Sol–gel auto-combustion synthesis of Ni–CexZr1−xO2 catalysts for carbon dioxide reforming of methane
Sol–gel auto-combustion synthesis of Ni–CexZr1−xO2 catalysts for carbon dioxide reforming of methane
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DOI：
10.1039/c3ra42522c
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发表时间：
2013-10
期刊：
影响因子：
3.9
通讯作者：
K. Tao;Shenghu Zhou;Qiuju Zhang;Chunlong Kong;Qingxiang Ma;N. Tsubaki;Liang Chen
中科院分区：
文献类型：
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作者：
K. Tao;Shenghu Zhou;Qiuju Zhang;Chunlong Kong;Qingxiang Ma;N. Tsubaki;Liang Chen
对溶胶-凝胶自燃烧法和传统共沉淀法制备的Ni-Ce0.8Zr0.2O2催化剂上甲烷二氧化碳重整（甲烷干重整）进行了对比研究。我们表明溶胶-凝胶自燃烧对于制备热稳定的均相混合金属氧化物催化剂非常有前景。自燃合成催化剂由于其较小的Ni晶粒尺寸以及Ni和Ce0.8Zr0.2O2之间的密切相互作用而表现出较高的初始活性和稳定性。相比之下，共沉淀催化剂表现出较差的活性并迅速失活。快速失活是由于在具有较大镍晶体尺寸的共沉淀催化剂上沉积的碳具有较高的石墨化程度造成的。我们还发现溶胶-凝胶自燃烧合成催化剂的物理化学性质和催化活性与金属硝酸盐（MN）/柠檬酸（CA）比率密切相关。高MN/CA比导致更剧烈的燃烧行为以及相应的合成催化剂更高的结晶度。相反，较低的 MN/CA 比会导致更多的碳物质残留和较差的催化性能。 Ce/Zr比也对Ni-Ce0.8Zr0.2O2催化剂的相结构、还原性、氧空位和催化性能产生深远的影响。立方相的Ni–Ce0.8Zr0.2O2催化剂由于高还原性、高Ni分散度和强Ni-CexZr1−xO2相互作用以及大量的氧空位而表现出最好的催化性能。
Carbon dioxide reforming of methane (methane dry reforming) over Ni–Ce0.8Zr0.2O2 catalysts prepared by a sol–gel auto-combustion method and a conventional co-precipitation method were comparatively studied. We show that sol–gel auto-combustion is very promising for preparing thermal stable homogeneous mixed metal oxide catalysts. The auto-combustion synthesized catalyst exhibited higher initial activity and stability due to its smaller Ni crystalline size and intimate interaction between Ni and Ce0.8Zr0.2O2. In contrast, the co-precipitated catalyst showed poor activity and deactivated rapidly. The rapid deactivation was caused by a higher graphitization degree of the deposited carbon over co-precipitated catalyst with larger Ni crystalline size. We also found that the physico-chemical properties and catalytic activity of sol–gel auto-combustion synthesized catalysts were closely related to the metal nitrate (MN)/citric acid (CA) ratio. High MN/CA ratio led to more violent combustion behaviour and an accordingly higher degree of crystallization of the synthesized catalyst. In contrast, a low MN/CA ratio resulted in more carbon species residues and poor catalytic performance. The Ce/Zr ratio also had a profound influence on the phase structure, reducibility, oxygen vacancies and catalytic performance of Ni–Ce0.8Zr0.2O2 catalysts. Ni–Ce0.8Zr0.2O2 catalyst with cubic phase exhibited the best catalytic performance because of high reducibility, high Ni dispersion and strong Ni-CexZr1−xO2 interaction, and considerable amounts of oxygen vacancies.