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) catal yst in its "fresh" and "used" form. [Catal. Today 56 (2000) 335] was analys ed by employing the Corrugated Pore Structure Model (CPSM-nitrogen) reporte d 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 surfac e area distributions were deduced via the CPSM fitting over the relevant hy steresis loop and compared to those obtained by applying various convention al methods. CPSM predictions of the total specific pore surface area, are i n perfect agreement with BET estimates, while those calculated by the Rober ts method, irrespective of the hysteresis loop branch chosen, deviate subst antially. 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 cat alysts 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.