Reactivity of V{sub 2}O{sub 5} catalysts for the selective catalytic reduction of NO by NH{sub 3}: Influence of vanadia loading, H{sub 2}O, and SO{sub 2}

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1996.0182· OSTI ID:471621

Amiridis, M D ^[1]; Wachs, I E; Deo, G ^[2]

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1. W.R. Grace & Co.-Conn, Columbia, MD (United States)
2. Lehigh Univ., Bethlehem, PA (United States); and others

A systematic investigation of the selective catalytic reduction (SCR) of NO by NH{sub 3} over V{sub 2}O{sub 5}/TiO{sub 2} catalysts of variable vanadia loading has been carried out at 623 K. Kinetic studies were conducted both in the presence and in the absence of H{sub 2}O and SO{sub 2}. The structure of the various catalysts, as well as adsorbed species present on their surface, was characterized by in situ Raman and infrared spectroscopies. Under dry and SO{sub 2}-free conditions, the turnover frequency of the SCR reaction was found to go through a maximum with vanadia surface coverage at approximately half a monolayer. The observed decrease in the SCR turnover frequency at vanadia surface coverages exceeding half a monolayer can be attributed to the loss of strong acid sites which are associated with the TiO{sub 2} support. Addition of H{sub 2}O to the reacting gas mixture results in a decrease in the SCR turnover frequency of approximately 40-50%, which is independent of the vanadia surface coverage. In situ Raman results suggest that such a decrease can be attributed to the competitive adsorption of H{sub 2}O on the active vanadia sites. The presence of SO{sub 2} in the gas phase during the SCR reaction results in a significant increase of the turnover frequency at low vanadia surface coverages, while is has no effect at vanadia surface coverages above half a monolayer. Raman and infrared results suggest that the effect of SO{sub 2} can be attributed to the formation of surface sulfate species, which are only present on the titania surface below half a monolayer coverage due to repulsive interactions between the surface vanadia and sulfate species. 32 refs., 5 figs., 2 tabs.

• OSTI ID: 471621
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 161; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
33 ADVANCED PROPULSION SYSTEMS
40 CHEMISTRY
ABSORPTION SPECTROSCOPY
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
HETEROGENEOUS CATALYSIS
NITRIC OXIDE
RAMAN SPECTROSCOPY
SELECTIVE CATALYTIC REDUCTION
VANADIUM OXIDES