Pore structure analysis of an SCR catalyst using a new method for interpreting nitrogen sorption hysteresis

Nitrogen sorption hysteresis of a selective catalytic reduction (SCR) catalyst in its "fresh" and "used" form. [Catal. Today 56 (2000) 335] was analysed by employing the Corrugated Pore Structure Model (CPSM-nitrogen) reported elsewhere [Ind. Eng, Chem. Res. 39 (2000) 3747 and Ind. Eng. Chem. Res., 39 (2000) 3764]. The BET surface area and intrinsic pore volume, and surface area distributions were deduced via the CPSM fitting over the relevant hysteresis loop and compared to those obtained by applying various conventional methods. CPSM predictions of the total specific pore surface area, are in perfect agreement with BET estimates, while those calculated by the Roberts method, irrespective of the hysteresis loop branch chosen, deviate substantially. CPSM prediction of tortuosity factors (CPSM-tortuosity [Ind. Eng. Chem. Res., in press]) for the catalysts under consideration were found to be: tau (CpSM,fresh) = 4.6 and 4.5. These values are typical of porous catalysts and approach those determined experimentally (i.e, tau = 5-6 [Appl. Catal. 10 (1996) 2991). The pore volume distribution of the latter catalyst obtained from mercury porosimetry measurements approaches that deduced by the CPSM method. (C) 2001 Elsevier Science B,V. All rights reserved.