Effect of Al2O3 doping on the structure and performance of an Al2O3/Fe2O3 catalyst for mercury oxidation

In this study, the thermal stability of a Fe2O3 catalyst for mercury oxidation was significantly improved by doping with Al2O3. After 1 hr, the catalyst doped with 10 wt.% Al2O3 still exhibited a mercury conversion efficiency of 70.9%, while the undoped sample even lost its catalytic activity. Doping with Al2O3 retarded the collapse of the catalyst mesoporous structure during high-temperature calcination, and the doped samples maintained a higher specific surface area, smaller pore size, and narrower pore size distribution. Transmission electron microscope images revealed that after calcination at 350 degrees C, the average size of the catalyst grains in Fe2O3 was 23.4 nm; however, the corresponding values for 1%Al2O3/Fe2O3, 3%Al2O3/Fe2O3, and 10%Al2O3/Fe2O3 were only 13.3, 7.1, and 4.7 nm, respectively. Results obtained from X-ray diffraction and thermogravimetry coupled with differential scanning calorimetry confirmed that doping with Al2O3 also retards the crystallization of the catalysts at high temperature, constraining catalyst grains to a smaller size. (C) 2019 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.