Study of Separation Behavior of Activated and Non-Activated MOF-5 as Filler on MOF-based Mixed-Matrix Membranes in H<Subscript>2</Subscript>/CO<Subscript>2</Subscript> Separation

In this study, cubic and tetragonal structures of MOF-5 (C-MOF-5 and T-MOF-5) were successfully synthesized, characterized and incorporated into cellulose acetate (CA) polymer matrix in the range of 6, 9 and 12 wt % to fabricate mixed matrix membranes (MMMs). The effects of smaller pore size of T-MOF-5 and more ZnO molecules in T-MOF-5, on the H₂ and CO₂ permeation properties of C-MOF-5/CA and T-MOF-5/CA MMMs were investigated. The all novel MMMs were prepared using the solution casting method and characterized by FTIR, TGA and SEM. SEM images as well as results of FTIR and TGA analyses confirmed good adhesion between both MOF-5s and CA matrix. Addition of both C-MOF-5 and T-MOF-5 into the CA improved the gas transport properties of the CA, especially in H2 separation. The H₂/CO₂ selectivity continued the increasing trend at 9 wt % and did not significantly reduce even at 12 wt % due to good adhesion between both MOF-5s and CA. The highest H₂/CO₂ selectivity was obtained at 12 and 9 wt % loading of C-MOF-5 and T-MOF-5, respectively. By changing the filler from C-MOF-5 to T-MOF-5, the increasing and reducing of adsorption site of H₂ and CO₂ (respectively), and also reducing in pore size, caused the appearance of H₂ permeability to not change much but the CO2 permeability to reduce. Accordingly, the H₂/CO₂ selectivity in all T-MOF-5/CA MMMs is higher than that in all C-MOF-5/CA MMMs. According to obtained results, the activated MOFs (i.e., C-MOF-5 in this study) are not always the best choices for separation process.     

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.     

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.     

Conversion of Syngas to LPG and Aromatics Over Commercial Fischer-Tropsch Catalyst and HZSM-5 in a Dual Bed Reactor

The commercial Co-based Fischer-Tropsch catalyst and HZSM-5 were tested in a single reactor process. FT catalyst was evaluated at 463 K, whereas HZSM-5 was evaluated at various temperatures (523, 573, and 623 K). The effect of syngas flow rate, HZSM-5 temperature and loading on liquefied petroleum gas (LPG) and aromatics selectivities were investigated. HZSM-5 addition suppressed the formation of CO₂ and CH₄, and remarkably enhanced the simultaneous formation of LPG and aromatics. The optimal operating conditions were identified as: T_HZM-5 = 623 K, HZSM-5 loading = 2.5 g, and GHSV = 4.8 L_syngas/(g_cat h).     

甲苯乙基化反应中ZSM-5沸石预处理及氧化物改质剂的影响

考察了几种国产ZSM-5型沸石上甲苯乙基化的催化性能。用直接合成法制得的ZSM-5型沸石经水蒸汽及积炭处理,发现沸石的甲苯乙基化反应的对位选择性增长次序为:水处理<积炭处理<(积炭处理+水处理),而活性正好相反。用几种氧化物作添加剂对沸石改性后,其甲苯乙基化对位选择性的提高顺序为P_2O_5-MgO及P_2O_5>Sb_2O_3>MgO,而改性后活性大小次序为MgO>P_2O_5-MgO>Sb_2O_3>P_2O_5。经20毫升催化剂上反应表明,由P_2O_5-MgO复台氧化物改性的HZSM-5沸石的活性可达12.5％左右,对位选择性可达97％以上。     

利用IR、XPS研究H(M)ZSM-5沸石分子筛的表面酸性质

利用IR光谱和XPS谱图研究了H(M)ZSM-5(M=Al、Ga、Fe、B)沸石分子筛的表面酸性质,结果表明,它们都存在着Brnsted酸(简称B酸)与Lewis酸(简成酸),不同的杂原子分子筛具有不同浓度的B酸与L酸,它们的酸强度的变化规律HZSM-5>H[Ca]]ZSM-5>H(Fe]ZSM-5>H[B]ZSM-5。     

Catalytic Conversion of a Mesitylene and n-Decane Mixture in the Presence of Hydrogen Over ZSM-5 Based Catalysts

Conversion reactions of mesitylene and n-decane mixture over different catalysts prepared on the base of ZSM-5 zeolite were investigated. The influence of reaction temperature on the activity and selectivity of HZSM-5, DZSM-5, and Ni-Mo/ZSM-5 catalysts obtained from NH₄ZSM-5 zeolite was researched for this purpose. According to received results it can be concluded that mesitylene mostly exposed to isomerization and disproportionation, n-decane exposed to hydrocracking reactions up to C₁–C₄ hydrocarbon gases. The catalysts were characterized by textural properties and crystallinity. Thermal oxidation characteristics of coke deposited on the catalysts surface were also researched.     

The Conversion of Syngas to Liquid Fuels in a Dual-Bed Single Reactor Process

The effects of HZSM-5 temperature and weight hourly space velocity (WHSV) on conversion of syngas to liquid fuels were investigated in a single reactor process. The temperature of FT catalyst was constant (463 K), whereas the temperature of HZSM-5 varied (523, 573, 623 K). The value of WHSV ranged between 16 and 24 h^?1. HZSM-5 addition suppressed the formation of CH₄ and remarkably enhanced the formation of iso-C₅-C₁₂ paraffins. An increase of HZSM-5 temperature resulted in an enhancement of gaseous hydrocarbons, C₁₈₊ paraffins, and olefins. The optimal HZSM-5 temperature and WHSV were identified as 523 K and 16 h^?1, respectively.     

Transformation of Cycloparaffin over Zeolite-Supported Metal Catalyst for Improving the Octane Number of Gasoline

Abstract

In order to improve the octane number of gasoline, Ni/HZSM-5 and NiMo/HZSM-5 catalysts were prepared by impregnation method, and their activities for hydrocracking, hydroisomerization, and aromatization were investigated by the transformation of cylcohexane. The experimental results show that the conversion of cyclohexane is affected greatly by the reaction temperature. The production of methyl-cyclopentane is the result of the hydroisomerization of cyclohexane. The olefin distribution reveals that the hydrocracking reaction of cyclohexane over acidic zeolite catalyst probably obeys the dimolecular mechanism and the C₅ and C₇ olefins come from the cracking of the dimer of cyclohexane. The activities of the presulfided Ni/HZSM-5 and NiMo/HZSM-5 catalyst for the transformation of cyclohexane were evaluated and the product selectivities for two presulfided catalysts are similar to those obtained over reduced Ni/HZSM-5 catalyst.     

A Study on Modified HZSM-5 Aromatization for FCC Light Gasoline

Abstract

In this article, the HZSM-5 type zeolite catalysts modified with zinc nitrate and calcium nitrate are prepared by impregnation method. The FCC gasoline (<75°C fraction) is observed and studied on the modified HZSM-5 type zeolite catalysts. The results are that the Z _x -HZSM-5 type zeolite catalysts have a high initial aromatic yield but a rapid deactivation. The C _y -HZSM-5 type zeolite catalysts have a lower aromatic yield and a familiar deactivation comparing to Z _x -HZSM-5. The HZSM-5 type zeolite catalysts modified with bimetal zinc nitrate and calcium nitrate have a rather low initial aromatic yield but a long catalyst life; among them, the C_3.5Z_2.0HZSM-5 has the best performance. And also, the C_3.5Z_2.0HZSM-5 type zeolite catalyst has demonstrated good regenerated performance. After regenerated three times, the catalyst still has a good stability. The reaction operational conditions are also observed and studied. The results are that the optimal reaction temperature is 450–490°C, the liquid hours space velocity (LHSV) is 1 h^?1 and the reaction pressure is 0.1 MPa.     

正戊烷热裂解一次反应机理的数值模拟

Materials studio与Aspen软件相结合,提出了一种单体烃热裂解自由基机理的理论研究新方法,并用该方法研究了正戊烷热裂解的一次自由基反应机理。结果表明,正戊烷有可能发生的热裂解一次反应共25个,经过Aspen软件对单路径和合并路径的反复计算,最终确定18个自由基反应为主要反应;这18个反应分别构成了由H·、CH3·和C2H5 ?3个自由基组成的链传递循环反应。其中C2H5与正戊烷链传递最短的优势占领了先机,形成以2 C5H11·分解为首的C2H5·循环,生成C2H6和C3H6;CH·需要1 C3H7分解后才能形成以1 C5H11和3 C5H11·为首的4个循环,按产物多少依次为,1 C5H11·生成CH4和双倍的C2H4,3 C5H11·生成1 C4H8和CH4,3 C5H11生成2 C5H10和H2,1 C5H11·生成1 C5H10和H2。最后,笔者对分子模拟中出现的与裂解规律不相符的计算数据进行了剖析。     

不同HZSM-5催化剂上苯与乙醇的烷基化反应

 以正丁胺为模板剂、水玻璃为硅源、硫酸铝为铝源,采用水热晶化法合成出酸性和晶粒大小不同的ZSM-5分子筛,通过XRD、BET、SEM、NH3-TPD和Py-IR方法对催化剂进行了表征,并在连续流动固定床反应器上对其进行了苯与乙醇烷基化反应性能评价。结果表明,ZSM-5催化剂的酸性质是影响苯与乙醇烷基化反应中苯转化率和乙苯选择性的重要因素,晶粒大小在一定程度上对乙苯的选择性有影响。酸性弱、酸量少的小晶粒ZSM-5分子筛乙苯选择性和苯的转化率能同时达到最优。考察了操作条件对催化性能较好的小晶粒HZSM-5分子筛上苯与乙醇烷基化反应苯的转化率和乙苯选择性的影响,得到该催化剂的最佳反应条件：反应温度380 ℃,苯/醇摩尔比3 ~ 5,质量空速3 ~ 5 h-1。     

C_9芳烃在不同结构分子筛催化剂上的反应

在C9芳烃轻质化的研究中,分别以1,2,4-三甲苯、邻甲乙苯及异丙苯为原料,对它们在不同结构分子筛(包括纳米HZSM-5,Hβ,HMOR沸石)催化剂上的反应进行了研究。实验结果表明,Hβ催化剂的初始活性最高并表现出较好的歧化能力,纳米HZSM-5催化剂则表现出较好的的脱烷基能力,HMOR催化剂的性能介于前两者之间。在C9芳烃的反应中,带有伯烷基、仲烷基和叔烷基的C9芳烃反应活性依次增加。随反应温度的升高,带有伯烷基和仲烷基的C9芳烃依次进行异构化、歧化和脱烷基反应;而带有叔烷基的C9芳烃则以脱烷基反应为主。各催化剂的酸性强弱顺序为:HMOR>Hβ>纳米HZSM-5,其活性高低顺序为:Hβ>纳米HZSM-5>HMOR,这说明分子筛催化剂的结构对C9芳烃反应的影响大于其酸性的影响。     

Alkylated 2,2′-bithiophenes and 2-phenylthiophenes in the composition of pyrolysis products of high-sulfur kerogen

Compounds from the 5-n-alkyl-2,2′-bithiophene, 5-n-alkyl-5′-methyl-2,2′-bithiophene, 5-n-alkyl-2-phenylthiophene, and 5-n-alkyl-2-o-tolylthiophene homologous series were synthesized to prove their presence in the pyrolysis products of sulfur-rich kerogen. A study of the pyrolysis products of sulfur-vulcanized polybutadiene confirmed that these compounds can be formed via the thermal transformation of n-alkyl polysulfur-bound fragments of sulfur-rich kerogen. The earlier proposed scheme that assumes the dependence of the composition of the pyrolysis products of sulfur-rich kerogen on its saturation with sulfide bridges was experimentally corroborated.     

Aromatization of Cyclopentane Over ZSM-5 Catalysts: A Proposal of Reaction Pathway

Abstract

The conversion of cyclopentane over HZSM-5 and GaZSM-5 was studied at 500–600°C in a fixed bed flow reactor. The reaction over HZSM-5 showed that cyclopentane was first cracked to liquified petroleum gas (LPG) that consecutively aromatized to BTX and C₉₊ aromatics. While over GaZSM-5, cyclopentane preferred to oligomerize to larger intermediate namely cyclic hydrocarbon pool that could be converted to C₉₊ aromatics and then cracked to benzene toluene and xylene and LPG. The higher activity was obtained by lowering Si/Al ratio of the parent HZSM-5 and increasing reaction temperature.     

Synthesis of 1,4,5-trimethyl-7-thiabicyclo[2.2.2]octan-2-one from 3,7-dimethyl-5-thianonan-2,8-dione

It was found that the heating of 3,7-dimethyl-5-thianonan-2,8-dione at 50°C in ethanol in the presence of potassium hydroxide yields 1,4,5-trimethyl-7-thiabicyclo[2.2.2]octan-2-one as a mixture of 5-exo-and 5-endo-isomers in the ratio of 5:1. The oxidation of thiabicyclooctanone with hydrogen peroxide and its reduction with sodium borohydride result in 1,4,5-trimethyl-7-thiabicyclo[2.2.2]octane-2-one-7,7-dioxide and 1,4,5-trimethyl-7-thiabicyclo[2.2.2]octane-2-ol, respectively.     

ZSM-5沸石膜的有机胺焙烧过程对膜性能的影响

利用差热和热重分析研究了正丁胺模板剂体系合成的ZSM -5沸石及其膜的模板剂焙烧脱除过程中的热性能变化 ,用H2 和C3H8单组分气体的渗透性能评价了不同焙烧程序的沸石膜的完整性。结果表明 ,模板剂脱除温度在 35 0～ 5 0 0℃之间 ,焙烧升温速率越慢 ,模板剂产生的热变化越小 ,越有利于保持沸石膜的完整性。尽量选用慢的升温速率 ( 35 0～ 5 0 0℃ ,0 5～ 1℃ /min)焙烧脱除有机胺 ,可避免沸石膜产生较大的裂缺 ,保持膜的完整性     

Selective nano alumina supported vanadium oxide catalysts for oxidative dehydrogenation of ethylbenzene to styrene using CO2 as soft oxidant

Nano alumina-supported V₂O₅ catalysts with different loadings have been tested for the dehydrogenation of ethylbenzene with CO₂ as an oxidant. High surface area nano-alumina was prepared and used as support for V₂O₅ as the catalyst. The catalysts were synthesized by impregnation techniques followed by calcinations and microwave treatment, denoted as V₂O₅/γ-Al₂O₃-C and V₂O₅/γ-Al₂O₃-MW, respectively. The V₂O₅ loading was varied on nano-alumina from 5 to 30 wt%. The support and catalysts were characterized by X-ray diffraction (XRD), Barett–Joyner–Halenda (BJH) pore-size distribution, N₂-adsorption isotherms, Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and temperature programed desorption (TPD-NH₃). The characterization results indicated that V₂O₅ is highly dispersed on alumina up to 30%-V₂O₅/γ-Al₂O₃-MW prepared by MW method. The TPD studies indicated that there are significant differences in acid amount and strength for V₂O₅/γ-Al₂O₃-C and V₂O₅/γ-Al₂O₃-MW-catalysts. The catalytic activity of the prepared catalysts was evaluated in the temperature range 450–600 °C in relation to the physicochemical properties and surface acidity. The results revealed that optimum catalytic activity and selectivity (～100%) toward styrene production were obtained using 10% V₂O₅/γ-Al₂O₃-MW catalyst treated with microwave.     

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.     

High performance liquid chromatography method for the determination of patulin and 5-hydroxymethylfurfural in fruit juices marketed in Malaysia

A rapid, simple, improved method for the simultaneous determination of patulin (PAT) and 5-hydroxymethylfurfural (5-HMF) in fruit juices is described. The target compounds were extracted with ethyl acetate using vortex followed by high performance liquid chromatographic separation. PAT and 5-HMF were separated within 4 min using Poroshell C18 column with acetonitrile:water (1:9, v/v) as the mobile phase. Under the optimized conditions, the detection limits of PAT and 5-HMF were 0.25 and 0.46 ng mL⁻¹, respectively while the quantification limits were 0.76 and 1.40 ng mL⁻¹, respectively. The recoveries of PAT and 5-HMF at 50, 750 and 5000 ng g⁻¹ ranged from 92.8 to 108%. The proposed method was applied to fivety-six fruit juices (apple, mango, pineapple, guava, lychee, tamarind, soursop and mixed fruit) and PAT was found in three samples ranging from 13.1–33.7 ug L⁻¹. 5-HMF was found in all the samples ranging from 0.08 to 91.5 mg L⁻¹. Liquid chromatography-tandem mass spectrometry with triple quadrupole analyzer was used to confirm the presence of 5-HMF and PAT in some of the contaminated samples.