The Effect of Gamma-Al2O3 Support on the NO Adsorption on Pd4 Cluster

Journal of the Brazilian Chemical Society

Almeida, Wagner B. de¹  Carneiro, José W. M.¹  Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil¹  Carauta, Alexandre N. M.¹  Ferreira, Glaucio B.¹  Prates, Letícia M.¹  Universidade Federal Fluminense, Niterói, Brazil¹  Centro de Tecnologia Mineral, Rio de Janeiro, Brazil¹  Cruz, Maurício T. M.¹  Correia, Julio C. G.¹  Fundação Técnico-Educacional Souza Marques, Rio de Janeiro, Brazil¹ 

关键词:  Pd clusters;    DFT;    supported-Pd clusters;    alumina;    NO adsorption;    back-donation;   

DOI  :  10.5935/0103-5053.20160096

学科分类：化学（综合）

来源: SciELO

【 摘 要 】

The effect of γ-Al2O3 support on the NO adsorption on Pd4 clusters was investigated by means of density functional theory (DFT) calculations. Pd4 adsorbed on γ-Al2O3 (represented by a Al14O24H6 cluster) changes its preferential geometry from tetrahedral to a distorted planar structure. The alumina support promotes a higher dispersion in the palladium catalyst and reduces the NO adsorption energy to -25.6 kcal mol-1 (computed at B3LYP/LANL2DZ/6-311+G(d)), in close agreement with the experimental value of -27.2 kcal mol-1. On the bare planar Pd4 cluster the NO molecule adsorbs in a bridge arrangement, with adsorption energy of -41.2 kcal mol-1. Adsorption on the tetrahedral Pd4 cluster occur preferentially in an atop mode, with adsorption energy of -30.6 kcal mol-1. Charge density analysis show that the electron flux between the NO molecule and Pd4 depends on the adsorption form, with back-donation being stronger in the bridge adsorption mode.

【 授权许可】

Unknown