A Density Functional Study On The Self Promoting Reduction Reaction Mechanism Of NO Catalyzed By Au

With the rapid development of economy in China, the speeding up urbanization process, air pollution is getting worse in most metropolises. The fast addition of vehicles, automotive emission is one of the most important reason responsible for the pollution of environment. NO is one of the major component of the emissions although there are several other NOX. It is a hot issue to explore the method which can decompose or degrade NO effectively, and the research of its mechanism where it produce environmental friendly N2 also receives much attention. In order to acquire the microscope information of those reactions, and analyse the inner relationship between its structure and catalytic performance, and reveal the essence of its catalytic activity, this article put quantum chemical calculation to systematiclly research those reactions. Those reactions are Self-promoting reaction of NO, degrading NO dimolecular reaction with metallic catalysis, and adsorpting reaction among the surface of metal catalysis. By the means of theoretical calculation, the optimum reaction path was found, which could be a solid theoretical foundation for the reduction of NO in experiment.(1) The reaction between NO and NO has been studied by using the method of density functional theory(DFT) at the B3LYP/6-311+g(d,p) and the high-level electron-correlation CCSD(T)/6-311+g(d,p) single-point levels. The geometry structure of the stationary point of the reaction potential surface were completely optimized by total parameters. All the transition states are verified by the vibrational frequency analysis and the intrinsic reaction coordinate(IRC) calculations. The results show that Self-promoting reaction of NO are via multi-channel, which is the direct reaction channel, the Cis reaction channel, the Trans reaction channel(rotational polymerization reaction, direct polymerization). They are all endothermic reactions. It is the main reaction channel that NO dimolecular generate trans-dimer through one of the NO molecular rotated, then trans-(NO)2 decomposed into N2 and O2. The crucial reaction step deals with the trans-(NO)2 decomposing to N2O and O free radical, its energy barrier is 146.1 kJ/mol. Obviously the energy barrier is very high, the reaction barely react. We need suitable catalysis.(2) The reaction microscope mechanism of NO dimolecule among triangle Au3 cluster and several other metal analysis has been studied theoretically by using the method of density functional theory(DFT) at the B3LYP. Under the catalytic effect of Au3 cluster, the energy barrier of its Self-promoting reaction is 54.9KJ/mol, but the energy barrier of N2O degradation still up to 185.OKJ/mol. Compared with Pd、Ag、Cu、Pt、 Co metallic analysis, the analytic effect of metal Rh in the reaction of N2O decomposition is unbelievable, the energy barrier is only 20.5 KJ/mol. The research goal (NO self-promotion reduction which produced environmental friendly N2 in the condition of low temperature and room pressure) could be achieved among the Au and Rh double metallic catalytic effect.(3) The reaction mechanism of gaseous phase NO dimolecule among the Au(111) or Au(111) hybrid Rh atom has been studied theoretically by using the method of first principal density functional theory(DFT) at the DMOL3 computational procedure. These possible reaction path and reaction potential surface have been calculated and analysed. N2 are produced in the surface of Au(111) effectively, it can be took the advantage of this analytical reaction path. Two elementary steps are contained in the reaction of produced N2, first, NO dimer deoxidation formed N2O, than N2O deoxidation formed N2 and O atom. N2O*→N2*+O* in the surface of Au(111) is the speed control step in the reaction, the activation energy is 161.1KJ/mol. In order to reduce the activation energy, the reaction where N2O adsorb and decompose in the surface of Au(111)@Rh and produce N2 and O free radical was calculated, which the activation energy in the elementary reaction is only 96.3KJ/mol.