Synthesis and characterization of catalysts produced from paper mill sludge I. Determination of NOx removal capability

Characteristics and catalytic properties of a series of carbon-based cataly sts (CBCs) produced from paper mill sludge were evaluated. The major proces ses involved in the production of the catalysts were chemical activation, i mpregnation, pyrolysis, and post pyrolysis rinsing. The porous structure, c atalytic activity and thermostability of the catalysts were tailored during the production stage by introducing hetero-atoms (zinc chloride, and ferri c nitrate) in the carbon structure. Characterization of the produced CBCs i ncluded determination of the surface area, pore size, and pore size distrib ution (PSD) from standard N-2-adsorption isotherm data. The extent of graph itization and the presence of metal crystals were identified from X-ray dif fraction (XRD). The limit of the catalyst gasification was estimated from t hermogravimetric analysis (TGA) conducted in an oxidized environment. The N Ox reduction capability of the produced catalysts was evaluated in the pres ence of carbon monoxide using a fixed bed reactor. The reaction temperature ranged from 300 to 500 degreesC. It was shown that paper mill sludge is an excellent precursor for the production of CBCs with NO, removal capability of 66-94%. The catalytic capability of the produced CBCs varied according to the method of production, catalyst surface properties (surface area, por e structure, PSD), metal composition and reaction temperature. The highest NOx removal capacity was observed for the catalytic reactions carried out a t 400 degreesC. The mesoporous catalyst produced with a Zn:Fe molar ratio o f 1:0.5 exhibited the maximum NOx removal catalytic activity of 94%. (C) 20 00 Elsevier Science B,V. All rights reserved.