Development of mixed oxide catalyst for carbon dioxide hydrogenation to methanol.

本研究的目标是开发二氧化碳加氢制甲醇的混合金属氧化物催化剂。在上述工作的基础上，我们筛选了稳定甲酸盐物种的掺杂催化剂，发现Co-ZrO2二元催化剂对CO_2以碳酸盐形式吸附及其加氢生成吸附的甲酸盐物种具有很高的亲和力。甲酸盐物种被吸附在Co-Zr界面上，但即使在高Co负载量下，甲酸盐加氢制甲醇的效率也不高，甲醇选择性仍高达30%。为了解决这一问题，我们通过掺杂In和Co制备了双原子催化剂。催化剂的表征结果表明，In和Co都是原子分散的。随着甲醇产率的提高，In-Co-ZrO2催化剂的甲醇选择性提高到65%。机理研究表明，Co-Zr界面位促进了甲酸盐的稳定，In促进了甲酸盐加氢制甲醇的氢解离。Co和In之间的协同作用加速了甲醇的生成。动力学分析表明，In-TiO2二元催化剂对氢气的反应级数由二元催化剂的0.9降至三元催化剂的0.3，说明三元催化剂上的氢气活化得到了促进。在催化剂筛选过程中，In-TiO2二元催化剂在低温高压下表现出了良好的逆水煤气变换反应活性。这些结果被总结并发表在ChemCatChem杂志上。

The goal of this research is to develop mixed metal oxide catalyst for hydrogenation of carbon dioxide to methanol. Based on the proposal work we screened doped catalyst for stabilization of formate species and found that Co-ZrO2 binary catalyst shows high affinity for adsorption of CO2 as carbonate and its hydrogenation to adsorbed formate species. The formate species were adsorbed over the Co-Zr interface, however hydrogenation of formate to methanol was not efficient and methanol selectivity was 30 % even at high Co loading. Dual atom catalyst was prepared by doping In and Co in ZrO2 to overcome this issue. Characterization of catalyst revealed that both In and Co were atomically dispersed. Methanol selectivity increased to 65% over In-Co-ZrO2 catalyst along with increase in methanol yield. Mechanistic investigation showed that Co-Zr interfacial site facilitated the stabilization of formate and In was responsible for hydrogen dissociation for hydrogenation of formate to methanol. Methanol formation was accelerated due to the synergy between Co and In sites. Kinetic analysis showed that the order of reaction with respect to hydrogen reduced from 0.9 for binary catalyst to 0.3 for ternary catalyst indicating that hydrogen activation was promoted over the ternary catalyst.During screening of catalyst, In-TiO2 binary catalyst showed superior activity for reverse water gas shift reaction at low temperature and high pressure. These results were summarized and published in ChemCatChem journal.