Ruthenium promotion of Co/SBA-15 catalysts for Fischer-Tropsch synthesis in slurry-phase reactors

The aim of this work was to evaluate the catalytic properties of a Ru promoted Co/SBA-15 catalyst for Fischer-Tropsch synthesis （FTS）. The Ru promoted Co/SBA-15 catalyst was prepared by wet impregnation method and was characterized by X-ray diffraction, X-ray energy dispersion spectrophotometer, N2 adsorption-desorption, temperature-programmed reduction and transmission electron microscopy. The Fischer-Tropsch synthesis using the catalyst was carried out to evaluate the catalyst activity and its effect on FTS product distribution. The synthesis was carried out in a slurry reactor operating at 513 K, 20 atm, CO ： H2 molar ratio of 1 ： 1. X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15, proving that Co was present in the form of Co3O4 in the catalyst. The addition of cobalt in SBA-15 decreased the specific superficial area of the molecular sieve. Fischer-Tropsch synthesis activity and C5＋ hydrocarbon selectivity increased with the addition of Ru. The increases in activity and selectivity were attributed to the increased number of active sites resulting from higher reducibility and the synergetic effect of Ru and Co. Ru/Co/SBA-15 catalysts showed moderate conversion （40%） and high selectivity towards the production of C5＋ （80 wt%）.

Two-Bubble Class Model for Churn-Turbulent Regime in a Bubble Column Slurry Reactor of Fischer-Tropsch Synthesis

A model for a bubble column slurry reactor is developed based on the experiment of Rhenpreussen Koppers demonstration plant for slurry phase Fischer-Tropsch synthesis reported by Koelble et al. This model is applicable to the operation in the churn-turbulent regime and incorporates the information on the bubble size. The axial dispersion model is adopted to describe the flow characteristics of the Fischer-Tropsch slurry reactor. With the model developed, simulations are performed to identify the steady state behavior of a Fischer-Tropsch slurry reactor of commercial size. Predictions of the two-bubble class model is compared with that of the conventional single- bubble class model. The results show that under a variety of conditions, the two-bubble class model gives results different from those for the single-bubble class model.

Overview of Fischer-Tropsch Synthesis in Slurry Reactors

A brief review of Fischer-Tropsch synthesis specially in slurry reactors is presented, covering reaction kinetics, activity and selectivity of catalysts, product distribution, effects of process parameters, mass transfer and solubility of gas. Some important aspects of further research are proposed for improving both theories and production.

Nanosized cobalt-based catalyst prepared by supercritical phase condition for Fischer-Tropsch synthesis

A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis （FTS） were prepared by supercritical fluid drying （SCFD） method and common drying （CD） method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH4 and CO2 as well as higher yield of C5＋ products were achieved. The optimal performance of a 92% CO conversion and a 65% C5＋ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C5＋ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO2 byproduct, and higher yield of C5＋ products.

Recent advances in understanding the key catalyst factors for Fischer-Tropsch synthesis

Catalytic conversion of synthesis gas （CO＋H2） into hydrocarbons, also known as Fischer-Tropsch （FT） synthesis, is a crucial reaction for the translbrmation of non-petroleum carbon resources such as coal, natural gas, shale gas, coal-bed gas and biogas, as well as biomass into liquid fuels and chemicals. Many factors can influence the catalytic behavior of a FT catalyst. This review highlights recent advances in understanding some key catalyst factors, including the chemical state of active phases, the promoters, the size and the microenvironment of active phase, which determine the CO conversion activity and the product selectivity, particularly the selectivity to C5 ＋ hydrocarbons.

Modelling-based Optimisation of the Direct Synthesis of Dimethyl Ether from Syngas in a Commercial Slurry Reactor

In the present study, we developed a multi-component one-dimensional mathematical model for simulation and optimisation of a commercial catalytic slurry reactor for the direct synthesis of dimethyl ether （DME） from syngas and CO2, operating in a churn-turbulent regime. DME productivity and CO conversion were optimised by tuning operating conditions, such as superficial gas velocity, catalyst concentration, catalyst mass over molar gas flow rate （W/F）, syngas composition, pressure and temperature. Reactor modelling was accomplished utilising mass balance, global kinetic models and heterogeneous hydrodynamics. In the heterogeneous flow regime, gas was distributed into two bubble phases： small and large. Simulation results were validated using data obtained from a pilot plant. The developed model is also applicable for the design of large-scale slurry reactors.

Modeling and optimization of industrial Fischer–Tropsch synthesis with the slurry bubble column reactor and iron-based catalyst

To optimize industrial Fischer-Tropsch （IT） synthesis with the slurry bubble column reactor （SBCR） and iron- based catalyst, a comprehensive process model for IT synthesis that includes a detailed SBCR model, gas liquid separation model, simplified CO2 removal model and tail gas cycle model was developed. An effective iteration algorithm was proposed to solve this process model, and the model was validated by industrial demonstration experiments data （SBCR with 5.8 m diameter and 30 m height）, with a maximum relative error 〈 10% for predicting the SBCR performances. Subsequently, the proposed model was adopted to optimize the industrial SBCR performances simultaneously considering process and reactor parameters variations. The results show that C5＋yield increases as catalyst loading increases within 10-70 ton and syngas H2/CO value decreases within 1.3-1.6, but it doesn＇t increase obviously when the catalyst loading exceeds 45 ton （about 15 wt% concentration）. Higher catalyst loading will result in higher difficulty for wax/catalyst separation and higher catalyst cost. There- fore, the catalyst loading （45 ton） is recommended for the industrial demonstration SBCR operation at syngas H2/ CO = 1.3, and the C5 ＋ yield is about 402 ton＂ per day, which has an about 16% increase than the industrial dem- onstration run result.

Mathematical Simulation and Design of Three-Phase Bubble Column Reactor for Direct Synthesis of Dimethyl Ether from Syngas

A three-phase reactor mathematical model was set up to simulate and design a three-phase bubble column reactor for direct synthesis of dimethyl ether （DME） from syngas, considering both the influence of part inert carrier backmixing on transfer and the influence of catalyst grain sedimentation on reaction. On the basis of this model, the influences of the size and reaction conditions of a 100000 t/a DME reactor on capacity were investigated. The optimized size of the 10000 t/a DME synthesis reactor was proposed as follows： diameter 3.2 m, height 20 m, built-in 400 tube heat exchanger （Ф 38×2 mm）, and inert heat carrier paraffin oil 68 t and catalyst 34.46 t. Reaction temperature and pressure were important factors influencing the reaction conversion for different size reactors. Under the condition of uniform catalyst concentration distribution, higher pressure and temperature were proposed to achieve a higher production capacity of DME. The best ratio of fresh syngas for DME synthesis was 2.04.

Fischer-Tropsch Reaction Kinetics of Cobalt Catalyst in Supercritical Phase

Fischer-Tropsch synthesis under supercritical phase condition was examined in a continuous and a high-pressure fixed bed reactor by employing a cobalt catalyst （Co-Ru/γ-Al2O3）. An integral reactor model involving Fischer-Tropsch reaction kinetics in the supercritical fluid n-hexane was used to describe the overall performance. On the basis of Langmuir-Hinshelwood-Hougen-Watson （LHHW） model, the reaction rate constants were obtained for the rate equations of CO conversion to CH4 formation under supercritical conditions.

Modeling of a slurry bubble column reactor for Fischer-Tropsch syn- thesis

On the basis of the global CO consumption rate model, the lumped product distribution model and the sedimenta- tion-dispersion model of a catalyst, a steady-state, one-dimensional mathematical model of the slurry bubble column reactor for Fischer-Tropsch synthesis were established. The mathematical simulation of the slurry bubble column reactor for Fischer-Tropsch synthesis was carried out under the following typical industrial operating conditions： temperature 230 ℃, pressure 3.0 MPa, gas flow 5x 105 m3/h, catalyst content in slurry phase 30%, reactor diameter 5.0 m and the composition of feed gas： y（H2）=0.60, y（CO）=0.30, y（N2）=0.10. The influences of operating pressure, temperature and re（HE）Ira（CO） in feed gas on the reactor＇s reaction performance were simulated.

A Comprehensive Review of the Influence of Heat Exchange Tubes on Hydrodynamic,Heat,and Mass Transfer in Bubble and Slurry Bubble

Bubble and slurry bubble column reactors(BCRs/SBCRs)are used for various chemical,biochemical,and petro-chemical applications.They have several operational and maintenance advantages,including excellent heat and mass transfer rates,simplicity,and low operating and maintenance cost.Typically,a catalyst is present in addition to biochemical processes where microorganisms are used to produce industrially valuable bio-products.Since most applications involve complicated gas-liquid,gas-liquid-solid,and exothermic processes,the BCR/SBCR must be equipped with heat-exchanging tubes to dissipate heat and control the reactor’s overall performance.In this review,past and very recent experimental and numerical investigations on such systems are critically dis-cussed.Furthermore,gaps to befilled and critical aspects still requiring investigation are identified.

Synthesis of Iron-Carbide Nanoparticles:Identification of the Active Phase and Mechanism of Fe-Based Fischer-Tropsch Synthesis

Despite the extensive study of the Fe-based Fischer-Tropsch synthesis(FTS)over the past 90 years,its active phases and reaction mechanisms are still unclear due to the coexistence of metals,oxides,and carbide phases presented under realistic FTS reaction conditions and the complex reaction network involving CO activation,C-C coupling,and methane formation.To address these issues,we successfully synthesized a range of pure-phase iron and iron-carbide nanoparticles(Fe,Fe_(5)C_(2),Fe_(3)C,and Fe_(7)C_(3))for the first time.By using them as the ideal model catalysts on high-pressure transient experiments,we identified unambiguously that all the iron carbides are catalytically active in the FTS reaction while Fe_(5)C_(2) is the most active yet stable carbide phase,consistent with density functional theory(DFT)calculation results.The reaction mechanism and kinetics of Fe-based FTS were further explored on the basis of those model catalysts by means of transient high-pressure stepwise temperature-programmed surface reaction(STPSR)experiments and DFT calculations.Our work provides new insights into the active phase of iron carbides and corresponding FTS reaction mechanism,which is essential for better iron-based catalyst design for FTS reactions.

前驱体物相转变对浆态床合成甲醇催化剂活性的影响

采用并流共沉淀法,通过考察老化温度,研究CuO/ZnO/A l2O3催化剂前驱体晶相及组成的变化对浆态床催化合成甲醇的反应活性的影响.结果表明,前驱体的物相转变对浆态床合成甲醇活性影响显著,单斜晶系锌孔雀石(Cu,Zn)2CO3(OH)2和斜方晶系绿铜锌矿(Cu,Zn)5(CO3)2(OH)6晶体是产生高活性催化剂的主要物相.随着Cu2+/Zn2+进入Zn5(CO3)2(OH)6/Cu2CO3(OH)2晶格,离子同晶取代量增加,催化剂前驱体中形成了固定铜锌比的锌孔雀石和绿铜锌矿物相.焙烧后催化剂比表面积增大,CuO-ZnO固溶体协同作用加强,浆态床催化合成甲醇的活性提高.

机械搅拌反应釜内三相淤浆床甲醇合成宏观反应动力学

本文研究机械搅拌反应釜内三相淤浆床甲醇合成的宏观反应动力学，反应压力５ＭＰａ，反应温度为２１０～２５０℃，采用０．１２５～０．１５４ｍｍ（１００目～１２０目）Ｃ３０１铜基甲醇合成催化剂，食品级液体石蜡作惰性液相介质，反应气体含ＣＯ、ＣＯ＿２、Ｈ＿２、Ｎ＿２及ＣＨ＿４，搅拌器转速９５０ｒ／ｍｉｎ。实验测定宏观反应动力学数据，应用改进高斯－牛顿法参数估值，获得宏观动力学方程。

三相淤浆床甲醇含成反应器大型冷模研究

以空气-水-催化剂和空气-液体石蜡油-催化剂两种系统为对象，研究了内置垂直管束式换热器三相淤浆床甲醇合成反应器的流体力学性质──平均气含率、床层压降、固体完全悬浮的临界表观气速。考察了各种因素对流体力学性质的影响，并得到关于气含率的经验关联式：

三相床甲醇合成过程I.富CO合成气甲醇合成宏观反应动力学

以液体石蜡为液相介质 ,在富 CO合成气条件下研究了 C30 2铜基催化剂上 CO、CO2 加氢合成甲醇的宏观反应动力学 ,得到了相应的动力学模型 ,通过对模型进行比较 ,认为在 CO浓度较高的情况下 ,幂函数模型优于 Langmuir- Hinshelwood模型。实验结果表明 ,催化剂和液相介质在富 CO合成气条件下表现出良好的适应性。

浆态相甲醇合成催化剂的失活机理

浆态床甲醇合成过程具有重要的工业应用价值,影响该过程工业化的根本原因是催化剂易失活.以合成气为原料,医用液体石蜡为溶剂,在5MPa,260℃和1100ml/(g.h)的反应条件下于浆态床反应器中考察了铜基甲醇合成工业催化剂C301的稳定性,并采用程序升温还原、X射线衍射、透射电镜、扫描电镜、扫描电镜能谱、元素分析和N2物理吸附等表征方法对不同失活程度的催化剂的物相组成和形貌进行了表征.结果表明,在本实验条件下,失活催化剂无中毒现象,但随着反应时间的延长,催化剂晶粒长大,比表面积减小,积炭和热烧结现象较明显,但不伴随活性组分铜的流失.

工业固定床Fe-Cu-K催化剂浆态床F-T合成适应性研究

采用连续搅拌釜式反应器,在接近F-T合成实际工况下考察了工业固定床Fe-Cu-K催化剂浆态床F-T合成反应性能,研究反应温度、压力、原料气空速和氢碳摩尔比等操作参数对催化剂反应活性、产物选择性和稳定性的影响,实验总运转时间达2 500h;同时采用扫描电镜技术(SEM)对催化剂的抗磨损性能进行了研究,结果表明,操作参数对催化剂的活性、选择性和目标产物产率有较大的影响,工业固定床Fe-Cu-K催化剂具有一定的抗磨损性能,F-T合成烃产物分布合理;催化剂具有较高的稳定性,在589h的稳定条件运行内,催化剂的失活速率为0. 23% /d(以CO转化率的降低计);在整个运行期间CH4 选择性维持在较低的水平。

CuCrAl和CuCrZr低温液相合成甲醇催化剂的研究

用络合共沉淀法制备了CuCrAl和CuCrZr复合氧化物液相合成甲醇催化剂 ,其比表面分别达到 119和 116m2 /g .在5 0～ 5 5MPa和 383K条件下 ,分别用间歇式和流动式反应釜考察了催化剂的活性和稳定性 .结果表明 :CuCrAl和CuCrZr的活性均明显高于CuCr;CuCrAl的活性略高于CuCrZr,但甲酸甲酯 (MF)的选择性明显低于CuCrZr;两者在 12h内未见活性明显下降 .甲醇钠在反应过程中部分转化为甲酸钠和NaOH .CuCrAl和CuCrZr有较高的氢解活性可抑制甲醇钠与MF生成甲酸钠 ,从而有较低的甲酸钠浓度 .但是 ,Al2 O3 和ZrO2 的酸性有利于甲醇脱水 ,引起甲醇钠水解生成NaOH .溶剂对CuCr基催化剂的活性和选择性有明显影响 .

浆态相低温甲醇合成用的CuCr/CH_3ONa催化体系的反应性能

在液相介质为二甲苯、甲醇或液体石蜡，温度１００～１４０℃、压力３．５～４．７ＭＰａ条件下，使用Ｈ２／ＣＯ＝２的合成气，在１Ｌ搅拌釜内考察了自制的ＣｕＣｒ／ＣＨ３ＯＮａ催化体系的浆态相低温甲醇合成的反应性能。结果表明液相介质以二甲苯为佳，ＣＯ转化率随压力而升高，温度以１２０℃为宜。４４ｈ的连续运转表明以ＣＯ转化率为代表的该催化体系的反应性能基本稳定。