Regeneration of commercial SCR catalysts by washing and sulphation: effect of sulphate groups on the activity

The use of bio-fuels is becoming more important because of the environmental benefits associated with these fuels. Deactivation of SCR catalysts applied in bio-fuel plants is a major problem due to the high potassium content of bio-fuels and therefore, great potential lies in finding regeneration processes that can be used commercially. Exposing the catalyst surface to sulphate groups generated by SO2 or H2SO4 is a promising way to rejuvenate the initial activity of the catalyst. The chemical stability of the sulphate groups was investigated by the interaction of the SCR reactant gases with the sulphate-promoted catalysts. Sulphate ions deposited on the surface of the TiO2/V2O5/WO3 were thermally stable at 420 degreesC. The introduced sulphate groups were chemically unstable when the catalyst was treated with the SCR reactants at 400 degreesC, but were chemically stable when the catalyst was exposed for the SCR reactants at 350 degreesC. Sulphation after water treatment provided more chemically stable surface sulphate groups at 400 degreesC. The presence of sulphate groups enhanced the number and the strength of the surface acid sites. The amount of ammonia bound to the Bronsted acid sites decreased with the potassium content of the catalyst while the amount of ammonia adsorbed on the Lewis acid sites was almost unaffected. Since potassium both retarded the redox potential of the surface vanadia species and decreased the amount of ammonia bound to the Bronsted acid sites, it is important to wash the strongly deactivated catalyst before sulphation. (C) 2001 Elsevier Science B.V. All rights reserved. (Less)

[1]  I. Nam,et al.  Characteristics of V2O5 supported on sulfated TiO2 for selective catalytic reduction of NO by NH3 , 2000 .

[2]  H. Stenger,et al.  Oxidation of sulfur dioxide over supported vanadia catalysts: molecular structure – reactivity relationships and reaction kinetics , 1999 .

[3]  O. Saur,et al.  Acidic properties and stability of sulfate-promoted metal oxides , 1992 .

[4]  E. Tronconi,et al.  Theoretical and experimental study of the interaction between NOx reduction and SO2 oxidation over DeNOx-SCR catalysts , 1996 .

[5]  R. Mcfarlane,et al.  An infrared study of sulfated silica , 1987 .

[6]  TakahashiKazumasa,et al.  IMPROVEMENT OF V2O5–TiO2 CATALYST FOR NOx REDUCTION WITH NH3 IN FLUE GASES , 1981 .

[7]  J. Dumesic,et al.  Vanadia/Titania Catalysts for Selective Catalytic Reduction (SCR) of Nitric-Oxide by Ammonia: I. Combined Temperature-Programmed in-Situ FTIR and On-line Mass-Spectroscopy Studies , 1995 .

[8]  C. Odenbrand,et al.  Regeneration of commercial TiO2-V2O5-WO3 SCR catalysts used in bio fuel plants , 2001 .

[9]  G. Centi,et al.  Surface characterization of a grafted vanadium–titanium dioxide catalyst , 1985 .

[10]  E. Tronconi,et al.  A complete model of SCR monolith reactors for the analysis of interacting NOx reduction and SO2 oxidation reactions , 1994 .

[11]  Alexis T. Bell,et al.  The effects of structure on the catalytic activity and selectivity of V2O5/TiO2 for the reduction of NO by NH3 , 1992 .

[12]  James A. Dumesic,et al.  Vanadia-Titania Catalysts for Selective Catalytic Reduction of Nitric-Oxide by Ammonia , 1995 .

[13]  Hiroyuki Kamata,et al.  The role of K2O in the selective reduction of NO with NH3 over a V2O5(WO3)/TiO2 commercial selective catalytic reduction catalyst , 1999 .

[14]  C. Odenbrand,et al.  Deactivating effects of lead on the selective catalytic reduction of nitric oxide with ammonia over a V2O5/WO3/TiO2 catalyst for waste incineration applications , 1998 .

[15]  R. T. Yang,et al.  Selective Catalytic Reduction of NO with NH3 on SO−24/TiO2 Superacid Catalyst , 1993 .

[16]  Jyh-Ping Chen,et al.  Role of WO3 in mixed V2O5-WO3/TiO2catalysts for selective catalytic reduction of nitric oxide with ammonia , 1992 .

[17]  Young Gul Kim,et al.  Characteristics of Mordenite-Type Zeolite Catalysts Deactivated by SO2for the Reduction of NO with Hydrocarbons , 1998 .

[18]  G. Busca.  FT-IR study of the surface chemistry of anatase-supported vanadium oxide monolayer catalysts , 1986 .

[19]  Harvey G. Stenger,et al.  Oxidation of sulfur dioxide to sulfur trioxide over supported vanadia catalysts , 1998 .

[20]  Jyh-Ping Chen.  Mechanism of poisoning of the V2O5/TiO2 catalyst for the reduction of NO by NH3 , 1990 .

[21]  P. Forzatti,et al.  Chemical, structural and mechanistic aspects on NOx SCR over commercial and model oxide catalysts , 1998 .

[22]  E. Tronconi,et al.  Oxidation of sulfur dioxide to sulfur trioxide over honeycomb DeNoxing catalysts , 1993 .

[23]  T. Jin,et al.  Mechanism of acidity generation on sulfur-promoted metal oxides , 1986 .

[24]  H. Stenger,et al.  Oxidation of SO2over Supported Metal Oxide Catalysts , 1999 .

[25]  R. C. King,et al.  Handbook of X Ray Photoelectron Spectroscopy: A Reference Book of Standard Spectra for Identification and Interpretation of Xps Data , 1995 .

[26]  G. Busca,et al.  FT-IR characterization of the surface acidity of different titanium dioxide anatase preparations , 1985 .

[27]  C. Tripp,et al.  The structure and stability of sulfated alumina and titania , 1986 .

[28]  H. Knözinger,et al.  Acidity of WOx/TiO2 Catalysts for Selective Catalytic Reduction (SCR) , 1993 .

[29]  A. Faessler,et al.  Oxygen K-spectra and electronic structure of the oxyanions SO32−, SeO32−, TeO32− and SO42−, SeO42−, TeO42− , 1980 .

[30]  P. Ciambelli,et al.  The influence of sulphate on the catalytic properties of V2O5-TiO2 and WO3-TiO2 in the reduction of nitric oxide with ammonia , 1996 .

[31]  James A. Dumesic,et al.  Kinetics of Selective Catalytic Reduction of Nitric Oxide by Ammonia over Vanadia/Titania , 1996 .

[32]  N. Topsoe.  Characterization of the nature of surface sites on vanadia-titania catalysts by FTIR , 1991 .

[33]  Pio Forzatti,et al.  Selective reduction of nitrogen oxides (NOx) by ammonia over honeycomb selective catalytic reduction catalysts , 1993 .

[34]  K. Tanabe.  New Solid Acids and Bases: Their Catalytic Properties , 1990 .

[35]  E. Tronconi,et al.  Dynamic Investigation of the Role of the Surface Sulfates in NOx Reduction and SO2 Oxidation over V2O5−WO3/TiO2 Catalysts , 1998 .

[36]  G. Deo,et al.  Reactivity of supported vanadium oxide catalysts: The partial oxidation of methanol , 1994 .

[37]  M. Ziolek,et al.  Influence of sulfur dioxide adsorption on the surface properties of metal oxides , 1996 .

[38]  Satoru Kurita,et al.  The effect of the vanadium component on the life of the WO3-TiO2 catalyst used for the reduction of NOx with NH3. , 1982 .