Ga／HZSM—5催化剂中镓的状态及其颁的XPS研究

利用ＸＰＳ技术对不同Ｇａ／ＨＺＳＭ－５镓组分的分布状态进行考察。结果表明镓与分子筛之间产生了相互作用，以活性组分和游离太镓存在，且镓呈外表面富集。还原、氧化处理对镓的状态及分布有明显的影响。关联催化活性评价结果，认为与ＨＺＳＭ－５产生相互作用的镓组分为低碳烷烃催化芳构化反应的活性物种。镓的均匀分布有利于提高催化活性。     

Ga2O3／HZSM—5催化剂的XRD,XPS和TPR研究

利用ＸＲＤ、ＸＰＳ、ＴＰＲ等技术对Ｇａ２Ｏ３／ＨＺＳＭ－５催化剂进行表征，结果表明，催化剂中镓组分以聚集态和分散态的形式存在，其中聚集态中α－Ｇａ２Ｏ３在一定条件下可转化为β－Ｇａ２Ｏ３；分散态又可分为游离Ｇａ２Ｏ３和与ＨＺＳＭ－５产生相互作用的镓组分，催化剂预处理条件及反应一再生过程对镓的分布及状态有较大影响。     

EFFECT OF CATALYST CONCENTRATION ON CATALYTIC PERFORMANCE IN LIQUID PHASE DIMETHYL ETHER SYNTHESIS FROM SYNGAS

利用ＺＳＭ－５型沸石可将轻烃选择性地转化为苯，甲苯和二甲苯。ＨＺＳＭ－５催化剂上丙烷转化率和芳烃选择性都很低，但在ＨＺＳＭ－５上添加Ｇａ或Ｐｔ－Ｇａ（双金属改性）后丙烷转化率和芳烃选择性都有很大提高。实验结果表明，Ｇａ／ＨＺＳＭ－５催化剂经氢气高温预处理后，其上的Ｂｒｏ．．ｎｓｔｅｄ酸中心数目减少。铂的加入促进了镓物种的还原，而还原的镓物种可以中和相当一部分催化剂表面Ｂｒ．ｎｓｔｅｄ酸中心，然后形成高度不饱和的催化活性中心。这些中心可以作为Ｌｅｗｉｓ中心，从丙烷和反应中间产物中拔除Ｈ－，使丙烷高选择性地生成芳烃     

添加Ru的Mo/HZSM-5催化体系上的甲烷无氧脱氢芳构化

研究了在Ｍｏ／ＨＺＳＭ－５催化剂中添加过渡金属阳离子以改变催化剂的反应性能，提高甲烷无氧脱氢芳构化的反应活性和稳定性，在添加第二组分的催化剂中，Ｍｏ－Ｒｕ／ＨＺＳＭ－５具有最佳的反应活性和稳定性，Ｒｕ的加使甲烷的转化率上原来的６％－７％提高以９．８％，采用比表面积及孔分布测定，Ｘ射线衍射，程序升温还原，程序升温氨脱附和差热分析等表征方法研究了Ｍｏ－Ｒｕ／ＨＺＳＭ－５催化剂的物理化学性质，结果表明，     

Mo/HZSM-5丙烷芳构化催化性能及其吸附量热的研究

采用等量浸渍法制得一系列不同担载量的Ｍｏ／ＨＺＳＭ－５催化剂,运用ＸＲＤ和ＦＴＩＲ方法考察了Ｍｏ物种在催化剂表面的分散状态,首次采用微分吸一热技术对Ｍｏ／ＨｚＳＭ－５催化剂的表面酸性进行表征。同时研究了催化剂对丙烷芳构化的反应活性。结果表明：对于担载Ｍｏ的ＨＺＳＭ－５分子筛催化剂,Ｍｏ物种在ＨＺＳＭ－５分子筛表面上顺序为ＨＺＳＭ－５〉１％Ｍｏ／ＨＺＳＭ－５〉２％Ｍｏ／ＨＺＳＭ－５分子筛本身表面的酸     

Zn／HZSM－5分子筛上乙烯、乙烷芳构化的协同作用机理

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．     

Zn／HZSM—5分子筛上乙烯,乙烷芳构化的协同作用机理

运用ＮＨ３－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，芳构化反庆的活性和选择性均与Ｚｎ／ＨＺＳＭ－５的双中心Ｚｎ＾２＋－Ｌ酸的相互匹配密切相关。Ｂ酸和Ｌ酸存在最适合     

Ga/HZSM-5芳构化催化剂的研究——K、V、B第二组分改性对甲醇、丙烷转化的影响

考察了Ｋ、Ｖ、Ｂ等对Ｇａ／ＨＺＳＭ５催化剂的改性后表面酸性质和Ｇａ组分状态分布的变化以及对甲醇、丙烷芳构化催化作用的异同。结果表明，Ｖ、Ｂ改性后提高了甲醇转化的芳烃选择性，降低了丙烷的芳构化活性。在Ｂ改性催化剂上，甲醇／丙烷偶合转化生成产物中芳烃的选择性低，但低碳烯烃的选择性高。最后提出对不同的催化反应过程，要求不同的强酸中心与活性组分镓相匹配。     

Pt-Ga/HZSM-5催化剂上丙烷芳构化

考察了Ｐｔ／ＨＺＳＭ－５，Ｇａ／ＨＺＳＭ－５和Ｐｔ－Ｇａ／ＨＺＳＭ－５上的丙烷芳构化反应，其中Ｐｔ－Ｇａ／ＨＺＳＭ－５双组份催化剂上有较高的丙烷反应活性和芳烃选择性，用程序升温还原（ＴＰＲ）和Ｈ２化学吸附法表征催化剂，发现Ｐｔ与Ｇａ的协同相互作用促进了Ｇａ＾３＋的还原，使其峰温向低温移动的７０℃，且双组分催化剂中Ｐｔ的Ｈ２吸附性能大大降低，使催化剂表成乙烯加氢能力降低，从而提高了产物芳烃的选择性，     

P—HZSM—5催化剂上合成对异丙基苯酚的研究

研究了在Ｐ－ＨＺＳＭ－５上苯酚与异丙醇烷基化合成对异丙基苯酚（ｐ－ＩＰＰ）的反应,考察了磷含量对催化反应性能的影响,用ＮＨ３－ＴＰＤ和Ｐｙｒ－ＩＲ表征也Ｐ－ＨＺＳＭ－５的表面酸性质 ,结果表明,磷改性ＨＺＳＭ－５可提高ｐ－ＩＰＰ选择性（达９５％）。而降低了苯酚的转化率,并导致酸量减少和酸强度减弱,磷与分子筛的相互作用引起了分子筛脱铝,焙烧温度对活性和选择性均有影响,分子筛在９７３Ｋ、Ｐ－ＨＺＳＭ＿     

27Al和29Si MAS-NMR对Mo/HZSM-5催化剂的研究

使用＾２９Ａｌ固体离分辨核磁技术对甲烷无氧芳构化催化剂Ｍｏ／ＨＺＳＭ－５分子筛进行了研究，发现ＨＺＳＭ－５分子筛本体中仅含有少量非骨架Ａｌ，Ｍｏ物种与分子筛骨架Ａｌ的相互作用随Ｍｏ担载量以及焙烧的温度的升高而增加，在高温焙烧下，Ｍｏ物种会使分子筛骨架严重脱铝，并且生成Ａｌ２（ＭｏＯ４）３新相，最终导致分子筛骨架塌陷，催化性能下降。     

Studies on Mo／HZSM-5 Complex Catalyst for Methane Aromatization

The influence of adding Fe,Cr,Co,and Ga into 3%Mo/HZSM-5 catalyst on methane aromatization,and the influence of additives ratio on methane conversion,selectivity to hydrocarbons and coke,as well as distribution of aromatics were investigated.The experimental results showed that the addition of Fe,Cr,Co and Ga promoted the dehydrogenation and dissociation of methane.The results of NH3-TPD indicated that the acidity of HZSM-5 was changed by adding Fe and Co components,consequently the catalytic properties of Mo/HZSM-5 were changed.It was also revealed that strong acid sites were the center of methane aromatization.The results of XRD characterization showed that the crystallinity of Mo on ZSM-5 zeolite was increased after adding Fe,Co additives.     

Effect of Fe-Mo promoters on HZSM-5 zeolite catalyst for 1-hexene aromatization

The promotional effect of Fe-Mo species introduced into HZSM-5 (Zeolyst Int., SiO₂/Al₂O₃ ≈ 30) zeolite catalyst by the wetness impregnation method for the 1-hexene aromatization was investigated. The structure and catalytic performance for the aromatization of 1-hexene over xFeyMo-ZSM-5 catalysts in comparison with unmodified HZSM-5 catalysts were studied. The xFeyMo-ZSM-5 catalysts contain fixed loading (5 wt%) and variable Fe/Mo ratio. The catalysts were characterized by BET, ICP-AES, HRSEM-EDS, HRTEM, XRD, FTIR, H₂-TPR, NH₃-TPD, and pyridine DRIFT spectroscopy. The characterization data confirmed the existence of Fe and Mo species in the zeolite matrix. With Fe and Mo species implementation to HZSM-5 zeolite, the amount of the acid sites decreased, but the selectivities to C₉₊ aromatics increased. The catalyst evaluation was performed at 350 °C for 6 h on-stream at atmospheric pressure using a fixed-bed quartz tube reactor. The selectivity to products of different carbon number was affected by the Fe/Mo ratio within the zeolite. It was found the product distribution of grouped fractions of C₁–C₁₇₊ from the liquid product. The results indicate that the optimum ratio of Fe/Mo is 1–1.5. The highest selectivity for gasoline and distillate ranges was obtained for the 2.5wt%Fe2.5wt%Mo- and 3wt%Fe2wt%Mo-ZSM-5 samples, which was higher than that for parent HZSM-5 catalyst.     

锌含量对Zn/HZSM-5催化剂性能的影响

 研究了不同锌含量的Zn／HZSM－5分子筛的表面酸性及其对正己\r\n烷芳构化反应的催化活性、选择性和稳定性．结果表明,锌组元的引入\r\n减少了HZSM－5表面的B酸,增加了L酸,总酸量增大;正己烷转化率随\r\n锌含量的增加先降低后升高;芳烃产率和芳构化选择性则随锌含量的增\r\n加先增大后趋于平缓;反应过程中催化剂的积炭速度、孔体积和比表面\r\n积下降速度都随着锌含量的增加而加快;锌含量大于1％时,Zn／HZSM\r\n－5的催化稳定性不如HZSM－5,且随着锌含量的增加失活速度加快．优\r\n选的锌含量为1．0％～2．9％．此外,讨论了Zn／HZSM－5的催化性能\r\n与其表面性质的关系．     

La／HZSM—5催化剂上丙烷的芳构化反应研究

采用浸渍法和离子交换法制备了La/HZSM-5分子筛催化剂,用于丙烷芳构化反应,利用XRD,SPS,FT－IR,NH3－TPD技术考察了La对HZSM－5分子筛结构和表面酸性的影响,引入La后能显著提高HZSM－5的丙烷芳构化活性,其中由离子交换法得到的催化剂效果最佳,在反应温度550度,空速600h^-1条件下,丙烷转化率和芳烃选择性分别达到94．58％,68．99％,在La/HZSM-5中分子筛结晶度下降,B酸中心减少,L酸中心增多,离子交换法制备的催化剂比浸渍法催化剂的这种变化更显著,同时更有利于La3 进入分子筛孔道内,并与分子筛产生强相互作用,新增加的L酸中心可能是芳构化反应的活性中心。     

甘油辅助HZSM-5分子筛的制备及其甲烷无氧芳构化催化性能研究

以正硅酸乙酯(TEOS)为硅源,甘油为辅助剂,在水热条件下合成HZSM-5分子筛。考察甘油添加量、晶化时间对HZSM-5分子筛的晶粒尺寸、相对结晶度和酸性等性质及其甲烷无氧芳构化催化性能的影响。利用X射线衍射(XRD)、扫描电镜(SEM)、氨程序升温脱附(NH_3-TPD)等分析手段对不同条件合成的HZSM-5分子筛样品进行表征。结果表明,在添加一定量的甘油辅助剂的条件下,通过调控晶化时间,可以提升HZSM-5分子筛的相对结晶度,在一定程度上抑制无定型SiO_2的产生,增加其酸量。在甲烷无氧芳构化反应中,甘油辅助合成的HZSM-5分子筛催化剂表现出优良的催化性能,与未添加甘油合成的HZSM-5分子筛催化剂相比,甲烷转化率、苯选择性和芳烃选择性均有较大提高,且具有较强的稳定性与容炭能力。     

甲烷在MoO_3／HZSM－5分子筛催化剂上的非氧催化转化

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．     

Propane Aromatization over Mo／HZSM—5 Catalysts

Impregnation,mechanical mixing and hydrothermal treatment methods were used to introduce molybdenum species into the HZSM-5 zeolite ,the structure and surface acidity of the catalysts were studied by means of XRD,FT-IR ,NH3-TPD,TPR and XPS,The effects of Mo content and reaction time on stream on the aromatization of propane were investigated,It was found that the performance of the Mo/HZSM-5 catalst prepared by the hydrothermal treatment method was much better than that of the other two catalysts,For example ,under the reaction conditions of 823 K and 600h^-1, propance conversion and aromatics selectivity over the catalyst prepared by hydrothermal pretreatment could reach 89.17% and 78.56%,respectively,XRD and XPS results showed that the Mo species in the catalysts prepared by hydrothermal treatment were highly dispersed on the surface of the HZSM-5,and lartger amounts of them could penetrate into the HZSM-5 channel ,as compared with the other two kinds of catalysts,These factors may be responsibled for their high activities for propane aromatization,IR and NH3-TPD studies indicated that the number of Broensted acid centers decreased and the Lewis acid centers increased after Mo was introduced into the HZSM-5 zeolite.     

Methane dehydrogenation and aromatization in the absence of oxygen on Mo/HZSM-5: A study on the interaction between Mo species and HZSM-5 by using Al and Si MAS NMR

By using a high-resolution solid state nuclear magnetic resonance spectrometer with ²⁷Al and ²⁹Si probes, the interaction between Mo species and HZSM-5 of frsol|Mo/HZSM-5 catalysts has been studied. The results show that there is a strong interaction between Mo species and HZSM-5 zeolite. The framework aluminum in the zeolite can be easily extracted by the introduction of Mo species. The extractability of framework aluminum by Mo species increases with increasing Mo loading and the calcination temperature. The extraction process leads to the formation of non-framework Al at first and then a new crystalline phase of Al₂(MoO₄)₃. The dealumination of the catalyst having a Mo loading of 15% and had been calcined at 973 K is so severe that all the aluminum in the framework are extracted and no framework Al could be detected by ²⁷Al MAS NMR. The catalyst, therefore, lost its catalytic activity for methane dehydrogenation and aromatization in the absence of oxygen. The Si/Al ratio measured from ²⁹Si MAS NMR further confirms the dealumination process observed by ²⁷Al MAS NMR. The MAS NMR results give us an evidence that Al₂(MoO₄)₃ crystallites are much less active for the reaction.