八碳芳烃临氢异构化反应动力学模型

针对某实际工业异构化装置,在已开发的八碳芳烃临氢异构化反应网络的基础上,将系统中的八碳环烷烃和八碳链烷烃作为一个集总组分,提出新的六组分异构化反应网络,由此建立了适用于工业生产的八碳芳烃临氢异构化反应动力学模型.考虑结焦对催化剂活性的影响,提出了一种经验形式的催化剂失活函数,能够合理地描述催化剂失活过程.采用四五阶Runge-Kutta法对模型方程进行数值求解,基于多套稳态平衡数据采用差分变尺度优化算法(BFGS)对动力学参数进行估计,进而在不同操作条件下对模型进行验证.结果表明估计值与工业标定值相当吻合,达到了工业应用的模拟精度要求.     

Kinetic model for hydroisomerization reaction of C8-aromatics

Based on the reported reaction networks, a novel six-component hydroisomerization reaction network with a new lumped species including C₈-naphthenes and C₈-paraffins is proposed and a kinetic model for a commercial unit is also developed. An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke formation on the catalyst surface during the long-term operation. The Runge-Kutta method is used to solve the ordinary differential equations of the model. The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimization method (BFGS). The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predictions and the plant observations. __________ Translated from Journal of Chemical Engineering of Chinese Universities, 2007, 21(3): 429–435 [译自: 高校化学工程学报]     

Light olefin production by catalytic co-cracking of Fischer–Tropsch distillate with methanol and the reaction kinetics investigation

Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C_2–C_6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C_2–C_5 olefins, while for C_6–C_8 olefins,monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C_3–C_5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.     

甲苯歧化与C9芳烃烷基转移反应动力学模型和模拟分析

A new kinetic model for commercial unit of toluene disproportionation and C9-armatiocs transalkylation is developed based on the reported reaction scheme.A time based catalyst deactivation function taking weight hourly space velocity（WHSV）into account is incorporated into the model,which reasonably accounts for the loss in activity because of coke deposition on the surface of catalyst during long-term operation.The kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimiza- tion method.Sets of plant data at different operating conditions are applied to make sure validation of the model and the results show a good agreement between the model predictions and plant observations.The simulation analysis of key variables such as temperature and WHSV affecting process performance is discussed in detail,giving the guidance to select suitable operating conditions.     

不同类型催化剂对异丁烯齐聚反应过程的影响

采用固定床反应器分别探究了三类催化剂（固体磷酸催化剂、酸性阳离子交换树脂催化剂以及分子筛催化剂）对异丁烯齐聚过程的影响。实验结果表明：固体磷酸催化剂适用于C₈烯烃的生产,酸性阳离子树脂催化剂及改性的分子筛催化剂（Hβ）适合生产C₁₂烯烃。异丁烯齐聚产物C₈～C₁₆（清洁燃料油）因无芳烃、无硫,在石化工业中具有非常广泛的应用潜力;由三种类催化剂的评价结果来看,C₈～C₁₆的选择性最高时均能接近100%,但是固体磷酸催化剂和酸性阳离子树脂催化剂的异丁烯原料转化率比Hβ分子筛催化剂低,Hβ催化作用下异丁烯转化率可以达到88%。     

A LUMPED KINETIC MODEL FOR DEHYDRATION OF ETHANOL TO HYDROCARBONS OVER HZSM-5

A kinetic model for the conversion of ethanol to hydrocarbons over HZSM-5 catalyst has been developed. The model is based on data from ethanol dehydration experiments conducted in a fixed-bed integral reactor at atmospheric pressure and temperatures of 150°C to 360°C, and is the first which integrates the major reaction pathways of both dehydration and higher hydrocarbon formation over ZSM-5 zeolite. In the model C₃-C₆ olefins, C₃-C₅ paraffins, and C₆⁺ hydrocarbons are treated as lumped species, while ethanol, diethyl ether, ethylene, and ethane are treated individually. Nonlinear parameter estimation using quasilinearization and least squares as the objective function has been implemented to estimate rate constants, adsorption equilibrium constants, and activation energies. The Langmuir-Hinshelwood rate expressions successfully correlated the experimental data.     

碳四烯烃制丙烯催化剂及其工业应用

研究碳四烯烃催化裂解制丙烯BOC-1催化剂的放大制备及其工业应用,详细介绍催化剂放大制备后实验室小试和工业应用评价结果。BOC-1催化剂在工业生产装置中运行和再生性能良好,丙烯单程收率28.5%,碳四烯烃转化率82.1%,催化剂使用周期17天,各项性能指标均超过洛阳炼化宏力化工有限责任公司的工业催化剂水平,适合进一步推广使用。建立由烯烃催化裂解、吸收稳定、气分、MTBE醚化和烷烃分离5个单元组成的碳四烯烃资源综合利用工艺流程,并使用VMGSim流程模拟软件进行模拟计算。结果表明,采用新工艺流程,碳四烯烃综合利用率99.3%,聚合级丙烯收率35.19%。     

不同粒径Pd/Al2O3催化乙炔加氢反应微观动力学分析

采用等量浸渍法制备了α-Al₂O₃负载的系列Pd催化剂,运用BET、XRD、ICP-AES、CO化学吸附、TEM等手段对催化剂进行了表征;根据部分析因实验设计方案进行动力学实验,采用微观反应动力学方法模拟和分析了所获稳定期本征动力学实验结果。结果发现,制备所得催化剂Pd颗粒的平均粒径分别为1.6、3.4、5.5 nm,CO化学吸附所测定达到活性稳定期后的催化剂表面Pd原子数与Hardeveld模型计算的Pd（111）表面原子数一致;模拟结果表明该微观动力学模型可以很好地模拟不同粒径催化剂上的动力学结果,在所研究范围内表面最丰物种为C₂H₄^*和C₂H₃^*,通过微观与宏观动力学的特征判断3种催化剂上乙炔加氢的速率控制步骤为乙烯基加氢生成乙烯。     

Oxidative coupling of methane as studied by temperature programmed reaction and transient response methods.

A study of methane coupling in non-steady-state conditions has been undertaken in order to clear up some aspects of the reaction mechanism. Calcium oxide, obtained by marble decomposition, has been used directly as catalyst or as a support for small percentages of some metal oxides, namely Na₂O, PbO, Bi₂O₃.

The temperature programmed reaction method was used to follow the progress of the formation of C₂-hydrocarbons and carbon dioxide with the temperature for every type of catalyst: this provided evidence of the role of Na₂O in giving a significant increase in the formation of ethylene. On the other hand temperature programmed desorption runs confirmed that Na₂O enhances the adsorptive properties of calcium oxide towards carbon dioxide, but particularly towards methane and C₂-hydrocarbons: however the desorption of hydrocarbons is accompanied by reaction between the adsorbed species with substantial formation of carbon dioxide.

Runs employing the transient response method confirmed that the presence of Na₂O increases the adsorptive properties of the catalyst towards methane and C₂-hydrocarbons, and showed that the surface reaction can be considered determining from a kinetic point of view in the formation of C₂-products, while CO₂ desorption is the rate limiting step in the complete oxidation.

The type of adsorbed oxygen seems to be one of the most important factors determining the prevailing of one or of the other path.     

Synthesis of C2H4 by partial oxidation of CH4 over LiCl/NiO

Alkali halide added transition metal oxides produced ethylene selectively in oxidative coupling of methane. The role of alkali halides has been investigated for LiCl-added NiO (LiCl/NiO). In the absence of LiCl the reaction over NiO produced only carbon oxides (CO₂ + CO). However, addition of LiCl drastically improved the yield of C₂ compounds (C₂H₆ + C₂H₄). One of the roles of LiCl is to inhibit the catalytic activity of the host NiO for deep oxidation of CH₄. The reaction catalyzed by the LiCl/NiO proceeds stepwise from CH₄ to C₂H₄ through C₂H₆ (2CH₄ → C₂H₆ → C₂H₄). The study on the oxidation of C₂H₆ over the LiCl/NiO showed that the oxidative dehydrogenation of C₂H₆ to C₂H₄ occurs very selectively, which is the main reason why partial oxidation of CH₄ over LiCl/NiO gives C₂H₄ quite selectively. The other role of LiCl is to prevent the host oxide (NiO) from being reduced by CH₄. The catalyst model under working conditions was suggested to be the NiO covered with molten LiCl. XPS studies suggested that the catalytically active species on the LiCl/NiO is a surface compound oxide which has higher valent nickel cations (Ni^(2+δ)+ or Ni³⁺). The catalyst was deactivated at the temperatures>973 K due to vaporization of LiCl and consumption of chlorine during reaction. The kinetic and CH₄---CD₄ exchange studies suggested that the rate-determining step of the reaction is the abstraction of H from the vibrationally excited methane by the molecular oxygen adsorbed on the surface compound oxide.     

Selective catalytic reduction of nitrogen oxide by hydrocarbons over mordenite-type zeolite catalysts

The reduction of NO by hydrocarbons such as C₂H₄, C₂H₆, C₃H₆, and C₃H₈ has been investigated over mordenite-type zeolite catalysts including HM, CuHM, NZA (natural zeolite), and CuNZA prepared by an ion-exchange method in a continuous flow fixed-bed reactor. NO conversion over CuNZA catalyst reaches about 94% with 2000 ppm of C₃H₆ at 500°C. As reductants, alkenes seem to exhibit a higher performance for NO conversion than alkanes regardless of the catalysts. No deterioration of the catalytic activity due to carbonaceous deposits for CuNZA was observed above 400°C even after 30 h of on-stream time, but SO₂ in the feed gas stream causes a severe poisoning of the CuNZA catalyst. The effect of H₂O on NO conversion was significant regardless of the catalysts and the reductants employed in this study. However, CuNZA catalyst shows a unique water tolerance with C₃H₆. The reaction path of NO to N₂ is the most important factor for high performance of this catalytic system. NO is directly reduced by a reaction intermediate, C_n′H_m′(O) formed from hydrocarbon and O₂, N₂O is another reaction intermediate which can be easily removed by C_n′H_m′(O).     

Catalytic degradation of polyethylene over SAPO-37 molecular sieve

The degradation of high-density polyethylene (HDPE) was studied alone and in presence of silicoaluminophosphate type silicoaluminophosphate (SAPO-37) as catalyst. This material was synthesized by the hydrothermal method using tetrapropylammonium hydroxide and tetramethylammonium chloride as organic templates. The characterization by X-ray diffraction, infrared spectroscopy, thermogravimetry and scanning electron microscopy showed that typical faujasite structure for the SAPO-37 was obtained. The total acidity, determined by n-butylamine adsorption, it was equivalent to 0.558 mmol g⁻¹, corresponding to moderate acid strength. For catalytic reaction, a physical mixture of 25%SAPO-37/HDPE was decomposed in a thermobalance at heating rates of 5, 10 and 20 °C min⁻¹, from 380 to 520 °C. At the maximum degradation rate, the products were collected in a cold trap and analyzed by a coupled gas chromatograph/mass spectrometer. The degradation of HDPE without catalyst was carried out at the same conditions for comparison with the obtained data with SAPO-37. The HDPE alone suffers decomposition to a wide range of hydrocarbons (C₅–C₂₅) while in the presence of catalyst, light hydrocarbons (C₂–C₁₂) were obtained. By the application of the Vyazovkin model-free kinetic method, it was observed that the activation energy decreased from 290 kJ mol⁻¹ for HDPE alone, to 220 kJ mol⁻¹ for 25%SAPO-37/HDPE, evidencing that SAPO-37 is an effective catalyst for polyethylene degradation.     

全结晶ZSM-5分子筛催化剂研究及工业应用

制备了全结晶ZSM-5分子筛催化剂,采用XRD、SEM、N2物理吸附-脱附及NH3-TPD等对催化剂进行表征,并考察其用于碳四烯烃催化裂解制丙烯(OCC)反应的催化性能。结果表明,制备的全结晶ZSM-5分子筛催化剂比常规成型的催化剂具有更高的结晶度、更大的比表面积、更丰富的孔结构以及更多的活性中心。高空速有利于反应的进行,提高压力对反应不利,升高温度有利于提高产物丙烯收率。在实验室研究的基础上,将全结晶ZSM-5分子筛催化剂用于OCC工业装置,取得良好的应用效果。     

SBA-15固载酸性离子液体催化酯化反应性能

为了减少离子液体用量及解决催化剂分离问题,采用键合法制备了以SBA-15为载体的固载化离子液体催化剂[C₃SO₃HCP]HSO₄/SBA-15,通过FT-IR、TG、XRD、BET和TEM分析了催化剂的结构和稳定性。并将其应用于催化丁二酸酐和乙醇的酯化反应。结果表明:[C₃SO₃HCP]HSO₄被成功固定在SBA-15上,且具有较高的热稳定性和催化活性,克服了非均相催化剂活性不高与均相催化剂难以分离的不足。在催化剂用量为反应物总质量的5%、n(C₄H₄O₃):n(C₂H₅OH)=1:3,反应温度80℃;反应时间4 h、带水剂用量为反应物总质量的30%的条件下,酯收率达93.7%,且该催化剂循环使用8次后,仍具有较高的催化活性。此外,还考察了以[C₃SO₃HCP]HSO₄/SBA-15为催化剂催化合成系列酯也获得了较高的酯收率,且易于与产物酯分离。     

RIC-200型二甲苯异构化催化剂再生性能

RIC-200型二甲苯异构化催化剂2010年9月在中国石油化工股份有限公司天津分公司芳烃联合装置上首次工业应用,催化剂的异构化活性为23.6%,乙苯转化率为21.5%,C8芳烃损失质量分数2.67%。连续运转45个月,需对催化剂进行再生。RIC-200型催化剂的首次工业再生采用低氧氮气分步烧焦法。结果表明,催化剂上积炭去除干净,再生催化剂的初始异构化活性为23.7%,乙苯转化率为30.4%,活性恢复良好。调整稳定后,C8芳烃损失质量分数2.2%,选择性良好,表明RIC-200型催化剂具有良好的再生性能。     

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg~(-1)·h~(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.     

Catalytic decomposition of light alkanes, alkenes and acetylene over Ni/SiO2

The decomposition of different hydrocarbons (CH₄, C₂H₆, C₂H₄, C₂H₂, C₃H₈, and C₃H₆) over Ni (5 wt.%)/SiO₂ catalysts was carried out. The initial rates of decomposition of the hydrocarbons, the kinetic curves of the decomposition and the kinetic curves of the hydrogenation of deposited carbon into methane depended on the types of hydrocarbons. In addition, the catalytic life of the Ni/SiO₂ catalyst was also dependent on the types of hydrocarbons, i.e. the life was longer according to the order, alkanes>alkenesacetylene.

The carbons deposited on the catalyst were characterized by SEM and Raman spectroscopy. The appearances of the deposited carbons were different among alkanes, alkenes, and acetylene, i.e. a zigzag fiber structure from methane, and a rolled fiber structure from alkenes and acetylene. From Raman spectra of the deposited carbons, it was found that the degree of graphitization of deposited carbon was higher in the order, alkanes>alkenes>acetylene. These results suggest that the mechanism of decomposition of hydrocarbons and the growth mechanism of carbon fibers on the catalyst were different among alkanes, alkenes and acetylene.     

Pyrolysis kinetics of waste automobile lubricating oil

The kinetics of waste automobile lubricating oil have been studied experimentally and modeled mathematically. Experiments were carried out in the tubing bomb microreactor at a temperature of 420–440°C and reaction times of 5–50 min. Volatile pyrolysis products were identified and quantitatively determined by gas chromotography. A lump model of combined series and parallel reactions for oil formation is proposed. Conversion data fitted first order kinetics for C₅–C₁₁ and C₁₂–C₂₅. The kinetic parameters were determined by nonlinear least-squares regression of the experimental data. These calculated values of the product distribution were found to be in agreement with the experimental data.     

Nitric oxide reduction by ethylene over Pt-ZSM-5 under lean conditions: steady-state activity

Steady-state activity of Pt-ZSM-5 catalysts has been investigated experimentally for the NO + C₂H₄ + O₂ reaction under highly oxidizing conditions, typical of lean-burn gasoline engine exhaust. Effects of temperature, space velocity, feed concentration, Pt loading and water vapor on the catalytic activity have been examined using a packed-bed laboratory reactor. The catalytic activity of Pt-ZSM-5 is discussed in comparison with that of Cu-ZSM-5 and Pt/Al₂O₃. Results show that Pt-ZSM-5 catalysts are much more active than Cu-ZSM-5 catalysts for lean-NO_x reduction at low temperatures, while the kinetic behavior of Pt/Al₂O₃ is very similar to that of Pt-ZSM-5. Conversion of both NO and C₂H₄ during the NO + C₂H₄ + O₂ reaction over Pt-ZSM-5 around the reaction lightoff temperature is strongly inhibited by the presence of NO. The NO/C₂H₄ ratio in the feedstream is an important factor determining the NO reduction activity of the catalyst, and there exists an optimum value of this ratio for a maximum conversion of NO. Based on the steady-state NO conversion data, a correlation between the reactor performance and the feed concentration has been developed, and the feasibility of Pt-based catalysts for lean-NO_x reduction is discussed in terms of their activity, selectivity and durability.