Investigation of ZSM-5/MCM-41 Composite Molecular Sieve for Reducing Olefin Content of FCC Gasoline

ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N_2 adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h^(-1),and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.

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.

HMCM-22/MCM-41的制备及其在甲苯碳酸二甲酯烷基化中的催化性能

以自制的HMCM-22作为原料,与中孔分子筛MCM-41的凝胶在水热条件下进行组装得到HMCM-22/MCM-41中微孔复合分子筛,采用XRD、N2吸附-脱附及NH3-TPD等方法对合成样品进行表征。结果表明,合成的样品同时具有中孔分子筛MCM-41与微孔分子筛HMCM-22的特点。采用固定床微型连续流反应器对HMCM-22/MCM-41复合分子筛催化甲苯与碳酸二甲酯(DMC)的烷基化反应性能进行了评价,考察了反应温度、甲苯与DMC摩尔配比及空速对烷基化反应的影响。实验发现,HMCM-22/MCM-41催化甲苯DMC烷基化反应的产物中,对二甲苯的选择性远高于间位和邻位异构体的选择性,表现出良好的催化活性和选择性。

新型MCM-22/MCM-41复合分子筛上FCC汽油降烯烃芳构化反应

采用纳米组装法合成MCM-22/MCM-41微孔/介孔复合分子筛,分别以H-MCM-22和H-MCM-22/MCM-41为催化剂,在固定床微反装置上对FCC汽油进行降烯烃芳构化的对比考察。结果表明,在反应时间2h内,与MCM-22相比,MCM-22/MCM-41具有高的芳构化性能和持久的初始活性,复合分子筛汽油改质的产物中,芳烃体积分数由28.58%上升至51.1%,烯烃体积分数由34.04%降至5.8%。探讨了新型H-MCM-22/MCM-41复合分子筛用于FCC汽油改质的操作条件以及催化剂失活再生性能。结果表明,最佳反应条件为:反应温度400℃,压力2MPa,空速3h^(-1)。失活催化剂经过两次再生,降烯烃芳构化性能基本不变。

MCM-22/MCM-41复合分子筛改质FCC汽油研究

采用纳米组装法合成了MCM-22/MCM-41复合分子筛,在固定床微反装置上进行催化裂化汽油改质研究,考察了芳构化反应和降烯烃效果。结果显示,MCM-22/MCM-41复合分子筛较单组分MCM-22具有更强的芳构化性能,并且初始活性高,稳定性好。催化裂化汽油经复合分子筛催化改质,芳烃体积分数由28.6%升至51.1%,烯烃体积分数由34.0%降至5.8%。MCM-22/MCM-41复合分子筛用于FCC汽油改质的适宜操作条件:反应温度400℃,压力2 MPa,液时空速3 h-1。

MCM-22/MCM-41复合分子筛的设计 制备与表征

微孔分子筛是重要的择形催化剂,具有均匀发达的微孔和强酸性,但其孔径较小,大分子难以进入孔道,这大大限制了其工业应用范围。本文采用的MCM-22分子筛就是已经进行工业化应用的微孔分子筛代表之一。介孔分子筛材料在催化、吸附与分离以及化学组装制备先进材料和分子器件等方面具有潜在的应用价值。但是,由于介孔分子筛材料较低的水热稳定性和较弱的酸性,极大地影响了其在催化研究中的广泛应用。本文采用的介孔材料MCM-41具有规则孔道结构,在多相催化、吸附分离、复合材料、纳米组装等领域有着重要的学术研究与应用价值。本文中以微孔分子筛Na-MCM-22为内核,合成一种中微孔复合分子筛Na-MCM-22/MCM-41。通过XRD、SEM、IR、N2吸附脱附和TPD等手段对复合材料进行了表征。研究结果表明,复合材料同时具有中孔分子筛MCM-41和微孔分子筛Na-MCM-22的特点,并且和纯MCM-41分子筛相比孔壁增厚,孔径变大;与纯微孔分子筛Na-MCM-22相比,复合分子筛的酸性明显减弱,BET计算其孔径分布主要集中于0.7和3.0nm。

Efficient catalytic conversion of jatropha oil to high grade biofuel on Ni-Mo_(2)C/MCM-41 catalysts with tuned surface properties

The activity of Mo_(2) C-based catalyst on vegetable oil conversion into biofuel could be greatedly promoted by tuning the carbon content,while its modification mechanism on the surface properties remained elusive.Herein,the exposed active sites,the particle size and Lewis acid amount of Ni-Mo_(2) C/MCM-41 catalysts were regulated by varying CH_(4) content in carbonization gas.The activity of Ni-Mo_(2) C/MCM-41 catalysts in jatropha oil(JO)conversion showed a volcano-like trend over the catalysts with increasing CH_(4) content from 15%to 50%in the preparation process.The one prepared by 25%CH_(4) content(NiMo_(2) C(25)/MCM-41)exhibited the outstanding catalytic performance with 83.9 wt%biofuel yield and95.2%C_(15)-C_(18) selectivity.Such a variation of activity was ascribed to the most exposed active sites,the smallest particle size,and the lowest Lewis acid amount from Ni^(0) on the Ni-Mo_(2) C(25)/MCM-41 catalyst surface.Moreover,the Ni-Mo_(2) C(25)/MCM-41 catalyst could also effectively catalyze the conversion of crude waste cooking oil(WCO)into green diesel.This study offers an effective strategy to improve catalytic performance of molybdenum carbide catalyst on vegetable oil conversion.

Cracking of a Used Lubricant Oil Using NiMo/MCM-41 and the Mixture of Ni/MCM-41 and H-MCM-41 Catalysts

Catalytic activities of NiMo/MCM-41 and the mixture of Ni/MCM-41 with H-MCM-41 in cracking used ULO （lubricant oil） have been studied. This work was started by synthesis of aluminosilicate （MCM-41） at ratio of Si/AI = 50, using CTAB （cetyltrimethylammonium bromide） as a template, and TMAOH （tetramethylammonium hydroxide） as co-surfactant, where a hydrothermal process at 100 ℃ was conducted for 12 h. Organic compounds were then burned out from the dry solid material by calcination at 540 ℃. Ni/MCM-41 and H-MCM-41 were produced by ion exchange method, followed by reduction and calcination treatments, respectively, while NiMo/MCM-41 was produced by impregnation method followed by calcination. Product of MCM-41 was characterized by XRD （X-ray Diffraction）, Fourier FTIR （transform infra red spectrophotometric）, TEM （transmission electron microscopic） and BET （brunauer-emmet-teller） methods. Performance of the catalytic activities were shown by both of NiMo/MCM-41 and the mixture of 1：1 of H-MCM-41 and Ni/MCM-41 were mixed with the ULO at ratio of 1：200 （w/v） in a stainless steel reactor, then they were heated at 420 ℃. The products of cracking were analyzed using GC-MS （gas chromatography-mass spectrometry）. Results of the work showed that the MCM-41 was successfully synthesized. Using mixture of Ni/MCM-41 and H-MCM-41 catalysts, 56.6% of ULO could be converted to OLP （organic liquid product）. However, using NiMo/MCM-41 catalyst only 28.5% OLP could be produced. GC-MS analyses showed that cracking of the ULO at 420 ~C using NiMo/MCM-41 catalyst gave conversion 4.3% and 8.8% to gasoline like and diesel like fractions, respectively, while using mixture of Ni/MCM-41 and H-MCM-41 catalysts, conversion of 12.2% and 14.8% respectively to gasoline like and diesel like fractions were obtained.

Production of Carbon Nanotubes and Hydrogen Catalyzed with Ni/MCM-41 Catalysts

Methane catalytic decomposition (MCD) over Ni/MCM-41 catalysts was tested in a microreactor to simultaneously produce hydrogen and carbon nanotubes (CNTs). The methane conversion reached 30% to 47% at a moderate temperature range from 400°C to 600°C and the catalytic activity of the catalysts remains stable during 500 min steam on time. CNTs were chiefly formed through tip-growth mode, due to the weak interaction between the metallic Ni and the support. Most of the Ni particles are located on the tip of the produced CNTs, which avoids rapid deactivation of the catalyst resulted from carbon encapsulation. Large Ni particles usually lead to the formation of CNTs with big diameter. During the reaction, the shape of Ni particles changed from pseudo-sphere to diamond-like. All the CNTs consist of multiple layer walls and are curved in certain degree.

Hydrosilylation of olefins over rhodium complex anchored over thioether-functionalized MCM-41

The hydrosilylation of alkenes with triethoxysilane has been achieved at 120 C in the presence of 0.01 mol%of thioetherfunctionalized MCM-41 anchored rhodium complex,affording the corresponding addition products in 68-91%yields.This supported rhodium complex can be reused several times without noticeable loss of activity.Our system not only solves the basic problems of catalyst separation and recovery,but also avoids the use of phosphine ligands.

Preparation of MCM-41 in Industrial Scale and Its Application in Heavy Oil Processing

A series of MCM 41 molecular sieves have been prepared on an industrial scale, and the effect of preparation factors such as aging temperature, pH values on the structure and pore distribution of the MCM 41 product have been studied by using X ray diffraction(XRD), thermogravimetric(TG) and electron microscopy(TEM). It is shown that the pH values have a significant effect on the crystallinity of the synthesized product. Under proper conditions, the MCM 41 prepared on an industrial scale has the same performance as the samples prepared on an Lab scale. The prepared MCM 41 was used as a modifier of zeolite Y for fluid catalytic cracking(FCC) of residual oil. It is shown that the addition of the MCM 41 in the zeolite Y catalyst increases the pore size, and surface area of the catalysts, which helps to increase the yield of gasoline and diesel and decrease the production of gaseous product and carbon deposition in the catalyst. The better performance of the MCM 41 modified zeolite Y catalyst is believed to be due to its adjustment on the acidity and increase of the pore size.

A facile synthesis of terminal arylacetylenes via Sonogashira coupling reactions catalyzed by MCM-41-supported mercapto palladium(0) complex

A variety of terminal arylacetylenes have been conveniently synthesized in good to high yields via Sonogashira coupling of aryl iodides with （trimethylsilyl）acetylene catalyzed by MCM-41-supported mercapto palladium（0） complex, followed by desilylation under mild conditions. This polymeric palladium catalyst can be reused many times without any decrease in activity.

Fluorescence of Nanosized Composite of Mesoporous Molecular Sieve and Europium (Ⅲ) Complex

Rare earth complexes Eu(Phen)_2(TTA)(Bipy)(NO_3)_3 and Eu(L)_x(TTA)_(4-x)(NO_3)_3 (L=Phen or Bipy; x=4, 3, 2, 1, 0) solutions (1×10^(-3) mol·L^(-1)) were prepared in EtOH. The luminescent experimental results show that the synergy effect of Phen and TTA exists in Eu^(3+) complexes. But when the ligands of Bipy and TTA coexist in europium complex, the synergy effect does not exist. If a solution of a europium complex has a specific electron configuration of excited state, the solution of the complex has an intensity of fluorescence and a quantum yield. 2.5×10^(-5) mol·L^(-1) Eu(Phen)_2(TTA)_2(NO_3)_3 solution (λ_(ex)=347.0 nm) possesses a maximal quantum yield (0.25) and the strongest fluorescent intensity. The nanosized mesoporous molecular sieves possess spherical cage structure that is fit for preparation of composite materials with encapsulation method. The research results of XRD and IR show that the guest molecule is encapsulated into the channels of the host. The thermostability of the guest molecule in the channels of the host (CH_3)_3Si-MCM-41 is enhanced. The fluorescent intensity and the half-life of nanosized composites of (CH_3)_3Si-MCM-41 and Eu^(3+) complexes are stronger and longer than those of encapsulation products of MCM-41 and Eu^(3+) complexes. Supramolecular encapsulation products emit characteristic radiation of Eu^(3+) ion, vesting in the transitions of (()~5D_0→()~7F_J) (J=0, 1, 2, 3, 4), respectively; each excitation peak of fluorescent spectra of the composites is assigned to an excited electron configuration of Eu^(3+) ion. The host with lipophilic channels is more favourable to fluorescence of the rare earth complex than hydrophilic mesoporous molecular sieve; The fluorescent intensity of (CH_3)_3Si-MCM-41-Eu(Phen)(TTA)_3(NO_3)_3 can match with that of Eu(Phen)(TTA)_3(NO_3)_3 powder sample. These results could be assumed to result from strong radiation absorption of the guest complex molecule (blue shift of maximum excitation wavelength), greatly reducing of silanol group vibration relaxation of the host (CH_3)_3Si-MCM-41, energy transfer from host to guest, and presence of discrete luminescent center associated with nanosized material structures. The selectivity of host to guest and the interaction between the host and the guest influence greatly the luminescent properties of supramolecular system.

Plastic upgrading via catalytic pyrolysis with combined metal-modified gallium-based HZSM-5 and MCM-41

Currently,the conversion of waste plastics into high-value products via catalytic pyrolysis enables the advancement of plastics’open-loop recycling.However,enhancing selectivity remains a critical challenge.This study introduces a novel approach to catalytic pyrolysis,utilizing a combination of MCM-41 and modified gallium-based HZSM-5 catalysts,to achieve exceptional selectivity for aromatic liquid-phase products from linear low-density polyethylene.Firstly,to enhance the probability of dehydroaromatization optimization,the type and proportion of metal active sites within the HZSM-5 catalyst are fine-tuned,which would establish equilibrium with acid sites,resulting in a remarkable 15.72%increase in the selectivity of aromatic hydrocarbons.Secondly,to enhance the accessibility of volatiles to active sites,mesoporous MCM-41 with cracking capabilities is introduced.The doping ratio of MCM-41 is meticulously controlled to facilitate the diffusion of cracked volatiles to the active centers of modified gallium-based HZSM-5,enabling efficient reforming reactions.Experimental findings demonstrate that MCM-41 significantly enhances the dehydroaromatization activity of the modified gallium-based HZSM-5 catalyst.Under the influence of MCM-41:Zr_(2)Ga_(3)/HZSM-5=1:2 catalyst,the selectivity for aromatic hydrocarbons reaches an impressive 93.11%,with a notable 60.01%selectivity for benzene,toluene,ethylbenzene,and xylene.Lastly,this study proposes a plausible pathway for the generation of high-value aromatic hydrocarbons using the combined catalyst.

MCM-41-Supported Bidentate Phosphine Rhodium Complex： An Efficient and Recyclable Heterogeneous Catalyst for the Hydrosilylation of Olefins

MCM-41-supported bidentate phosphine rhodium complex （MCM-41-2P-RhC13） was conveniently synthesized from commercially available and cheap γ-aminopropyltriethoxysilane via immobilization on MCM-41, followed by reacting with diphenylphosphinomethanol and rhodium chloride. It was found that the title complex is a highly efficient catalyst for the hydrosilylation of olefins with triethoxysilane and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 10 consecutive trials without any decreases in activity.

MCM分子筛催化裂化小桐子油制备燃料油的研究

以硅铝比30∶1的MCM-22和全硅的MCM-41分子筛作为催化剂、小桐子油为原料,在实验室自制的小型催化裂化反应装置中进行催化裂化制备燃料油实验。通过考察不同裂化温度、质量空速对催化裂化反应的影响,确定优化的反应条件。结果表明:MCM-22催化裂化的最佳工艺条件为裂化温度510℃、质量空速5. 25 h^(-1); MCM-41催化裂化的最佳工艺条件为裂化温度530℃、质量空速5. 25 h^(-1)。MCM-22催化裂化后产物酸价(KOH)较低(1. 32 mg/g),优于MCM-41催化剂;但MCM-41催化裂化小桐子油转化率较高,优于MCM-22催化剂;两种催化剂催化裂化产物多为芳烃类化合物。

A novel and effective Zn/PEI-MCM catalyst for the acetylene hydration to acetaldehyde

MCM-41 material was modified by polyethyleneimine (PEI) using ultrasonic assisted impregnation method with different PEI loading (P-MCM-x, x=0–15 wt%). The synthesised P-MCM-x materials and corresponding Zn/P-MCM-x catalysts were characterised by FTIR, XRD, TEM, BET, XPS, TG and H2-TPR, as well as their catalytic performance in the hydration of acetylene was investigated. The results showed that the modified materials retained the mesoporous structure with good thermostability, and the corresponding Zn/P-MCM-x displayed the higher catalytic performance than that of Zn/MCM-41 catalyst, especially for the Zn/P-MCM-12 catalyst with about 88%C2H2 conversion and 85%selectivity, and the optimal content of PEI is 12 wt%. More importantly, the introduction of PEI enhanced metal-support interaction to make the better metal dispersion and more active sites, and the charge transfer from N atom to Zn species. These all would be responsible for the high activity of the modified Zn catalysts in the acetylene hydration.