Enhancement of Propylene Production in a Downer FCC Operation using a ZSM‐5 Additive

The effects of high severity operation and ZSM‐5 addition on the FCC product yield distribution have been studied in a down‐flow reactor unit. VGO cracking at high reaction temperatures of 500–650 °C increases the yield of light olefins (propylene and butenes) with a corresponding loss in gasoline yield and increase in dry gas formation. Similar behavior is observed with the addition of 0–20 wt % ZSM‐5 additive, however, with no increase in dry gas. The combination of the two effects (high severity and ZSM‐5 addition) makes the FCC unit an excellent source of light olefins for downstream petrochemical and alkylation units. The novel process configuration increased the light olefin yield without significant loss in gasoline by suppressing thermal cracking reactions and dry gas formation.     

动植物油生产清洁燃料和低碳烯烃的替代加工工艺

Since the production cost of biodiesel is now the main hurdle limiting their applicability in some areas, catalytic cracking reactions represent an alternative route to utilization of vegetable oils and animal fats. Hence, catalytic transformation of oils and fats was carried out in a laboratory-scale two-stage riser fluid catalytic cracking （TSRFCC） unit in this work. The results show that oils and fats can be used as FCC feed singly or co-feeding with vacuum gas oil （VGO）, which can give high yield （by mass）of liquefied petroleum gas （LPG）, C2-C4 oletms, tor example 45% LPG, 47% C2-C4 olefins, and 77.6% total liquid yield produced with palm oil cracking. Co-feeding with VGO gives a high yield of LPG （39.1%） and propylene （18.1%）. And oxygen element content is very low （about 0.5%） in liquid products, hence, oxygen is removed in the form of H2O, CO and CO2. At the same time, high concentration of aromatics （C7-C9 aromatics predominantly） in the gasoline fraction is obtained after TSRFCC reaction of palm oil, as a result of large amount of hydrogen-transfer, cyclization and aromatization reactions, Additionally, most of properties of produced gasoline and diesel oil fuel meet the requirements of national standards, containing little sulfur. So TSRFCC technology is thought to be an alternative processing technology leading to production of clean fuels and light olefins.     

流化催化裂化汽油改质和增产低碳烯烃的研究

采用GL型催化剂,在小型固定流化床实验装置上考察了反应温度、剂油比、空速和水油比等操作条件对流化催化裂化(FCC)汽油催化改质汽油的产品分布、低碳烯烃(丁烯、丙烯和乙烯)产率和族组成的影响。实验结果表明,在一定反应条件下,FCC汽油通过催化改质可以降低烯烃含量,提高芳烃含量和辛烷值,在满足新汽油标准的同时提高了低碳烯烃的产率。此外,较高的反应温度、剂油比和水油比以及较低的空速有利于FCC汽油催化改质和增产低碳烯烃。     

Behavior of sulfur species present in atmospheric residue in fluid catalytic cracking

The selective removal of sulfur species in atmospheric residue (AR) is strongly wanted since the species of the hydrodesulfurized AR (HDS-AR) define the sulfur content of the product gasoline in the subsequent fluid catalytic cracking (FCC). Hence, the correlations between sulfur species in HDS-AR and FCC gasoline were explored in the present study. HDS-AR was fractionated into vacuum gas oil (VGO) and vacuum residue (VR) by distillation. Reactivities of HDS-AR (S = 3000 mass ppm) and its VGO (S = 900 mass ppm) were measured by micro activity test to clarify which fractions and sulfur compounds in HDS-AR were converted into gasoline and its sulfur species. The yields and sulfur contents of the product gasoline were 45.0 mass% and 52 mass ppm from HDS-AR and 47.7 mass% and 14 mass ppm from VGO, respectively. The sulfur content of the gasoline from HDS-AR was markedly higher than that from HDS-VGO. The saturate and aromatic fractions in HDS-AR are mainly converted to the gasoline in the FCC process, providing similar gasoline yields from HDS-VGO and HDS-AR. Thiophene, methylthiophenes, and benzothiophenes were major sulfur species in both gasolines from HDS-AR and HDS-VGO. Such sulfur species are concluded to be derived from benzothiophenes in VGO and dibenzothiophenes in VR fractions, respectively through hydrogen transferring ring opening and dealkylation during FCC. Sulfur compounds are also produced from H₂S and olefins in FCC, increasing the sulfur content in the product gasoline. The larger sulfur content in the gasoline from HDS-AR than that from HDS-VGO is ascribed to more H₂S being produced during the FCC process as well as dibenzothiophenes being present in the feed.     

Study on reformulation of fluid catalytic cracking gasoline and increasing production of light olefins

The effects of reaction temperature, mass ratio of catalyst to oil, space velocity, and mass ratio of water to oil on the product distribution, the yields of light olefins (light olefins including ethylene, propylene and butylene) and the composition of the fluid catalytic cracking (FCC) gasoline upgraded over the self-made catalyst GL in a confined fluidized bed reactor were investigated. The experimental results showed that FCC gasoline was obviously reformulated under appropriate reaction conditions. The olefins (olefins with C atom number above 4) content of FCC gasoline was markedly reduced, and the aromatics content and octane number were increased. The upgraded gasoline met the new standard of gasoline, and meanwhile, higher yields of light olefins were obtained. Furthermore, higher reaction temperature, higher mass ratio of catalyst to oil, higher mass ratio of water to oil, and lower space velocity were found to be beneficial to FCC gasoline reformulation and light olefins production.     

A process for producing ultraclean gasoline by coupling efficient hydrodesulfurization and directional olefin conversion

To solve the contradiction between ultradeep hydrodesulfurization (HDS) and octane recovery in clean gasoline production, this article proposes a novel two‐stage fluid catalytic cracking (FCC) gasoline hydro‐upgrading process with the selective HDS catalyst in the first reactor and the complemental HDS and octane recovery catalyst in the second reactor. The process achieved the relayed removal of sulfur‐containing compounds with different natures, providing itself with excellent HDS performance, and the hydroisomerization and aromatization of olefins in the second stage endowed the process with superior octane recovery ability and high product yield while remarkably reducing the olefin content of FCC gasoline. The process was also featured by low hydrogen consumption due to the low first‐stage olefin saturation and the balanced second‐stage hydrogenation and dehydrogenation. The two‐stage process developed here sheds a light for efficiently producing ultralow sulfur gasoline from the poor‐quality FCC gasoline of high olefin and sulfur contents. © 2012 American Institute of Chemical Engineers AIChE J, 59: 571–581, 2013     

In-situ synthesis and catalytic activity of ZSM-5 zeolite

ZSM-5 zeolite has been hydrothermally synthesized in-situ on the external surface of calcined kaolinite in the presence of n-butylamine. This supported zeolite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and N₂ adsorption. Several synthesis variables were systematically investigated, including SiO₂ to Al₂O₃ ratio, pH, crystallization time, and crystallization temperature. After mixing the ZSM-5 with a Fluid Catalytic Cracking (FCC) catalyst, catalytic performance was evaluated by cracking vacuum gas oil (VGO) in a micro-fixed bed reactor. ZSM-5 addition was favorable for the production of light olefins by catalytic cracking of VGO.     

Fluid catalytic cracking feed hydrotreatment and its severity impact on product yields and quality

This paper investigates the effect of fluid catalytic cracking (FCC) feed hydrotreatment and its severity increase on product yields and quality obtained in a commercial and a laboratory MAT FCC units. The hydrotreatment of Ural heavy vacuum gas oil reduces not only sulfur, nitrogen, Conradson carbon and metals content in the FCC feed but also increases the mononuclear aromatic hydrocarbons content by 8% absolute at almost no change in the total aromatics content. Regardless of this 8% increase of the mononuclear aromatics in the hydrotreated FCC feed the conversion increase in both commercial and laboratory MAT units was only 2%. The severity increase in the FCC feed hydrotreater leads to a higher conversion in the FCC, higher hydrogen transfer rate that results in higher isobutane/butylenes ratio, lower gasoline olefins content, and higher gasoline motor octane number. The hydrotreatment of the Ural heavy vacuum gas oil exhibited the same changes in FCC catalyst selectivities: lower coke and LCO selectivities and higher gasoline selectivity in both commercial riser FCC unit that has between 2 and 3 s time on stream, and the fixed bed reactor MAT unit, that has 30 s time on stream.     

加氢渣油催化裂化14集总动力学模型的建立

以加工加氢渣油的茂名石化3#重油催化裂化装置（RFCC）的工业数据为基础,针对加氢渣油的特点,提出了以渣油4组分作为划分原料集总的催化裂化14集总动力学模型,通过分步求解法求取动力学参数,并应用工业实测数据进行验证,验证结果表明该模型不仅能较好地预测催化裂化产品分布,而且还能较准确预测主要产品性质,较好地反映了加氢渣油催化裂化反应规律,可为工业装置操作的优化提供指导。     

The performance of solid phosphoric acid catalysts and macroporous sulfonic resins on gasoline alkylation desulfurization

Sulfur removal has received increasing attention in recent years primarily for environmental protection purpose. As an attractive technology in the case of gasoline, OATS (olefinic alkylation of thiophenic sulfur) proposed to separate sulfur compounds by distillation after being weighed down by alkylation with olefins in the feed. In this paper, alkylation reactions of thiophenic compounds were studied over solid phosphoric acid catalysts (SPAM and SPAS using MCM-41 and Silicalite-1 zeolite as supporters respectively) and macroporous sulfonic resins (including NKC-9, D005-2 and Amberlyst 35) with model gasoline and FCC (fluid catalytic cracking) gasoline. Results showed that macroporous sulfonic resins showed better performance than solid phosphoric acid catalysts under milder conditions in both feeds. Among the resins, Amberlyst 35 was the most suitable catalyst for the application of catalytic distillation for its good performance at the temperature range of 353-413 K in FCC gasoline. However, the selectivity of isoamylene dimerization over Amberlyst 35 decreased with the temperature, which was harmful to the product yield and catalyst stability. Besides, different activity orders of solid phosphoric acid catalysts in model gasoline and FCC gasoline were explained by combining the acidic properties of the catalysts with the species of olefins in two feeds.     

轻烃催化裂解制低碳烯烃反应规律与原料特征化

利用小型固定床实验装置对比研究了轻烃模型化合物的催化裂解性能,从优到劣的顺序依次是正构烯烃、正构烷烃、环烷烃、异构烷烃、芳香烃。正构烷烃、异构烷烃与环烷烃催化裂解的总低碳烯烃收率有较大差别,但是总低碳烯烃选择性却均在56.57%左右。研究了直馏石脑油的催化裂解性能,发现乙丙烯收率和总低碳烯烃收率随反应温度的升高及重时空速的降低而逐渐增大;在反应温度680℃、重时空速4.32 h^-1和水油稀释比0.35的条件下,乙丙烯收率35.87%（质量）,总低碳烯烃收率为41.94%（质量）。针对轻烃催化裂解提出了原料特征化参数KF,它是原料H/C原子比、相对密度与分子量的函数,能较好地表征轻烃原料的催化裂解性能。     

Study on reformulation of fluid catalytic cracking gasoline and increasing production of light olefins

The effects of reaction temperature, mass ratio of catalyst to oil, space velocity, and mass ratio of water to oil on the product distribution, the yields of light olefins (light olefins including ethylene, propylene and butylene) and the composition of the fluid catalytic cracking (FCC) gasoline upgraded over the self-made catalyst GL in a confined fluidized bed reactor were investigated. The experimental results showed that FCC gasoline was obviously reformulated under appropriate reaction conditions. The olefins (olefins with C atom number above 4) content of FCC gasoline was markedly reduced, and the aromatics content and octane number were increased. The upgraded gasoline met the new standard of gasoline, and meanwhile, higher yields of light olefins were obtained. Furthermore, higher reaction temperature, higher mass ratio of catalyst to oil, higher mass ratio of water to oil, and lower space velocity were found to be beneficial to FCC gasoline reformulation and light olefins production. __________ Translated from Chemical Reaction Engineering and Technology, 2006, 22(6): 532–538 [译自: 化学反应工程与工艺]     

Catalytic conversion of commingled polymer waste into chemicals and fuels over spent FCC commercial catalyst in a fluidised-bed reactor

A commingled post-consumer polymer (CPW#1) was pyrolysed over spent fluid catalytic cracking (FCC) commercial catalyst (ECat-1) using a laboratory fluidised-bed reactor operating isothermally at ambient pressure. The influence of reaction conditions including catalyst, temperature, ratios of commingled polymer to catalyst feed and flow rates of fluidising gas was examined. The conversion for spent FCC commercial catalyst (82.7 wt%) gave much higher yield than silicate (only 14.2 wt%) and the highest yield (nearly 87 wt%) was obtained for ZSM-5. Greater product selectivity was observed with ECat-1 as a recycled catalyst with about 56 wt% olefins products in the C₃–C₇ range. The selectivity could be further influenced by changes in reaction conditions. Valuable hydrocarbons of olefins and iso-olefins were produced by low temperatures and short contact times used in this study. It is also demonstrated that the use of spent FCC commercial catalyst and under appropriate reaction conditions can have the ability to control both the product yield and product distribution from polymer degradation, potentially leading to a cheaper process with more valuable products.     

催化裂化提升管反应器中颗粒聚团裂化反应的数值模拟

Behavior of catalytic cracking reactions of particle cluster in fluid catalytic cracking (FCC) riser reactors was numerically analyzed using a four-lump mathematical model. Effects of the cluster porosity, inlet gas velocity and temperature, and coke deposition on cracking reactions of the cluster were investigated. Distributions of temperature, gases, and gasoline from both catalyst particle cluster and an isolated catalyst particle are presented. The reaction rates from vacuum gas oil (VGO) to gasoline, gas and coke of individual particle in the cluster are higher than those of the isolated particle, but it reverses for the reaction rates from gasoline to gas and coke. Less gasoline is produced by particle clustering. Simulated results show that the produced mass fluxes of gas and gasoline increase with the operating temperature and molar concentration of VGO, and decrease due to the formation of coke.     

我国FCC催化剂的发展近况

阐述了国内近几年FCC催化剂在重油催化裂化、汽油降烯烃、脱硫及多产低碳烯烃方面的进展.提高抗重金属污染能力、用中孔沸石代替 ZSM-5小孔沸石及大幅度提高催化剂基质的活性仍是今后研发 FCC催化剂的热点.     

煤或天然气经甲醇制低碳烯烃工艺研究新进展

由煤或天然气经甲醇制低碳烯烃工艺是解决石油资源紧张、低碳烯烃需求量越来越大等问题的有效路线。介绍了几种有代表性的经甲醇制低碳烯烃工艺,包括美国UOP/Hydro甲醇制烯烃工艺,中国科学院大连化学物理研究所的合成气经由二甲醚制低碳烯烃(SDTO)工艺,德国Lurgi公司的甲醇制丙烯工艺,以及甲醇制烯烃与AtoFina/UOP烯烃裂解的集成工艺;分析了各工艺目前达到的技术指标及最近的技术改进,关注了各工艺近几年的工业化进程。除了SDTO工艺外,其他几种工艺有望在未来几年内实现工业化。国内甲醇制低碳烯烃工艺的开发应借助于流化催化裂化成熟的工程设计经验,同时加大甲醇制烯烃工艺流化床催化剂的开发力度。     

Kinetic study of crude oil-to-chemicals via steam-enhanced catalytic cracking in a fixed-bed reactor

This study presents new experimental results on the direct conversion of crude oil to chemicals via steam-enhanced catalytic cracking. We have organized the experimental results with a kinetics model using crude oil and steam co-feed in a fixed-bed flow reactor at reaction temperatures of 625, 650, and 675°C over the Ce-Fe/ZSM-5 catalyst. The model let us find optimum conditions for crude oil conversion, and the order of the steam cracking reaction was 2.0 for heavy oil fractions and 1.0 for light oil fractions. The estimated activation energies for the steam cracking reactions ranged between 20 and 200 kJ/mol. Interestingly, the results from kinetic modelling helped in identifying a maximum yield of light olefins at an optimized residence time in the reactor at each temperature level. An equal propylene and ethylene yield was observed between 650 and 670°C, indicating a transition from dominating catalytic cracking at a lower temperature to a dominating thermal cracking at a higher temperature. The results illustrate that steam-enhanced catalytic cracking can be utilized to effectively convert crude oil into basic chemicals (52.1% C2-C4 light olefins and naphtha) at a moderate severity (650°C) as compared to the conventional high-temperature steam cracking process.     

烯烃与环烷烃在催化裂化中反应的异同点

烯烃和环烷烃是催化裂化原料中常见的两种分子类型,对这两类分子反应特点和反应规律的研究对于深入认识催化裂化反应具有重要意义。采用计算化学工具,详细研究烯烃和环烷烃裂化过程中的热力学和动力学。结果表明,在B酸中心作用下,烯烃主要发生裂化反应;在L酸中心作用下,烯烃容易发生环化反应生成环烷基正碳离子,并进一步发生反应生成环烷烃和环烯烃;环烷烃的裂化反应受到热力学限制,反应发生较为困难;烯烃环化反应和环烷烃裂化反应互为逆反应,在催化裂化过程中烯烃环化反应占据优势。     

掺炼催化回炼油FCC原料加氢处理工艺技术研究

将富含芳烃的催化回炼油进行加氢处理后再进行催化裂化,可以有效的改善催化裂化装置的操作,提高催化裂化装置的目的产品收率,改善催化裂化目的产品质量,可以为企业带来显著的经济效益.