高效抗积炭钙钛矿负载Ni催化剂用于甲烷重整制氢

发布时间：2018-06-06 13:50

本文选题：钙钛矿载体 + 甲烷重整制氢　；参考：《南昌大学》2017年硕士论文

【摘要】：甲烷重整反应可充分利用天然气资源,缓解温室效应,同时能产生高效、洁净的二次能源氢气,因而受到世界各国研究学者的广泛关注。镍基催化剂活性相对较高,且价格低廉、资源丰富,是理想的甲烷重整催化剂。但是镍基催化剂存在活性组分容易烧结聚集,高温反应条件下积炭严重等缺点,导致催化剂中毒失活。镍基催化剂需要解决的核心问题是,如何提高Ni~0活性组分的分散度以及如何阻止Ni晶粒在高温重整反应中聚集。本文从理解甲烷重整制氢机理入手,深入研究了Ni活性组分与载体的相互作用、催化剂结构、以及如何有效控制Ni晶粒尺寸等方面出发,设计合成了几种高效抗积炭重整催化剂。1、采用甘氨酸燃烧法(GNC)、溶胶凝胶法(SG)、共沉淀法(CP)设计合成了三种La FeO_3载体;负载Ni活性组分后结合DBD等离子体技术处理得到催化剂用于甲烷水蒸气重整反应。研究结果表明,GNC和SG法比CP法制备的催化剂表现出更好的催化活性。虽然使用CP法制备的催化剂载体比表面积最大,但是负载Ni后催化剂活性最差且最不稳定;使用SG法制备催化剂载体比表面积最小,综合催化活性和催化稳定性两者因素,其催化性能最佳。经过DBD等离子处理后,H2-TPR结果表明,催化剂活性中心Ni与LaFeO_3载体相互作用增强,从而使活性金属Ni~0在载体表面的分散度增强。SEM和TGA-DSC结果证实,使用等离子处理能有效抑制Ni/LaFeO_3-CP-P催化剂表面积炭生成。2、研究了LaNiO_3@SiO_2核壳型催化剂用于甲烷干气重整反应。以水热法制备立方形貌的LaNiO_3,使用正硅酸四乙酯TEOS为硅源,CTAB阳离子表面活性剂作模板剂,制备了一系列不同壳层厚度的核壳型催化剂用于甲烷干气重整反应。研究结果表明,采用SiO_2壳层包裹的核壳La NiO_3催化剂,表现良好的催化剂活性和优越的抗积炭性能。这归因于SiO_2壳层的保护作用,有效控制了金属Ni的纳米颗粒尺寸防止其在高温下烧结和聚集,并且使积炭缺少物理生长空间,这可能是提高催化剂活性和抗积炭性能的本质原因。
[Abstract]:Methane reforming can make full use of natural gas resources, alleviate Greenhouse Effect and produce high efficiency and clean secondary energy hydrogen, so it has been paid more and more attention by researchers all over the world. Nickel based catalyst is an ideal catalyst for methane reforming because of its relatively high activity, low price and abundant resources. However, nickel based catalysts have some disadvantages such as easy sintering and aggregation of active components and serious deposition of carbon under high temperature reaction conditions, which lead to deactivation of catalyst poisoning. The key problems to be solved for nickel based catalysts are how to improve the dispersion of active components of Ni~0 and how to prevent Ni grains from aggregating in high temperature reforming reaction. Based on understanding the mechanism of methane reforming hydrogen production, the interaction of Ni active component with support, the structure of catalyst and how to effectively control the grain size of Ni were studied. Three kinds of La FeO_3 carriers were designed and synthesized by using glycine combustion method, sol-gel method and co-precipitation method. After supported Ni active component was treated by DBD plasma technique, the catalyst was used for methane steam reforming. The results showed that the catalyst prepared by GNC and SG showed better catalytic activity than that prepared by CP method. Although the specific surface area of the catalyst prepared by CP method was the largest, the catalyst activity was the worst and the most unstable after Ni loading, and the catalyst support prepared by SG method had the smallest specific surface area, which combined the catalytic activity and catalytic stability factors. Its catalytic performance is the best. After DBD plasma treatment, the results of H2-TPR show that the interaction between Ni, the active center of the catalyst, and the support of LaFeO_3 is enhanced, thus the dispersion of the active metal Ni~0 on the surface of the support is enhanced. Plasma treatment can effectively inhibit the formation of carbon deposition on the surface of Ni/LaFeO_3-CP-P catalyst. The LaNiO_3@SiO_2 core-shell catalyst was used in dry gas reforming of methane. A series of core-shell catalysts with different shell thickness were prepared by hydrothermal method for methane dry gas reforming using tetraethyl orthosilicate (TEOS) as the template of CTAB cationic surfactants. The results show that the core-shell La NiO_3 catalyst coated with SiO_2 has good catalytic activity and excellent resistance to coke deposition. This is attributed to the protective effect of the SiO_2 shell, which effectively controls the size of the metal Ni nanoparticles to prevent them from sintering and aggregating at high temperature, and makes the carbon deposition lack of physical growth space. This may be the essential reason for the improvement of catalyst activity and resistance to carbon deposition.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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