Abstract Titania-supported nickel catalysts (3, 6, 12 and 20 wt% Ni/TiO2) were prepared by a sol–gel method. The results showed that the CO2 conversion increased with increasing Ni content and 20 wt% Ni/TiO2 exhibited the highest CO2 conversion and CH4 yield. The results on XRD and EXAFS revealed unit cell expansion and lattice distortion, which indicated that Ni2+ was incorporated into the TiO2 lattice. Upon increasing the Ni content, the NiO phase was observed. The oxidation states of nickel and titanium were analyzed to be +2 and +4, respectively for fresh catalysts. After pretreatment by H2, Ni2+ was converted to Ni0 and this electronic state remained unchanged during the course of methanation while Ti4+ was kept unaltered for fresh catalysts and those during the reaction. The addition of Ni led to the formation of oxygen vacancy and NiO phase which might act as adsorption sites for CO2 and H2, respectively.

中文翻译：

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二氧化钛负载镍对二氧化碳甲烷化的催化活性

摘要 通过溶胶-凝胶法制备了二氧化钛负载的镍催化剂（3、6、12 和 20 wt% Ni/TiO2）。结果表明，CO2 转化率随着 Ni 含量的增加而增加，20 wt% Ni/TiO2 表现出最高的 CO2 转化率和 CH4 产率。XRD 和 EXAFS 的结果揭示了晶胞膨胀和晶格畸变，这表明 Ni2+ 已结合到 TiO2 晶格中。随着Ni含量的增加，观察到NiO相。对于新鲜催化剂，镍和钛的氧化态分别分析为 +2 和 +4。用H2预处理后，Ni2+转化为Ni0，这种电子态在甲烷化过程中保持不变，而Ti4+在新鲜催化剂和反应过程中保持不变。