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Vanadium supported on sulfated Ti-pillared clay catalysts (STi-PILCs) issued from different Ti-precursors were investigated for selective catalytic reduction (SCR) of NO by NH3 in the presence of O2. The STi-PILCs supports were prepared by hydrolysis of a series of organic or inorganic Ti-precursors; Ti(OCH3)4, Ti(OC2H5)4, and TiCl4 with H2SO4, and then modified with vanadium introduced by impregnation method. The unpromoted and promoted vanadium pillared clays were characterized using chemical analysis, N2-physisorption, NH3-TPD, H2-TPR, and tested for SCR of NO by NH3. It was found that the textural and acidic properties of the STi-PILC materials are influenced by the nature of the Ti-precursor; and the use of Ti-methoxide allows the synthesis of STi-PILC with the highest acidity. The presence of vanadium on STi-PILC supports reduces their surface areas and porous volumes, creates new redox sites, and enhances the reducibility of the sulfate groups leading to better redox properties of the binary V-STi-PILCs. After vanadium addition, the STi-PILC materials issued from Ti(OCH3)4, exhibited higher NO reduction activity at high temperature. These results underline the importance of the Ti-precursor for the preparation of the STi-PILC support, and the role of vanadium to increase the redox properties of V-STi-PILC catalyst for the SCR of NO by NH3. [ABSTRACT FROM AUTHOR]

Abstract: Vanadium supported on unsulfated and sulfated Ti-pillared clays are developed for the selective catalytic reduction (SCR) of nitrogen oxide (NO) by ammonia. The unsulfated Ti-pillared clays (TiM-PILC) were prepared by hydrolysis of titanium methoxide (Ti(OCH3)4) with HCl. The same procedure was employed using H2SO4 in order to obtain the sulfated Ti-pillared clays (STiM-PILC). All the pillared materials were characterized before and after vanadium addition by chemical analysis, XRD, N2-physisorption, TGA, NH3-TPD, H2-TPR and UV–vis. It was found that the sulfation or the addition of a low amount of vanadium into the TiM-PILC reduces the surface area but improves the acidity of the material. The addition of vanadium to the STiM-PILC decreases the surface area, the number of acid sites and the stability of the sulfate species but enhances the redox properties of the material. The STiM-PILC and the V-TiM-PILC exhibit higher NO removal activity at high temperature than the TiM-PILC. The presence of both sulfate and a low amount of vanadium (2wt.%) in the TiM-PILC leads to an excellent active and selective catalyst for SCR-NO with NH3. [Copyright &y& Elsevier]