Multidisciplinary determination of the phase distribution for VOX–ZrO2–SO42−–sepiolite catalysts for NH3-SCR (original) (raw)
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A series of vanadium-based SCR catalysts supported on sulfated or tungstated ZrO2 were synthesized and characterized by means of N2-BET, XRD, NH3-TPD and in situ Raman spectroscopy. The effect of potassium doping on the properties of vanadia species was studied in detail. A number of catalyst preparation parameters were examined, including the choice of precipitant, variation of carrier surface area, potassium poisoning, crystallinity, and ZrO2-phase composition. The results show that the catalyst structure and SCR activity are affected from the synthesis route by the support crystallinity and morphology, the surface composition, and the molecular configuration of the dispersed vanadates. It was observed that poisoning with potassium had a negligible effect on the surface vanadate species (especially the V
Journal of Catalysis, 2004
ZrO2–SO4 powders were prepared through a single step sol–gel reaction by modulating the conditions of the alkoxide hydrolysis and polycondensation steps. Sulfuric acid or (NH4)2SO4 was employed as the sulfating agent. The samples were calcined at 890 K and characterized as to phase composition crystallinity (XRD) and surface area porosity (BET method). Surface functionalities were investigated by TGA/FTIR, FTIR, DRIFTS,
Synthesis of nano-sized ZrO 2 and its use as catalyst support in SCR
Catalysis Communications, 2009
The present paper presents a simple method for the reliable preparation of nano-scaled ZrO 2. In this wet synthesis, a stable Zr sol is produced by using a mixture of Zr(OC 3 H 7) 4 , HNO 3 and H 2 O. Precipitation is firstly achieved when ammoniac conditions are adjusted. Zirconia is formed by annealing the gel-like product at 200°C resulting in agglomerated particles. De-agglomeration is simply achieved by ultrasonic exposure leading to particles of about 60 nm revealing a BET surface area of 150 m 2 /g. The beneficial effect of this nano-sized material as compared to bulk ZrO 2 is shown in SCR using corresponding Fe 2 O 3 /ZrO 2 patterns.