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采用密度泛函理论方法研究了Au10团簇催化CO氧化反应的详细机理。对CO、O_2、O、CO_24种主要吸附物及CO+O_2、CO_2+O、CO+O和CO+O+O4种共吸附物的吸附行为进行计算,得到最佳活性吸附位。模拟反应分别按照Langmuir-Hinshelwood(LH)机理和Eley-Rideal(ER)机理进行,其中LH机理包括L1、L2两条路径,ER机理包括E1、E2两条路径。通过比较各路径活化能得到:CO+O_2→CO_2+O反应按照LH机理进行的可能性较大,并且相比较L1、L2两条路径,由于反应按照L1路径进行时只需克服33.9和56.4kJ·mol-1的能垒,所以反应更易按照L1路径进行,最佳反应路径为O_2(gas)+CO(gas)→O_2(ads)+CO(gas)→O_2(ads)+CO(ads)→OCOO(ads)→O(ads)+CO_2(ads);CO+O→CO_2反应分别克服6.9和4.3kJ·mol-1能垒,放热352.1kJ·mol-1,说明低温下吸附态的O原子很容易与CO反应生成第2个CO_2分子。
The detailed mechanism of the catalytic CO oxidation of Au10 clusters was studied using density functional theory. The adsorption behavior of 24 main adsorbents CO, O 2, O, CO_ 2 and CO 2 O, CO 2 O, CO + O and CO + O + O were calculated and the optimum adsorption sites were obtained. The simulated reactions were performed according to the Langmuir-Hinshelwood (LH) mechanism and the Eley-Rideal (ER) mechanism, respectively. The LH mechanism includes two paths L1 and L2, and the ER mechanism includes two paths E1 and E2. By comparing the activation energies of different pathways, we found that the reaction of CO + O_2 → CO_2 + O is more likely to be carried out in accordance with the LH mechanism. Compared with L1 and L2 paths, the reaction only needs to overcome 33.9 and 56.4kJ · Mol -1, so the reaction is easier to follow the path of L1. The optimal reaction path is O_2 (gas) + CO (gas) → O_2 (ads) + CO (gas) → O_2 (ads) → OCOO (ads) → O (ads) + CO 2 (ads); CO + O → CO 2 reaction respectively overcomes the energy barrier of 6.9 and 4.3 kJ · mol -1 and exotherms 352.1 kJ · mol -1, O atoms easily react with CO to form the second CO 2 molecule.