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文章是以硝酸铁为铁源,十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯(TEOS)为硅源在超声波微波的条件下形成的Fe-MCM-41分子筛,通过XRD,SEM,EDS对样品进行表征,说明该分子筛具有单维的六边形孔道结构,杂化铁原子已进入MCM-41分子筛骨架中,形成了预期的产物。将Fe-MCM-41分子筛作为催化剂催化苯,通过改变其浓度和选用不同配比的催化剂对苯进行催化实验,得出最佳的反应浓度为5 g/L,最佳的催化剂配比为60∶1,在此条件下苯的最大转化率为18.65%。 相似文献
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分子筛类催化剂上甲烷选择性催化还原NOx研究进展 总被引:2,自引:0,他引:2
选择性催化还原NOx是处理工业废气和稀燃汽车尾气NOx的有效方法。由于还原剂甲烷廉价易得,甲烷选择性催化还原NOx(简称CH4-SCR)已成为近年来的研究热点,而分子筛类催化剂因催化活性高而得到广泛研究。本文综述了CH4-SCR脱除NOx体系中不同金属负载的分子筛催化剂及反应机理方面的研究进展,包括Co系、Pd系、In系等分子筛催化剂在催化性能、反应机理及掺杂改性等方面的研究现状,并提出了分子筛类催化剂用于CH4-SCR的研究方向。 相似文献
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选择性催化还原NOx的反应机理研究 总被引:12,自引:1,他引:11
选择性催化还原法(SCR)脱除NOx具有较高的效率,是目前工业中应用最广泛的工艺。催化还原NOx的反应过程相当复杂。概括了H2、CO、烃类、NH3和尿素等作为还原剂选择性催化还原氮氧化物的各种反应机理,详细论述了催化还原过程中形成的中间体,如亚硝基甲烷、烯醇式物质[CH2=O)、NO2[NH4+]2、NOy、CxHyOzN、CxHyOz、NO+、NCO或CtHxOyNz等,并讨论了催化剂和载体表面上的氧空缺和活性中心对SCR的影响,展望了这一领域的研究方向。 相似文献
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助剂掺杂对Fe-MCM-41在环己烷氧化反应中催化性能的影响 总被引:2,自引:0,他引:2
以硅酸钠为硅源,十六烷基三甲基溴化铵为模板剂,硝酸铁为金属源,水热法直接合成Fe-MCM-41,再辅以助剂Co和Cr形成双金属掺杂的介孔材料,采用XRD、N2吸脱附、TG-DTA、FTIR、ICP对材料的结构和物化性质进行表征。以乙腈为溶剂,H2O2为氧化剂,考察所制备的材料对环己烷氧化的催化活性和选择性的影响。结果表明,与Fe-MCM-41的催化性能相比,FeCo-MCM-41会使环己烷的转化率下降,但环己醇的选择性增加;而FeCr-MCM-41会使环己烷的转化率和环己酮的收率增加。 相似文献
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z以硅酸钠为硅源,十六烷基三甲基溴化铵为模板剂,硝酸铁为金属源,水热法直接合成Fe—MCM-41,再辅以助剂co和cr形成双金属掺杂的介孔材料,采用XRD、N2吸脱附、TG—DTA、FTIR、ICP对材料的结构和物化性质进行表征。以乙腈为溶剂,H2O2为氧化剂,考察所制备的材料对环己烷氧化的催化活性和选择性的影响。结果表明,与Fe—MCM41的催化性能相比,FeCo—MCM41会使环己烷的转化率下降,但环己醇的选择性增加;而FeCr—MCM41会使环己烷的转化率和环己酮的收率增加。 相似文献
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过渡金属/分子筛催化剂上选择性催化还原氮氧化物的研究进展 总被引:1,自引:1,他引:0
综述了近十年来过渡金属/分子筛催化剂上氨和碳氢化合物选择性催化还原NOx方面的研究进展。在NH3-SCR体系,着重介绍了铜基和铁基分子筛催化剂的研究状况,探讨了分子筛催化剂在该体系中的失活原因;在HC-SCR体系,总结了不同过渡金属、分子筛类型、还原剂、H2O和SO2等对催化剂活性的影响,探讨了目前比较公认的碳氢化合物选择性催化还原NOx的反应机理。最后展望了分子筛催化剂在选择性催化还原NOx领域今后的研究方向。 相似文献
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Ying Wan Jianxin Ma Zheng Wang Wei Zhou Serge Kaliaguine 《Applied catalysis. B, Environmental》2005,59(3-4):235-242
The selective catalytic reduction of NO by propene in the presence of excess oxygen over Cu-Al-MCM-41 catalyst has been studied by a number of catalytic techniques to characterize the structural, chemisorptive and reactive properties. The characterization using XRD and NMR revealed that the structure of Cu-Al-MCM-41 remained unchanged after the reaction. The active sites related to the reduction of NO and the reaction mechanism were explored based on the data of H2 temperature programmed reduction (TPR), NO temperature programmed desorption (TPD), X-ray spectrometry (XPS) and in situ FT-IR. The results showed that a redox of Cu ions in Cu-Al-MCM-41 between monovalent and divalent states happened during the selective catalytic reduction of NO, and the reduction seemed to proceed via the intermediate of organic nitro compounds produced by the reaction of propylene adspecies and NO2. In addition, the presence of oxygen is essential to the formation of NO2 intermediate and to the cycle of active center between Cu2+ and Cu+. However, it also caused the deep oxidation of propylene, leading to the depletion in reducing agent at higher temperature. 相似文献
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Acidity and catalytic activity of the mesoporous aluminosilicate molecular sieve MCM-41 总被引:1,自引:0,他引:1
Robert Mokaya William Jones Zhaohua Luan Maria D. Alba Jacek Klinowski 《Catalysis Letters》1996,37(1-2):113-120
The acidity and catalytic properties of aluminosilicate mesoporous molecular sieves with the MCM-41 structure and bulk Si/Al ratios in the 10–60 range have been investigated. The incorporation of 4-coordinate aluminium into the structure of MCM-41 generates both BrØnsted and Lewis acid sites in amounts increasing with the degree of incorporation. However, the BrØnsted/Lewis acid population ratio is independent of the content of aluminium. The number and strength of acid sites generated are comparable to those of a pillared acid-activated clay and lower than in zeolite H-Y with Si/Al=3.65. Aluminosilicate MCM-41 is a moderate catalyst for the conversion of cumene which proceeds predominantly via catalytic cracking to propene and benzene. The sample of MCM-41 with the highest content of framework aluminium (Si/Al=10) has the largest number of BrØnsted acid sites and exhibits highest catalytic activity. 相似文献
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Influence of aluminium sources on the synthesis and catalytic activity of mesoporous AlMCM-41 molecular sieves 总被引:1,自引:0,他引:1
Mesoporous AlMCM-41 molecular sieves were synthesized using various aluminium sources, viz., sodium aluminate, aluminium sulphate, aluminium isopropoxide and pseudoboehmite. The influence of different aluminium sources on the framework substitution of aluminium as well as on the catalytic properties of t-butylation of phenol was studied. Among the aluminium sources, the use of sodium aluminate for the AlMCM-41 synthesis showed maximum incorporation of aluminium in the framework. Further, the catalyst also showed good catalytic activity for the chosen reaction. 相似文献
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氮氧化物选择催化还原的研究进展 总被引:11,自引:2,他引:9
氮氧化物(NOx)是大气的主要污染物之一。含氧气氛中,在催化剂的帮助下使还原剂与废气中的NOx反应并将其还原为N2的催化过程称为选择催化还原(SCR),是目前研究较多的消除NOx污染的方法之一。综述了选择催化还原方法的研究现状与应用前景。 相似文献
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ZSM-5/MCM-41复合分子筛的微波合成及催化性能 总被引:1,自引:0,他引:1
用微孔沸石硅源法微波合成ZSM-5/MCM-41复合分子筛,采用XRD、BET和NH3-TPD技术对合成分子筛进行表征。结果表明,复合分子筛具有类MCM-41 的典型六方介孔结构,同时具有中孔和微孔结构,复合分子筛的总酸量介于HMCM-41酸量与HZSM-5酸量之间。利用脉冲微反装置考察合成分子筛的邻二甲苯异构化催化性能。结果表明,ZSM-5/MCM-41复合分子筛具有高于同硅铝比的MCM-41、ZSM-5和ZSM-5/MCM-41的机械混合物的催化活性。 相似文献