微反应器内对甲砜基甲苯硝化反应动力学研究

对甲砜基甲苯硝化反应由于反应迅速、高放热和非均相等特性,难以获得较为准确的动力学数据。以硝硫混酸为硝化试剂,在微反应器内对对甲砜基甲苯均相硝化反应动力学进行研究,构建包含微混合器、毛细管微反应器、毫秒级在线淬火模块的连续流微反应系统,测定了均相硝化反应动力学参数。在质量分数为88%的硫酸、温度为10～25℃、停留时间为1～5 s的条件下,确定该反应是二级反应,指前因子为7.16×10¹²L/(mol·s),活化能为50.65 kJ/mol。同时在实验研究范围内对建立的动力学模型进行验证,结果表明,实测值与拟合计算值吻合良好,模型具有有效性,对工业设计和安全控制具有重要意义。     

甲苯甲醇烷基化制对二甲苯动力学模型

采用固定床反应器,在消除内外扩散影响的基础上,在反应温度480~560℃、甲苯甲醇总质量进料空速2 h-1、甲苯甲醇物质的量之比为1~6、水与甲苯物质的量之比为2~6和氢气与甲苯物质的量之比为2~8的条件下,研究了在自制沸石分子筛催化剂上甲苯甲醇烷基化反应的本征动力学,建立了包括甲苯甲醇烷基化制对二甲苯、二甲苯间异构化、二甲苯深度烷基化生成三甲苯和甲醇生成烯烃等7个反应的完整反应网络。采用非线性优化方法进行参数估算,并对模型的适用性进行了误差分析和统计检验。结果表明,甲醇生成烯烃反应的加入使模型能较好地反映出甲苯甲醇物质的量比对反应结果的影响,甲苯甲醇烷基化制对二甲苯的表观活化能为76.66 k J/mol,通过误差分析和统计检验表明,动力学模型是适用的。     

乙炔法气相合成醋酸乙烯工业固定床反应器优化操作的研究

用非等温固定反应器，参照工业生产条件，对新型Ｚｎ（Ａｃ）２一活性炭催化剂上合成醋酸乙烯的宏观动力学进行了实验研究。对实验数据进行计算机模拟的结果表明，在实际条件范围内乙炔与醋酸在新鲜催化剂上的反应速率仅与乙炔的分压有关，并且假设该反应为１级反应时，实验数据的拟合精度能充分满足要求。由此导出了相应的宏观反应动力学方程，为进一步研究该反应的失活动力学和建立工业固定床反应器模型提供了有关的基础方程和数据     

甲苯的光催化降解及其动力学研究

进行了以自制锐钛型Fe3+-TiO2催化降解甲苯的研究,在自制的光催化反应器中,室温下以40 W白炽灯为光源,分析了TiO2的掺Fe3+量、催化剂投放量、甲苯初始浓度和溶液初始pH等因素的影响.结果表明:自制锐钛型Fe3+-TiO2能较有效地催化降解甲苯.在pH为2,TiO2掺Fe3+量为5％(物质的量分数)、催化剂投放量为2.0 g/L时对1.2 g/L甲苯的去除率在5h内可达60％以上.甲苯的降解过程表现为一级反应,表观反应速率常数k为0.0666 h-1,反应可用Langmuir-Hinshelwood动力学方程描述.     

乙炔法气相合成醋酸乙烯工业固定床反应器优化操作的研究（Ⅰ）乙炔、醋酸在Zn（Ac）2—活性炭催化剂上合成醋酸乙烯反应的宏观动力学

用非等温固定床反应器，参照工业生产条件（反应温度为１６０～２１０℃、进口乙炔气与醋酸的摩尔比为５～９），对新型Ｚｎ（Ａｃ）２—活性炭催化剂上合成醋酸乙烯的宏观动力学进行了实验研究。对实验数据进行计算机模拟的结果表明，在实验条件范围内乙炔与醋酸在新鲜催化剂上的反应速率仅与乙炔的分压有关，并且假设该反应为１级反应时，实验数据的拟合精度能充分满足要求。由此导出了相应的宏观反应动力学方程，为进一步研究该反应的失活动力学和建立工业固定床反应器模型提供了有关的基础方程和数据。     

微通道反应器中油酸与低级醇的酯化反应研究

本研究以高酸值油酸为原料,采用微通道反应器与0.38*12mm毛细管相连接,建立了快速酸催化制备生物柴油的微结构反应器。进行了油酸酯化反应,寻找合适的反应条件。考察了停留时间、醇酸摩尔比、催化剂浓度、反应温度对酯化反应的影响。在78℃条件下,油酸与低级醇反应停留时间仅为10 min,产率可达80%以上;与传统釜式反应器相比,微反应器减少了催化剂用量,缩短了反应时间,提高了反应过程中的安全性。此外,建立了均相动力学模型。确定了生物柴油的酯化反应的速率常数和活化参数。     

环己烷液相无催化剂的氧化动力学研究

采用搅拌釜反应器,在确认已排除传质因素对反应速率影响的情况下,研究了环己烷液相无催化剂的氧化反应动力学。应用自由基理论及最优化计算技术,从导出的8个候选动力学模型中,确定了最佳的动力学模型,它能满意地描述环已烷氧化过程。该动力学可为环己烷氧化工业生产操作条件的优化、反应器的选型及工业设计提供依据。     

CO在成型催化剂上脱除NOx的反应动力学模型

采用实验和模拟相结合的方法研究了NO_x在固定床反应器中的吸附还原过程。选取商业常用的堇青石和TiO₂为主要的成型催化剂基体材料，以铜铁铈复合型金属氧化物为活性成分，制备了蜂窝成型催化剂，对蜂窝催化剂的吸附性能和脱硝还原活性进行测定。建立了固定床反应器中CO脱除NO_x的反应动力学模型，由于CO法脱硝反应的解耦分解，脱硝反应模型也由吸附模型和还原模型组成。吸附模型由固相和气相的微分质量平衡方程建立，还原模型由一组微分方程组成。通过固定床NO_x吸附曲线和不同温度下NO_x的转化率对模型中的关键参数进行了拟合，得到了CO在成型催化剂上脱除NO_x的反应动力学模型，该模型与实验数据吻合较好。在此基础上，模拟了其他条件下吸附过程的穿透曲线和还原反应的转化率。此模型能较好地揭示CO在蜂窝催化剂上还原NO_x的反应动力学，为CO法成型催化剂脱除NO_x的实验或者工程提供理论指导。     

甲苯的NO／O2硝化新工艺

采用间歇式高压反应器研究了甲苯的NO2／O2硝化反应，考察了反应条件对反应活性的影响。结果表明，适当的催化剂比表面和酸中心对此硝化反应是必要的。在HZSM-5分子筛为催化剂的情况下，NO／甲苯配料比为2：1(摩尔比)，O2压力0．5MPa，控制反应温度为45％，反应时间3h，反应的转化率达到100％，对硝基甲苯的选择性为45％，较混酸法高。     

费托合成微反应器研究进展

费托合成技术能将煤、天然气和生物质等含碳资源间接转化为液体燃料, 对于缓解我国油品资源短缺的现状具有重要意义。本文在介绍费托合成技术的原理以及微反应器优势的基础上, 对费托微反应器的相关研究工作进行了总结。在反应器的类型介绍部分, 分析了填充型和壁面涂覆型两大类微反应器各自的特点, 与壁面涂覆型微反应器相比, 填充型反应器有压降大、导热性能相对较差等问题, 而在整体式微反应器中应用的催化剂层壁面涂覆技术则可有效地避免这些问题。在数值分析方面, 指出费托合成相关的模拟研究主要集中在通过建立反应动力学模型, 对微反应器内的温度场和产物分布进行分析, 并对操作工况和反应器结构的设计提供依据。最后指出, 目前费托合成微反应器在反应板片和冷却系统的结构优化与匹配设计、反应单元的组装、催化剂的壁面负载技术以及微反应器中的传输现象等研究领域, 还有很多方面需要研究, 在未来微反应器中费托合成技术会得到更大的发展。     

Deactivation kinetics of V/Ti-oxide in toluene partial oxidation

Deactivation kinetics of a V/Ti-oxide catalyst was studied in partial oxidation of toluene to benzaldehyde (BA) and benzoic acid (BAc) at 523–573 K. The catalyst consisted of 0.37 monolayer of VO_x species and after oxidative pre-treatment contained isolated monomeric and polymeric metavanadate-like vanadia species under dehydrated conditions as was shown by FT Raman spectroscopy. Under the reaction conditions via in situ DRIFTS fast formation of adsorbed carboxylate and benzoate species was observed accompanied by disappearance of the band of the monomeric species (2038 cm⁻¹) (polymeric species were not controlled). Slow accumulation of maleic anhydride, coupling products and/or BAc on the surface caused deactivation of the catalyst during the reaction. Temperature-programmed oxidation (TPO) after the reaction showed formation of high amounts of CO, CO₂ and water. Rate constants for the steps of the toluene oxidation were derived via mathematical modelling of reaction kinetics at low conversion and constant oxygen/toluene ratio of 20:1. The model allows predicting deactivation dynamics, steady-state rates and selectivity. The highest rate constant was found for the transformation of BA into BAc explaining a low BA yield in the reaction.     

Catalytic reduction of NOx over Cu/ZSM-5 catalyst

Catalytic decomposition of NO on Cu/ZSM-5 catalyst was carried out in tubular fixed-bed reactor at atmospheric pressure. The influence of temperature and flow rate on the reaction rate was investigated. The kinetic model of reaction was proposed and compared with the literature results. The formation of NO₂ during the catalytic decomposition of NO was also monitored. Therefore, additional experiments were performed aimed at examining the kinetics of NO oxidation under the same reaction conditions. Both kinetic models were used to develop the reactor model and to describe quantitatively the behavior of the overall reaction system. Satisfactory degree of correlation between experimental data and values predicted by reactor model has been achieved.     

Kinetics of the liquid phase synthesis and hydrolysis of butyl lactate catalysed by cation exchange resin

Esterification of lactic acid with butanol catalysed by cation-exchange resin was carried out in a batch reactor in dioxane and toluene. The reaction rate was found to be first order with respect to catalyst and acid concentrations. The inhibiting effect of water and butanol has been evaluated. The rate data were correlated with a kinetic model based on inhibition by water and butanol.     

Investigation of the Hydrogenation of Some Substituted Alkylbenzenes in a Laboratory Scale Trickle-Bed Reactor

The liquid–phase hydrogenation kinetics of toluene, cumene and mesitylene was studied over an alumina-supported nickel catalyst in a laboratory scale trickle-bed reactor operating isothermally at temperature of 75–115°C and at hydrogen pressures of 20–40 bar. The experiments performed in the absence of intraparticular diffusion resistance showed that the catalyst deactivated rapidly at the initial stage of the experiment, after which a virtually stable level of the catalyst activity was attained. The systematic kinetic experiments carried out with a stable aged catalyst revealed that cumene and mesitylene at high concentrations retarded the hydrogenation rate, whereas such an effect was not observable for toluene. The results of the kinetic experiments were interpreted quantitatively with a reaction mechanism involving sequential addition of hydrogen to absorbed aromatic molecules.     

Oxidative dehydrogenation of propane to propene, 1: Kinetic study on V/MgO

The reaction kinetics of the oxidative dehydrogenation of propane to propene over a V/MgO catalyst were studied. Both propane and propene oxidation kinetics were measured independently to quantify the rates of the parallel and consecutive reactions to propene and carbon oxides. Specific experiments to evaluate reaction products effects showed that water inhibited reaction rates but co‐feeding CO₂ or propene had no measurable effect on selectivity or conversion. Kinetic data generated under integral reactor conditions and over an inert membrane reactor have also been used to estimate the kinetic parameters. Selectivity decreased as the oxygen partial pressure increased; however, propene yield was relatively insensitive to oxygen concentration. A dual site Mars‐van Krevelen model characterizes the reaction kinetics well. The role of lattice oxygen was established by alternating pulses of propane and oxygen. This redox model is able to predict the experimental tendencies observed in the three types of reactor studied.     

甲苯液相氧化反应过程的模拟

甲苯液相空气氧化是环境友好的苯甲酸和苯甲醛生产工艺。根据在模拟工业条件下测定的动力学数据和观察到的实验现象,提出了该反应的反应机理和反应网络,建立了相应的动力学模型。根据该动力学方程,对现有工业生产过程进行了模拟,发现现有工业过程处于严重供氧不足的情况。提出了3种强化方案并分别对其进行了模拟计算和比较。模拟结果表明,通过增大空气供给量和采用富氧空气氧化均可有效强化现有工业生产过程。采用富氧空气氧化,其甲苯转化率可提高到22.24%,甲苯反应量可增大57%。采用增大空气量的方法,可提高甲苯反应量31%,甲苯转化率可提高到18.61%。若同时增大甲苯和空气负荷,甲苯反应量可提高71%。     

Catalytic Liquid Phase Oxidation of Toluene to Benzoic Acid

The production of benzoic acid from toluene in the liquid phase with pure oxygen was studied. Investigations have been carried out with a view to determining the most suitable reaction conditions with respect to operating variables including oxygen flow rate, reaction temperature, batch time and catalyst loading. In a series of batch experiments carried out at 4 atm, the optimum values of mole ratio of oxygen to toluene, temperature, reaction time, and catalyst loading were found to be 2, 157 °C, 2 h and 0.57 g/L, respectively. In addition, a kinetic study was carried out by taking into consideration the optimum reaction conditions. The model dependent on the formation of benzyl radical was found to be feasible for describing the catalytic oxidation of toluene to benzoic acid in the liquid phase. The activation energy was determined as 40 kJ/mol.     

Influence of the process parameters on temperature conditions and productivity of multitubular reactor for methanol to formaldehyde oxidation

The results of the parametric analysis of the methanol oxidation to formaldehyde on the basis of the kinetic model of reactions on an iron-molybdenum oxide catalyst and the two-dimensional model of a multitubular reactor were reported in the paper. The results of kinetic experiments on an industrial Fe-Mo granular catalyst were given. Calculation results were compared with industrial data. The possibilities of controlling the methanol oxidation to formaldehyde in multitubular reactors at varied plant unit productivity with consideration for process restrictions were theoretically studied. The effect of parameters on the temperature and concentration conditions in reactors at different ratios of catalyst and inert material loads was studied.