New TiO2 monolithic supports based on the improvement of the porosity

Titania monolithic supports produced with an additional macroporosity were prepared and their behaviour compared with commercial materials of the same composition. Activated carbon used as a template for macropore generation, was included in the preparation process of the ceramic dough. Mercury intrusion porosimetry (MIP), nitrogen adsorption-desorption, X-ray diffraction (XRD), TGA-DSC analyses were employed to study the modifications of the support properties. The systems prepared with the template, which was subsequently eliminated by thermal treatment, presented a notable increase in the macropore volume with respect to samples prepared without this pore generating agent (PGA), displaying a narrow pore size distribution with a mean pore diameter of 0.13 μm. The template was chemically inert and no modification on the crystal phases or the BET area was observed. The optimum composition was achieved for a sample produced with 10 wt.% of template and subsequently heat-treated in air at 550 °C to remove the PGA. Vanadia catalysts based on these supports displayed higher NOx conversions during the NO and NOx elimination by the SCR process at low temperature than the standard ones. This behaviour was related to the improvement in the effectiveness factor due to the reduction of the internal mass transfer limitations.