LaFeO3 Perovskites Obtained from Different Methods for NO + CO Reaction, Modeling and Optimization of Synthesis Process by Response Surface Methodology

Abstract

In this paper, LaFeO3 perovskite catalysts were synthesized by sol–gel combustion, pechini and co-precipitation methods and studied as catalysts for the catalytic reduction of NO with CO. The perovskite catalysts were characterized by XRD, BET, H2-TPR, SEM and DLS. The pechini synthesized perovskite showed the highest activity among the other catalysts in the catalytic reduction of NO with CO. The excellent catalytic activity of LaFeO3-pechini might be associated with its higher specific surface area, better low-temperature reducibility, more structural defects and more surface oxygen species. For pechini method as the best synthesize method, the effects of synthesis variables on activity of catalysts were studied by response surface methodology. RSM model could predict the experimental data for NO conversions at a good accuracy (R2 = 0.981). The model predicted that the relative importance of variables is as follows: calcination temperature > citrate/nitrate ratio > EG/citrate ratio. Under the optimum condition (citrate/nitrate ratio: 0.61, EG/citrate: 2.92 and calcination temperature: 600 °C), the predicted value of NO conversion (91.1%) was found to be in a good agreement with the corresponding actual value (89%).