[1]孙 超,张振洲,陈宝见,等.Na 对 Fe-Zn 催化剂结构及 CO2 加氢制烯烃的影响[J].郑州大学学报(工学版),2022,43(04):97-103.
 Effects of Na on Structure of Fe-Zn Catalysts and Their Consequences for Olefins Formation during CO2 Hydrogenation[J].Journal of Zhengzhou University (Engineering Science),2022,43(04):97-103.
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Na 对 Fe-Zn 催化剂结构及 CO2 加氢制烯烃的影响()
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《郑州大学学报(工学版)》[ISSN:1671-6833/CN:41-1339/T]

卷:
43
期数:
2022年04期
页码:
97-103
栏目:
出版日期:
2022-07-03

文章信息/Info

Title:
Effects of Na on Structure of Fe-Zn Catalysts and Their Consequences for Olefins Formation during CO2 Hydrogenation
作者:
孙 超 张振洲 陈宝见 杜春丽 涂维峰
文献标志码:
A
摘要:
二氧化碳加氢制备烯烃是实现二氧化碳转化的有效途径之一,二氧化碳先后通过逆水煤气反应和费托合成反应生成高附加值产品。 铁基催化剂具有很好的逆水煤气以及费托合成活性,然而 CO2 加氢制备烯烃过程中存在多种副反应,导致烯烃选择性较低。 如何提高铁基催化剂性能成为工业化的重要问题。 通过定量浸渍法制备一系列不同 Na 含量的 Fe-Zn 催化剂,采用稳态反应速率测定、原位 X 射线光电子能谱( In-situ XPS) 、原位 X 射线衍射( In-situ XRD) 以及原位漫反射红外傅里叶变换光谱( In- situ DRIFTS) 技术,探究碱金属 Na 对铁基催化剂结构及 CO2 加氢直接合成烯烃活性的影响。 研究发现:在 Fe-Zn 催化剂 CO 还原过程与 CO2 加氢反应过程中,碱金属 Na 的引入导致 Fe3 O4 含量降低,Fe5 C2 含量提高,表明碱金属 Na 有利于 Fe5 C2 生成, 同时 XPS 结果表明 Na 与 Fe5 C2 之间存在电子转移, 导致Fe5 C2 电子云密度增大,不利于烯烃二次加氢反应, 提高了烯烃与烷烃的比例; 此外 Na 可以调节表面CH x ∗ 物种比例,随着 Na 含量的提高,表面 CH∗ 与 CH2 ∗ 之间的比例增大,导致表面 CH∗ 物种的相对增加,有利于提高 C-C 耦合能力;Na 的引入可以提高 Fe-Zn 催化剂催化 CO2 加氢合成烯烃的性能,在温度 593 K 和反应压力 1. 5 MPa 时,CO2 转化率可达到 35% ,碳氢化合物中烯烃选择性高达 65% ,烯烷比大于6,且 CO 选择性较低为 18% 。
Abstract:
Formation of olefins directly from CO2 hydrogenation is one of the effective and valuable routs for utilization. Formation of high value-added products directly from CO2 -H2 mixtures may occur via a combination of reverse water-gas-shift ( RWGS) reaction and Fisher-Tropsch ( FT) synthesis over Fe based catalysts. This route produces by-products, which leads to a complex reaction system and low olefins selectivity. In this stu- dy, a series of Fe-Zn catalysts with Na were synthesized to get a deep insight into the effects of Na on the cata- lytic hydrogenation of CO2 and the structures of Fe-Zn catalyst at working state, by steady-state rate measure- ments, In-situ X-ray diffraction ( In-situ XRD), In-situ X-ray photoelectron spectroscopy ( In-situ XPS), In- situ diffuse reflectance infrared Fourier transform spectroscopy ( In-situ DRIFTS). Decorating with Na facilita- ted the formation of Fe5 C2 . Electron transfer occured between Na and Fe5 C2 , resulting in the increase of elec- tron density of Fe sites, which was not conducive to the secondary hydrogenation of olefin and improved the ra- tio of olefin to alkane. Decorating with Na facilitated C-C coupling by regulating the proportion of surface CH∗ species. The results showed that the Na exhibited the best catalytic performance for CO2 hydrogenation to ole- fins at 593 K and 1. 5 MPa. the selectivity of olefins in hydrocarbons was as high as 65%, the O / P ratio was up to 6, and the CO selectivity was below 18%.
更新日期/Last Update: 2022-07-03