钴基FT合成催化剂中原子碳物种的作用研究  

Study on the role of atomic carbon species in cobalt-based FT synthesis catalyst

作　　者：杨胜龙 王俊刚[1] 马中义[1] 陈从标[1] 刘岩[1] 张伟[1] 解启龙[1] 侯博[1] YANG Shenglong;WANG Jungang;MA Zhongyi;CHEN Congbiao;LIU Yan;ZHANG Wei;XIE Qilong;HOU Bo(State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院山西煤炭化学研究所煤炭高效低碳利用国家重点实验室,山西太原030001 [2]中国科学院大学,北京100049

出　　处：《燃料化学学报（中英文）》2024年第10期1426-1434,共9页Journal of Fuel Chemistry and Technology

基　　金：山西省研究计划(202103021224444,202102090301003);国家自然科学基金(22179136,22279155,22208361)资助。

摘　　要：费托合成是将合成气催化转化为长链重质烃的工艺过程。在此过程中,CO活化、歧化反应以及烃类脱氢反应都可以在催化剂表面形成碳物种,而碳物种对费托反应的作用一直存在争议。本工作通过对主要暴露面为HCP-Co(10-11)的单晶钴进行不同条件的预处理,构建了具有不同含量原子碳物种的模型催化剂,并采用程序升温加氢、拉曼光谱和红外光谱等表征手段对催化剂中的原子碳物种含量和存在形式进行分析。结果表明,在引入原子碳物种后,钴基催化剂的活性和CH_(4)选择性与原子碳物种数量和存在形式密切相关。含碳量为5.72%的P-Co-C3催化剂具有较高的CO转化率,可达72.2%;而含碳量为3.01%的P-Co-C2催化剂具有较低的CH_(4)选择性,仅为4.2%。此外,表征结果进一步证明该原子碳物种是以C(无定形碳)和CxHy两种形式共存,其在反应过程中参与了FT反应,进而提升其反应性能。The FT synthesis reaction is a process that catalytically converts syngas into long-chain heavy hydrocarbons.The Fischer-Tropsch reaction involves CO activation,disproportionation reactions,and hydrocarbon dehydrogenation reactions that can form carbon species on the catalyst surface.The role of carbon species in the Fischer-Tropsch reaction has been a topic of controversy.This paper reports the successful construction of model catalysts with varying atomic carbon species content.The catalysts were prepared by pretreating single-crystal cobalt with HCP-Co(10-11)as the main exposed surface under different conditions.The carbon species content and existing forms of the catalyst were characterized by temperature programmed hydrogenation,Raman spectroscopy and infrared spectroscopy.The study found that the activity and CH_(4)selectivity of the catalysts were closely related to the number and form of atomic carbon species introduced.With the increase of pretreatment time,the content of atomic carbon species deposited on the catalyst first increased and then decreased,and finally maintained a dynamic equilibrium,indicating that the content of atomic carbon species would remain unchanged with the increase of pretreatment time to a certain extent.The pre-treated catalyst was characterized by XRD,and no characteristic peak of CoO was found.The crystal structure is consistent with that of P-Co catalyst,and the influence of CoO and other crystal structure on the performance of FT synthesis is excluded.The P-Co-C3 catalyst,with a carbon content of 5.72%,achieved a high CO conversion rate of 72.2%,whereas the P-Co-C2 catalyst,with a carbon content of 3.01%,had a low CH_(4)selectivity of 4.2%.When the carbon content of P-Co-C1(2.76%)and P-Co-C2(3.01%)catalysts is low,the atomic carbon species mainly exists in the form of amorphous carbon(C).The presence of amorphous carbon in atomic carbon species covers part of methane generation sites,thus inhibiting methane generation,resulting in a decrease in methane selectivity.As the ca

关 键 词：原子碳物种 含碳量 存在形式 费托合成 

分 类 号：O643[理学—物理化学]