合成气制低碳醇钼基催化剂助剂的研究进展

钼基催化剂具有独特的抗硫性和抗积炭性,在合成气制低碳醇催化体系中最具发展前景。钼基催化剂催化性能受助剂的影响较大。碱金属的加入能明显提高催化剂对醇的选择性,但使CO转化率下降;碱金属盐中阴离子种类对反应活性影响显著;将Co、Ni、Rh等加入碱金属掺杂的催化剂中,可以提高C2+醇的选择性;助剂Rh有利于醇选择性的提高,但反应条件苛刻,成本较高。不同类型催化剂的催化反应机理不同,与表面物相种类有关。选择适当助剂,有望得到性能优良的CO加氢合成低碳醇钼基催化剂。     

氧化物助剂对费托合成钴基催化剂的促进作用

氧化物助剂促进的钴基催化剂具有费托合成反应活性和长链烃选择性高等特点,是高选择性地获得馏分油的关键,具有良好的应用和研究价值。本文针对氧化物助剂对钴基催化剂的促进作用,综述了氧化物助剂对钴基催化剂的结构、稳定性以及费托合成反应性能的影响,详细分析了氧化物助剂对钴基催化剂的还原性能和分散度的影响,同时介绍了影响氧化物助剂促进作用的因素,重点讨论了氧化物助剂的促进作用机理。并对如何更好地发挥氧化物助剂在钴基催化剂中的促进作用进行了展望:应加强氧化物助剂对钴基催化剂促进作用机理的基础研究,并且重视影响氧化物助剂促进作用的因素。     

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。     

F—T组元与CO加氢合成低碳醇

扼要介绍了不同种类的包含Ｆ－Ｔ组元的低碳醇合成催化剂，归纳总结了这一类催化剂的主要特点，认为所有的Ｆ－Ｔ催化剂都同时具备合成低碳醇和合成烃的双重性能，助剂或载体的主要作用是分散Ｆ－Ｔ组元，高度分散、高度均匀的活性组元分布状态是合成低碳醇反应必需的；载体或助剂所起的化学调变作用进一步改善了催化剂的活性和选择性，并由此试图对可能的新催化体系进行了预测。     

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。     

Cu-Fe基催化剂在煤基合成气制低碳混合醇中的应用

利用高性能催化剂将煤基合成气制成低碳混合醇成为煤基合成气利用的新方向,催化剂的选择成为合成反应的关键。介绍了改性甲醇合成催化剂、改性Fischer—Tropsch合成催化剂以及贵金属铑基催化剂等催化剂及其特点。作为Fischer—Tropsch合成催化剂之一的Ctl-Fe基催化剂因成本低、反应条件温和、具有较高的活性、醇和c：＋醇选择性而被广泛应用。重点介绍了Cu-Fe基催化剂的催化反应机理,以及主组分、助剂、载体类型和制备方法对其催化性能的影响。     

FTO反应铁基催化剂电子和结构助剂研究进展

合成气直接制烯烃（FTO）具有生产工艺简单、生产成本低廉等优点，近年来成为中国制烯烃的重要研究方向。铁基催化剂由于成本低、甲烷选择性低、链增长能力弱而备受关注。然而单一的铁基催化剂无法满足工业生产的需求，需要加入助剂提高催化剂的反应性能。综述了电子助剂（碱金属、碱土金属、过渡金属、稀土金属）和结构助剂（二氧化硅、三氧化二铝、二氧化锆等）的电子作用、结构作用对催化剂活性组分的还原、碳化的影响，分析了助剂负载量对催化剂反应性能的影响。指出电子助剂可以促进铁的碳化，增加催化剂的活性和低碳烯烃选择性；结构助剂可以有效提高催化剂晶体的分散性，增加催化剂比表面积，促进催化剂对低碳烯烃选择性。最后指出，助剂的负载量、协同作用及其相关的作用机理都有不足之处，应及时研究以促进FTO反应工业化进程。     

生产IIR的新型催化剂进展

综述几种可以用于异丁烯－异戊二烯高温共聚的新型催化剂体系,即活性阳离子络合催化体系,如叔酯或叔醚／四氯化钛催化体系;茂金属催化剂,如Ｃｐ２ＺｒＭｅ２／Ｂ（Ｃ６Ｆ５）３或（ＣＰｈ３）（Ｂ（Ｃ６Ｆ５）４）催化剂体系;烷基氯化铝共催化剂体系;可以改变相对分子质量分布的叔／醇／Ｌｅｗｉｓ酸催化体系,如异丙基醇／三氯化铝催化剂体系;用Ｌｅｗｉｓ酸活化了的卤代金刚烷体系。利用叔－醇／Ｌｅｗｉｓ酸催化体系合成的     

费托合成钴基催化剂稀土助剂改性研究进展

综述了近几年费托合成钴基催化剂稀土助剂改性方面的研究进展。针对稀土氧化物助剂对钴基催化剂的促进作用,重点分析了稀土氧化物对钴基催化剂的还原度、分散度和费托反应性能的影响,最后对钴基催化剂今后的发展趋势进行了展望。     

费托合成钴基催化剂稀土助剂改性研究进展

综述了近几年费托合成钴基催化剂稀土助剂改性方面的研究进展。针对稀土氧化物助剂对钴基催化剂的促进作用,重点分析了稀土氧化物对钴基催化剂的还原度、分散度和费托反应性能的影响,最后对钴基催化剂今后的发展趋势进行了展望。     

CuCo基催化剂催化CO2加氢合成低碳醇

利用共沉淀法制备二氧化碳加氢合成低碳醇的 Cu- Co基催化剂 ,采用 XRD和 TPR等方法对 Cu- Co基催化剂进行物理表征 ,考察制备催化剂时不同加料顺序对其物性的影响 ;同时 ,在反应压力 2 .5 MPa～ 3.0 MPa,反应温度 5 73K及空速 5 0 0 0 h-1～ 1 0 0 0 0 -1的条件下 ,利用固定床微型反应器对 Cu- Co基催化剂进行活性评价 .结果表明 ,催化剂制备时不同加料顺序影响催化剂的物相组成及几何结构 ;Cu- Co合金是合成低碳醇的活性物相 .     

Addition of propene to carbon monoxide-hydrogen in higher alcohol synthesis over unpromoted and caesium-promoted ZnCrO catalysts

Catalytic activity tests in higher alcohol synthesis over unpromoted and caesium-promoted ZnCrO catalysts with the addition of propene to CO-H₂ have been performed to clarify the role of alkenes in the chain growth to higher oxygenates. Over the unpromoted catalyst, the observed increments of selected products (1-butanol, 2-methyl-1-butanol, 1-methoxy-2-methyl-butane, C₇ ketone) upon the addition of propene are consistent with the occurrence of a hydrocarbonylation reaction of propylene to an aldehydic linear C₄ intermediate, which is successively transformed according to previously established reaction paths of higher alcohol synthesis over ZnCrO catalysts. Hydrocarbonylation is slower than aldol condensation, and the influence of propene addition is greatly reduced over the caesium-promoted catalyst as well as at higher reaction temperatures. We conclude that the contribution of alkenes to the reaction scheme of higher alcohol synthesis over alkali-promoted ZnCrO catalysts is apparently unimportant.     

Effect of cobalt promoter on Co–Mo–K/C catalysts used for mixed alcohol synthesis

The structures of sulfided Co–Mo–K/C catalysts were studied by means of X-ray diffraction (XRD), laser Raman spectra (LRS), and X-ray absorption fine structure (XAFS). Activities for alcohol synthesis via CO hydrogenation were used to characterize the catalytic performance of these catalysts. On the activated carbon support, molybdenum is mainly present as MoS₂ species which shrinks with the cobalt loading, while cobalt is mainly present in the form of “Co–Mo–S” phase at the low Co loading and partly in a Co₉S₈-like structure at higher Co loading. The catalysts exhibit outstanding performance for higher alcohol synthesis due to the addition of the promotion of cobalt. The activity for alcohol formation is optimized at a Co/Mo atomic ratio of 0.5. Co species operate as a synergistic system, rather than independently from the MoS₂ phase.     

Synthesis of Higher Alcohols from Syngas over Ultrafine Mo—Co—K Catalysts

Ultrafine Mo–Co–K catalysts were prepared and tested for higher alcohol synthesis. The catalysts exhibited high catalytic activity. The effect of the mole ratio of cobalt and molybdenum in the catalysts upon the catalytic performance of higher alcohol synthesis was investigated. Among the ultrafine Mo–Co–K catalysts, the best one corresponded to the Co/Mo mole ratio of 1:7. The XPS spectra revealed that molybdenum was present in two species: Mo⁶⁺ and Mo⁴⁺ on the surface of reduced catalysts, and the Mo⁴⁺ species content depended strongly on the Co/Mo mole ratio. The selectivity towards higher alcohols was found to be related to the Mo⁴⁺ species content. A linear relation between the selectivity and Mo⁴⁺ species content led to the conclusion that the Mo⁴⁺ species was the main active species for higher alcohol synthesis over the ultrafine Mo–Co–K catalysts.     

A Review of Molybdenum Catalysts for Synthesis Gas Conversion to Alcohols: Catalysts,Mechanisms and Kinetics

Recent literature on synthesis gas conversion to higher alcohols over Mo-based catalysts is reviewed. Density functional theory calculations show that Mo-CO adsorption is weakened by C, P, or S ligands and this facilitates CO dissociation, either directly on Mo₂C, or by H-assisted dissociation on MoS₂, Mo₂C, and MoP. Consequently, Mo-based catalysts have high hydrocarbon selectivity unless they are promoted with alkali metals and/or Group VIII metals. Promoted MoS₂ and MoP have alcohol selectivities of ～80 C atom % (CO₂-free basis) at typical operating conditions (5–8 MPa, H₂/CO = 2–1, 537–603 K), whereas on promoted Mo₂C, alcohol selectivities are ～60%. The kinetics of the synthesis gas conversion reactions over Mo-based catalysts have mostly been described by empirical power law models and the alcohol and hydrocarbon product distributions are consistent with a CO insertion mechanism for chain growth.     

合成气制低碳醇CuCrNi/CeO_2催化剂的改性研究

采用并流加料法制备改性前后的K-Cu/CeO_2催化剂。采用X射线粉末衍射(XRD)对催化剂进行表征;在DCS控制煤气化合成低碳醇实验装置中进行活性评价。结果表明,Fe的加入促进了CuO分散,在Cu-Fe物质的量比为7∶1.5时,具有更高的总醇选择性(45.97%)。     

加料方式对Cu-Co合成低碳醇催化剂性能的影响

低碳醇在汽油添加剂或汽油替代品减少尾气排放等方面具有潜在用途,用煤和天然气经合成气合成低碳醇的Cu-Co催化剂在较为缓和条件下具有较高的催化活性和C₂+OH醇选择性。采用不同沉淀方法制备系列Cu-Co催化剂,通过XRD、XPS、TPR和BET考察加料方式对催化剂前驱体和催化剂性能的影响。在5.0 MPa、250 ℃和空速5 000 h^-1条件下,使用加压固定床反应器考察合成低碳醇活性。研究结果表明,加料方式对催化剂性能有较大影响,采用共沉淀法制备的催化剂颗粒中各组分以纳米大小均匀分布,C₂+OH醇选择性最高;采用正加法制备的催化剂活性和C₂+OH醇选择性最低,催化剂颗粒中活性组分的分布呈壳层分布,Co在颗粒的表面富集;采用并流法和反加法制备的催化剂的醇分布遵从ASF规则,其链增长因子为0.42。实验结果表明,当Cu和Co在催化剂颗粒中以原子尺度分布时,催化活性最好。     

用于合成气制低碳醇的钼基催化剂研究进展

综述了用于合成气制纸碳醇的钼基催化剂的制备方法、反应条件和表面结构的变化规律,并总结了对活性中心的研究结果。     

NaY ZEOLITE–SUPPORTED POTASSIUM SALT CATALYSTS FOR DIPROPYL CARBONATE SYNTHESIS FROM TRANSESTERIFICATION ROUTE

The catalytic synthesis of dipropyl carbonate (DPC) from transesterification of dimethyl carbonate and propyl alcohol over NaY zeolite–supported potassium salt catalysts was investigated at atmospheric pressure. K₂CO₃/NaY and KOH/NaY catalysts exhibited better catalytic activity than other potassium salt catalysts. From infrared resonance (IR), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), it could be concluded that K₂CO₃/NaY and KOH/NaY catalysts showed preferable order degree of zeolite structure, which was associated with higher dispersal of the active species K₂O and extraction for part of the non-framework silicon and aluminum of the system after alkali treatment. And the partial extraction of the non-framework silicon and aluminum allowed the reactants and the products to pass through the pore of the catalysts easily and facilitated catalytic performance for DPC synthesis.