Performance Evaluation Studies of First- and Second-Stage Hydrocracking Catalysts Using Kuwait Vacuum Gas Oil Feedstocks

Abstract

In a two-stage hydrocracking process, two types of catalyst are used to remove undesirable contaminants (such as S, N, hydrogenation of aromatic compounds, etc.) and convert the heavy feedstock to lighter products. In the present work, individual set of experiments were conducted to obtain information regarding activity and selectivity with emphasis on the evaluation of kinetic parameters of first- and second-stage commercial catalysts used in hydrocracking process. The performance tests were conducted in a down-flow fixed-bed hydrocracking pilot plant using a single reactor. The hydrotreating type A catalyst and hydrocracking type B catalyst were used individually with typical Kuwaiti refinery feedstocks, namely, hydrotreated vacuum gas oil (HVGO) and unconverted residual oil (UCRO), respectively. The order of reaction in this study shows first-order kinetics for HDS and HDN over CAT-A, and first-order hydrocracking conversion over CAT-B. For CAT-A the activation energies were found for HDS and HDN reactions at 22 and 27.3 kcal/gmole, while for CAT-B activation energies were 27.4 kcal/gmole.     

减压蜡油加氢裂化催化剂组合动力学模型

以高压加氢裂化六集总动力学模型为基础,建立预测催化剂组合体系产品分布的数学模型。按固定馏程间隔将原料油和加氢裂化生成油划分为减压蜡油 加氢裂化尾油（>360℃）、柴油馏分（290～360℃）、喷气燃料馏分（175～290℃）、重石脑油馏分（65～175℃）、轻石脑油馏分（<65℃）和炼厂气（C4-）6个集总。分别以2种不同类型加氢裂化催化剂的实验数据为基础,采用Matlab 2011b数值计算软件和非线性最小二乘法对动力学模型参数进行了优化回归。以优化回归后的动力学模型参数为初值,调整部分模型参数,建立了预测催化剂组合体系产品分布的数学模型。用该模型计算得到的加氢裂化产品分布与实验值之间的一致性较好,其偏差均小于2%。     

Hydrocracking of Vacuum Gas Oil: Conversion,Product Yields,and Product Quality over an Industrial Hydrocracking Catalyst System

Pilot plant experiments were conducted over an industrial hydrotreating/hydrocracking catalyst system using vacuum gas oil fraction obtained from a refinery crude distillation unit. Extensive pilot plant data were generated on the performance of industrial hydrocracking catalyst system with respect to conversion, product yields, and product quality at various operating conditions. The pilot plant experiments were carried out in a dual-reactor hydrotreating pilot plant system with downflow mode of operation. The temperature varied from 360 to 400°C and liquid hourly space velocity varied from 0.8 to 2.4 hr^?1, keeping a constant pressure of 170 kg/cm² and H₂/HC feed ratio of 845 L/L. The hydrocracked total liquid product was distilled in a true boiling point distillation unit to obtain yields and qualities of different fractions such as naphtha, kerosene, diesel, and unconverted oil. The effect of operating conditions on the performance of the hydrocracking catalyst system was discussed in detail. The kinetics of hydrocracking reaction was studied using a simple first-order reaction and a complex four-lump reaction system and the kinetic parameters were reported.     

Application of a Continuous Kinetic Model for the Hydrocracking of Vacuum Gas Oil

Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and predicted product distributions indicated that the model was successful in predicting the products from hydrocracking reactions.     

Kinetic Study on the Hydrocracking Reaction of Vacuum Residue Using a Lumping Model

Abstract

Based on the experimental hydrocracking of vacuum residue, a kinetic study using a lumping model was carried out to gain insight into the characteristics of catalytic reactions. The lumped species were the saturates, aromatics, resins, and asphaltenes (SARA) constituents in the residue (798 K⁺) fraction and gas, naphtha, kerosene, gas oil, vacuum gas oil, and coke in the products. The pyrite reaction favoring hydrocracking to lighter products was more temperature-dependent than that using a mixture of pyrite and active carbon. The kinetic study showed that the addition of active carbon to pyrite limited the transformation of resins to asphaltenes.     

Kinetic Study on the Hydrocracking Reaction of Vacuum Residue Using a Lumping Model

Based on the experimental hydrocracking of vacuum residue, a kinetic study using a lumping model was carried out to gain insight into the characteristics of catalytic reactions. The lumped species were the saturates, aromatics, resins, and asphaltenes (SARA) constituents in the residue (798 K⁺) fraction and gas, naphtha, kerosene, gas oil, vacuum gas oil, and coke in the products. The pyrite reaction favoring hydrocracking to lighter products was more temperature-dependent than that using a mixture of pyrite and active carbon. The kinetic study showed that the addition of active carbon to pyrite limited the transformation of resins to asphaltenes.     

加氢裂化预处理催化剂按活性级配顺序的实验研究

基于加氢裂化预处理催化剂在不同分区反应规律,按催化剂活性由低到高和由高到低设计2种级配方案。以常规减压蜡油(VGO)为原料,对比考察2种级配方案加氢裂化预处理催化剂在不同预处理入口温度、床层温升、体积空速、反应压力下预处理效果的优劣以及长周期稳定性。结果表明：在催化剂活性由低到高的级配方案中,得到的精制油中氮含量、硫含量和芳烃含量均低于活性由高到低级配的方案;建立反应温度对于2套催化剂活性级配方案预处理效果影响的预测模型,发现精制油性质实验值与预测值偏差极小,可靠性较强;催化剂按活性由低到高级配时的长周期稳定性优于单一预处理催化剂体系,因此催化剂按活性由低到高级配使用可有效延长加氢裂化装置的运转时间。     

减压馏分油催化酯化脱酸的研究

采用浸渍法制备了ZnO/γ-Al2O3催化剂,并用其催化减压馏分油与甲醇进行酯化脱酸反应;考察了催化剂用量、甲醇用量、反应温度和反应时间对脱酸效果的影响,并对脱酸前后的馏分油进行了FTIR表征。实验结果表明,ZnO/γ-Al2O3催化剂具有较高的减压馏分油催化酯化脱酸活性。适宜的反应条件为:减压馏分油用量40 g,ZnO/γ-Al2O3催化剂用量为减压馏分油质量的1.25%,甲醇用量为减压馏分油质量的2.50%,反应温度260℃,反应时间1.00 h。在此条件下,脱酸率达到78%。FTIR表征结果显示,减压馏分油中的环烷酸与甲醇反应转化成酯类,达到了脱酸目的。与脱酸前的减压馏分油相比,脱酸后的精制馏分油酸值减小,运动黏度增加,闪点升高。     

采用减三线油回收裂解气高温余热方案的研究

针对乙烯急冷过程中裂解气420℃左右的热量被直接降级至220℃使用,从而造成高品位热量损失的现状进行了研究,提出了一种分等级回收裂解气高温余热的新工艺流程,即引入炼厂减三线油直接喷淋来自废热锅炉的高温裂解气,通过循环高温减三线油去发生高压蒸汽,与原工艺流程中急冷油循环去发生稀释蒸汽组合,构成分级多次回收高温裂解气余热的新流程。使用Aspen Plus软件模拟新流程和原流程,模拟结果表明,两种流程所能提供的总热量基本一致,新流程可以使裂解气高温余热同时副产高压蒸汽和稀释蒸汽。以640 kt/a乙烯装置为例进行经济核算,可增加经济效益798万元/a。     

低硅/铝比介孔USY分子筛的制备及其VGO加氢裂化性能

以低硅/铝摩尔比((n(Si)/n(Al)=7.0))USY分子筛为原料,通过低浓度碱溶液浸渍结合热处理的方法制备了介孔增强的MUSY分子筛.通过X射线衍射(XRD)、扫描电镜(SEM)、N2吸附-脱附曲线等手段对改性前后分子筛进行表征.结果表明,MUSY分子筛的介孔体积和介孔比表面积分别为0.31 cm3/g和150...     

渣油悬浮床加氢裂化技术的研究

介绍了抚顺石油化工研究院开发的渣油悬浮床加氢裂化工艺及催化剂 ,采用该催化剂加氢处理常、减压渣油 ,馏分油 (<5 3 8℃ ) ,单程收率达到 70 %以上。并在 2 0 0ml小型装置上进行了 5 0 0h的连续运转。采用尾油循环和其它组合工艺 ,可以得到较高的重渣油加氢转化率。     

白土补充精制过程中环烷酸的吸附动力学、吸附平衡及热力学研究

研究了白土补充精制过程中,酮苯脱蜡油中的环烷酸在白土上的吸附问题。首先,借助电喷雾傅立叶变换-离子回旋共振质谱(ESI FT-ICR MS)对采自炼厂的酮苯脱蜡油中的环烷酸进行了分析鉴定,并对白土样品进行了XRD, BET, TG/DTA及SEM表征。其次,采用间歇操作的方式开展了一系列吸附实验,考察了温度、时间、初始酸浓度及剂油比对吸附过程的影响。Langmuir, Freundlich, Tempkin及 Dubinin-Radushkevich (D-R) 吸附模型被用于研究环烷酸在白土上的吸附平衡。同时,拟一级动力学模型、拟二级动力学模型及内扩散模型被用于研究环烷酸在白土上的吸附动力学。结果表明,D-R模型、拟一级动力学模型可分别较好地描述该过程的吸附平衡、吸附动力学行为。热力学计算数据表明该吸附过程可自发进行,且为吸热过程。本研究可为环烷酸在白土上的吸附脱除过程提供一个较为清晰的认识与理解。     

含硫渣油悬浮床加氢裂化性能釜式反应评定

在无外加硫化剂的情况下,在高压釜中对含硫常压渣油进行了悬浮床加氢裂化试验,得到了较优的加氢裂化条件。实验表明,由于原料本身含硫量较高,其中的硫作为硫化剂对所加入的催化剂进行了充分地硫化,在选定的实验条件下,可以得到较高的裂化转化率及相对较少的生焦量,有较好的加氢裂化效果     

切割点对长庆减压蜡油氮化物组成和催化裂化性能的影响

通过实沸点蒸馏和分子蒸馏对长庆原油的常压渣油进行减压蒸馏获得不同终馏点的减压蜡油,采用常规分析方法对其进行分析,并通过电喷雾 傅里叶变换离子回旋质谱(ESI FT-ICR MS)分析氮化物的组成,然后在固定流化床装置上考察了其催化裂化性能。结果表明,切割点从500 ℃提高到580 ℃,可以增加15百分点的减压蜡油收率,且理化性质和催化裂化性能均未明显变差,液体收率和轻油收率略有降低。电喷雾 傅里叶变换离子回旋质谱对氮化物的分析表明,减压蜡油中的碱氮化合物以喹啉系为主,而非碱氮化合物以咔唑系为主,切割点对氮化物的类型并无明显影响。     

直馏VGO中芳烃的分子组成特点

采用傅里叶变换离子回旋共振质谱分析了大庆、胜利、辽河和塔河4种VGO的芳烃化合物类型和碳数分布,并对分离得到的芳烃组分进行钌离子催化氧化实验来考察其侧链形态和长度。结果表明,各VGO芳烃主要由Z值为-6~-40的分子组成,在15~50的碳数范围内呈单峰连续分布,不同类型芳烃化合物在各VGO中的相对含量存在差异。芳烃分子的侧链形态主要是碳数小于25的正构烷基,异构烷基的量较少;大庆、胜利VGO芳烃分子中碳数大于9的长正构烷基较多,而塔河、辽河VGO芳烃分子中碳数小于9的短正构烷基较多。VGO中芳烃分子大多数以芳环上有多个正构烷基的形态存在,少量为单取代或有异构取代基。     

Maximizing Diesel Production From Vacuum Gas Oil Using a Two Stage Hydrocracker

In this study, a six-lump model was sufficient to describe the kinetics of vacuum gas oil (VGO) hydrocracking in order to maximize the production of middle distillate diesel. The kinetic lump model target was to obtain the reaction rate constants that represent all the hydrocracking reactions in the process. The operating conditions such as temperature, pressure, and hydrogen severity were tested to find the optimum parameters that maximize diesel yields. Mild hydrocracking operating conditions of temperature and pressure were used in a commercial hydrocracker with hydrogen severity similar to hydrotreating processes. The main reaction was the VGO conversion to diesel based on its high reaction rate constant compared with other reactions. In addition, the main reaction had the highest effect on catalyst deactivation based on the resulted deactivation factor. A multi-linear regression correlation was obtained for maximizing diesel production as a function of operating pressure, temperature, and hydrogen amount, keeping the diesel specifications within the market demand.     

浅谈渣油加氢裂化在我厂重油加工中的应用前景

文章根据中国石油玉门油田公司炼油化工总厂现有渣油加工流程和生产现状,考虑重油平衡、产品升级等影响炼厂效益的因素,提出了适合玉门油田炼油化工总厂重油加工的三种方案,并从投资、效益和升级潜力等方面对各方案进行了对比分析得出,渣油加氢工艺在玉门油田炼油化工总厂应用后不仅能满足重油平衡难题和燃料油升级需求,还能有效改善炼厂的加工流程和产品结构。渣油加氢作为重油加工的重要手段,不仅在环保和效益方面有很强的优势,对玉门油田炼油化工总厂未来的发展转型也有一定的实际意义。     

Characterization of Nitrogen Compounds in Vacuum Residue and Their Structure Comparison with Coker Gas Oil

In this study, the heteroatom classes and molecular structures of nitrogen compounds in vacuum residue are characterized by the electrospray ionization(ESI) Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) combined with the Fourier transform infrared(FT-IR) spectroscopy. The results demonstrate that three basic nitrogen compounds, N1(in which a molecule contains one nitrogen atom, similarly hereinafter), N1O1 and N2, are identified by their positive-ion mass spectra, and three non-basic nitrogen compounds, N1, N1O1, and N1S1, are characterized by their negative-ion mass spectra. Among these nitrogen compounds, the N1 class species are the most predominant. Combined with the data of ESI FT-ICR MS and FT-IR, the basic N1 class species are likely alkyl quinolines, naphthenic quinolines, acridines, benzonacridines, while the abundant non-basic N1 class species are derivatives of benzocarbazole. In comparison with CGO, the N1 basic nitrogen compounds in VR exhibit a higher average degree of condensation and have much longer alkyl side chains.     

蜡油加氢裂化工艺中金刚烷指纹化合物的分析及应用

选择单金刚烷及双金刚烷化合物作为烃指纹化合物,采用气相色谱/质谱（GC/MS）对其进行定性及定量分析,考察了不同加氢裂化条件下,金刚烷化合物的含量及其分布特点。结果表明,减压蜡油（VGO）经加氢裂化后,165℃～350℃中间馏分产品中存在丰富的金刚烷化合物;随着转化率的增加,双金刚烷化合物含量均不断增加,而部分单金刚烷化合物在高转化率条件下含量减少。在加氢裂化过程中,金刚烷化合物含量变化与烃类组成的变化密切相关,并且金刚烷化合物指纹参数与加氢裂化反应转化率呈现良好的线性关系,可监测加氢裂化反应深度及烃类变化。