Mn／ZSM-5催化剂及其SCR催化性能研究

采用液态离子交换法制备了不同含量的Mn／ZSM-5型分子筛催化剂,并考察了上述催化剂的物理化学特性及其在NH3-SCR反应中的催化性能。理化分析结果表明：所制备催化剂在Mn含量≤9．2％时具有高度的分散性,分子筛表面团聚的氧化锰颗粒粒径小于4nm;锰元素主要富集于分子筛的浅层及表面。催化性能研究结果表明：Mn含量达到1...     

Cr—MCM—48分子筛的催化活性研究

用掺杂Ｃｒ的ＭＣＭ－４８中介孔分子筛催化剂对α－二十醇催化氧化剂α－二十酸进行了考察研究了反应最佳温度和反应时间,并对目的反应的催化性能进行了评价。结果表明,添加适量的Ｃｒ可提高α－二十醇氧化成α－二十酸的收率。ＸＲＤ和ＩＲ技术表征结果表明,掺杂的Ｃｒ能进入ＭＣＭ－４８分子筛的骨架,反应产物的收率同分子筛催化剂的Ｌ酸相对含量有一定顺变关系,用红外光谱对目的产物进行了半定量分析。     

活性炭担载的Rh—Mo—K合成醇催化剂

采用XRD、EXAFS等技术研究微量贵金属Rh对活性炭担载的Rh-Mo-K合成醇催化剂结构的影响,并关联其催化性能。氧化态Rh-Mo-K／AC样品中Rh与Mo有着较强的相互作用,使得K2Mo2O7向MoO2转化。硫化还原后,Mo主要以MoS2微晶形式存在,其有序结构尺度随Rh含量的增加而减小。经Rh助剂修饰后,催化剂的合成醇催化性能有明显的提高。     

镍改性ZSM-5催化剂及其SCR催化性能

采用液态离子交换法制备了不同负载量的镍改性ZSM-5分子筛催化剂,并考察了上述催化剂的微观结构和物理化学特性及其在NH3-SCR反应中的催化性能。结果表明:在负载量<10.9%时镍在分子筛中具有高度的分散性,而随着镍负载量的进一步增加,分子筛表面开始出现较大的NiO颗粒;镍元素只以+2价存在于分子筛催化剂中;在NH₃-SCR反应中,镍负载量低于14.9%时,增加镍负载量将提高催化剂的低温活性;当反应温度超过300℃时,高温催化中心开始起作用,但随镍负载量的增加,高温活性开始下降时的温度逐渐降低。     

活性炭担载的Rh-M0-K合成醇催化剂

采用XRD、EXAFS等技术研究向微量贵金属Rh对活性炭担载的Rh-Mo-K合成醇催化剂结构的影响,并关联其催化性能。氧化态Rh-Mo-K／AC样品中Rh与Mo有着较强的相互作用,使得K2Mo2O7向MoO2转化。硫化还原后,Mo主要以MoS2微晶形式存在,其有序结构尺度随Rh含量的增加而减小。经Rh助剂修饰后,催化剂的合成醇催化性能有明显的提高。     

Cu/ZSM-5催化剂制备及SCR催化性能研究

采用固态离子交换法制备了不同Cu含量的Cu/ZSM-5改性分子筛型催化剂,并对其理化特性及SCR反应活性进行了表征。结果表明:所制备催化剂中Cu元素富集于分子筛的浅层及表面,并主要以二价铜的形式存在;随Cu含量增加,低温弱酸吸附峰和中温中强酸吸附峰面积增加,有利于提高低温SCR催化性能;铜含量超过13%后,Cu含量的增加对催化剂的低温SCR催化活性影响不大,但将导致高温SCR催化性能急剧恶化;b4催化剂兼具良好的高、低温SCR催化性能,值得深入研究。     

二氧化硅改性分子筛催化生物质基多元醇制备对二甲苯（英文）

本文证明了在二氧化硅改性的分子筛催化作用下,生物质基多元醇(如山梨醇、木糖醇、赤藓糖醇、甘油和乙二醇)可以经过催化裂解、烷基化和异构化等反应,生成高附加值的化学品(对二甲苯).与HZSM-5分子筛催化剂相比,二氧化硅改性的分子筛降低了分子筛催化剂的外表面酸和孔径,从而显著的提高对甲苯的选择性和产率.本文详细讨论了催化剂、甲醇添加剂、反应温度和不同类型多元醇原料对对二甲苯选择性和产率的影响.甲醇的添加促进多元醇催化裂解中的烷基化反应,提高了二甲苯的产率.在15%SiO_2/HZSM-5催化剂作用下,对二甲苯的产率最高可达到10.9 C-mol%,对二甲苯在二甲苯中选择性达到91.1%.本文通过研究相关重要反应和催化剂特性,揭示了生物质基多元醇催化裂解制备对二甲苯的反应路径.     

二氧化硅改性分子筛催化生物质基多元醇制备对二甲苯

本文证明了在二氧化硅改性的分子筛催化作用下,生物质基多元醇(如山梨醇、木糖醇、赤藓糖醇、甘油和乙二醇)可以经过催化裂解、烷基化和异构化等反应,生成高附加值的化学品(对二甲苯).与HZSM-5分子筛催化剂相比,二氧化硅改性的分子筛降低了分子筛催化剂的外表面酸和孔径,从而显著的提高对甲苯的选择性和产率.本文详细讨论了催化剂、甲醇添加剂、反应温度和不同类型多元醇原料对对二甲苯选择性和产率的影响.甲醇的添加促进多元醇催化裂解中的烷基化反应,提高了二甲苯的产率.在15%SiO_2/HZSM-5催化剂作用下,对二甲苯的产率最高可达到10.9 C-mol%,对二甲苯在二甲苯中选择性达到91.1%.本文通过研究相关重要反应和催化剂特性,揭示了生物质基多元醇催化裂解制备对二甲苯的反应路径.     

(K,Mo)Y分子筛中钼组分的EXAFS研究

应用同步辐射Eextended X-ray Ab sorption Fine S tructure(EXAFS)技术研究固态法制备的KHMoY分子筛的氧化态和硫化态样品以及硫化态KHY／MoO3样品中钼组分的局域配位环境结构,并与KHMoY和KHY／MoO3 样品催化加氢活性结果进行对照。结果表明,随原子比（K＋2Mo）／Al的变化,钼原子周围的配位环境有显著的差异。当（K＋2Mo）／Al时,KHMoY和KHY/MoO3硫化后,钼组分主要以MoS2小原子簇分散在分子筛超笼中;（K＋2Mo)/Al&gt;1时,钼组分则有两种存在环境,即分子筛超笼中的和分子筛外表的钼组分。分子筛超笼中的Mo S2原子簇的催化加氢合成醇选择性较高;分子筛外表面的MoS2微小颗粒的尺寸相对于超笼中的要大许多,其合成醇选择 性较低。     

γ—Mo2N和分子筛负载的钼氮化物的结构表征

采用程序升温氮化的方法制备了分子筛负载的钼氮化物催化剂，并用EXAFS方法研究了氮化前后Mo原子的局城配位情况．氮化前负载MoO3样品的径向结构函数中有三个峰，其中前两个嫁对应着最近的Mo-O配位壳层，但是第一个峰与第二个峰的比例比晶体MoO3中的比例大很多，表明分子筛负载的MoO3具有更露密的结构．氮化以后,Mo2N样品的径向结构函数中有三个峰，对应于一个Mo-N和两个Mo-N配位壳层，与面心立方模型符合得很好．根据XRD和EXAFS谱的计算表明，Mo2N中的N原子使Mo-Mo键拉长并削弱．分子筛负载的Mo2N样品具有与非负载Mo-N样品近似相同的径向结构函数，只是对应于Mo—N壳层的峰较弱，表明负载的Mo2N具有更大的结构无序性．     

Methane non-oxidative aromatization on Mo/ZSM-5: Effect of adding triethoxyphenylsilanes into the synthesis system of ZSM-5

A series of ZSM-5 zeolites were synthesized by adding triethoxyphenylsilane (PTEOS) into the initial sol of the synthesis system. The samples were studied by XRD, SEM, N₂ adsorption-desorption and acid assessment of d₃-acetonitrile adsorption. Characterization results showed that the crystal size of the ZSM-5 zeolites could be adjusted in a certain range by introducing different contents of PTEOS. Besides, the resultant materials possess hierarchical porosity in addition to those micropores generated by the MFI channels. Moreover, supported Mo/ZSM-5 catalysts were prepared, and their catalytic performances were investigated in the methane non-oxidative aromatization. It was found that the Mo/ZSM-5 catalyst, bearing suitable crystal size and mesoporous characteristic showed relatively high shape-selectivity to benzene and high stability for the reaction of methane aromatization.     

Physicochemical characteristics of ZSM-5/SAPO-34 composite catalyst for MTO reaction

SAPO-34 and ZSM-5 are the most well-known catalyst for MTO reaction. A combination of ZSM-5 and SAPO-34 might give rise to optimal catalyst to meet a change of market demand for ethylene, propylene and butadiene. In this study, we have developed ZSM-5/SAPO-34 composite catalysts to control the composition of light olefins in MTO reaction. ZSM-5/SAPO-34 composite catalysts showed very different physicochemical and catalytic properties with respect to ZSM-5 and SAPO-34 synthetic procedure. The physicochemical properties of the composite catalysts have been compared by XRD, SEM, N₂ isotherm, FT-IR and NH₃-TPD. Their catalytic performances were also evaluated for MTO reaction. The series composite catalyst synthesized by successive crystallization of SAPO-34 synthetic gel after ZSM-5 crystallization exhibited relatively high catalytic performance.     

Synthesis of Pt modified ZSM-5 and beta zeolite catalysts: influence of ultrasonic irradiation and preparation methods on physico-chemical and catalytic properties in pentane isomerization

Influence of preparation methods and ultrasound irradiation on physico-chemical and catalytic properties was investigated by synthesizing Pt-ZSM-5 and Pt-Beta catalysts by in-situ and impregnation methods and applying ultrasound irradiation to synthesis gel mixture of ZSM-5 and Beta zeolites. It was concluded from the X-ray powder diffraction patterns of Pt-ZSM-5 and Pt-Beta zeolite catalysts that introduction of Pt by in-situ method and ultrasound irradiation did not influence the structures of ZSM-5 and Beta zeolites. Morphology of ZSM-5 and Beta zeolites were investigated by scanning electron microscopy. SEM micrographs showed that the Pt-ZSM-5-IS-US catalyst synthesized by in-situ method with ultrasound irradiation resulted in smaller crystals of ZSM-5 than Pt-ZSM-5-IS catalyst prepared without ultrasound irradiation. Furthermore SEM micrographs of Pt-Beta-11-IS-US zeolite synthesized using ultrasound irradiation showed much smaller crystals than Pt-Beta-11-IM indicating that ultrasound irradiation had a significant effect on the morphology of Beta zeolite. Conversion of n-pentane and selectivity to iso-pentane over the Pt-ZSM-5-IS-US zeolite catalysts prepared by ultrasound irradiation during in-situ introduction of platinum was higher than the catalysts prepared without the ultrasound irradiation. Furthermore ultrasound irradiated and in-situ synthesized Pt-Beta-11-IS-US catalyst also showed higher selectivity to iso-pentane than Pt-H-Beta-11-IM prepared by impregnation method.     

CuCoMn-zeolite双功能催化剂转化生物质基合成气制取液态烃

选用四种不同的分子筛(SAPO-34, ZSM-5, Y, MCM-41)与CuCoMn(高醇合成组元)构成双功能催化剂,利用N₂吸脱附、H₂-TPR、XRD、NH₃-TPD等表征了催化剂的结构性质. 研究了催化剂在生物质基合成气一段法制取液态烃燃料的应用. 相比于CuCoMn催化剂,加入分子筛的双功能催化剂均不同程度地提高了液体烃燃料的选择性及收率,且收率按顺序递减呈CCM-ZSM-5>CCM-SAPO-34>CCM-Y>CCM-MCM-41. 同时,共沉淀法制备的CuCoMn-ZSM-5 (20wt%, Si/Al=100) 具有最佳的CO转化率(76%)及液体产物收率(30%). 相比于CuCoMn氧化物,双功能催化剂的比表面及孔容均得到提高. CCM-ZSM-5具有适中的微孔尺寸和中等强度的酸性,增加CCM-ZSM-5中ZSM-5含量或降低ZSM-5中的Si/Al比,均有利于提高酸性位的数量,主要是较弱的酸性位. 而共沉淀法制备的CCM-ZSM-5具有更好的金属分散性及还原性能.     

Comparison of Fe-AlPILC and Fe-ZSM-5 catalysts used for degradation of methomyl

Catalytic performances of Fe-AlPILC (14 wt.% Fe) and Fe-ZSM-5 (5 wt.% Fe) catalysts are compared in the wet oxidative degradation of methomyl. Fe-ZSM-5 exhibits outstanding whereas Fe-AlPILC shows only mediocre activity. Positions of iron are analysed in the two catalysts by Mössbauer spectroscopy. Iron is in highly dispersed state in Fe-AlPILC whereas in the other case a hematite/ZSM-5 composite is formed. The catalytic activity is attributed to iron located and stabilized in ionic dispersion.     

Ultrasound-assisted rapid hydrothermal design of efficient nanostructured MFI-Type aluminosilicate catalyst for methanol to propylene reaction

The influence of ultrasound-assisted rapid hydrothermal synthesis of aluminosilicate ZSM-5 catalysts was examined in this work. A series of MFI-type nanostructured materials with sonochemical approach and conventional heating were synthesized and evaluated for conversion of methanol to propylene reaction. The prepared samples were tested by characterization analyses such as XRD, FESEM, BET-BJH, FTIR, TPD-NH₃ and TG/DTG. The obtained results confirmed that ultrasound treatment enhanced the nucleation process and crystal growth for ZSM-5 sample synthesized at moderate temperature of 250 °C. Therefore, it was found the formation of pure MFI zeolite with high crystallinity and improved textural, structural and acidic properties for ZSM-5(UH-250) sample compared with the other zeolites. This observation was attributed to the relationship between the perfect crystallization mechanism and catalytic properties, which led to producing an efficient MFI zeolite toward the optimal catalytic performance. In this manner, the methanol conversion and products selectivity of prepared materials were carried out in MTP reaction at 460 °C and atmospheric pressure. The ZSM-5(UH-250) zeolite with slower deactivation regime exhibited the constant level of methanol conversion (84%) and high propylene selectivity (78%) after 2100 min time on stream. Moreover, the synthesis pathway for MFI zeolite at moderate temperature and also deactivation mechanism of improved sample were proposed.     

Key factor affecting the structural and textural properties of ZSM-5/MCM-41 composite

ZSM-5/MCM-41 micro/mesoporous composite materials were synthesized by the hydrothermal technique with alkali-treated ZSM-5 zeolite as source of silica and aluminum and characterized by various physico-chemical techniques such as X-ray diffraction (XRD), nitrogen sorption at 77 K, transmission electronic microscopy (TEM), FTIR spectroscopy and NH₃ temperature programmed desorption (TPD) techniques. The effect of concentration of CTAB in the synthesis of these solids has been investigated, the mesopore volume, surface area and surface acidity decrease with increasing the concentration of CTAB. Increasing the CTAB concentration causes the recrystallization of zeolite ZSM-5 and it disadvantage the formation of mesoporous materials MCM-41. The catalytic activity of ZSM-5/MCM-41 materials has been evaluated in the Friedel–Crafts acylation of anisole with benzoyl chloride as alkylating agent. The results revealed the reaction to be influenced by surface area, pore volume and surface acidity.     

Iron Species Present in Fe/ZSM-5 Catalysts – Influence of the Preparation Method

The Fe species present in Fe/ZSM-5 catalysts prepared by ionic exchange in aqueous solution or in the solid state are investigated. The samples were characterized by XRD, EPR, Mössbauer Spectroscopy (MOS-S) and chemical analysis. XRD showed that the peak intensity decreased with the increase in Fe content in the samples. EPR and MOS-S showed that the Fe atoms in all the activated samples appear as Fe⁺³, independently of the method used in the catalyst preparation. The MOS-S data also showed that Fe/ZSM-5, prepared by ion exchange in the solid state presented lower hematite content and more Fe species in charge-compensation sites, the responsible for the catalytic activity, as confirmed by the behavior in the propane oxidation.