生物质到生物燃料—费托合成催化剂的研究进展

费托合成反应是煤、甲烷和生物质等非油基碳资源转化制高品质液体燃料或化学品的重要途径。以生物质基合成气为原料,利用传统的Fe、Co催化剂制备生物燃料引起普遍关注。本文简要总结了近年来高性能Fe基和Co基费托合成催化剂的发展,以及近年来新型材料和核壳结构的双功能催化剂在费托合成中的应用。重点关注了生物质合成气方面的应用,比较了Fe、Co催化剂在该应用中的特点。虽然Co基催化剂较Fe基催化剂有更好的活性,但在BTL（Biomass-To-Liquid）过程中需要考虑多种因素,Fe基催化剂可能更具优势,开发廉价高性能的Fe基催化剂可能成为BTL-FT催化剂的发展方向。     

生物质气合成二甲醚实验研究

采用水蒸汽气化木屑制备生物质气,在下游的重整反应器内,通过两段催化重整焦油,焦油裂解率高得96.70%.在双功能催化剂JC207/HZSM-5催化剂上,对生物质气合成二甲醚进行了实验研究.利用原生物质气以及脱碳生物质气考察了不同温度、压力和空速对合成二甲醚的影响.结果表明,在260℃,4 MPa、2400 L/(kgcat·h)条件下,原生物质气的CO单程转化率达到67.95%,单位质量催化剂的最大二甲醚时空收率0.338g/(gcat·h).脱碳生物质气的CO单程转化率达到75.52%,单位质量催化剂的最大二甲醚时空收率0.583g/(gcat·h).     

生物质气化催化剂的研究现状

在生物质气化过程中,由于焦油的产生以及生成的小分子可燃气体较少的特点,影响了生物质气化技术的进一步推广和应用。使用催化剂是一种可以提高小分子可燃气体品位、提高生物质利用效率、减少焦油产生的经济可行的办法。文中叙述了生物质气化催化剂的研究概况,并着重介绍了各种催化剂使用的效果。     

秸秆类生物质催化合成甲醇的实验研究

为了将农业废弃物转变为燃料甲醇，对玉米秸秆燃气进行合成气优化实验，在5MPa压力下，采用等温积分反应器和国产C301铜基催化剂，对合成气进行催化合成甲醇的实验研究。     

基于Ni/Al2O3整体式催化剂的生物质气化合成气甲烷化研究

以生物质气化模拟合成气H2/CO/N2为原料气,以堇青石蜂窝陶瓷为基体制备Ni/Al2O3整体式催化剂,通过扫描电镜(SEM)、比表面积(BET)、X射线衍射(XRD)、程序升温反应法(TPR)、热重分析(TG)等表征分析手段,考察催化剂制备方法(浸渍法和溶胶-凝胶法)、温度(250~550℃)及空速GHSV(6000~14000 mL/(g·h))对催化剂甲烷化性能的影响。结果表明:浸渍法制备的Ni/Al2O3催化剂(DIP-Ni/Al2O3)与溶胶-凝胶法制备的Ni/Al2O3催化剂(SGNi/Al2O3)相比,前者甲烷化性能较好。在H2、CO、N2物质的量之比为3∶1∶1且空速为10000 mL/(g·h)条件下,浸渍法制备的Ni/Al2O3催化剂在400℃时甲烷化性能最佳,且该条件下CO转化率为98.6%,CH4选择性为90.9%。当H2、CO、N2物质的量之比为3∶1∶1且温度为400℃时,在实验空速范围内,浸渍法制备的Ni/Al2O3催化剂CO转化率和CH4选择性均基本稳定在90%,甲烷化性能较好。     

生物质油气化制取合成气模拟研究

基于Aspen~(plus)建立生物质油纯氧气流床气化工艺模型,通过灵敏度分析初步探讨工艺条件、不同氧含量和生物质油等参数对气化结果的影响,并对不同气化介质的气化结果进行比较。模拟研究表明:氧气当量系数ER约为0.37,气化温度可达约1280℃,生物质油纯氧气化有效气成分可达约90%。在无外部供氧条件下,合成气的CH_4含量过高;随O_2在空气中比例降低,CH_4含量成倍上升;水蒸气的加入有利于抑制CH_4生成。     

秸秆合成气催化合成甲醇催化剂优化试验研究

生物质能是一种可再生能源,为了研究秸秆类生物质转化为燃料甲醇以有效地利用生物质能,采用热化学方法在下吸式固定床气化炉中生产低热值燃气,对该燃气进行脱硫、脱氧、焦油催化分解、纯化、配氢等优化试验,制备出秸秆合成气。在直流流动等温积分反应器中进行了催化合成甲醇的试验,在235℃和5MPa条件下进行了催化剂种类及粒度对合成甲醇的影响试验。试验结果表明:合成甲醇的适宜催化剂型号为C301,最优化颗粒粒度为0.833mm×0.351mm,该研究为生物质(秸秆)气催化合成甲醇的深入研究提供了基础数据。     

百吨级生物质合成气合成二甲醚中试系统设计及运行分析

该系统以农业废弃物玉米芯经富氧气化制备的低H_2/CO合成气为气源,采用固定床一步法合成二甲醚工艺,高效生产DME产品.运行结果表明,在空速为650h~(-1)和1200h~(-1)时,CO单程转化率分别为82.00%和73.55%.DME选择性分别为73.95%和69.73%,DME时空产率分别为124.28kg/(m~3·h)和203.80kg,(m~3·h).生物质合成气的深度脱氧和脱焦油是保证合成系统稳定运行的关键.合成尾气H_2/CO较高,经脱CO_2后循环利用可大大提高DME的产率.     

生物质气一步法合成二甲醚本征动力学研究

采用双功能催化剂,在压力3～6MPa,反应温度220～270℃,质量空速3.0～6.0L/(gcat.h)条件下,在固定床反应器中对脱碳生物质气一步法合成二甲醚动力学进行研究。用单纯形法与遗传算法相结合进行优化拟合模型参数,回归得到对应于甲醇合成、甲醇脱水和水煤气变换反应的反应动力学表达式,经检验该模型可靠,模型计算值与实验数据吻合良好。     

生物质合成气合成甲醇

在高压微型反应装置上进行了生物质合成气合成甲醇的实验研究。利用组成为V(H2)/V(CO)/V(CO2)/V (N2)=50/25/20/5的富CO2原料气考察了不同温度、压力和空速条件下甲醇的时空产率、甲醇和水的选择性等指 标。结果表明,在所考察的范围内,温度、压力和空速对甲醇的产率和选择性都有影响。在反应压力为4．6MPa, 空速为7000h-1时,时空产率的最大值为0．69g/(mL·h),甲醇的选择性范围为93％-97．2％。和富CO的原料气 相比,利用富CO2的生物质合成气合成甲醇,甲醇的时空产率和选择性都有所下降,时空产率下降的幅度在 10％-30％之间,选择性的下降幅度在2％-8％之间。通过控制适宜的操作条件,可降低甲醇的产率和选择性 的下降幅度。     

三种生物质气催化制甲醇的比较

比较了由生物质衍生的3种气体：含N_2且未调节C／H比的气体(A)、不含N_2但未调节C／H的气体(B)、不含N_2且调节C／H的气体(C)催化合成甲醇的性能。在P=4MPa、r=260℃、SV=5280h~(-1)下,与气体(C)比,气体(A)和气体(B)所得甲醇产率分别下降47.2％和25.5％,甲醇浓度分别下降1.4％和1.6％。反应温度对含CO_2的气体(A)和(B)合成甲醇的性能有重要影响,在260℃时甲醇产率和浓度都达到最佳值。大量CO_2的存在导致甲醇浓度的下降,CO_2含量越高,所得甲醇的浓度越低。     

A simple coupled ANNs-RSM approach in modeling product distribution of Fischer-Tropsch synthesis using a microchannel reactor with Ru-promoted Co/Al2O3 catalyst

A simple approach using hybrid artificial neural networks (ANNs)-response surface methodology (RSM) was developed to model the detailed product distribution using Ru-promoted cobalt-based catalyst with Al₂O₃ as the support in a microchannel reactor for Fischer-Tropsch (FT) synthesis. Using the independent process parameters for training, the established model is capable of predicting hydrocarbon production distributions, ie, paraffin formation rate (C₂-C₁₅) and olefin to paraffin ratio (OPR C₂-C₁₅) within acceptable uncertainties. The ANNs-RSM model and comprehensive mechanistic model using the Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach were compared to identify a few inherent advantages of the proposed model in modeling complex FT synthesis. The proposed ANNs-RSM model shows its appealing merits, ie, faster converge and higher accuracy (less than ±10% uncertainties was achieved from ANNs-RSM model, while LHHW model achieved less than ±15% uncertainties except a few exceptional high errors uncertainties at certain experimental conditions). The statistical significances to the product distributions and hydrocarbon formation rate during FT synthesis could be easily identified and quantitatively analyzed by the established ANNs-RSM model. The future effective alternative of kinetic study of the complex system such as FT synthesis in the microstructured reactor might follow the methods of using empirical reliable approach for process optimization together with mechanistic kinetic study for detailed reaction pathway discrimination.     

Hydrogen production from ethanol over Co/ZnO catalyst in a multi-layered reformer

A Co/ZnO catalyst was prepared by coprecipitation method, and was applied for ethanol steam reforming. The effect of reaction conditions on the ethanol steam reforming performance was studied in the temperature ranges from 400 °C to 600 °C and the space velocity ranges from 10,000 h⁻¹ to 120,000 h⁻¹ in a fixed bed reactor. The Co/ZnO showed high activity with an ethanol conversion of 97% and a H₂ concentration of 73% at a gas hourly space velocity of 40,000 h⁻¹ and a moderately low temperature of 450 °C. EXAFS analysis for fresh and spent samples confirms that Co phase maintains during reaction. The catalyst was then loaded into a multi-layered reformer of which the design concept allows for integrating endothermic steam reforming, exothermic combustion and evaporation in a reactor. The performance of the compact reformer demonstrated that the hydrogen production rate satisfy a PEMFC stack power level of 540 W suitable for portable power supplies.     

Stable and high-performance N-micro/mesoporous carbon-supported Pt/Co nanoparticles-GDE for electrocatalytic oxygen reduction in PEMFC

The current research presented a novel type of stable and high-performance electrocatalyst for oxygen reduction reaction (ORR). For this purpose, N-micro/mesoporous carbon-supported Pt/Co nanoparticles (NPs) were synthesized through a two-step procedure. The Co–N-micro/mesoporous carbon support was first prepared by the direct carbonization of zeolitic imidazolate framework-67 (ZIF-67). Next, the N-micro/mesoporous carbon-supported Pt/Co NPs were synthesized by galvanic replacement of Pt (IV) ions with Co nanoparticles. The surface properties and chemical structure of the prepared electrocatalyst were measured by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), N₂ adsorption-desorption, energy dispersive spectrometry (EDS) techniques. The results confirmed the desirable properties of the prepared electrocatalyst which enhanced the ORR kinetic. The ORR performance of the prepared electrocatalyst was examined utilizing the catalyst coated membrane electrode (CCME) in the homemade half-cell. The ORR performance of N-micro/mesoporous carbon-supported Pt/Co NPs loaded on the gas diffusion electrode (Pt/Co-NC-GDE) was evaluated in an acidic solution. The electrochemical tests exhibited the superior current density and power density of the Pt/Co-NC-GDE (?58.7 mAcm^?2 at 0.3 V/RHE and 17.6 mW cm^?2) compared to those of Pt/C-GDE (?43.7 mAcm^?2, and 13.1 mW cm^?2). Furthermore, durability tests indicated the higher stability of Pt/Co-NC-GDE than Pt/C-GDE.     

溶胶-凝胶法制备TiO2·SiO2/beads及其光催化性能的研究

研究以四异丙醇钛 [Ti (iso OC3 H7) 4 ]、硅酸乙酯为原料 ,以空心玻璃微球为载体 ,用溶胶 凝胶法制备可漂浮附载型复合光催化剂TiO2 ·SiO2 /beads的过程 ,利用附载型复合光催化剂降解有机磷农药。结果表明 :附载型复合光催化剂活性显著提高 ,牢固性增强 ,TiO2 ·SiO2 摩尔比存在最佳值。n (TiO2 ) /m (SiO2 ) =30 / 70时 ,光催化剂活性最高 ,其活性是同样降解条件下 ,同样含量DegussaP 2 5TiO2 的 2倍左右     

LiNi1/3Co1/3Mn1/3O2/polypyrrole composites as cathode materials for high-performance lithium-ion batteries

Polypyrrole is successfully introduced to enhance the reaction stability and ionic conductivity of LiNi_1/3Co_1/3Mn_1/3O₂ material through an ultrasound dispersion method and applied as cathode materials for lithium-ion batteries. This polymer can significantly advance the electrochemical properties. Expectedly, the 8 wt.% LiNi_1/3Co_1/3Mn_1/3O₂/polypyrrole composite has lower mixing degree of Li⁺/Ni²⁺, higher c/a value, which delivers the first discharge capacity of 199.2 mAh g⁻¹, which abate to 121.3 mAh g⁻¹ in the 300th cycle at 0.2 C between 2.5 and 4.5 V. Even at 3 C, it continues to reveal a reversible capacity of 86.4 mAh g⁻¹ after 100 cycles. All the consequences implied that the 8 wt.% LiNi_1/3Co_1/3Mn_1/3O₂/polypyrrole verified a minor charge transfer resistance and better Li⁺ diffusion ability, hence establishing preferable rate and cycling performance compared with the primordial LiNi_1/3Co_1/3Mn_1/3O₂.     

Graphite modified LiNi1/3Co1/3Mn1/3O2 cathodes with improved performance for lithium-ion battery

通过丝网印刷方法用石墨改性LiNi_1/3Co_1/3Mn_1/3O₂（NCM）电极片的表面。采用X射线衍射（XRD）和扫描电子显微镜（SEM）表征未改性和改性电极片的晶体结构和形貌特征,恒流充放电测试评估两种样品的电池性能,CV和EIS测试比较两种样品的电化学极化程度。结果表明,改性NCM电极的晶体结构没有明显变化;在改性电极片的表面上检测到了片状石墨;在截止电压为4.3 V的条件下改性样品比未改性样品具有更好的循环性能和倍率性能;石墨印刷的样品可以减缓电化学极化的增加。