红外光谱研究固体氢基质中金属催化降解CO2的反应机理

Laser-ablated transition metal atoms are deposited in low temperature solid hydrogen that is doped with CO2 (mole ratio is H2:CO2=1000:1) to give metal hydrides.Annealing and irradiation with UV-VIS induce metal hydrides reacting with CO2 to give chemical reacton intermediates, which are identified through FTIR spectra,isotopic substitutions, and quantum chemical calculations. At the same time the reaction mechanisms are studied by intrinsic reaction coordinate (IRC) calculations and bonding characters are investigated by natural bond orbital (NBO) analysises. Our project will focus on following three objectives: (1) titanium atoms catalyze CO2 reduction with H2 in solid normal hydrogen; (2) titanium atoms reduce CO2 with H2 in solid parahydrogen; (3) transition metals such as V, Cr, Fe, Mn,et al reduce CO2 with H2 in solid normal and parahysrogen. The results of this study will give new approach to design novel catalyst for hydrogen strorage and CO2 readuction.

激光溅射产生过渡金属原子束,在氢基质条件下与CO2共沉积在低温基片上。利用低温固体氢基质隔离技术结合红外光谱，同位素取代，和量子化学计算，研究过渡金属催化降解CO2反应活性中间体结构及反应性能。同时应用量子化学理论计算对化学反应机理和化学键特征进行深入研究，提出通过H2和CO2反应产生有机化合物的反应机理。具体研究内容包括：（1）研究金属Ti在一般固体氢中降解CO2的反应中间体结构及反应机理研究，（2）在固体仲氢中Ti降解CO2的反应机理研究，（3）在低温固体氢中V, Cr, Co, Fe, Mn等过渡金属降解CO2的反应中间体及反应机理研究。本项目研究结果为设计氢气储存及CO2降解中的新型催化剂提供新思路。

本项目利用低温固体氢基质隔离技术结合红外光谱和量子化学计算，研究了B-N （N = Si, Ge, Sn等），Ce-N及Be-SO2的成键特征，发现了罕见的B-H-Si等三中心两电子缺电子氢桥键，进一步拓展了金属氢桥键的概念。研究了金属（B, Be, Sc，Ti，V，Cr等）在氢基质条件下催化降解CO2反应活性中间体结构及反应性能，提出通过金属氢化物活化CO2的反应机理。首次在氢基质中测定了金属氢化物和CO2生成HM(η2-O2CH)、HM(η2-O2CH) (η2-H2)、Cr(η2-O2CH)2（M = 金属原子）等反应中间体，并对化学成键特征进行了深入探究。