ENVIRONMENTAL ENGINEERING SCIENCE Volume 24, Number 8, 2007 © Mary Ann Liebert, Inc. DOI: 10.1089/ees.2006.0227 Catalytic Oxidation of CO and CH 4 As Well As Mixture of CO and CH 4 with Nano and Micro Fe 2 O 3 Soonchul Kwon, 1,2 Maohong Fan, 1,2,* and Thomas D. Wheelock 1 1 Center for Sustainable Environmental Technologies and 2 Department of Civil, Construction and Environmental Engineering Iowa State University Ames, IA 50011 ABSTRACT The nano and micro Fe 2 O 3 were evaluated for their performances in catalyzing the simultaneous oxida- tion of CO and CH 4 , two typical air pollutants generated during some fuel processing and utilizations. The major factors investigated for their effects on oxidation include temperature, space time, and con- centrations of CO and CH 4 . Experimental results indicated that nano Fe 2 O 3 is much more effective than micro Fe 2 O 3 in catalyzing the oxidation of CO and CH 4 . Key words: simultaneous oxidation; catalyst; nanoparticles, iron oxide; carbon monoxide; methane 1065 *Corresponding author: Center for Sustainable Environmental Technologies and Department of Civil, Construction and Envi- ronmental Engineering, 273 MD, Iowa State University, Ames, IA 50011. Phone: 515-294-3951; Fax: 515-294-3091. E-mail: mfan3@mail.gatech.edu INTRODUCTION M ANY CATALYSTS have been used to improve reac- tion rates of oxidations, especially at low temper- ature ranges. With the development of industries, a vari- ety of air pollutants during fuel processing and utilization including carbon monoxide (CO), methane (CH 4 ), and volatile organic compounds (VOCs) have been emitted into atmosphere. People are increasingly concerned about their environmental and health effects caused. One of the conventional methods used for controlling these air pol- lutants is thermal oxidation. One of the problems with thermal oxidation-based methods is its high energy de- mand. To solve the problem, people are increasingly in- terested in developing different types of catalysts to lower the oxidation temperatures of these air pollutants (An- derson et al., 1961). Expensive catalysts including platinum (Pt), palladium (Pd), and rhodium (Rh) have been extensively studied for oxidations of many air pollutants (Berlund, 1994; Bry- den and Ragland, 1996) due to their high catalytic activ- ities and stabilities. However, they are too expensive to be widely used. Therefore, it is necessary to develop cost- effective catalysts for oxidizing air pollutants. Among those interested is iron oxide because of its low cost, ther- mal stability, and sintering resistance (Anderson et al., 1961; Hill, 1977; He et al., 2003). Some researchers have recently studied the application of nanoscale catalysts in removal of waste gas streams (Kim and Park, 2002; Li et al., 2003; Paredes et al.,