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.     

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.     

改性Mo/HZSM-5催化剂上的甲烷无氧芳构化的研究

考察了Mo担载量及反应条件对改性Mo/HZSM-5催化剂甲烷无氧芳构化性能的影响。结果表明,Mo担载量对催化剂表面有所影响,从而影响了催化剂的性能,Mo担载量w(Mo)=6%的催化剂性能最佳;反应温度为973K、空速为1400ml/(g-cat.h)时6%Mo/HZSM-5苯收率最高可达5.25%。     

Mo/纳米MCM-49上甲烷无氧芳构化研究

本文研究了Mo/纳米MCM-49催化剂上甲烷无氧芳构化反应.考察了反应温度对甲烷转化率及苯的收率的影响.反应温度在973 K,催化剂取得良好催化活性,甲烷转化率为11～12%,生成苯的选择性为80%～90%.本文还对催化剂稳定性、积碳行为以及再生条件进行了考察.研究表明Mo/纳米MCM-49催化剂稳定性远远超过Mo/ZSM-5催化剂稳定性.通过直接焙烧和添加定量的MoO3活性组分的方法可大幅度延长催化剂的寿命.     

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.     

在改性的Mo/HZSM-5催化剂上的甲烷无氧芳构化

在750℃、0 1MPa、纯甲烷进料、空速为1704h-1、固定床反应条件下,用Cu、Cr、Ba、Ni、V对Mo/HZSM 5催化剂进行了改性研究,使芳烃收率高达13%～15%,同时对催化剂的稳定性和反应机理进行了分析。     

STUDY ON EFFECT OF MODIFICATION WITH BORON ION ON CATALYTIC PROPERTY OF [B] ZSM-5 ZEOLITE CATALYST

A series of [B] ZSM-5 zeolite catalysts modified with B³⁺ have been prepared in this paper and studied for catalytic property in toluene/ethene alkylation reaction. Acidity of the modified catalysts was determined through three methods including TPD, IR and Hammett. The analytical results indicated that after boron had gone into the catalyst channel, the channel and pores were partly blocked by boron oxide and acidity of the modified catalysts have been changed. The results of toluene/ethene alkylation reaction on the modified [B] ZSM-5 zeolite with boron showed that selectivity of p-ethyltoluene reached 96.80% when its catalytic activity was 22.92%. Moreover, the stability of the modified catalyst was also satisfactory.     

分子筛对甲醇制轻烯烃反应烃类产物选择性的影响

采用XRD、SEM、XRF、BET、NH₃-TPD等方法表征USY、Beta、ZSM-5、ZSM-22、SAPO-41和SAPO-34分子筛的物相、组成、结构和酸性,并采用脉冲微反技术考察这些分子筛催化甲醇转化反应活性及烃类产物选择性随反应温度的变化。结果表明,三维十二元环的USY和Beta分子筛的甲醇转化催化活性最高,其次为二维十元环的ZSM-5分子筛,一维十元环的ZSM-22分子筛最低。分子筛的孔结构与孔径尺寸具有择形效应,与反应温度共同影响高选择性烃类产物的碳链长度。大孔分子筛在反应温度450℃以下时的C₄ 烃选择性最高;在反应温度400℃以上时,中孔ZSM-5、ZSM-22和SAPO-41分子筛的C₃烃选择性最佳,小孔SAPO-34分子筛的C₃烃和C₂烃选择性最高。随着反应温度升高,高选择性烃产物的碳数降低。ZSM-5和SAPO-34分子筛是特别适合于甲醇制丙烯和乙烯的择形催化剂,这2种分子筛在催化选择性方面还具有优异的升温特性,在400~550℃范围,随着反应温度升高,产物中乙烯和丙烯的总选择性提高,副产物中丙烷、C₄、C₅和C₆₊烃的选择性降低,甲烷选择性略有增加。     

Mo/HZSM-5催化剂上甲烷脱氢芳构化反应——分子筛水蒸气脱铝的影响

采用蒸汽脱铝法对HZSM-5分子筛进行预处理,利用XRD、N2物理吸附及NH3微分量热吸附对分子筛的结构和酸性质进行表征,在关联催化剂的活性评价结果的基础上,研究了分子筛的结构、酸性质对Mo/HZSM-5催化剂反应性能的影响。结果表明,市售的母本HZSM-5分子筛上,少量的强B酸中心的存在,促使了反应中间物种的深度脱氢,造成催化剂在反应过程中发生严重积炭;水蒸汽处理的HZSM-5分子筛,其骨架结构和酸性质随处理温度的不同而改变。923K蒸汽处理的分子筛,结晶度显著降低,骨架结构的严重受损导致了微孔的阻塞和B酸中心的大量减少,不利于C2中间物种的芳构化;823K处理的HZSM-5分子筛,骨架铝脱出相对缓和,在有效地消除了母本分子筛原有的强B酸中心的同时,又保持着较高的结晶度,改善了分子筛的抗积碳能力,因此其Mo基催化剂的甲烷芳构化反应性能较传统制备的Mo/HZSM-5催化剂有显著提高。     

Mo/HZSM-5催化剂上甲烷脱氢芳构化反应—催化剂制备方法的影响

采用高温蒸汽处理的方法对机械混合法制备的Mo/HZSM-5催化剂进行了改良,利用XRD、XPS等表征催化剂的晶相组成、Mo物种的分散度。结果表明,Mo/HZSM-5催化剂的甲烷脱氢芳构化性能与其Mo物种的分散度密切相关。机械混合法制备的催化剂上,Mo物种主要以微晶的形式分布在分子筛的外表面,由于缺少分子筛孔道择形保护,使积炭副反应的容易发生。经高温蒸汽处理后,催化剂上Mo物种的分散度显著提高,有较多的Mo物种迁移至分子筛的孔道内,并与B酸发生强相互作用生成钼氧二聚体。因此在甲烷芳构化反应中,蒸汽处理的Mo/HZSM-5催化剂显示出较强的抗积炭能力,甲烷转化活性及芳烃的选择性较传统机械混合法制备的催化剂有明显提高。     

Ni/ZSM-5 CATALYST FOR CH4 REFORMING WITH CO2

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.     

催化剂中Y与ZSM-5分子筛比例对裂化、齐聚和氢转移反应的协作影响

本研究的目的是通过考察催化剂中Y分子筛和ZSM-5分子筛的优化组成,来开发新型催化剂以实现催化裂化过程中同时获得低烯烃含量汽油和高丙烯产率。本研究中制备了5种不同Y分子筛和ZSM-5分子筛比例的复配催化剂,采用小型固定流化床反应器,以催化汽油为原料,在480℃反应温度下考察了复配催化剂中Y和ZSM-5的协同作用对质子化裂化、β-断裂、齐聚和氢转移反应选择性的影响。结果表明：复配分子筛催化剂（Y：ZSM-5=1：4）具有最高的质子化裂化和β断裂反应的能力,甚至高于纯ZSM-5分子筛催化剂。另一方面,复配分子筛催化剂（Y：ZSM-5=3：2）的氢转移反应能力最高,而纯Y分子筛催化剂具有最高的齐聚反应能力。对所有5种催化剂而言,提高转化率均会增强质子化裂化和氢转移反应的选择性,但会减少β-断裂反应的选择性。然而,转化率增加时,齐聚反应的选择性未见明显增加。     

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.     

CO_2／H_2合成低碳烯烃催化剂的制备方法及反应条件

研究了Ｆｅ３（ＣＯ）１２／ＺＳＭ－５的制备方法及反应条件对ＣＯ２／Ｈ２合成低碳烯烃反应性能的影响。结果表明，采用该实验室发展的分步回流浸渍法能有效地将Ｆｅ３（ＣＯ）１２负载在ＺＳＭ－５分子筛上。该催化剂在常压下对ＣＯ２／Ｈ２合成低碳烯烃反应有良好的催化性能。     

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.     

Nickel–molybdenum sulfide naphthalene hydrogenation catalysts synthesized by the in situ decomposition of oil-soluble precursors

Nickel–molybdenum sulfide catalysts for the hydrogenation of aromatic hydrocarbons have been prepared by the in situ decomposition of oil-soluble precursors Mo(CO)₆ and Ni(С₇H₁₅СOO)₂ in a hydrocarbon feedstock and characterized by HRTEM and XPS. The resulting Ni–Mo sulfide material exhibits high catalytic activity in the naphthalene hydrogenation reaction. An optimum Mo/Ni ratio of 1/2 has been selected.     

氧化镍改性的ZSM-5催化剂对甲苯和甲醇择形甲基化反应稳定性的影响

在常压下,以N₂为载气,采用固定床反应器考察了NiO改性的ZSM-5催化剂催化甲苯和甲醇择形烷基化反应的性能。采用Ar物理吸附、XRD、XRF、TEM、XPS、H₂-TPR、NH₃-TPD、Py-IR、UV-Vis、UV-Raman、TG、GC-MS等手段表征所制备的催化剂。结果表明,在ZSM-5催化剂上负载质量分数为3%或5%的Ni,催化剂的稳定性明显得到提高。在催化甲苯甲基化反应后,NiO改性ZSM-5催化剂上出现了金属Ni,这可能是由于在积炭过程中,伴随着氢转移过程或者是水消炭反应过程而产生的H2将NiO还原为金属Ni;而且,催化剂的积炭量明显降低,同时作为积炭前驱体的稠环芳烃的生成量也明显减少,推测可能是由于金属Ni的存在,抑制了烷基苯脱氢生成稠环芳烃积炭前驱体的反应,因而提高了催化剂的稳定性。     

Hydrocracking of Polyolefin Thermal Cracking Waxes Over Ni-loaded Molecular Sieve Catalysts

The hydrocracking of thermal cracking waxes obtained from pyrolysis of polyolefin at 360°C for 120 min has been studied using Ni-loaded molecular sieves catalysts. According to XRD, TPR, and BET data, the presence of nickel oxide did not seem to damage the crystalline framework of the catalytic supports. Hydrocracking experiments were carried out in a stirred autoclave reactor at 300°C for 120 min under 2.0 MPa of hydrogen. The results suggested the existence of a balance between the acid and metal function over bifunctional catalysts, which affects hydrogenation and hydroisomerization of thermal cracking waxes. Hydrocracking reactions took place extensively over mixture of Ni/HBeta and ZSM-5, leading toward higher fractions of gases (30.2%) and diesel (23.5%). The higher fractions of gasoline (33.5%) and lube base oil (19.0%) were obtained over mixture of Ni/HSAPO-11 and ZSM-5. In contrast, hydrocracking reaction occurred in a lower extent over mixture of Ni/NMCM-41 and ZSM-5, which produces lube base oil with lower pour point (–10°C), gasoline and diesel with lower bromine numbers (1.1 and 0.8 g Br₂/100 g sample). The viscosity index of lube base oil was in the range of 131–171 over all three mixed catalysts.     

球形ZSM-5分子筛的制备及其在甲醇制芳烃反应中的应用

以ZSM-5分子筛为主要原料,采用水柱成型法制备球形分子筛颗粒,通过低温N2吸附-脱附、XRD、智能颗粒强度试验机等手段对样品进行表征,对黏结剂种类进行筛选,考察了黏结剂用量、不同后处理过程对球形分子筛物性的影响,并进行了应用性能评价。结果表明：黏结剂优选铝胶,随着铝胶用量的增加产品强度逐渐增大;铝胶的加入量为40%,硝酸铝进行后处理,可制备孔体积0.34 mL/g、比表面积282 m2/g、强度38 N/颗的球形分子筛颗粒;将其负载Zn-Ni活性组分应用于甲醇制芳烃反应中,液体收率、芳烃收率及选择性均优于条形催化剂。     

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%.