Pd/ZSM-5/MCM-41催化剂加氢脱硫性能研究

本工作将三种材料：全硅MCM-41 （Si-MCM-41）、通过机械混合Si-MCM-41和HZSM-5得到的Z-MCM-41-M、通过在HZSM-5外部包覆Si-MCM-41制备得到的Z-MCM-41,采用XRD、N₂吸附-脱附、NH₃-TPD、Py-IR手段进行了表征.分别以这些材料为载体,制备出负载型贵金属Pd催化剂,以二苯并噻吩（DBT）为模型化合物,在固定床反应器上进行加氢脱硫（HDS）性能考察.反应结果表明,载体的表面积或分散程度并不是影响负载型Pd催化剂HDS性能的关键性因素,催化剂的HDS性能受到载体的孔尺寸和载体的酸性双重影响.负载在酸性载体上表现出较好的HDS性能和加氢选择性,与溢流氢有关.其中,在三种催化剂中,Pd/Z-MCM-41催化剂表现出最高的HDS活性和优异的加氢活性,说明在载体的介孔孔道结构中引入微孔的酸中心对提高加氢脱硫活性有重要影响,仅靠机械混合方式制备的载体不能将介孔的孔道优势与微孔的酸性优势表现出来,不能产生较好的协同催化作用,具有介孔孔道结构和适中酸性的Z-MCM-41复合材料是潜在的贵金属加氢脱硫催化剂载体.     

含铜MCM-48催化剂上糠醛选择性加氢制糠醇

 以MCM-48为载体,采用新颖的负载方法(有机官能团化法)制备了铜基负载型催化剂. 结果表明,活性组分以较高的负载量均匀地分散在载体MCM-48表面,且负载活性组分后,分子筛的结构未被明显破坏. 本文首次将采用此负载方法制备的铜基MCM-48催化剂用于糠醛选择性加氢制糠醇反应,并得到了较高的活性、稳定性及糠醇选择性,该催化剂可以与商业催化剂相比,具有潜在的工业应用价值. 与一维结构的MCM-41相比,三维孔道结构的MCM-48有效避免了孔堵塞,大大提高了催化剂的稳定性. 引入助剂镧有利于羰基加氢,明显提高了糠醛的转化率. 使用后的催化剂并未被氧化,催化剂失活的主要原因之一是积炭.     

HY/MCM-41/γ-Al2O3负载的硫化态Ni-Mo-P催化剂上萘的加氢

 采用水热法合成了不同SiO2/Al2O3比的MCM-41介孔分子筛. 并分别以HY/MCM-41/γ-Al2O3, HY/γ-Al2O3和γ-Al2O3为载体,用浸渍法制备了Mo-Ni-P催化剂. 以萘为模型化合物,考察了硫化态Mo-Ni-P催化剂的加氢活性. 结果表明,不同载体负载的催化剂催化活性均随着活性组分负载量的增大而提高,其中掺杂大比表面MCM-41的HY/MCM-41/γ-Al2O3所负载的催化剂催化活性提高幅度最大. 由于MCM-41与HY分子筛在酸性和孔结构上存在互补性,因而催化剂对萘加氢存在协同作用. 提出了萘加氢的反应机理,认为反应网络包括两个平行路径: 一是萘加氢生成四氢萘后发生异构化或开环反应; 二是萘加氢生成四氢萘后进一步加氢生成十氢萘,继而发生异构化或开环反应.     

HY／MCM-41／γ-A12O3负载的硫化态Ni-Mo-P催化剂上萘的加氢

采用水热法合成了不同SiO2／Al2O3比的MCM-41介孔分子筛．并分别以HY／MCM-41／γ-A1203，HY／γ-A12O3和γ-Al2O3为载体，用浸渍法制备了Mo-Ni-P催化剂．以萘为模型化合物，考察了硫化态Mo-Ni-P催化剂的加氢活性．结果表明，不同载体负载的催化剂催化活性均随着活性组分负载量的增大而提高，其中掺杂大比表面MCM-41的HY／MCM-41/γ-Al2O3所负载的催化剂催化活性提高幅度最大．由于MCM-41与HY分子筛在酸性和孔结构上存在互补性，因而催化剂对萘加氢存在协同作用．提出了萘加氢的反应机理，认为反应网络包括两个平行路径：-是萘加氢生成四氢萘后发生异构化或开环反应；二是萘加氢生成四氢萘后进-步加氢生成十氢萘，继而发生异构化或开环反应．     

MCM-41-HY复合分子筛的合成及其在深度加氢脱硫中的应用

在水热条件下合成了包覆型MCM-41-HY复合分子筛.采用XRD、N2气吸附和SEM等方法对其进行了表征.结果表明,MCM-41-HY复合分子筛和MCM-41与H型Y沸石(HY)的机械混合物明显不同,在复合分子筛MCM-41-HY中,中孔相MCM-41附晶生长在HY沸石上,将HY包覆起来.以二苯并噻吩为模型化合物,考察了该材料担载NiMo催化剂的加氢脱硫活性.结果表明,MCM-41-HY复合分子筛与MCM-41和HY的机械混合物担载NiMo催化剂的加氢脱硫(HDS)活性相当,但MCM-41-HY复合分子筛担载NiMo催化剂的裂化活性较低.其裂化活性不同的原因在于其载体孔道结构和酸性位的分布不同.     

全硅MCM-41担载的加氢脱硫催化剂的TPR研究

用TRP技术研究了以全硅MCM-41(Si-MCM-41)和HNO3交换的全硅MCM-41(H-MCM-41)为载体制备的Ni-Mo、Co-Mo和Ni-W加氢脱硫(HDS)催化剂的还原性能，并以0．8(wt)％二苯并噻吩(DBT)的十氢萘溶液为模型化合物，在高压固定床反应器上考察了上述催化剂的加氢脱硫(HDS)反应性能。结果表明，Si-MCM-41经稀HNO3交换后，所担载的Ni-Mo和Ni-W催化剂还原性能、HDS活性和加氢活性有显著变化，但对Co-Mo催化剂影响不大。这说明在Ni-Mo／H-MCM-41和Ni-W／H-MCM-41中可能存在氢溢流现象，DBT的HDS活性与载体表面酸性和氢溢流有关。     

MCM-41负载的La, Ce和Pt催化剂上三氯乙烯的低温催化燃烧

 分别采用直接水热合成法和浸渍法制备了Si-MCM-41, La-Si-MCM-41和Ce-Si-MCM-41介孔材料及其负载的Pt催化剂. 小角X射线衍射、氮气吸附和扩展X射线精细结构分析表明, La和Ce元素进入了MCM-41分子筛的骨架结构. NH3程序升温脱附测试未检测到含La和Ce样品表面的酸性. 所制备的催化剂具有较高的三氯乙烯催化燃烧活性及生成CO2和HCl的选择性.     

新型介孔分子筛KIT-1加氢脱硫催化剂的研究

制备了新型的结构排列无序的介孔分子筛KIT-1和负载Ni, Mo的KIT-1加氢脱硫催化剂。实验结果表明MoO3较易分散在KIT-1的表面,而NiO则容易在其表面形成小晶粒。与以MCM-41和NaY分子筛为载体的Ni, Mo催化剂相比, KIT-1负载催化剂具有较高的加氢脱硫催化活性,因为KIT-1载体具有相互交错的三维孔道结构, 有利于反应物和产物的扩散, 而不容易受孔道堵塞的影响。     

巯基功能化介孔材料高效锚定钯负载型催化剂的制备及其苯酚加氢催化性能

以含巯基官能团有机硅烷修饰的介孔材料MCM-41和SBA-15为载体, 采用浸渍-氢气还原法制备了高分散和高活性的负载型Pd催化剂. X射线衍射、N₂吸附-脱附和透射电子显微镜表征结果显示, 所制Pd催化剂Pd-SH-MCM-41和Pd-SH-SBA-15具有很好的长程有序结构、分布均匀的孔径、高比表面积及高度分散的Pd颗粒. 苯酚加氢反应结果表明, 以Pd-SH-MCM-41和Pd-SH-SBA-15为催化剂时, 在80℃, 1.0MPa反应1h, 苯酚转化率达99%以上, 环己酮选择性为98%. 它们的催化活性为商业Pd/C催化剂的5倍, Pd/MCM-41和Pd/SBA-15催化剂的3倍. 这可归因于介孔材料表面修饰的巯基官能团对Pd的锚定作用, 避免了Pd颗粒的团聚, 使其高度分散在介孔材料上.     

负载型铜系分子筛催化剂在苯酚羟基化反应中的应用

以介孔分子筛MCM-41、MCM-48和AIMCM-41以及微孔分子筛Naβ和MOR为载体,分别采用有机官能团化法和分步水热合成法制备了系列负载型催化剂,考察了其在苯酚羟基化反应中的活性;得到了不同载体类型、不同负载方法及不同助剂与反应活性的对应关系．结果表明：以微孔分子筛为载体的催化剂对副产物有明显的抑制作用．介孔分子筛AIMCM-41,MCM-41,MCM--48为载体时,催化剂在苯酚羟基化反应中的活性顺序为AIMCM-41〉MCM-48〉MCM-41,助剂镧和钴的引入可以有效抑制副产物的产生．     

Polycondensation of benzyl chloride over Ga- and In-modified ZSM-5 type zeolites and Si-MCM-41 or Montmorillonite-K10 supported GaCl3 and InCl3 catalysts

Performance of In- and Ga-modified ZSM-5 type zeolites (namely, In₂O₃/H-ZSM-5, Ga₂O₃/H-ZSM-5, H-GaMFI and H-GaAlMFI) and InCl₃ or GaCl₃ supported on high silica mesoporous MCM-41 or on Mont.-K10 in the liquid phase polycondensation of benzyl chloride to polybenzyl has been investigated. Influence of solvent (namely, dichloroethane, n-heptane and ethanol) and temperature on the rate of polycondensation of benzyl chloride over the catalyst (InCl₃/Si-MCM-41) showing highest polycondensation activity has also been studied. The In- and Ga-containing solid catalysts show good or high activity in the polycondensation reaction at the reaction condition normally employed in the benzylation of aromatic compounds by benzyl chloride. However, the polycondensation is strongly influenced by the solubility of the polybenzyl polymer in the reaction medium and consequently by the solvent used as the reaction medium.     

Benzylation of benzene and substituted benzenes by benzyl chloride over InCl3, GaCl3, FeCl3 and ZnCl2 supported on clays and Si-MCM-41

Liquid phase benzylation of benzene by benzyl chloride to diphenyl methane over InCl₃, GaCl₃, FeCl₃ and ZnCl₂ supported on commercial clays (viz. Montmorillonite-K10, Montmorillonite-KSF and Kaolin) or on high silica mesoporous MCM-41 (at 60, 70 and 80 °C) has been investigated. The supported InCl₃, GaCl₃ and FeCl₃ showed high activity for the benzylation of benzene. The redox function created due to the impregnation of the clays or Si-MCM-41 by InCl₃, GaCl₃, FeCl₃ or ZnCl₂ seems to play a very important role in the benzylation process. Among the catalysts, the InCl₃/Mont.-K10 showed both high activity and high selectivity for the benzylation. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene>toluene>mesitylene>anisole. The InCl₃ (or GaCl₃)/Mont.-K10 (or Si-MCM-41) catalyst showed high benzene benzylation activity even in the presence of moisture in the reaction mixture. The catalyst can also be reused in the benzylation for several times. Kinetics of the benzene benzylation (using excess of benzene) over the supported metal chloride catalysts have also been thoroughly investigated. A plausible reaction mechanism for the benzylation over the supported metal chloride catalysts is proposed.     

晶化时间对ZSM-5/MCM-48复合分子筛结构及MTG反应性能的影响

采用两步晶化法制备ZSM-5/MCM-48微介孔复合分子筛,通过调变前驱体溶胶的晶化时间获得不同结构的ZSM-5/MCM-48基分子筛催化剂。采用XRD、N₂-吸附、SEM、TEM、FT-IR和Py-FTIR等手段进行表征,结果表明,前驱体溶胶的晶化时间对ZSM-5/MCM-48复合分子筛的结构和表面酸性产生重要的影响,而特定结构的复合分子筛基催化剂可以显著改变甲醇制汽油（MTG）反应的产物分布,与ZSM-5基催化剂相比显著降低了油品中芳烃和均四甲苯的含量。阐明了其催化作用机制是由于介孔结构的MCM-48对微孔结构的ZSM-5界面或表面的修饰作用。     

Synthesis and catalytic performance of bimetallic NiMo- and NiW-ZSM-5/MCM-41 composites for production of liquid biofuels

This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide( CTAB) surfactant with silica-alumina from ZSM-5 zeolite,prepared from natural kaolin by the hydrothermal technique. Subsequently,the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure,confirmed by XRD,SEM,TEM,EDX,NH_3-TPD,XRF and N_2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 NiW-ZSM-5/MCM-41 Ni-ZSM-5/MCM-41 Mo-ZSM-5/MCM-41 W-ZSM-5/MCM-41 NiMo-ZSM-5 NiW-ZSM-5 ZSM-5/MCM-41 ZSM-5 MCM-41. It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products,identified by simulated distillation gas chromatography-flame ionization detector( SimDis GC-FID),are gasoline( 150-200 ℃; C5-12),kerosene( 250-300 ℃; C5-20) and diesel( 350 ℃; C7-20).Moreover,the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference( P 0.05) at 95% confidence level,evaluated by SPSS analysis.     

Extraordinarily high activity in the hydrodesulfurization of 4,6-dimethyldibenzothiophene over Pd supported on mesoporous zeolite Y

Design and preparation of highly active hydrodesulfurization (HDS) catalysts is very important for the removal of air pollution. Herein, we report an extraordinarily active HDS catalyst, which is synthesized by loading of Pd on mesoporous zeolite Y (Pd/HY-M). The mesoporous zeolite Y is successfully synthesized using a water glass containing N,N-dimethyl-N-octadecyl-N-(3-triethoxysilylpropyl) ammonium [(C(2)H(5)O)(3)SiC(3)H(6)N(CH(3))(2)C(18)H(37)](+) cation as a mesoscale template. Compared with mesoporous Beta and ZSM-5 supported Pd catalysts (80.0% and 73.4% for Pd/HBeta-M and Pd/HZSM-5-M, respectively) as well as commercial catalyst of γ-Al(2)O(3) supported Pd catalyst (31.4%), Pd/HY-M catalyst exhibited very high activity in HDS of 4,6-dimethyldibenzothiophene (4,6-DM-DBT, 97.3%). The higher activity of Pd/HY-M than that of Pd/HBeta-M and Pd/HZSM-5-M is assigned to the larger micropore size of zeolite Y compared to that of Beta and ZSM-5. Theoretical simulation and adsorption experimental data show that 4,6-DM-DBT has difficulty entering the micropores of ZSM-5 and Beta zeolites, but the micropores of Y zeolite are accessible.     

多级孔ZSM-5负载的钴催化剂的费-托合成催化性能

采用水蒸气辅助转晶(SAC)法合成了粒径均一(180 nm)的纳米ZSM-5颗粒,颗粒间堆积形成大量的开放介孔,与ZSM-5的微孔共同形成多级孔结构。以该材料为载体采用满孔浸渍法制备了负载量为15%(质量分数)的钴催化剂。采用XRD、SEM、TEM、N_2物理吸附-脱附等表征技术对多级孔ZSM-5载体及其负载催化剂的形貌和结构进行了表征,并对催化剂的费-托合成催化性能进行了测试。结果表明,相比于大颗粒的ZSM-5和商业ZSM-5,多级孔ZSM-5负载的钴催化剂的费-托合成活性最高,CH_4选择性最低,C_(5-20)产物的选择性高达68.9%,这归因于多级孔ZSM-5的介孔孔道有效地促进反应过程中产物的传质扩散以及ZSM-5微孔骨架上的酸中心促进了长链烃产物的二次加氢裂解。     

Synthesis and catalytic performance of ZSM-5/MCM-41 composite molecular sieve from palygorskite

ZSM-5/MCM-41 composite molecular sieve has been hydrothermally synthesized through a two-step crystallization process using palygorskite (PAL) as silicon and aluminum source. The products were characterized by various means and their catalytic properties for acetalization of cyclohexanone and esterification of acetic acid and n-butanol were also investigated. In the first step ZSM-5 zeolite could be formed from the acid-treated PAL after hydrothermal treatment using tetrapropylammonium bromide as template. XRD patterns, N₂ adsorption and desorption data, and TEM images show that the composite obtained in the secondary step had a well-ordered mesoporous MCM-41 phase and a microporous ZSM-5 zeolite phase. Compared with ZSM-5, ZSM-5/MCM-41 composite possessed more total acid amount, weak acid sites and large pore structure due to the formation of MCM-41 and exhibited higher catalytic activity for the acetalization and esterification reaction.     

沸石载体结构对甲烷无氧芳构化性能的影响

考察了担载MoO₃的沸石催化剂上甲烷的无氧芳构化性能,并与沸石结构相关联.结果表明,孔径与苯分子动态直径相当的ZSM-5、ZSM-8、ZSM-11和β沸石等是甲烷无氧芳构化催化剂的良好载体,其中3%MoO₃/HZSM-11具有最高的甲烷芳构化活性和稳定性,973K下的转化率和苯选择性分别为8.0%和90.9%;6%MoO₃/HZSM-8与7%MoO₃/H-β芳构化性能相当.以HMCM-41和HSAPO-34为载体时芳构化活性很低,以HMOR、HX和HY为载体时仅有少量乙烯生成,而以HSAPO-5和HSAPO-11为载体时未检测到烃类生成.     

ZSM-5/MCM-41复合分子筛的合成与表征

以碱处理的ZSM-5浆液为硅铝源,通过水热自组装过程合成了介孔-微孔复合孔道结构的分子筛,并采用XRD、BET、HRTEM、Py-IR和水热处理等手段对合成分子筛进行了表征。结果表明,碱处理ZSM-5时的苛刻程度是影响复合分子筛合成的重要因素,适宜的碱处理条件为NaOH浓度1 mol/L、80℃时处理1 h。表征结果表明,复合分子筛具有规整互通的微孔-介孔梯级复合孔道结构,孔容、比表面积和平均孔径分别为0.63 mL/g,684 m²/g和3.76 nm,属典型的MCM-41结构;与MCM-41相比,复合分子筛的B酸(尤其是强B酸)酸量明显增强,水热稳定性显著提高。