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Selective catalytic reduction of nitric oxide with ammonia: A theoretical ab initio study
Author(s) -
Zhanpeisov Nurbosyn U.,
Higashimoto Shinya,
Anpo Masakazu
Publication year - 2001
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.1423
Subject(s) - chemistry , ab initio , catalysis , dissociation (chemistry) , ammonia , inorganic chemistry , adsorption , octahedron , ammonium , selective catalytic reduction , brønsted–lowry acid–base theory , ab initio quantum chemistry methods , ion , organic chemistry , molecule
Ab initio quantum chemical studies at the HF/Lanl2dz level were carried out to investigate the interaction of ammonia, NO, and a mixture of the two with vanadia/titania. It was found that the replacement of Ti 6c by V 6c is the only feasible way to form highly dispersed vanadia over the titania. The VO species thus formed will be in octahedral symmetry with the axial distortions, and no tetrahedrally coordinated V species can be formed. Ammonia fully covers the catalyst surface either through the associative interaction with the Lewis acid site of Ti 5c or the dissociative adsorption channels. The dissociation of ammonia on the O site bridging the Ti 6c and V 6c octahedra and on the VO group can proceed with the highest gain in energy. The formation of an adsorbed ammonium ion was found to be an energetically highly unfavorable process. The VO group is no longer expected to play a major role in the stabilization of the surface ammonium ion. NO can be activated on the Ti 5c site of the catalyst containing predissociated ammonia on the bridging O site and VO group. It can be expected that the SCR reaction products are formed through the reactions of both adsorbed NO and NH 2 or the desorbed NH 2 group with NO in the gas phase. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001