title: DRIFTS study of ammonia activation over CaO and sulfated CaO for NO reduction by NH3.
abstract: CaO catalyzes NH(3) oxidation, while sulfated CaO catalyzes NO reduction by NH(3) in the presence of O(2), and the adsorption and transformation of ammonia over CaO and sulfated CaO has been investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to understand their catalytic mechanism. It has been found that ammonia is first adsorbed over Lewis or Brönsted acid sites, and later undergoes hydrogen abstraction giving rise to either NH(2) amide or NH imide intermediates. The intermediates react with NO or lattice O to produce N(2) or NO. Comparing the DRIFTS of NH(3) adsorption over CaO and sulfated CaO, it is obvious that ammonia adsorbed over CaO is activated mainly in NH form apt to react with surface oxygen to produce NO, while ammonia adsorbed over sulfated CaO is activated mainly in NH(2) form apt to reduce NO. The DRIFTS results agree with experimental data and explain the catalytic mechanisms of CaO and sulfated CaO.
authors.affiliation: Key Laboratory for Thermal Science and Power Engineering of Minister of Education, Department of Thermal Engineering, Tsinghua University, Beijing, 100084, China.
authors.forename: Xinfang
authors.initials: X
authors.lastname: Yang
authors.forename: Bo
authors.initials: B
authors.lastname: Zhao
authors.forename: Yuqun
authors.initials: Y
authors.lastname: Zhuo
authors.forename: Yang
authors.initials: Y
authors.lastname: Gao
authors.forename: Changhe
authors.initials: C
authors.lastname: Chen
authors.forename: Xuchang
authors.initials: X
authors.lastname: Xu
mesh_terms: D000327:Adsorption; D000393:Air Pollutants / Q000737:chemistry*; D000641:Ammonia / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013431:Sulfates / Q000737:chemistry*; D013696:Temperature
chemical_list: D000393:Air Pollutants; D017610:Calcium Compounds; D010087:Oxides; D013431:Sulfates; D009569:Nitric Oxide; D000641:Ammonia; C016538:lime