Synthesis and Characterization of Nanosized ZSM-5 Zeolite with Mesoporous Carbon Nanotube as Templates

Preparation of nanocrystalline ZSM-5 has been proven possible with carbon matrix by using confined space synthesis. In combination with the hydrothermal method, by the use of a mesoporous carbon nanotube as the inert support material, ZSM-5 with SiO₂/Al₂O₃ ratios of 100 was successfully synthesized with an average crystal size of 27 nm. Their structures were preliminarily characterized by x-ray power diffraction (XRPD) and infrared spectroscopy (IR), and scanning electron microscopy (SEM), respectively. At the same time, we put forward the mechanism about the confined space synthesis in terms of the results.     

Confined Space Synthesis of ZSM-5 Nanozeolite in Self-assembly Supersolubilizing Reversed Micelles

Abstract

The self-assembly method for ZSM-5 nanozeolite syntheses was demonstrated in terms of proposed confined space synthesis. The supersolubilizing reversed micelles formed in neutral oil were confirmed to play a key role of mesoreactors for the confined space ZSM-5 synthesis. The results observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques revealed that both the rates of nucleation and growth and the crystal morphologies in size and shape were controlled well in supersolubilizing reversed micelles and that the approach provided superfine nanozeolite with the crystal sizes and shapes similar to the supersolubilizing reversed micelles. The N₂ adsorption results of a typical sample showed that the mesopores and macropores existing in synthesized products were derived from interparticle spaces and the textural mesoporosities were different from those in well-known ordered mesoporous materials. Furthermore, the adsorption/desorption behaviors correlated considerably well with the crystal sizes for all the samples. In addition, the heterogeneous nucleation and growth of nanosized crystals were suggested for understanding of the confined space synthesis in mesoscale reactors.     

Ni/ZSM-5 CATALYST FOR CH4 REFORMING WITH CO2

Abstract

For good physical and chemical proprieties of ZSM-5 and its selectivity to higher hydrocarbons it is selected as support carrier. In this paper CH₄ reforming with CO₂ to synthesize heavier hydrocarbons over Ni/ZSM-5 catalyst is investigated. The reforming reaction is operated at 1073K under the ambient pressure in a fixed-bed tabular reactor. As promoter rare earth oxides, La₂O₃, CeO₂, Pr₆O₁₁ and Nd₂O₃ are separately added to Ni/ZSM-5 and Ni-La/ZSM-5(NZL), Ni-Ce/ZSM-5(NZC), Ni-Pr/ZSM-5(NZP) and Ni-Nd/ZSM-5(NZN) are formed accordingly. For convenience, they are recorded as Ni-RE/ZSM-5. When these catalysts are used in the reforming reaction the yield of heavier hydrocarbons is obviously increased. The structure of Ni-RE/ZSM-5 catalysts before and after reaction is systematically characterized by XRD, XPS, TEM, SEM, ICP and FTIR. After 10 hours reaction there are more carbon deposit on Ni-RE/ZSM-5 catalyst than Ni/ZSM-5, but their structure are not destroyed and carbon deposit is easy gasified.     

The Effect of Metal Introduced Over ZSM-5 Zeolite for C9 Heavy Aromatics Hydrodealkylation

Abstract

Five different (Bi, Ni, Mo, Pt, H)/ZSM-5 catalysts were tested for hydrodealkylation (HDA), isomerisation, dehydrogenated, cyclistion, and poly-alkyl-aromatics activities. Experiments were performed in a fixed-bed microreactor between 300°C and 420°C, at a total pressure of 0.8 MPa and a liquid hourly space velocity of 1.0 h^?1. Pt (Mo)/ZSM-5 catalysts enhanced activity in terms of better balance between metal nanoparticles formed and acid sites. Pt-loading catalysts were the best overall catalysts, producing high C₉ alkyl-aromatics (isopropylbenzene) conversion (95.9%), high HDA selectivity (92.2%), and relatively low reaction temperature. Mo-loading catalysts, despite producing the high conversion, required the higher reaction temperatures.     

Evaluation and modeling of Fischer-Tropsch synthesis in presence of a Co/ZrO2 catalyst

Abstract

The present work focused on the application of response surface methodology (RSM), Box–Behnken design (BBD), for prediction of products distribution of Fischer-Tropsch synthesis (FTS) using a Co/ZrO₂ catalyst in a fixed bed reactor. The effect of four independent operating variables such as reaction temperature, pressure, space velocity and H₂/CO ratio on the responses (CH₄ and C₅⁺ selectivities) in FTS were investigated. The analysis of variance (ANOVA) results showed that the suggested quadratic models could well predict CH₄ and C₅⁺selectivities. The optimized operating condition was temperature 200.73?°C, pressure 20?bar, space velocity 1662.58?h^?1 and H₂/CO ratio 1.93.     

无有机胺模板剂法制备ZSM-5@Silicalite-1核壳材料

ZSM-5@Silicalite-1核壳材料由于其表面纯硅Silicalite-1分子筛能够有效覆盖ZSM-5分子筛表面的酸性位,从而抑制外表面积炭反应,提高其在甲醇转化、烯烃裂解、烷基化等反应中的稳定性及特定产物选择性.但是,ZSM-5@Silicalite-1核壳材料合成需使用有机胺模板剂导向合成,且合成体系采用较...     

Influence of zeolite type on activity of Fischer-Tropsch iron catalysts

The influence of zeolite type on the product composition, activity, and stability of a binary Fischer-Tropsch iron-containing catalyst was studied. It was shown that the redistribution of acid sites takes place during zeolite shaping with alumina, and, as a result, the relative amount of strong acid sites decreases and the proportion of medium-strength acid sites increases. Zeolites ZSM-5 and ZSM-12 appeared to be the most active in secondary reactions of hydrocarbon conversion under the conditions of hydrocarbon synthesis from CO and H₂.     

Effects of Modified Co-Mo Catalysts for FCC Gasoline HDS on Catalytic Activity

Abstract

In this article, a series of catalysts with HZSM-5/γ-Al₂O₃, HZSM-5/TiO₂-γ-Al₂O₃ as supports, bearing Co-Mo as active components, were prepared, and the catalysts were modified with alkaline earth and VIII, IB metal oxide. The catalysts were evaluated by hydrodesulfurization for QILU FCC gasoline. The experiment results showed that: (1) the RON (research octane number) of effluents rose with the increase of ZSM-5 mass percent in the support, but the HDS ratio reduced; (2) the catalysts with ZSM-5/TiO₂-Al₂O₃ as support had higher HDS ratio but lower RON of effluent; and (3) the catalysts modified with metal oxide had higher RON of effluent, but lower HDS ratio, compared with the stuff, and as to RON of effluent and hydrodesulfurization ratio for the modified catalysts, it had the following order: Ba-modified > Fe-modified > Cu-modified.     

Butene-2 Oligomerization to Heavy Olefins over ZSM-5 Zeolite

Abstract

Butene-2 oligomerization to chemical feedstocks is investigated over ZSM-5 catalysts with varying silica-to-alumina ratio and compared with the performance over silica-supported phosphoric acid (SSPA). Butene-2 is oligomerized more efficiently at 4 MPa and 1 hr^?1 over ZSM-5 zeolite with liquid yield ≥66.6%, selectivity to heavy product ≥54.5%. The products over ZSM-5 are also less branched.     

Catalytic Cracking of <Emphasis Type="Italic">n</Emphasis>-Hexane and <Emphasis Type="Italic">n</Emphasis>-Heptane over ZSM-5 Zeolite: Influence of SiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Ratio

The performance of two types of ZSM-5 zeolite catalysts (MFI-type zeolite, SiO₂/Al₂O₃ = 50 and 300) was studied in the catalytic cracking of n-hexane and n-heptane as a model compound of light naphtha for production of light olefins at 500, 550, and 600°C. The physicochemical properties of ZSM-5 catalysts were characterized by means of XRD, BET, SEM and NH₃-TPD. The influence of SiO₂/Al₂O₃ molar ratio was investigated on conversion and product selectivity. ZSM-5 zeolite yielded higher conversion in the cracking of n-hexane compared to n-heptane and maximum conversion was achieved over ZSM-5(50) at 600°C. ZSM-5(50) showed higher alkane selectivity rather than olefins. It was found that ZSM-5(300) was more desirable in terms of having significant selectivity to light olefins as well as producing high propylene to ethylene ratio. The maximum propylene to ethylene ratio of 2.7 and 2.48 was observed over ZSM-5(300) at 500°C for n-hexane and n-heptane cracking, respectively.     

Study on product distribution and catalytic performance of ZSM-5 in methanol conversion to gasoline-range hydrocarbons (MTHC)

Precise product distribution data is very important for kinetic modeling of chemical reactions and chemical reactor design. In this work, H-ZSM-5 catalyst was hydrothermally synthesized and characterization tests including XRD, XRF, BET, and NH₃-TPD revealed its physicochemical properties. Then, methanol conversion into hydrocarbons over ZSM-5 was investigated with WHSV of 4 h^?1 at reaction temperature 410°C. Product distribution result indicated that C₃-C₅⁺ and C₂⁼-C₄⁼ were the major products in gaseous phase, and in liquid phase xylenes, three methyl benzene and C₁₀⁺ aromatics were the main components. It was also observed that the synthesized ZSM-5 had good performance in the methanol to hydrocarbons process and gave rise to highest activity (100%) during 10 h of operation approximately.     

多孔载体上制备ZSM－5沸石膜的研究

多孔载体上制备ＺＳＭ－５沸石膜的研究樊拴狮，史小农，李春华，王金渠（大连理工大学吸附与无机膜研究所，大连１１６０１２）关键词沸石膜，ＺＳＭ－５，生成机理１引言沸石是一种很有前途的无机材料，具有均一的、小于１０的孔径及耐高温性能好、机械强度大、化学稳定...     

Hydroisomerization performance of platinum supported on ZSM-22/ZSM-23 intergrowth zeolite catalyst

Hydroisomerization catalysts Pt/ZSM-22,Pt/ZSM-23,and Pt/ZSM-22/ZSM-23 were prepared by supporting Pt on ZSM-22,ZSM-23,and intergrowth zeolite ZSM-22/ZSM-23,respectively.The typical physicochemical properties of these catalysts were characterized by X-Ray Diffraction(XRD),N2 absorption-desorption,Pyridine-Fourier Transform Infrared(Py-FTIR),Transmission Electron Microscopy(TEM),X-Ray Fluorescence(XRF),Scanning Electron Microscopy(SEM) and NH3-Temperature Programmed Desorption(NH3-TPD),and the performance of these catalysts in n-dodecane hydroisomerization was evaluated in a continuous down-flow fixed bed with a stainless steel tubular reactor.The characterization results indicated that the intergrowth zeolite ZSM-22/ZSM-23 possessed the dual structure of ZSM-22 and ZSM-23,and the catalyst Pt/ZSM-22/ZSM-23 had similar pores and weak acidity to Pt/ZSM-22 and Pt/ZSM-23 catalysts.Moreover,Pt/ZSM-22/ZSM-23 catalyst showed a high selectivity in hydroisomerization of long chain n-alkanes to mono-branched isomers.The evaluation results for n-dodecane hydroisomerization indicated that the activity of Pt/ZSM-22/ZSM-23 was the lowest,while the hydroisomerization selectivity was the highest among the three catalysts.The maximum yield of i-dodecane product was 68.3% over Pt/ZSM-22/ZSM-23 at 320 oC.     

Catalytic study for methanol aromatization over hierarchical ZSM-5 zeolite synthesized by kaolin

Hierarchical and conventional ZSM-5 zeolites were synthesized through steam-assisted crystallization approach using acid-treatment kaolin clay as the silica and aluminium sources. The samples were characterized by XRD, SEM, NH₃-TPD, N₂-physisorption and TG techniques. The results showed that hierarchical ZSM-5 had rich mesopores and bigger specific surface. In conversion of methanol to aromatics, hierarchical and conventional ZSM-5 zeolites showed higher selectivity for aromatics compared with commercial ZSM-5. Under the conditions of 450 °C, 0.15 MPa, the synthesized hierarchical ZSM-5 showed longest lifetime of 380 h, which was 2 and 6 times than those of conventional and commercial ZSM-5, respectively.     

The Catalytic Dehydration of Bio-ethanol to Ethylene on SAPO-34 Catalysts

SAPO-34 catalysts were synthesized by hydrothermal method, and characterized by X-ray diffraction (XRD), NH₃ temperature-programmed desorption (NH₃-TPD) and thermogravimetric-differential thermal analysis (TG-DTA). The synthesized catalysts were tested for dehydration of bio-ethanol to ethylene in comparison with commercial ZSM-5 and γ-Al₂O₃. The home-made SAPO-34 catalysts exhibited similar bio-ethanol conversion and ethylene selectivity at 60°C and 110°C lower compared to commercial ZSM-5 and γ-Al₂O₃ catalysts, respectively, indicating higher low-temperature activity. It was found that the crystallinity and surface acidity of synthesized SAPO-34 decreased after 4 h on stream, which is attributed to the carbonaceous deposits on catalyst confirmed by TG-DTA.     

钛硅ZSM—5分子筛的合成与表征

采用水热晶化法，利用比较廉价的正丁胺为模板剂合成出Ｔｉ－ＺＳＭ－５型分子筛，探讨了它的合成影响因素，利用ＸＲＤ、ＳＥＭ、ＩＲ等方法对Ｔｉ－ＺＳＭ－５分子筛的结构作了表片，结果表明钛已进入分子筛骨架。     

Supported Bifunctional Cobalt Catalysts for CO and H<Subscript>2</Subscript> Conversion to Fuel Fractions of Hydrocarbons

of Supported bifunctional cobalt catalysts for the direct conversion of synthesis gas to liquid fuelfraction hydrocarbons (HCs) have been studied. The effect of ZSM-5 zeolite in the structure of the support preformed using a boehmite binder on the catalytic and physicochemical properties of the catalysts has been examined. The synthesized catalysts exhibit high mechanical strength; therefore, they can be used in tubular Fischer–Tropsch (FT) synthesis reactors. The efficiency of the supported bifunctional Со/(Аl₂O₃–ZSM-5) catalysts is determined by the number of active metal cobalt sites, the degree of dispersion of the cobalt crystallites, and the total surface acidity. An increase in the catalyst acidity leads to an increase in the fuel fraction selectivity owing to long-chain HCs. At the same time, the activity of the catalysts decreases; therefore, a decrease in their efficiency is observed. It is assumed that this finding is attributed to the diffusion limitations between the HC synthesis and hydrotreating sites.     

泡沫结构多级孔ZSM-5分子筛的制备与表征

以商用聚氨酯泡沫为硬模板,采用原位水热法,在100℃下晶化48 h,在聚氨酯泡沫骨架表面形成厚度为1 μ m且致密、连续的分子筛膜,经高温焙烧去除聚氨酯泡沫硬模板和合成分子筛所用的有机模板剂后,获得了可自支撑的泡沫结构多级孔ZSM-5分子筛。XRD、SEM和N₂吸附-脱附表征证实,该多级孔分子筛完全复制了聚氨酯泡沫的三维网络骨架结构,因而具有大孔-介孔-微孔复合孔道结构。采用微波法,在相同实验条件下仅需反应8 h,即可获得泡沫结构的ZSM-5分子筛。该泡沫结构多级孔分子筛在吸附、分离以及催化领域具有潜在的应用价值。     

Hydrogenation of aromatic hydrocarbons over nickel–tungsten sulfide catalysts containing mesoporous aluminosilicates of different nature

The hydrogenation of naphthalene, toluene, and 2-methylnaphthalene used as model compounds; the hydrodearomatization of the methylnaphthalene fraction; and the hydrocracking of oil sludge over Ni–W sulfide catalysts supported on BEA/TUD, BEA/SBA-15, and ZSM-5/SBA-15 composites containing SBA-15 and TUD mesoporous silicates have been studied. Catalytic tests have been conducted in an autoclave at 300–400°C and an initial hydrogen pressure of 50–90 atm. It has been found that the highest activity is exhibited by the catalyst based on the ZSM-5/SBA-15 (1) composite prepared by the double-templating synthesis and characterized by a specific surface area of 400 m²/g and an acidity of 409 μmol/g. Thus, in the case of dearomatization of the methylnaphthalene fraction at 300°C and an H₂ pressure of 50 atm, the content of diaromatic compounds has decreased from 99.0 to 53.4%, while the amount of sulfur compounds has decreased almost 15-fold. The hydrocracking of oil sludge over NiW/ZSM-5/SBA-15 (2) at 400°C and an H₂ pressure of 90 atm has led to an increase in the content of light fractions to 52%.     

CH_(3)COONa改性ZSM-5分子筛及其类芬顿催化性能北大核心CSCD

目的利用改性ZSM-5分子筛负载Fe高效降解有机胺废水。方法实验采用不同浓度的CH_(3)COONa溶液对ZSM-5分子筛进行改性处理,通过XRD、N_(2)吸附及SEM方法对处理前后的样品进行表征,考查了不同浓度的CH_(3)COONa溶液对ZSM-5分子筛结构特征和物化性能的影响。将处理前后的ZSM-5分子筛负载Fe,进行高浓度有机胺废水的催化降解。结果CH_(3)COONa溶液改性对分子筛晶体形貌影响较小,能够在对分子筛微孔结构破坏程度较小的基础上,形成微孔-介孔多级孔结构。结论当CH_(3)COONa溶液浓度为4 mol/L时,有机胺废水的COD去除率高达93.1%。