iulian Dugulan Alexander Parastaev Guanna Li Emiel J. M. Hensen Nikolay Kosinov 《Angewandte Chemie (International ed. in English)》2023,62(32):e202306196
Non-oxidative coupling of methane is a promising route to obtain ethylene directly from natural gas. We synthesized siliceous [Fe]zeolites with MFI and CHA topologies and found that they display high selectivity (>90 % for MFI and >99 % for CHA) to ethylene and ethane among gas-phase products. Deactivated [Fe]zeolites can be regenerated by burning coke in air. In situ X-ray absorption spectroscopy demonstrates that the isolated Fe3+ centers in zeolite framework of fresh catalysts are reduced during the reaction to the active sites, including Fe2+ species and Fe (oxy)carbides dispersed in zeolite pores. Photoelectron photoion coincidence spectroscopy results show that methyl radicals are the reaction intermediates formed upon methane activation. Ethane is formed by methyl radical coupling, followed by its dehydrogenation to ethylene. Based on the observation of intermediates including allene, vinylacetylene, 1,3-butadiene, 2-butyne, and cyclopentadiene over [Fe]MFI, a reaction network is proposed leading to polyaromatic species. Such reaction intermediates are not observed over the small-pore [Fe]CHA, where ethylene and ethane are the only gas-phase products. 相似文献
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甲烷在Ni/TiO_2催化剂表面的活化 总被引:1,自引:0,他引:1
考察了Ni/TiO2催化剂甲烷部分氧化和二氧化碳重整制合成气的反应活性,实验表明,以TiO2为载体的镍系催化剂对于甲烷部分氧化制合成气反应具有较好的活性,尤其对H2的选择性较高,对二氧化碳重整制合成气反应具有较好的低温反应活性.采用脉冲-质谱在线分析等技术,在无气相氧条件下向Ni/TiO2催化剂脉冲CH4,发现甲烷在催化剂表面的活化(转化)及其氧化产物的选择性与金属催化剂表面氧的浓度密切相关.CH4与Ni/TiO2催化剂作用过程中存在明显的氢溢流和氧溢流现象,可能是这种溢流效应使得N/TiO2催化剂具有良好的反应活性和抗积碳性能. 相似文献
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以碳酸锶为甲烷吸附活化的模型催化剂,用切换变应答、CH4(CO2)-TPD等技术,对甲烷的吸附、碱性对催化剂性能的影响进行了研究,结果表明,甲烷在碳酸锶上的活化显示出明显的酸碱活化机理特征,瞬变应答及TPD结果均证明,甲烷在碳酸锶表面有较强的吸附,其脱附温度约310℃,关联结果表明,甲烷转化率及C2烃收率与催化剂表面SrO碱性中心浓度有非常一致的顺变关系,因此催化剂表面的酸碱中心可能是甲烷的选择活 相似文献
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高温下,甲烷在Mo/HZSM-5分子筛上可直接生成苯[1].虽然低温下甲烷能被Mo/HZSM-5催化剂表面的—OH所活化[2],但对甲烷在高温下的活化过程知之甚少,然而这却是很重要的.我们采用原位红外光谱技术,研究了甲烷在高温下Mo/HZSM-5催化... 相似文献
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Li—Ni—La—O系复合氧化物催化剂上甲烷氧化偶联的研究 总被引:2,自引:0,他引:2
考察了Li-Ni-La-O系催化剂的组成、结构及反应条件对甲烷氧化偶联反应活性的影响。在780℃、CH4:O2:N2=2:1:7、空速15000h^-1时,C2烃收率可达25.8%。XRD、IR、XPS及SEM等的结构分析表明,在LiLa1-xNixO2催化剂中,当0.1≤x≤0.9时,该催化剂由LiNiO2和La2Ni1-yLiyO4-λ两相组成,x<0.3时出现了LiLaO2相,La2Ni1- 相似文献