The role of different active sites on Ni/CeO₂ catalysts in the CO₂ methanation has been studied. Two types of active sites have been identified: CO₂ chemisorption and dissociation sites at the NiO-ceria interface and H₂ dissociation sites on Ni⁰ entities. Additionally, the proportion of these active sites has been optimized to maximize the activity. For these purposes, Ni/CeO₂ catalysts with different proportion of active sites were prepared varying the Ni-incorporation method and controlling the structure of the ceria support in order to modify the NiO-ceria interaction. According to XPS, the optimal proportion of both sites required to achieve the maximum conversion was 25% Ni⁰ and 75% NiO-ceria for H₂ and CO₂ dissociation, respectively. In situ DRIFTS and Isotopic experiments with ¹³C¹⁸O₂ showed that this optimal catalyst keeps the catalyst surface clean of carbon intermediates under reaction conditions, while surface bicarbonates are accumulated on a catalyst with an excess of active sites for CO₂ chemisorption/dissociation.

研究了Ni / CeO ₂催化剂上不同活性位在CO ₂甲烷化中的作用。已经确定了两种类型的活性位点：NiO-二氧化铈界面处的CO ₂化学吸附和解离位点以及Ni ⁰实体上的H ₂离解位点。另外，这些活性部位的比例已被优化以最大化活性。为了这些目的，通过改变Ni掺入方法和控制二氧化铈载体的结构来制备具有不同活性部位比例的Ni / CeO ₂催化剂，以改变NiO-二氧化铈的相互作用。根据XPS，实现最大转化率所需的两个位点的最佳比例为25％NiH ₂和CO ₂离解的NiO-二氧化铈分别为⁰和75％。用¹³ C ¹⁸ O ₂进行的原位DRIFTS和同位素实验表明，这种最佳催化剂在反应条件下保持催化剂表面上的碳中间体清洁，而表面碳酸氢盐则堆积在具有过量活性位点的催化剂上，以进行CO ₂化学吸附/解离。