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.     

Catalyst and process scale-up for Fischer-Tropsch synthesis

Liquid-phase Fischer-Tropsch technology was demonstrated in a bubble column at DOE's Alternative Fuels Development Unit. The 19-day run demonstrated the technology at a pilot scale and addressed scale-up issues such as catalyst activation, catalyst performance and hydrodynamics. The catalyst performance and reactor hydrodynamics were in line with expectations throughout the run.     

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。     

甲醇合成工艺进展

介绍了国内外甲醇合成工艺进展,对甲醇的气相合成工艺与液相合成工艺作了对比,指出液相合成工艺是甲醇生产未来发展的方向。认为国内外在液相甲醇合成工艺的基础研究和应用基础研究方面已做了比较充分的前期工作,利用这些研究成果,在工业上开发新的甲醇合成工艺路线是完全可能和十分必要的     

Continuous production of biodiesel with supercritical methanol: Optimization of a scale-up plug flow reactor by response surface methodology

A scale-up plug flow reactor was evaluated for the continuous production of biodiesel from refined palm kernel oil (PKO) with supercritical methanol and optimized by response surface methodology. The effects of the operating temperature (270–350 °C), pressure (15.0–20.0 MPa) and methanol:PKO molar ratio (20:1–42:1) were evaluated at a constant residence time of 20 ± 2 min by using a central composite design. Analysis of variance demonstrated that a modified quadratic regression model gave the best coefficient of determination (R² = 0.9615) and adjusted coefficient of determination (Adj. R² = 0.9273). The interaction terms in the regression model illustrated small synergistic effects of both temperature–pressure and temperature–methanol:PKO molar ratio. The optimal conditions were 325 ± 5 °C, 18.0 ± 0.5 MPa and a methanol:PKO molar ratio of 42 ± 2:1, attaining a maximum production rate of 18.0 ± 1.5 g biodiesel/min with a fatty acid methyl ester content of 93.7 ± 2.1%. The product obtained from the optimal conditions had high cetane number, and could be considered as a fuel additive for cetane number enhancement.     

A new approach for scale-up of bubble column reactors

The reactor of choice for the Fischer-Tropsch synthesis is a slurry bubble column. One of the few disadvantages of bubble columns is the difficulties associated with their scale-up. The latter is due to complex phases’ interactions and significant back-mixing.     

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。     

Application of methanol synthesis reactor to large-scale plants

The developing status of world large-scale methanol production technology is analyzed and Linda's JW low-pressure methanol synthesis reactor with uniform temperature is described. JW serial reactors have been successfully introduced in and applied in Harbin Gasification Plant and the productivity has been increased by 50% and now nine sets of equipments are successfully running in Harbin Gasification Plant,Jiangsu Xinya, Shandong Kenli,Henan Zhongyuan, Handan Xinyangguang,' Shanxi Weihua and Inner Mongolia Tianye. Now it has manufacturing the reactors of 300,000 t/a for Liaoning Dahua. Some solutions for the structure problems of 1000 ～5000 t/d methanol synthesis rectors are put forward.     

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

To optimize industrial Fischer–Tropsch(FT) synthesis with the slurry bubble column reactor(SBCR) and ironbased catalyst, a comprehensive process model for FT synthesis that includes a detailed SBCR model, gas liquid separation model, simplified CO_2 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 b 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 C_(5+) yield increases as catalyst loading increases within 10–70 ton and syngas H_2/CO value decreases within1.3–1.6, 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. Therefore, the catalyst loading(45 ton) is recommended for the industrial demonstration SBCR operation at syngas H_2/CO = 1.3, and the C_(5+) yield is about 402 ton" per day, which has an about 16% increase than the industrial demonstration run result.     

对撞流反应器甲醇合成实验研究

液相法甲醇合成由于有惰性液体介质的存在,气液相间传质对反应起到了一定的阻碍作用,对撞流反应器使用喷嘴将催化剂浆料雾化从而强化了气液相间传质。文中在对撞流反应器内对甲醇合成温度、合成气比例、气流量、浆料循环量以及喷嘴个数进行了考察,结果表明,温度控制在230℃左右操作比较适宜,二氧化碳参与反应对甲醇合成较为有利,合成气流量在22.4 L/min以后时空产率几乎不再增加,增加浆料循环量和采用对置式二喷嘴或四喷嘴比单喷嘴时空产率和出口甲醇体积分数都有所增加。由结果可知,利用喷嘴雾化和液体对撞可以显著地增强气液传质从而达到增加液相甲醇合成时空产率的目的。     

费托合成鼓泡浆态床反应器气体添加模拟研究

采用建立数学模型的方法在鼓泡浆态床反应器体系中讨论了气体添加对费托合成反应行为的影响。先采用惰性气体添加的方法找到最适合鼓泡塔反应器体系的气体添加模拟方法,在最优方法中,随气体添加相应改变总压和扩散高度以保持合成气分压和空速不变。采用该方法讨论了二氧化碳和烯烃对反应行为的影响。结果表明,随二氧化碳添加量的增加,合成气转化率降低,二氧化碳的添加使得总烯烷摩尔比增加,二氧化碳添加主要通过水煤气变换反应影响费托合成行为;烯烃添加将抑制小于其碳数的烃类的生成,促进大于其碳数的烃类的生成。     

Investigation of Fischer-Tropsch synthesis performance and its intrinsic reaction behavior in a bench scale slurry bubble column reactor

A bench scale slurry bubble column reactor (SBCR) with active-Fe based catalyst was developed for the Fischer-Tropsch synthesis (FTS) reaction. Considering the highly exothermic reaction heat generated in the bench scale SBCR, an effective cooling system was devised consisting of a U-type dip tube submerged in the reactor. Also, the physical and chemical properties of the catalyst were controlled so as to achieve high activity for the CO conversion and liquid oil (C₅₊) production. Firstly, the FTS performance of the FeCuK/SiO₂ catalyst in the SBCR under reaction conditions of 265 °C, 2.5 MPa, and H₂/CO = 1 was investigated. The CO conversion and liquid oil (C₅₊) productivity in the reaction were 88.6% and 0.226 g/g_cat-h, respectively, corresponding to a liquid oil (C₅₊) production rate of 0.03 bbl/day. To investigate the FTS reaction behavior in the bench scale SBCR, the effects of the space velocity and superficial velocity of the synthesis gas and reaction temperature were also studied. The liquid oil production rate increased up to 0.057 bbl/day with increasing space velocity from 2.61 to 3.92 SL/h-g_Fe and it was confirmed that the SBCR bench system developed in this research precisely simulated the FTS reaction behavior reported in the small scale slurry reactor.     

Fischer-tropsch synthesis in a stirred tank slurry reactorndashreaction rates

The effect of process variables (temperature, pressure, space velocity, and H₂/CO feed ratio) on the Fischer-Tropsch synthesis on a promoted fused iron catalyst was studied in a slurry phase stirred tank reactor (STR). Operating conditions were chosen such that some of the data could be compared with previously reported results, but experiments were also performed at more extreme conditions (temperatures up to 280°C and pressures up to 2.86 MPa) than previously studied in a slurry phase STR. The catalyst activity compares well with previous studies at an H₂/CO feed ratio of 1.0 and 1.8, but the activity is lower than previously reported values in the 0.64-0.72 range of H₂/CO feed ratios. Spacetime-yield increases with pressure, and reactor productivity is best increased by increasing pressure at a constant pressure to space velocity ratio. The water-gas-shift reaction is near equilibrium at high conversions, and always proceeds at a slower rate than the Fischer-Tropsch synthesis in a STR.     

甲醇液相氧化羰基化合成碳酸二甲酯催化剂的研究进展

介绍和比较了甲醇液相氧化羰基化合成碳酸二甲酯各类催化剂的结构特点及其催化性能,认为选择无Cl的活性组分可以从根本上解决现有催化剂存在的失活和设备腐蚀问题,是新一代催化剂的发展方向;基于CuⅠ活性位特征进行催化剂设计与制备,有效控制活性位的数量、分布和落位,提高分散均匀度,进而调节催化剂的化学表面结构可望获得理想的催化性能。     

Catalyst mixing in bubble column slurry reactors

The reported experimental data of Pandit and Joshi (1984) on axial and radial steady-state catalyst concentration in a semibatch bubble column slurry reactor is interpreted by the dispersion model. The elliptic partial differential equation with its associated boundary conditions is solved analytically for catalyst concentration by the method of separation of variables. The proposed model adequately fits the experimental data.     

Biomass pyrolysis in a circulating fluid bed reactor for the production of fuels and chemicals

An approach for biomass flash pyrolysis in a circulating fluid bed (CFB) reactor with continuous solids regeneration is described in this study. The unit is capable of performing conventional and catalytic biomass pyrolysis with the proper solid selection. The production of improved quality liquid products in a direct step through catalytic pyrolysis is investigated in this work. Both conventional and catalytic biomass pyrolysis can be effectively performed in this CFB unit. Flash pyrolysis conditions were achieved and liquid product yields of ∼70 wt% (on biomass feed) were obtained. The effect of specific operating variables including the type of inorganic solid material and the solid/biomass ratio was established on the final liquid product quality and yield. Solid materials considered included silica sand, a commercial fluid catalytic cracking catalyst and a ZSM-5 additive. Catalytic biomass pyrolysis generally leads to the production of additional water, coke and gases compared to conventional pyrolysis. However, the obtained liquid product quality and composition is improved.     

低温甲醇合成研究进展

日本学者Tsubaki等开创了一种全新的低温甲醇合成反应路径。该路径以含有二氧化碳的合成气为反应原料,使用单一低碳醇(包括甲醇)同时作为催化剂和溶剂,实现了反应原料一氧化碳在低温(443 K)条件下,一步转化率达到70%～100%。原位红外和多种表征手段证明,该反应能够在低温条件下进行,是由于催化剂上吸附的甲酸盐物种可以和多种低碳醇溶剂在低温条件发生酯化反应,生成相对应的甲酸酯。而生成的甲酸酯很容易在低温条件下,铜基催化剂表面,发生加氢反应,生成甲醇和相应的溶剂醇。该种全新的甲醇合成路径克服了常规甲醇合成过程中,甲酸盐必须在高温条件下才能发生加氢反应的关键步骤。同时,还介绍了适用于低温甲醇合成反应的金属Cu/ZnO催化剂制备方法的研究进展。全新的溶胶-凝胶-燃烧法、固相研磨-燃烧法以及甲酸辅助燃烧法直接制备高活性、纳米尺度、高分散的金属Cu/ZnO催化剂,而不需要额外的还原流程。     

Oxygen mass transfer coefficient in bubble column slurry reactor with ultrafine suspended particles and neural network prediction

The gas–liquid volumetric mass transfer coefficient was determined by the dynamic oxygen absorption technique using a polarographic dissolved oxygen probe and the gas–liquid interfacial area was measured using dual‐tip conductivity probes in a bubble column slurry reactor at ambient temperature and normal pressure. The solid particles used were ultrafine hollow glass microspheres with a mean diameter of 8.624 µm. The effects of various axial locations (height–diameter ratio = 1–12), superficial gas velocity (u_G = 0.011–0.085 m/s) and solid concentration (ε_S = 0–30 wt.%) on the gas–liquid volumetric mass transfer coefficient k_La_L and liquid‐side mass transfer coefficient k_L were discussed in detail in the range of operating variables investigated. Empirical correlations by dimensional analysis were obtained and feed‐forward back propagation neural network models were employed to predict the gas–liquid volumetric mass transfer coefficient and liquid‐side mass transfer coefficient for an air–water–hollow glass microspheres system in a commercial‐scale bubble column slurry reactor. © 2012 Canadian Society for Chemical Engineering