浆态反应器中苯氯化反应的宏观动力学

采用自行设计的三相鼓泡浆态实验反应器 ,在半连续操作条件下 ,通过改变催化剂粒度 ,消除了内扩散的影响 ;测定了不同催化剂浓度、通氯量以及苯回流量条件下的苯氯化反应的宏观动力学数据。建立了宏观动力学模型 ,并由实验数据估计出模型参数 ,模型计算值和实验值吻合较好     

Estimation of overall effectiveness factors for parallel catalytic reactions

Approximate analytical expressions of overall effectiveness factors for parallel catalytic reac-tions occurring in a spherical catalyst pellet with both internal and external mass transfer resistancesare obtained after taking the information given by asymptotic solutions valid for small and largevalues of Thiele moduli.This approximate procedure is feasible for power law as well asLangmuir-Hinshelwood kinetics and the agreement between the approximation and the numerical re-sults is good enough for practical purposes.Moreover,the method does not require any iterative ortrial-and-error computation,and can be conveniently applied in most practical calculations for reac-tors giving reliable results.     

费托合成铁基催化剂浆态床反应性能的研究

为了获得工艺参数对铁基催化剂费托合成产品分布的影响规律,在浆态床反应器中考察了反应温度、反应压力、氢碳比、空速对铁基催化剂费托合成反应性能的影响。结果表明,温度升高时,催化剂活性、CO_2和CH_4选择性均升高,产物向轻组分分布;压力增大时,催化剂活性和CO_2选择性升高,CH_4选择性下降,产物向重组分分布;随氢碳比的增加,催化剂活性和CH_4选择性升高,CO_2选择性下降,C_(5+)呈下降趋势;随空速增加,催化剂的活性和CO_2选择性下降,CH_4选择性上升,C_(5+)向轻质烃分布。选择合适的工艺条件,可有效改善铁基催化剂的费托合成反应性能,控制碳链长度和产物的分布,提高费托合成反应的经济性。     

浆态光催化反应器有机模拟废水光催化氧化特性与动力学

采用循环式浆态光催化反应器对苯甲酰胺模拟废水光催化氧化特性和动力学进行了研究,系统地考察了操作条件对模拟污染物光催化降解的影响,并与搅拌式和鼓泡床式浆态光催化反应器中苯甲酰胺的降解效果进行对比.结果表明,循环式浆态光催化反应器中光催化剂的用量、污染物的初始浓度和初始pH值对模拟污染物光催化降解性能的影响存在适宜值;体系中H₂PO^-₄、Cl^-、Cu²⁺、Al³⁺对其光催化降解过程有明显的抑制作用.与传统的搅拌式和鼓泡床式浆态光催化反应器相比,循环式浆态光催化反应器中催化剂和废水的混合效果较好,光利用率高,较大程度上减少催化剂的用量和提高废水处理能力.同时,对不同催化剂的用量和污染物初始浓度下的光催化氧化反应动力学研究表明,此过程符合拟一级动力学,催化剂表面反应速率常数k₀和催化剂吸附平衡常数K_TiO2分别为0.0279 min^-1和17.99 L•g^-1.     

A scale-up strategy for low-temperature methanol synthesis in a circulating slurry bubble reactor

Slurry bubble column reactors are being increasingly utilized in the large-scale conversion of coal or natural gas to liquid hydrocarbons and alcohols. A new suite of tools for developing low-temperature methanol synthesis in circulating slurry bubble reactors is explored in this study. The scale-up strategy consisting of hydrodynamics in cold flow units, catalyst performance evaluation in an autoclave, and process investigation in a pilot-scaled circulating slurry bubble reactor is presented. This methodology should be helpful for designing and scaling-up the low-temperature methanol synthesis and other related processes in slurry bubble column reactors, which will enhance and speed them towards commercial application.     

Isobutene hydration over Amberlyst-15 in a slurry reactor

The synthesis of tertiary butyl alcohol (TBA) via isobutene (iB) hydration was studied over Amberlyst-15 sulfonic acid catalyst particles using pure water and aqueous TBA solutions in a bubbling slurry reactor. Preliminary studies to investigate mass transfer effects showed that pore diffusion was present for catalyst particles greater than 165 μm in diameter. Therefore, intrinsic kinetic measurements were made using 90.5 μm catalyst particles and a catalyst loading of 10 kg m⁻³. The kinetic measurements revealed that iB hydration is a pseudo-first-order reaction with an activation energy of 69 kJ mol⁻¹. Isobutene hydration experiments using TBA concentrations in water revealed a hindering effect of TBA, which indicates that separation of TBA formed by iB hydration in three-phase reactors using catalytic distillation is promising from a process design perspective.     

Approximate analytical solutions for a biofilm reactor model with Monod kinetics and product inhibition

This paper presents a method for obtaining approximate analytical solutions based on a Taylor series linearization technique for a biofilm reactor with Monod kinetics and product inhibition. Of the two inhibition types investigated, the linear inhibition solution was in explicit form, while the exponential inhibition solution was in series form. The results of the approximate solution agree well with the numerically exact solution.     

Low-temperature methanol synthesis in a circulating slurry bubble reactor

A circulating slurry bubble reactor was developed to synthesise methanol via methyl formate from the gas mixture of carbon monoxide and hydrogen at low temperature. The strategy for designing and scaling up the bubble reactor involved a preliminary understanding of fluid dynamics in a cold model, continuous operations under industrial conditions and a parallel experiment in an autoclave. Per-pass syngas conversion was investigated during 100-h operations. The axial profile of solid catalyst concentration was measured just before the shutdown and the composition of liquid product was analysed after the shutdown. These results show that the circulating slurry bubble column will become a potential reactor for the commercial process of low-temperature methanol synthesis after the catalyst system has been improved.     

Investigation of low-temperature methanol synthesis in a bubble column slurry reactor with a flash column

Reaction performance of a CuCr/CH₃ONa catalyst for the low-temperature methanol synthesis was examined in a bubble column slurry reactor with a flash column (BCSR/FC). The BCSR/FC was operated at 4.5 ± 0.2 MPa/110–120 °C for BCSR and 0.4 ± 0.1 MPa/80–90 °C for FC, although fluctuation of operation parameters was larger. Syngas conversion decreased from 71.0% to 19.8% during the operation test in 100 h, which was attributed to consumption of CH₃ONa and a negative effect of the emulsifier OP-10 used.     

Determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors

A methodology for the determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors under the reaction conditions is presented. The mass transfer resistances affect significantly the overall mass transfer rate, the design equation and consequently the scale up of the reactor. There is not established methodology to separate the mass transfer resistances under reaction conditions by changing catalyst loading and manipulating the process variables, pressure and agitation speed. This allows to avoid the use of different catalyst particles and give the chance to calculate the mass transfer resistances without caring about the type of catalyst. We calculate each mass transfer resistance under conditions which do not allow to neglect any of the resistances. It is shown that the level off of mass transfer rate which is developed in the plot of mass transfer rate against agitation speed plots is not enough to determine the limiting regime. The hydrogenation of styrene over Pd/C (5% catalyst content) is used as case study to demonstrate the methodology. © 2016 American Institute of Chemical Engineers AIChE J, 63: 273–282, 2017     

Isobutane dehydrogenation reaction in a packed bed catalytic membrane reactor

A packed-bed catalytic ceramic membrane reactor (PBCMR) was used for the isobutane dehydrogenation reaction. The experimental results have shown that through the use of the membrane reactor one can attain better conversions and yields than in a conventional reactor operating under the same outlet pressure and temperature, and feed composition conditions.     

微结构反应器中CuZnAlZr催化剂CO变换反应动力学研究

在基于泡沫金属材料的微结构反应器中进行CO变换反应,考察CuZnAlZr催化剂的CO变换反应动力学。对实验数据进行最小二乘非线性回归,所得反应速率方程与实验数据吻合。利用所得到的动力学方程,针对典型醇类重整气组成,分析了为燃料电池提供氢源的CO变换反应器的体积功率密度,结果表明,CuZnAlZr微结构反应器是为小型燃料电池提供氢源的有效方案。     

Selectivity of partial hydrogenation reactions performed in a pore-through-flow catalytic membrane reactor

The selectivity of partial hydrogenation reactions of unsaturated substrates was studied in a membrane reactor operating at 323 K and 40 bar hydrogen pressure. The reactor system was constructed as a loop of a saturation vessel and a membrane module in which the reaction mixture was resaturated with hydrogen up to 100 times. In a porous membrane made from cross-linked polyacrylic acid palladium nanoparticles were incorporated as catalysts. A well-defined residence time within the membrane was achieved due to a defined pore structure of the membrane and a convective mass flow of the reaction mixture through the membrane. The selectivity for the partially hydrogenated products was investigated as a function of the pore size of the PAA membrane and was compared to commercially available catalysts. Compared to experiments with supported catalysts (Pd/C and Pd/Al₂O₃) in a slurry and a fixed bed reactor the selectivity for the desired products could be increased by 3% (1-octyne) up to 40% (geraniol).     

浆态床鼓泡反应器中气含率的分布

为了解浆态床鼓泡反应器中气含率的分布规律,在浆态床鼓泡反应器冷模试验装置中,以空气-液体石蜡-氧化铝微球为试验介质对装置内部的气含率进行研究。利用压差法研究了表观气速、浆液固含量等操作条件对反应器床层总体气含率的影响,利用光纤探针法研究了浆态床反应器不同操作条件对局部气含率的影响,总结了反应器内部气含率的分布规律,并由此对工业浆态床鼓泡反应器的设计进行了研究。结果表明:浆态床反应器的总体气含率随表观气速的增大而增大,固体细颗粒的加入能适当降低总体气含率;在反应器底部,分布器对气体的均布作用明显,但表观气速的增大能够弱化分布器的作用;在反应器的中上部气含率不受分布器的影响,沿反应器径向呈现"中间高,边缘低"的分布趋势;在工业费托浆态床中,表观气速不宜低于0.12 m/s,内过滤系统适宜设置于反应器中上部靠近器壁的位置。     

Modeling a dense polymeric catalytic membrane reactor with plug flow pattern

A theoretical study on a tubular membrane reactor assuming isothermal operation, plug flow pattern and using a dense polymeric catalytic membrane is performed. The reactor conversion for an equilibrium gas-phase reaction generically represented by AB is analyzed, considering the influence of the product’s sorption and diffusion coefficients. It is concluded that the conversion of such a reaction can be significantly improved when the overall diffusion coefficient of the reaction product is higher than the reactant’s one and/or the overall sorption coefficient is lower, and for Thiele modulus and contact time values over a threshold. Though a sorption coefficient of the reaction product lower than that of the reactant may leads to a conversion enhancement higher than that one obtained when the reaction product diffusion coefficient is higher than that of the reactant, the contact time value for the maximum conversion is much higher in the first case. In this way, a higher diffusion coefficient for the reaction product should be generally preferable, because it leads to a lower reactor size. The performance of a dense polymeric catalytic membrane reactor depends in a different way on both sorption and diffusion coefficients of reactants and products and then a study of such a system cannot be based only on their own permeabilities. Favorable combinations of diffusion and sorption coefficients can affect positively the reactor’s conversion.     

浆态床中CO2加氢直接合成二甲醚的双功能催化剂

采用共沉淀沉积法制备了CuO-ZnO-Al2O3-ZrO2/HZSM-5双功能催化剂,利用XRD、BET、H2-TPR、NH3-TPD等手段进行表征。在连续流动加压浆态床反应器中,以医用石蜡为惰性液相介质,研究了其对CO2加氢直接合成二甲醚的催化反应,考察了不同温度、不同压力、不同氢碳比和不同空速对反应结果的影响。研究表明,提高反应温度有利于提高CO2转化率,但使二甲醚的选择性降低;增大压力和氢碳比有利于提高CO2转化率和二甲醚的选择性;增大空速会使CO2转化率和二甲醚选择性均呈现下降趋势。     

Gas holdup and bubble dynamics in a three-phase internal loop reactor with external slurry circulation

As modified three-phase fluidized reactors, loop reactors have been widely used in the area of chemical and energy processes. An external slurry circulation is introduced into a traditional internal loop reactor to improve the transfer between gas and slurry phases. Gas holdup and bubble dynamics are investigated by using the double-sensor conductivity probe technique in the present work. The results show that gas holdup inside the draft tube is greatly affected by the geometrical configuration and is much higher than that in the corresponding section of the annular region. Local, section-averaged, and overall gas holdups increase with increasing superficial gas velocity, while the effects of solid loading and external slurry circulation velocity are less significant than that of superficial gas velocity. Both local bubble size and bubble rise velocity vary significantly in different regions.     

Effect of catalyst loading on gasliquid mass transfer in a slurry reactor: A statistical experimental approach

A statistical experimental design was employed to study the effects of pressure, temperature, catalyst loading, and mixing speed on the solubilities (C*) and volumetric gas/liquid mass transfer coefficients (k_L^a) for H₂, N₂, CO, CH₄ and C₂H₄ in a liquid mixture of hexanes containing iron oxide catalyst in a 4-litre agitated autoclave. Statistical correlations for k_L^a values for the gases used were developed. Mixing speed and solid concentration showed the strongest effects on k_L^a. At low catalyst concentrations, a maximum in k_L^a was observed and at concentrations > 37 mass%, k_L^a decreased by more than one order of magnitude.