Vasireddy, Sivakumar (40)

(M = Mn, Co)
Sivakumar Vasireddy and Joseph J. Pignatello*
Department of Environmental Sciences, Connecticut Agricultural Experiment
Station, New Haven, CT 06511
Abstract. Methyl bromide is an effective fumigant for commodities and
structures, but emissions of methyl bromide from fumigation chambers are
detrimental to stratospheric ozone. Our earlier studies on development of
catalysts for combustion of methyl bromide showed that CeO2 based catalysts
are active and stable due to their remarkable redox properties and oxygen
storage capacities. The best catalyst found was 1%Pt/30%CeO2-Al2O3, which
shows 100% conversion at temperatures as low as 400 oC1. The aim of the
current phase of this research is to develop CeO2 based catalysts for the
complete oxidation of methyl bromide without costly noble metals and that
work at temperatures much lower than 400 °C. For this purpose, MOx-CeO2
(M = Mn, Co) catalysts with different supports, ZrO2 and Al2O3, were prepared.
The catalysts were characterized using N2 adsorption/desorption, X-ray
diffraction, X-ray photoelectron spectroscopy and inductively coupled plasmamass spectrometry (ICP-MS). The effect of combustion process parameters
such as temperature (200–500 °C), gas hourly space velocity (GHSV) and
reaction time are reported. Mg-Al hydrotalcite materials were tested to scrub
the brominated byproducts HBr and Br2 from product gas mixture. Catalytic
oxidation by ceria-based catalysts appears to be a promising approach for
eliminating MB from QPS fumigation vent streams.
CeO2-MOx (M = Mn, Co)
CH3Br + 3/2(7/4) O2
Δ ≤ 400 °C
CO2 + H2O + HBr(1/2Br2)
1. C. Y. Chen and J. J. Pignatello, Appl. Catal. B: Envi., 142-143 (2013) 785-794.