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Fe—Mo/KZSM—5上甲醇氧化为甲醛的研究 总被引:1,自引:0,他引:1
采用浸渍法制备了Fe/Mo/HZSM-5和Fe-Mo/KZSM-5分子筛催化剂,利用NH3-TPD和O2-TPD对催化剂的表面酸性和吸附O2物种进行了表征,考察了温度、Mo/Fe摩尔比,空气/甲醇摩尔比及WHSV对催化性能的影响。实验结果表明,在Fe-Mo/KZSM-5催化剂上,适宜的反应条件下,甲醇转化率接近100%,甲醛选择性达到90.6%,同时还进行了96h的催化剂的稳定性实验。 相似文献
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CuZSM—5分子筛上苯酚羟化制苯二酚 总被引:1,自引:0,他引:1
在Na2O-SiO2-CuO-H2O体系中以15%TPABr-85%HMDA为模板剂合成了CuZSM-5分子筛,并用XRD,IR及SEM等方法进行了表征,考察了CuZSM-5分子筛催化苯酚与过氧化氢的羟化活性,研究了催化剂用量,反应温度,反应时间及n(PbOH)/n(H2O2)等对羟化活性的影响。 相似文献
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镝对固体超强酸催化剂ZrO2-Dy2O3/SO42--HZSM-5的酸性和稳定性的影响 总被引:9,自引:0,他引:9
合成了固体超强酸催化剂ZrO2-Dy2O3/SO4^2-,并将其负载于分子筛HZSM-5上,制成复合型固体超强酸催化剂ZrO2-Dy2O3/SO4^2-HZSM-5)以下简称催化剂ZDSH),采用Hammett批示剂法,吸附吡淀的TPD法,考察催化剂ZDSH的酸强度及其分布;通过热重分析(TGA)、差热分析(DTA)方法,考察镝对催化剂ZDSH稳定性的作用;运用红外光谱(IR)法,分析催化剂ZDS 相似文献
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低碳烷烃合成芳烃的研究:Ⅱ.Zn—HZSM—5催化剂上丙烷的转化 总被引:6,自引:0,他引:6
对ZSM-5型高硅沸石进行了锌改性,制备了不同锌含量的Zn/HZSM-5催化剂。以丙烯为原料,在反应温度470 ̄550℃,空速1 ̄7h^-1条件下反应,并考察了催化剂的稳定性。结果表明,Zn/HZSM-5较HZSM-5在原料转化率变化不大的情况下,芳烃选择性有较大提高,液体产物收率明显增加。氨TPD和吡啶吸附红外光谱表明,Zn/HZSM-5较HZSM-5总酸量低,L酸量多,B酸量少。丙烷在线热重分 相似文献
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本文应用碱性气体吸附的红外光谱和TPD技术研究了FeZSM-5(F_4)的酸性,酸性顺序为:H-F_4>Fe_2O_3/F_4>F_4原粉>水热处理的K-F_4>Li-F_4>NaF_4>K-F_4>NaOH/F_4,比较了酸强度和积炭对乙苯氧化脱氢性能的影响,以及催化剂酸碱性质与积炭的关系.结果表明,乙苯氧化脱氢反应是在酸碱协同作用下进行的,积炭也参与了氧化脱氢反应,催化剂表面上L酸中心产生的具有一定C、H、O比的积炭具有高的氧化脱氢活性.碱金属阳离子改性的具有L酸中心的FeZSM-5是乙苯氧化脱氢的高活性催化剂。 相似文献
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Zn/HZSM-5分子筛上乙烯、乙烷芳构化的协同作用机理 总被引:2,自引:0,他引:2
运用NH_3-TPD、IR-OH、Py-IR、CO-IR及XPS等手段对Zn/HZSM-5及其浸碱催化剂的酸组分和金属组分构成的L酸性质进行了表征,考察了催化剂对乙烯、乙烷的芳构化作用.发现Zn/HZSM-5中形成了Zn ̄(2+)-L强酸中心,使分子筛的B酸中心减少.浸碱也可使分子筛的B酸减少,芳构化反应的活性和选择性均与Zn/HZSM-5的双中心Zn ̄(2+)-L酸和B酸的相互匹配密切相关,B酸和L酸存在最适合匹配,因此Zn/HZSM-5在乙烯、乙烷芳构化反应中存在最佳锌含量. 相似文献
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Ling Ping ZHOU Wei LI Ke Yi TAO Xuan Wen LI He Xuan LI College of Chemistry Molecular Engineering Peking University Beijing Department of Chemistry Nankai University Tianjin 《中国化学快报》2000,11(9)
IntroductionStyrene is one of the most important industrial monomers. At present, styrene is mainlyproduced by alkylation of benzene with ethylene followed by oxidative dehydrogenationof the resulting ethylbenzene. However, this process is very expensive and complex. Anew method of synthesizing ethylbenzene and styrene directly from toluene and methanewas discovered by Khcheyan el al. ', and Yakovich and Bakareva2. The process wouldpotentially reduce the cost because of the production of sty… 相似文献
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Ling Ping ZHOU Wei LI He Xuan LI Ke Yi TAO College of Chemistry Molecular Engineering Perking University Beijing Department of Chemistry Nankai University Tianjin 《中国化学快报》2002,13(9):911-914
Methane is the most abundant component of natural gas. The direct conversion of methane into chemical feedstock or transportable liquid fuel is an attractive process. In addition to oxidative coupling of methane, oxidative methylation of toluene with methane to styrene and ethylbenzene which has been investigated by Khcheyan et al.1, provides another possibility of methane utilization. Recently, several research groups have employed some metal oxides for the oxidative methylation of toluene w… 相似文献
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Oxidative methylation of toluene with methane catalyzed by lithium modified molecular sieves 总被引:1,自引:0,他引:1
Lithium modified molecular sieves with different structures (X, Y, ZSM-5 and AlPO4-5) were studied as catalysts for oxidative methylation of toluene with methane. LiX zeolite was the most active catalyst
for attaining best yields of ethylbenzene and styrene. The effects of basicity, crystallinity and type of structure were examined. 相似文献
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Pavlina Kovacheva Katya Arishtirova Albena Predoeva 《Reaction Kinetics and Catalysis Letters》2003,79(1):149-155
The oxidative methylation of toluene with methane is used as a test reaction for determining the activity, selectivity and
yield of C8 hydrocarbons (ethylbenzene and styrene) over different zeolite and zeolite-type catalysts, viz., X, Y, mordenite, ZSM-5, silicalite and AlPO4-5. Selectivity and basicity increase with decreasing Si/Al atomic ratio within the series of the same structural type. The
basicity, surface structure and structural integrity are characterized by TPD of CO2, XPS and IRS, respectively.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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CoAPSO—5分子筛的合成与性能 总被引:1,自引:0,他引:1
用水热晶化法合成了CoAPSO-5分子筛,用X射线衍射,电子探针,红外光谱以及吸附吡啶的红外光谱等方法对其结构和表面性质进行了研究,并用甲苯甲醇烷基化反应考察了其催化性能,结果表明,CoAPSO-5为中强酸性分子筛,具有较高的甲苯甲醇烷基化活性和对二甲苯选择性,对二苯收率高于20%,且烷基化活性和对二甲茉选择性出现了“同向效应”。 相似文献
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以ZSM-5/丝光沸石(MOR)复合分子筛为催化剂,对混合C4烃的催化转化反应进行了评价,并采用程序升温脱附和原位红外光谱技术对ZSM-5/MOR的酸性进行了表征. 结果表明,与ZSM-5相比, MOR具有很低的催化活性,但ZSM-5/MOR复合分子筛具有较高的催化活性,随着ZSM-5/MOR复合分子筛中ZSM-5含量的增加, C4烃转化率稍有升高;在C4烃转化率大致相同的情况下,乙烯和丙烯的总选择性比较接近,但苯和甲苯的总收率却快速升高. 随着ZSM-5/MOR复合分子筛中ZSM-5含量的增加,弱酸和中强酸的酸量逐渐减少,强酸的酸量有所增加. 由于ZSM-5/MOR复合分子筛中MOR对ZSM-5起到分散作用而产生更多的L酸中心,且此L酸中心处于分子筛的外表面而具有较高的能量,导致苯和甲苯的总收率升高. 相似文献
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通过对比不同孔结构分子筛的甲苯甲醇烷基化催化性能,发现分子筛孔道尺寸与目标芳烃分子动力学尺寸的有效匹配以及孔道空间限制效应对反应路径的约束管理,对实现高性能烷基化至关重要。并结合XRD、BET、NH3-TPD和SEM表征分析,通过先后负载La2O3和P2O5对硅铝比为60的ZSM-5进行复合改性修饰,提升其骨架水热稳定性的同时,选择性地消除内外表面大部分强酸中心,保留弱+中强酸作为烷基化催化活性位,所得MAT-HZSM-5催化该反应表现出很高的甲醇烷基化效率和良好的反应稳定性,在氮气反应气氛下,连续运行500 h无明显失活迹象,甲苯转化率维持在35%-38%,二甲苯选择性60%-77%,甲醇烷基化效率大于90%。 相似文献
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Adebajo MO Long MA Frost RL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(4):791-799
The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Br?nsted acid concentration decreases but this metal ion exchange does not totally remove Br?nsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Br?nsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination of the zeolite catalysts during reaction since their catalytic performance was retained after use. 相似文献