石脑油催化裂解结构化反应器反应特性的CFD模拟

以石脑油为原料,采用催化裂解六集总动力学模型,建立描述结构化反应器内催化裂解的反应器数学模型,并利用CFD软件对结构化反应器内的石脑油催化裂解性能进行数值模拟。通过改变孔道直径、反应器长度以及反应器内温度、气体入口速率考察反应器结构尺寸和反应条件对目标产物乙烯、丙烯的收率及石脑油转化率的影响。结果表明,反应器孔道直径的增加,目标产物收率减小,反应器长度20 mm时反应完全,升高反应温度和增大入口速率均有利于目标产物的生成。在入口温度680 ℃和入口速率0.4 m·s^-1条件下,石脑油转化率92%,乙烯收率19.3%,丙烯收率23.1%。而在相同反应条件下的固定床反应器中乙烯收率10.3%,丙烯收率13.3%,石脑油转化率80.0%。     

大庆重石脑油蒸汽热裂解集总动力学模型

通过对自建小型裂解装置实验数据的分析,建立了大庆重石脑油蒸汽热裂解反应8集总动力学物理模型,并用Matlab语言对Marquardt⁺⁺ 法进行编程求取了该物理模型的动力学参数。通过对模型计算值与实验值的相对误差分析表明：原料集总因分得较少,相对误差较大,约为10%,但主要产品产率的最大相对误差不超过7%,其中乙烯产率的平均相对误差为1.62%,说明所建模型较好地反映了大庆重石脑油蒸汽裂解反应规律,可以较好地预测主要产品分布。     

大庆重石脑油蒸汽热裂解10集总动力学模型

由于大庆重石脑油正构和异构烷烃、五元和六元环烷烃的裂解性能差异较大,在大庆重石脑油8集总动力学模型的基础上,建立了将重石脑油划分为4个原料集总的10集总动力学模型。引入浅度裂解的概念,采用分层和分步相结合的方法求取了反应速率常数,并进一步回归得到了各反应的活化能和指前因子。实验值与预测值对比分析表明,该模型具有更好的预测能力,可为更宽范围的原料预测提供参考数据。     

基于结构导向集总的FCC汽油催化裂解分子尺度动力学模型

利用结构导向集总模型构造烃分子和编制反应网络,并结合Monte Carlo模拟方法,建立了催化裂化（FCC）汽油催化裂解反应的分子尺度动力学模型。结构导向集总模型选用7个分子结构片段表示催化汽油中的分子,生成2000个共计92种烃类分子代表催化汽油原料组成。模型选取催化汽油中含量较多的11种单体烃作为模型化合物研究其催化裂解反应行为,并以此为依据制定反应规则,求取模型所需反应速率常数。模拟结果表明,应用结构导向集总模型和Monte Carlo模拟方法进行催化裂解分子尺度动力学建模是可行的,能对多种反应产物的产率进行预测。模拟值和实验结果符合良好,相对误差基本在10%以内。模型对延长反应时间后的产品收率有一定的预测能力。     

低温费托合成轻质油品蒸汽裂解性能研究

通过对低温费托合成粗油品经加氢精制和加氢裂化反应生产的石脑油、轻柴油物性和组成分析,确定蒸汽裂解初步反应条件;通过分析不同条件下蒸汽裂解情况,确定最佳裂解条件;结果表明,低温费托合成加氢石脑油双烯质量收率54.2%,三烯质量收率58.74%;低温费托合成裂化石脑油双烯质量收率49.6%,三烯质量收率54.33%;轻柴油双烯质量收率56.77%,三烯质量收率63.12%,三烯收率均高于常规石油基石脑油裂解三烯收率(50%及以下),是非常优质的乙烯裂解原料。     

集总方法在复杂反应动力学模型中的应用

介绍了集总方法在反应动力学建模中的应用进展,并结合建立大庆重石脑油蒸汽裂解集总动力学模型的经验,对用集总方法建立复杂反应体系动力学模型提出了几点经验和建议。     

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。     

基于十集总反应动力学的重油下行床碱性催化裂解CFD模拟

重油下行床碱性催化裂解工艺能够有效抑制催化剂结焦,从而达到较高的重油转化率,获得高收率的轻质油品和低碳烯烃,实现劣质重油的分级高值化转化。为了给该新型工艺的设计优化以及工业放大提供参考,本文建立了能够预测各低碳烯烃产率的十集总重油碱性催化裂解反应动力学模型,基于四阶Runge-Kutta法和BFGS最优化算法求解,获得了各反应路径的指前因子及活化能,并与实验数据进行对比,以验证所建立的动力学模型的准确性。基于耦合十集总反应动力学模型和双流体模型,对200万t·a^-1下行床反应器内的碱性催化裂解过程进行流体力学数值模拟计算,考察了剂油比、反应温度、反应时间、回炼比等操作因素对产物分布的影响规律。     

煤基、石油基石脑油裂解性能及经济性分析

间接液化煤制油过程中,副产大量煤基石脑油。从馏程、芳烃指数、族组成等方面,对煤基石脑油和石油基石脑油的物性进行了对比分析,可知煤基石脑油是优良的乙烯裂解原料。通过蒸汽裂解模拟计算及对比分析可知,煤基石脑油裂解的乙烯、丙烯、双烯(乙烯+丙烯)、三烯(乙烯+丙烯+丁二烯)收率均高于石油基石脑油。通过技术经济测算可知,用煤基石脑油替代石油基石脑油进行蒸汽裂解,具有较好的经济性。     

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。     

丙烯/1-丁烯无规共聚物与丙烯/乙烯抗冲共聚物的对比研究

对丙烯/1-丁烯无规共聚物(PPB)与丙烯/乙烯抗冲共聚物(PPE)的结晶行为进行对比,在等温结晶时,通过相对结晶度随时间的变化关系、等温结晶曲线等研究,表明丙烯/1-丁烯无规共聚物结晶速率明显低于丙烯/乙烯抗冲共聚物,同时丙烯/乙烯抗冲共聚物的等温结晶速率随乙烯单元含量增加没有明显降低。根据Avrami方程计算了共聚物的结晶活化能,证明丙烯/1-丁烯无规共聚物的结晶能力较丙烯/乙烯抗冲共聚物低。扫描电镜分析丙烯/1-丁烯无规共聚物在丁烯单元摩尔分数2.39%时没有韧性拉伸,而丙烯/乙烯抗冲共聚物在乙烯单元摩尔分数3%时出现韧性拉伸。     

Kinetic study of the methanol to olefin process on a SAPO-34 catalyst

In this paper, a new kinetic model for methanol to olefin process over SAPO-34 catalyst was developed using elementary step level. The kinetic model fits well to the experimental data obtained in a fixed bed reactor. Using this kinetic model, the effect of the most important operating conditions such as temperature, pressure and methanol space-time on the product distribution has been examined. It is shown that the temperature ranges between 400 °C and 450 °C is appropriate for propene production while the medium temperature (450 °C) is favorable for total olefin yield which is equal to 33%. Increasing the reactor pressure decreases the ethylene yield, while medium pressure is favorable for the propylene yield. The result shows that the ethylene and propylene and consequently the yield of total olefins increase to approximately 35% with decreasing the molar ratio of inlet water to methanol.     

大庆常渣催化裂解反应动力学模型

An 8-lump kinetic model was proposed to predict the yields of propylene,ethylene and gasoline in the catalytic pyrolysis process of Daqing atmospheric residue.The model contains 21 kinetic parameters and one for catalyst deactivation.A series of experiments were carried out in a riser reactor over catalyst named LTB-2.The kinetic parameters were estimated by using sub-model method,and apparent activation energies were calculated according to the Arrhenius equation.The predicted yields coincided well with the experimental values.It shows that the kinetic parameters estimated by using the sub-model method were reliable.     

环氧乙烷、环氧丙烷共聚合反应动力学研究

The copolymerization kinetics of ethylene oxide and propylene oxide in an atomizing-circulation reactor under semi-continuous operation is studied which is of great importance for molecular designation.The kinetic parameters are obtained by numerical optimization of the kinetic model.     

Kinetic modeling of oxidative dehydrogenation of propane with CO2 over MoOx/La2O3–Al2O3 in a fluidized bed

A 4-step kinetic model of CO₂-assisted oxidative dehydrogenation (ODH) of propane to C₂/C₃ olefins over a novel MoO_x/La₂O₃–γAl₂O₃ catalyst was developed. Kinetic experiments were conducted in a CREC Riser Simulator at various reaction temperatures (525–600 °C) and times (15–30 s). The catalyst was highly selective towards propylene at all combinations of the reaction conditions. Langmuir-Hinshelwood type kinetics were formulated considering propane ODH, uni- and bimolecular cracking of propane to produce a C₁-C₂ species. It was found that the one site type model adequately fitted the experimental data. The activation energy for the formation of propylene (67.8 kJ/mol) is much lower than that of bimolecular conversion of propane to ethane and ethylene (303 kJ/mol) as well as the direct cracking of propane to methane and ethylene (106.7 kJ/mol). The kinetic modeling revealed the positive effects of CO₂ towards enhancing the propylene selectivity over the catalyst.     

Analysis of gas phase compounds in chemical vapor deposition of carbon from light hydrocarbons

Product distributions in the pyrolysis of ethylene, acetylene, and propylene are studied to obtain an experimental database for a detailed kinetic modeling of gas phase reactions in chemical vapor deposition of carbon from these light hydrocarbons. Experiments were performed with a vertical flow reactor at 900 °C and pressures from 2 to 15 kPa. Gas phase components were analyzed by both on-line and off-line gas chromatography. More than 40 compounds from hydrogen to coronene were identified and quantitatively determined as a function of the residence time varied up to 1.6 s. Product recoveries were generally more than 90%. Analysis of the kinetics of the conversion of the hydrocarbons resulted in global reaction orders of 1.2 (ethylene), 2.7 (acetylene), and 1.5 (propylene). First order dehydrogenation reactions and third order trimerization reactions leading to benzene are decisive reactions for ethylene and acetylene, respectively. Conversion of propylene should also be based on two simultaneous reactions, a first order dissociation reaction, and second order reactions such as bimolecular reaction of propylene resulting an allyl and a propyl radical. These insights should be useful to develop a reaction mechanism based on elementary reactions in forthcoming studies.     

FI Catalysts: A Molecular Zeolite for Olefin Polymerization

A bis(phenoxyimine) group 4 transition metal catalyst (now known as FI catalysts) can discern ethylene from a mixture of ethylene and propylene at more than 99% selectivity. Denisty function theory (DFT) calculations revealed a spatially confined reaction site in the transition states of the migratory insertion which is just the right size for an ethylene molecule but too small for a propylene one. The substituents adjacent to the phenoxy‐oxygens are of crucial importance in developing the size/shape‐selectivity.     

High performance phosphorus-modified ZSM-5 zeolite for butene catalytic cracking

Phosphorus-modified ZSM-5 zeolites were prepared with a novel method, hydrothermal dispersion. XRD showed that the catalysts prepared by the hydrothermal dispersion had better hydrothermal stability than that by impregnation. At the same time, more pronounced cracking activity and higher yield of ethylene plus propylene were obtained on the phosphorus-modified ZSM-5 catalysts prepared by hydrothermal dispersion. Highest yield of ethylene plus propylene was obtained when the loading of phosphorus was 0.68%. The higher amount of phosphorus fixed on the pores of zeolite, higher hydrothermal stability and appropriate acid amount were the possible reasons for obtaining higher yield of ethylene plus propylene.     

Copolymerization of ethylene and propylene catalyzed by novel magnesium chloride supported,vanadium‐based catalysts

Two novel magnesium chloride supported, vanadium‐based Ziegler–Natta catalysts with 9,9‐bis(methoxymethyl)fluorene and di‐i‐butyl phthalate as internal donors were prepared and used in the copolymerization of ethylene and propylene. The catalytic behaviors of these catalysts were investigated and compared with those of traditional magnesium chloride supported, vanadium‐based catalysts without internal donors. Differential scanning calorimetry, gel permeation chromatography, and ¹³C‐NMR spectroscopy analysis were performed to characterize the melting temperatures, molecular weights, and molecular weight distributions as well as structures and compositions of the products. The copolymerization kinetic results indicated that the novel catalyst with 9,9‐bis(methoxymethyl)fluorene as an internal donor had the highest catalytic activity and optimal kinetic behavior in ethylene–propylene copolymerization with an ethylene/propylene molar ratio of 44/56. Low‐crystallinity and high‐molecular‐weight copolymers were obtained with these novel magnesium chloride supported, vanadium‐based catalysts. The reactivity ratio data indicated that the catalytic systems had a tendency to produce random ethylene–propylene copolymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Facile synthesis of ethylene–propylene fully alternating copolymer and comparison with random copolymer of similar composition

A precisely sequenced ethylene–propylene (EP) fully alternating copolymer was synthesized via trans‐1,4‐polymerization of isoprene catalyzed by Ziegler–Natta catalyst followed by hydrogenation. This EP copolymer was used as model polymer for studying structure–property relationship. An ethylene–propylene random copolymer (ethylene–propylene rubber [EPR]) with similar ethylene content was also prepared for comparison, and the effect of comonomer sequence distribution on properties was investigated. The copolymer chain structures were monitored by ¹H and ¹³C NMR and Fourier translation infrared. Differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and tensile tests were employed to determine the thermal and mechanical properties. The fully alternating copolymer EP gives a more precise glass transition comparing than EPR. Further understanding on thermal properties and aggregation behavior of ethylene–propylene copolymers is made possible by this comparative study. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45816.