催化裂化干气组分在沸石Y上吸附的分子模拟

Adsorption of catalytic cracking dry gas components, hydrogen (H2), nitrogen (N2), methane (CH4), ethane (C2H6) and ethylene (C2H4) in zeolite Y was studied by performing the Grant Canonical Monte Carlo (GCMC) simulations at 298 and 823K and a pressure range up to 10MPa. Simulation results were analyzed using Langmuir model and it presented fitting of dry gas components adsorption suggesting monolayer adsorption. C2H4 presented most single adsorption amount, which reached 7.63mol/kg at 298K under 200kPa. Thermodynamic parameters of Gibbs free energy change, enthalpy change and entropy change were analyzed based on adsorption equilibrium constant obtained from the GCMC simulations. The results suggested that it was more favorable for C2H4 to adsorb in zeolite Y. Adsorption molecules were in ordered arrangement in zeolite, and C2H4 exhibited more orderly arrangement than other components. Additionally, it was found that there was a competition between dry gas components for mixture adsorption, supercages were prior adsorption space. The competition was favorable to CH4 and C2H6, and competitive power was affected by temperature.     

FCC废催化剂细粉合成超细Y型分子筛

以FCC废催化剂细粉为原料,通过向合成体系中引入无机盐、调变碱度和结晶温度,可以控制Y型分子筛的粒径,得到了大比表面积超细Y型分子筛。以减压蜡油（VGO）为原料油,考察了超细Y型分子筛粒径对催化剂催化裂化反应性能的影响。结果表明,合成体系中引入NaCl可以显著降低Y型分子筛的粒径,较高的碱度和较低的合成温度有利于构建超细Y分子筛的骨架结构;减小分子筛的粒径可以提高轻油的选择性和重油转化率,以及催化剂的抗积炭性能;合成的超细分子筛还显示了优良的水热稳定性。     

不同碳数脂肪酸甲酯在HZSM-5分子筛中吸附行为的分子模拟

采用巨正则蒙特卡洛(GCMC)方法,从反应前驱步骤--吸附出发,在298~473 K下考察了C3~C7直链脂肪酸甲酯在HZSM-5分子筛中的吸附行为。结果表明：HZSM-5催化剂中存在两类吸附位点,分别在孔道交叉处(site I)和直孔道中(site II),并且氢键的形成导致客体分子和site I作用更强;升高温度降低了客体分子和吸附位点的作用强度,使饱和吸附量略有下降。此外,随着碳链长度增加,脂肪酸甲酯的空间位阻增大,体系中氢键数目降低,氢键键长增加,导致长链分子的吸附量显著下降。以上模拟结果从微观角度揭示了温度和链长对脂肪酸甲酯吸附性质的影响,为不同链长油脂分子催化裂解反应特性研究提供了理论指导。     

NaX沸石吸附储氢的分子模拟

采用巨正则系综蒙特卡罗(GCMC)方法,模拟了温度40～293K、压力10000kPa下,氢气在NaX沸石中的吸附行为。结果表明,氢吸附量随温度的升高而下降,随压力的增加而增加,40K时氢的最大吸附量为2.63%(质量分数)。吸附温度对氢在NaX沸石中的吸附位有重要影响,在较低温度下,阳离子和沸石骨架原子(O、Si和Al原子)是氢分子的稳定吸附位;而在较高温度下,仅沸石骨架原子是氢分子的稳定吸附位。     

改性Y型分子筛吸附脱除模拟油品中氯辛烷

分别采用离子交换法和等体积浸渍法对Na-Y分子筛进行改性。利用低温氮气吸附 脱附、X射线衍射、X射线荧光光谱和氨气程序升温脱附等手段对改性分子筛进行表征。考察了改性方法、交换的离子类型、吸附时间、吸附温度和吸附剂与油品质量比等因素对改性分子筛吸附脱除模拟油品中氯辛烷性能的影响,并研究了其再生循环使用性能。结果表明：离子交换法制备的Cu-Y分子筛的吸附脱氯性能高于等体积浸渍法制备的CuO/Y分子筛。经Co²⁺、Cu²⁺、Ag⁺改性的Y型分子筛,其脱氯性能较Na-Y分子筛显著增加,其中Cu-Y分子筛的脱氯性能最好。当Cu-Y分子筛与油品质量比为1∶5、吸附温度为20 ℃、吸附时间为1 h时,脱氯率达到91.9%。NH₃-TPD表征显示,分子筛的表面酸性对其脱氯性能具有显著影响,分子筛表面总酸量越大,其脱氯性能越高。Cu-Y分子筛再生循环使用7次后,其比表面积及酸量有少量减小,导致其脱氯性能略微降低。     

Molecular Simulation of Adsorption of Quinoline Homologues on FAU Zeolite

The Grand Canonical Monte Carlo(GCMC) simulation method was used to investigate the adsorption properties of quinoline homologues(quinoline, 2-methyl quinoline, and 2,4-dimethyl quinoline) on the FAU zeolite. The adsorption heat, adsorption isotherms, and adsorption sites of them were obtained. At the temperature ranging from 673.15 to 873.15 K, the Henry constant of quinoline homologues calculated on the FAU zeolite was applied to simulate their adsorption heat. And its value was more in accordance with the related data reported in the literature. The results showed that their isosteric heat decreased in the following order: 2,4-dimethyl quinoline(118.63 kJ/mol) 2-methyl quinoline(110.45 kJ/mol) quinoline(98 kJ/mol), and complied with the order of their adsorbate basicity. The competitive adsorption of three components of quinoline homologues on the FAU zeolite was calculated numerically at a temperature of 773.15 K and a pressure range of 0.1—100 MPa under the Universal force field. Their adsorption capacity decreased in the following order: quinoline 2-methyl quinoline 2,4-dimethyl quinoline. The smaller the molecule size of the adsorbate, the greater the saturated adsorption capacity would be. It was found that the quinoline homologues could be adsorbed in the main channels of 12- membered-ring framework of the zeolite. Simultaneously, the influence of silica/alumina ratio on the adsorption property of quinoline homologues in FAU zeolite was studied. The smaller the silica/alumina ratio, the greater the isosteric heat and adsorption capacity would be.     

Y分子筛催化异丁烷/丁烯烷基化反应中焦组分的吸附模拟

选取分子筛催化异丁烷/丁烯烷基化反应过程中不同结构类型和碳数的焦组分模型化合物,采用分子模拟方法计算模型化合物在Y分子筛孔道内B酸中心附近的稳定吸附构象,研究焦组分在Y分子筛孔道内的吸附能力差异性和堵孔效应。结果表明,不同结构类型焦组分的吸附能力由强到弱的顺序依次为烯烃类、烷基苯类、烷基萘类、烷烃类、烷基环己烷类、烷基萘烷类;焦组分碳数的增加对焦组分与B酸中心之间的相互作用并无影响;直链类焦组分对Y分子筛的孔道内呈二维空间占据,环状类焦组分对Y分子筛的孔道内呈三维空间占据,而双环类焦组分在X方向上对所在12元环孔道的径向空间占据更大,堵孔效应更明显。     

Preparation of the Modified Y Zeolite for Removal of Organic Sulfur Compounds from FCC Gasoline

Abstract

Ce(IV)-loaded modified NaY (NH₄Y) zeolite was prepared for selective adsorptive desulfurization from fluid catalytic cracked (FCC) gasoline. Ce(β)Y was obtained from NH₄Y using a liquid-phase ion-exchange method. Ce(IV)Y was obtained from calcining Ce(β)Y at 550°C. The structures of the Ce(IV)Y and NaY samples, selective adsorption of organic sulfur compounds on Ce(IV)Y and NaY zeolite, sulfur content of FCC gasoline, and mechanism for adsorption of thiophene on Ce(IV)Y and NaY zeolite were investigated using X-ray diffraction (XRD), gas chromatography–sulfur chemiluminescence detection (GC-SCD), sulfur analysis, Fourier transform infrared (FTIR), frequency response (FR), and intelligent gravimetric analysis (IGA). The selective adsorption desulfurization from FCC gasoline containing organic sulfur compounds (S = 135 μg/g) was investigated with Ce(IV)Y adsorbent for removal.

The sulfur content was reduced to 20.14 μg/g. The thiophene adsorption mechanism showed that Ce(IV)Y can adsorb thiophene via π electronic interaction directly, and thiophene and Ce(IV) can form a stable sulfur–metal bond (S-M bond) that enhances the adsorption capacity of Ce(IV)Y for thiophene. This method for the modification of NaY zeolite provides a promising selective desulfurization process to prepare clean fuels.     

NaA沸石分子筛吸水性能的研究

应用脉冲进样法和程序升温脱附技术,研究了NaA沸石分子筛在298—523K范围内对水的吸附性能和脱附再生性能,发现了NaA沸石分子筛上存在三种吸水位置。测定并讨论了NaA沸石分子筛用于气相脱水和再生的最佳操作温度和条件。     

化学链燃烧中燃料气体在CaSO4(010)表面吸附扩散特性的分子动力学模拟

以CaSO4为载氧体,采用分子动力学研究了化学链燃烧中不同温度时CO在CaSO4(010)表面的吸附扩散特性,并在反应温度为1173 K时与CH4、H2在CaSO4(010)表面的吸附扩散特性对比。结果表明：CO在CaSO4(010)表面的吸附为物理吸附,吸附强度随温度升高而减弱,吸附层与体相层的分层点为距离CaSO4(010)表面0.66 nm处;CO在xy平面方向的扩散能力随温度升高而上升,符合分子碰撞理论; CO吸附于CaSO4(010)表面的原因主要为静电作用所造成的弱相互作用。与CH4、H2相比,CO在CaSO4(010)表面的吸附能力最强,吸附层中含量最多;H2在xy平面方向扩散能力最强,体相层中体积占比最大;而CH4较弱的静电作用与H2较强的位阻作用导致了二者在CaSO4(010)表面吸附能力弱于CO。研究结果可为钙基载氧体的改进与优化提供理论基础。     

Capacity for Manufacture of Ethylbenzene from FCC Dry Gas Reached 1.28 Mt/a in China

The project R&D of the technology combining the gasphase alkylation and liquid-phase transalkylation and com- mercialization of the technology thereof jointly performed by CAS Dalian Institute of Chemical Physics (DICP), Fushun     

多室环流反应器中模拟FCC干气制乙醛

研究了在多室环流反应器(MALR)中用模拟催化裂化干气和空气制乙醛的过程,考察了MALR中气含率和液体循环速率与上升室表观气速之间关系的同时,还考察了反应温度、反应压力、原料气中乙烯含量及催化剂溶液中Pd2+含量对乙烯单程转化率和乙醛选择性的影响。实验结果表明,MALR中气体流速在0.461~0.545cm/s内气含率较大,液体循环速率仅在2.5~3.2cm/s较窄的范围内变化;合成乙醛的最佳条件为:反应温度100~120℃、反应压力0.5~0.6M Pa、催化剂溶液中Pd2+质量浓度0.6~0.9g/L。     

异丙基甲苯在Y型分子筛上吸附常数的测定

测定了对位与间位异丙基甲苯的穿透曲线。开发了一种优化方法，对吸附固定床穿透曲线试验数据进行非线性拟合，从而对吸附平衡常数进行估值。试验结果表明在对异丙基甲苯浓度小于２８％（质量）时，间异丙基甲苯浓度小于３５％（质量）时，吸附平衡存在线性关系，即ｑ＝βＣ＊。对异丙基甲苯在Ｙ型分子筛上吸附总传质系数小于间异丙基甲苯的总传质系数，这与二甲苯系统有显著差异，对过程设计与操作有一定意义     

催化裂化干气与苯烷基化制乙苯催化剂上积炭动力学

用热重法研究催化裂化干气与苯制乙苯催化剂上的积炭行为，考察了时间、温度和反应物浓度对积炭的影响。结果表明，在相同浓度下单组份积炭速度顺序为乙苯＞乙烯＞丙烯＞苯；双组份积炭速度顺序为苯－乙烯＞苯－丙烯。还研究了苯－乙烯、苯－丙烯和乙苯在催化剂上的积炭动力学，求得积炭活化能分别为１５．６、３１．５和１１．８ｋＪ／ｍｏｌ，并依此建立了积炭动力学方程。     

基于Y型沸石的解聚制备ZSM-5/Y沸石催化材料

以工业NaY沸石在碱性环境下解聚形成的硅、铝物种作为ZSM-5沸石生长的部分原料,通过补加适宜的硅物种和模板剂等,成功得到了具有核-壳结构的ZSM-5/Y沸石催化材料。采用XRD、FT-IR、NH3-TPD、SEM、EDS等对合成的材料进行表征,并以异丙苯和正庚烷的催化裂化反应评价了该复合材料作为裂解催化剂的催化活性,并与对应的机械混合物比较。结果表明,ZSM-5/Y沸石复合物的形成是一个由Y型沸石向ZSM-5沸石转变的过程,后合成的ZSM-5沸石包裹Y型沸石进行生长,形成以多晶Y型沸石为核,ZSM-5沸石为壳的复合物。ZSM-5/Y沸石复合物与对应的机械混合物的性质存在显著差异,并非两种沸石的简单加和。与对应的机械混合物相比,ZSM-5/Y沸石复合物催化正庚烷裂化反应的正庚烷转化率更高,低碳烃,特别是乙烯和丙烯的选择性更高;催化异丙苯裂化时,异丙苯转化率较低,壳层的孔道结构是其主要影响因素。     

催化裂化干气制乙苯过程中二甲苯生成研究

在进行乙烯烷基化热力学分析的基础上,在固定床上研究了催化裂化干气制乙苯过程中二甲苯生成,表明,丙苯和丁苯烷基转移有利于甲苯生成,二甲苯主要由甲苯歧化,及甲乙苯裂化和歧化生成,尤其是甲乙苯对生成二甲苯有利。乙苯原料中二甲苯对乙苯脱氢反应性能的影响也被考察。     

噻吩、吡咯、呋喃在H-FAU分子筛中吸附和扩散行为的分子模拟

采用蒙特卡洛方法(GCMC)和分子动力学方法(MD),研究了在823 K、100~1000 kPa条件下噻吩、吡咯和呋喃3种典型的杂原子分子在H FAU分子筛中吸附和扩散性能,分析了3种分子在H FAU分子筛中的概率密度分布、分子扩散动力学和径向分布函数(RDF)。单组分吸附模拟的结果表明,噻吩的饱和吸附量和吸附热最大,吡咯居中,呋喃最小。三元混合组分的吸附模拟表明：噻吩的吸附强度明显大于吡咯和呋喃;3种分子在分子筛的超笼和SOD笼中均有分布,且噻吩在超笼中更加集中;3种分子在孔道中扩散阻力的大小依次为噻吩、吡咯、呋喃;噻吩、吡咯和呋喃主要通过分子环区的离域电子及杂原子与孔道表面H质子进行作用。     

气液相法干气制乙苯工艺研究

研究了革与催化裂化于气中体积分数为10％～20％的乙烯在FX－02改性β沸石催化剂上进行烷基化反应合成乙苯的工艺条件,提出适宜的工艺条件为：干气分三段并联进料,反应温度140～160℃,本质量空速2h～(-1),苯与乙烯摩尔比6～8。在此条件下,乙烯转化率可达到80％～90％,催化剂经1000h运转,乙烯转化率未出现明显的降低。     

FCC汽油吸附脱硫工艺技术——LADS工艺

介绍了洛阳石化工程公司炼制研究所的专利技术－FCC汽油非临氢吸附脱硫（即／PADS）工艺技术，该技术采用固定床工艺，可根据原料性质和产品规格要求，灵活调整操作条件，使FCC汽油的硫含量满足产品规格的要求。失活的LADS－A吸附剂通过LADS－D脱附剂再生，可很好地恢复其吸附活性。该工艺过程简单，操作方便，汽油的辛烷值几乎不损失。