CuCo基催化剂中碱及氧化物助剂的作用

综述了几种助剂对合成低碳醇ＣｕＣｏ 基催化剂性能的影响． 碱金属（Ｋ） 的存在是必要的, 它可以提高产物中低碳醇 （特别是支链醇） 的选择性和收率; 稀土氧化物的引入有利于提高催化剂的热稳定性; ＺｎＡｌ氧化物助剂的作用主要体现在对催化剂比表面和稳定性的影响; ＺｒＯ２是一种新兴的催化剂助剂, 对甲醇合成有直接影响．     

费托合成制低碳烯烃钴基催化剂研究进展

概述了费托合成制低碳烯烃的背景和发展趋势,综述了费托合成制低碳烯烃反应机理和钴基催化剂的研究进展,重点评述了钴基催化剂活性相、助剂和载体等关键因素,探讨了活性相、助剂和载体对合成气制低碳烯烃的影响,并对费托合成制烯烃的研究提出了展望和建议。     

第一代固定床费托合成RFT-1催化剂中试

由中石化石科院研究开发的第一代固定床F—T合成RFT-1催化剂，目前通过中石化集团公司组织的中试评议，并得到评议专家的一致好评。所开发的RFT-1催化剂在载体、活性组元、外形和助剂上进行了优化，工业放大生产的催化剂活性和选择性都达到了较高水平，为2006年11月在镇海炼化3000吨／年的中试试验装置上应用奠定了基础。费托（F—T）合成是TGL技术中的关键及控制步骤，它是指合成气（CO＋H2）在催化剂的作用下转化成烃类的反应，产物包括烷烃和烯烃，并副产CO2和H2O以及醇、醛、酸、酮和酯等有机含氧化合物，产品经过深加工可得到优质液体燃料或化工产品。     

Co基催化剂用于低碳醇合成反应研究进展

分别从主催化剂、助剂和载体3个方面对目前研究较为集中的改性费托Co基低碳醇合成催化剂进行综述,指出了该催化剂存在的主要问题和今后研究的重点,同时对低碳醇催化剂未来的研究方向做出了预测。     

美国能源部的浆态床F—T合成技术

浆态床Ｆ－Ｔ合成技术是美国能源部Ｆ－Ｔ合成技术的主要开发项目。本文就浆态相Ｆ－Ｔ合成催化剂的开发、中试示范实验和浆态反应器的化工基础研究作一扼要的介绍。     

费托合成制低碳烯烃铁基催化剂研究进展

综述了费托合成制低碳烯烃铁基催化剂方面所取得的研究进展,重点介绍了催化剂活性相、助剂和载体等方面的关键因素,探讨了催化剂制备条件对合成气制烯烃的影响,最后对费托合成直接法制烯烃的研究提出了一些展望。     

美国能源部的浆态床F－T合成技术

浆态床Ｆ－Ｔ合成技术是美国能源部Ｆ－Ｔ合成技术的主要开发项目。本文就浆态相Ｆ－Ｔ合成催化剂的开发、中试示范实验和浆态反应器的化工基础研究作一扼要的介绍。     

β—巯基乙醇的合成新工艺

本文报道了β－巯基乙醇合成新工艺，优选出较佳的合成条件，用低碳醇为溶剂，碱金属硫酸盐为催化剂，以环氧乙烷和Ｈ２Ｓ在常压下合成β－巯基醇、产率较同方法的其它条件有很大提高。     

合成气制低碳醇催化剂研究进展

煤经合成气制备低碳醇是C1化工领域重要的组成内容之一,能够实现能源的清洁和高效利用。本文综述了近年来合成气制低碳醇反应所用催化剂的研究进展,重点介绍了助剂和载体对催化剂结构和性能的影响,指出构建具有均匀分布的双功能活性位点的催化剂是提高合成气制备低碳醇性能的关键。     

助剂锆对甲醇合成催化剂性能的影响

制备了不同锆含量的甲醇合成催化剂,对催化剂进行了XRD、H2-TPR、活性评价与选择性分析,开展了条件试验,并与工业上在用的其他同类型甲醇合成催化剂进行了性能对比,结果表明:助剂锆的加入可以与Cu互换形成共同体沉淀盐,有效分散活性单元Cu/ZnO共同体,提高催化剂的比表面积和Cu的分散度,从而提高催化剂的性能.但助剂的引入还会导致活性中间相含量下降,引起催化剂活性下降,确定了助剂锆的最佳含量.MJ型甲醇合成催化剂在活性、选择性、热稳定性等方面已达到或超过工业上在用的其他同类型甲醇合成催化剂产品.     

Major and Minor Reactions in Fischer–Tropsch Synthesis on Cobalt Catalysts

Minor reactions, accompanying the major reactions for building straight-chains of aliphatic hydrocarbons from the reactants CO and H₂ on the surface of cobalt catalysts, can contribute substantially to the understanding of the regime of Fischer–Tropsch synthesis. This goal affords precise mass balances, precise determination of product composition and consistent kinetic schemes for obtaining the right kinetic coefficients. The concept of self-organization of the Fischer–Tropsch regime is established from time dependence of activity, selectivity and catalyst structure. A process of thermodynamically controlled restructuring/segregation of the cobalt surface is addressed and understood as activating the catalyst and specifically, disproportionating on-plane sites into sites of lower coordination (on-top sites) and higher coordination (in-hole sites). These different sites appear to collaborate in the Fischer–Tropsch regime, with steps of coordination chemistry (comparable to those of transition metal complexes) on on-top sites and dissociation (specifically of CO) on in-hole sites and further in principle suppressed reactions on on-plane sites. This concept is developed and illustrated here with the results of several investigations such as tracing of activity and selectivity during the initial episodes of synthesis, experiments with added (¹⁴C-labeled) olefins and variation of synthesis parameters to see their specific influences. As minor reactions of coordination chemistry on on-top sites, reversible CH₂ cleavage from alkyl chains, CO insertion and ethene insertion are visualized. On on-plane sites CO methanation, olefin hydrogenation and olefin double bond shift are noticed, but much inhibited. As compared to Fischer–Tropsch on iron catalysts, the common Fischer–Tropsch principle appears to be the inhibition of chain desorption to allow for growth reactions of the adsorbed chains. Minor reactions and detailed kinetics on iron and cobalt catalysts differ basically.     

Carbon Coated Supports for Cobalt Based Fischer–Tropsch Catalysts

Cobalt based Fischer–Tropsch synthesis catalysts were prepared on carbon coated alumina supports. Carbon coating resulted in a decrease in the average cobalt crystallite size (down to 6 nm) and increased active cobalt metal surface area. Very importantly, the use of carbon on the alumina surface also altered the cobalt nitrate mechanism of binding and thermal decomposition, resulting in a significant change in the macroscopic cobalt distribution with improved inter-particle distances. The enhanced cobalt metal surface areas together with the significantly improved cobalt distribution/inter-particle distances resulted in cobalt Fischer–Tropsch synthesis catalysts with an activity that was increased by 40–75 % without having a negative influence on the methane selectivity.     

Low-Temperature Fischer–Tropsch Synthesis on Cobalt Catalysts—Effects of CO2

Effects of CO₂ on low-temperature Fischer–Tropsch synthesis were investigated with four different cobalt catalysts in an experimental study. CO₂ was found to behave as an inert gas component with three catalysts, however, a negative effect on Fischer–Tropsch reaction rate and catalyst deactivation was observed in one case (Co-La-Ru-SiO₂). CO₂ effects in a large-scale FTS slurry reactor were simulated by means of a mathematical reactor model using the kinetic information gained in the experiments. The reactor volume required for achieving a desired CO conversion must be higher if the syngas contains CO₂, more strongly in cases where the catalyst exhibits a deactivation behavior in the presence of CO₂. These model calculations can contribute to process optimization with respect to CO₂ removal before synthesis.     

Co/AC催化剂对F-T合成醇产物的影响

以活性炭为载体,采用真空浸渍法制备Co/AC催化剂,在浆态床反应器中考察反应温度、反应压力和空速等条件对F-T合成醇产物的影响。结果表明,升高反应温度对长链烃和醇的生成有利,醇类的选择性随着反应压力的增大而提高,但反应压力增至3.0 MPa后,继续增加反应压力对醇类选择性变化不大;随着空速的增大,液相产物中醇含量虽然增加,但醇的分布无变化。     

Polymerization Kinetics of Fischer‐Tropsch Reaction on Iron Based Catalysts and Product Grade Optimization

The polymerization kinetics of Fischer‐Tropsch reactions on a K‐promoted Fe catalyst was studied. To represent the product distribution, a kinetic model was developed based on alkyl and alkenyl mechanisms for hydrocarbon chain propagation, which were assumed to occur simultaneously in the Fischer‐Tropsch synthesis. The conclusion was drawn that superimposed Anderson‐Schulz‐Flory (ASF) distributions with different chain growth probabilities, on iron catalysts, can be the result of different chain growth mechanisms. The polymerization mechanism was used to obtain the product distribution for several conditions, and the optimum conditions for the production of transportation fuels were found.     

High Loading Fe-supported Fischer–Tropsch Catalysts: Optimization of the Catalyst Performance

The iron loading of catalysts, supported on SiO₂, was investigated between 10 and 75 wt%, with and without the addition of promoters (K and Cu), in order to highlight the different catalytic performances of the samples in the Fischer–Tropsch synthesis. An optimization study of the prepared catalysts (active metal/promoters ratio, catalysts’ activation procedure before the Fischer–Tropsch runs, influence of the feeding gas composition) is reported. The mechanical resistance of the catalysts was also evaluated using a suitable method involving ultrasound.     

助剂在钴基催化剂F-T合成重质烃反应中的应用

煤 /天然气经合成气生产洁净二次能源和化学品将在本世纪初成为重要的能源化过程 .在新的过程观念 ( SMDS法 )中 ,新型钴基催化剂的制备是 F- T合成重质烃反应中的关键问题 ,其中助剂可以对催化剂的活性和选择性进行调变 .概述了专利中常用的助剂如金属钌、氧化锆、氧化镧对钴基催化剂 F- T反应性能的影响及作用机制 ,指出添加适当的助剂可以在不影响催化剂的F- T反应活性的前提下 ,提高产物的长链烃 ( C5 )选择性 .     

Production of Higher Hydrocarbons from CO2 over Nanosized Iron Catalysts

The effects of the particle size of a Fe/Cu/K catalyst on CO and CO₂ hydrogenation reactions as well as the variation of crucial factors such as surface area and basicity, reduction, carburization, and catalytic behavior of precipitated Fe/Cu/K catalysts were evaluated. Hematite nanoparticle catalysts with various surface tensions were produced by homogeneous precipitation in alcohol/water solvents. The basicity of the K‐promoted iron catalyst was higher in iron catalysts with lower particle size. The increase in K‐basic sites at the surface of catalysts with smaller particle size was attributed to their higher surface areas. Elevation of catalyst basicity led to considerably stronger dissociative CO adsorption. Shifting the oxygen removal pattern to lower temperature was the consequence of faster nucleation of FeCx crystallites on promoted surface oxides. CO₂ hydrogenation can occur in two distinct direct and indirect routes via the Fischer‐Tropsch mechanism.     

Alcohol Synthesis via Fischer–Tropsch Synthesis over Activated Carbon Supported Alkaline Earth Modified Cobalt Catalyst

Although numerous efforts have been made in direct syngas conversion to higher alcohols via Fischer–Tropsch synthesis, the higher alcohols distribution remains a challenge. Here, we introduce alkaline earth metal oxide as promoter into activated carbon supported cobalt catalyst to tune distribution of higher alcohols. With the addition of Mg, the distribution of C_2-5 alcohols increase from 41.2 to 75.8% accompanying with distribution of C_6-18 alcohols decrease from 52.8 to 14.0%. Ba-promoted Co based catalyst (CoBa/AC) presents similar alcohols distribution to un-promoted catalyst, while the alcohol selectivity over CoBa/AC is higher than Co/AC. For promoted catalysts, the distribution of C_6-18 alcohols increased in the order of Mg?<?Ca?<?Sr?<?Ba. The characterization results exhibit that the promoter addition facilitates the cobalt carbide formation, which leads to enhancement of selectivity to higher alcohols. The available active cobalt sites of promoted Co based catalysts increase in the same above order of Mg?<?Ca?<?Sr?<?Ba.

Graphic Abstract

     

Catalyst Deactivation Rate During Hydrogenation of CO2 to Longer-Chained Hydrocarbons Over 6 wt% Potassium-Promoted Co/Al2O3 Catalyst

Catalysis Letters - The deactivation rate of 15%Co-6%K/Al2O3 Fischer–Tropsch catalyst during hydrogenation of CO2 to longer-chained hydrocarbons was investigated. The catalysts used were...