Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (10): 2123-2129.doi: 10.3866/PKU.WHXB20091040

• ARTICLE • Previous Articles     Next Articles

Acidities of Cu-[M’]MORand Ag-[M’]MOR (M’=B, Al, Ga, Fe)

LIU Jie-Xiang, WEI Xian, ZHANG Xiao-Guang, HAN En-Shan   

  1. School of Chemical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China|College of Chemistry, Nankai University, Tianjin 300071, P. R. China
  • Received:2009-04-13 Revised:2009-07-03 Published:2009-09-29
  • Contact: LIU Jie-Xiang, ZHANG Xiao-Guang E-mail:jxliu@hebut.edu.cn; xgzhang@nankai.edu.cn

Abstract:

NH3 adsorption in Mordenties H-[M']MOR, Cu-[M']MOR, and Ag-[M']MOR (M'=B, Al, Ga, Fe) was investigated using density functional theory (DFT) with the generalized gradient approximation (GGA) and the Becke exchange plus Lee-Yang-Parr correlation (BLYP) method as well as the DND basis set in the Dmol3 module. Equilibrium configurations and adsorption energies of NH3 in H-[M']MOR, Cu-[M']MOR, and Ag'[M']MOR were obtained and discussed. NH3 was adsorbed in H-[M']MOR by the interaction between the lone electron pair of nitrogen and the proton acidic site. NH3 was adsorbed in H-[Al]MOR, H-[Ga]MOR, and H-[Fe]MOR by chemical adsorption and in H-[B]MOR by physical adsorption which agreed well with results from the literature. NH3 was adsorbed in Cu-[M']MOR (or Ag-[M']MOR) through the chemical adsorption between the lone electron pair of nitrogen and the s empty orbital of the Cu+ (or Ag+) cation. Calculated adsorption energies showed that the acidities of H-[A1]MOR, Cu-[A1]MOR and Ag-[A1]MOR were the strongest among all the H-[M']MOR, Cu-[M']MOR and Ag-[M']MOR, respectively. The acidity decreased as follows: Cu-[M']MOR>Ag-[M']MOR>H-[M']MOR for the same atom substitution. In addition, Mulliken populations of counterpoise ions (H+, Cu+, and Ag+) and the NH3 molecule were also investigated and analyzed before and after adsorption.

Key words: Mordenite, Heteroatom, Counterpoise ion, Acidity, Density functional theory

MSC2000: 

  • O641