Catalytic oxidation of carbon monoxide using copper oxide nanoparticles supported on diatomite

Abstract

Background and aims: Carbon monoxide (CO) is a highly toxic, colorless, and odorless gas with a density close to the air, which is produced by natural processes and anthropogenic sources and is well known for its potential harmful and poisonous effects on humans. Inhalation of carbon monoxide gas can impair the heart and central nervous system. Diatomite supported nano copper oxide catalyst was used to investigate the catalytic oxidation of carbon monoxide. In this study, it was shown that how a low cost diatomaceous earth can be used as catalyst support. Methods: The required amount of copper oxide nanoparticles placed into 200 ml deionized water to prepare different concentrations (1wt%, 2wt%, 3wt%, 4 wt% and 5wt%) of nanoparticle, next the suspension liquid stirred for 30 min at pH of 7 at room temperature, and then 100g diatomite was added to the above solution. The nano CuO coating was implemented under sonication conditions in ultra sound bath for 20 min at room temperature, and gently stirring was then carried out for 2h. The prepared catalysts were characterized by Brunauer-Emmett-Teller (BET) surface area, scanning electron microscopy (SEM), X-ray diffraction (XRD) and porosimetry. The influence of reaction temperature, CuO loading, and calcination temperature on the catalytic activity of copper oxide nanoparticle supported on diatomite have been studied. Their catalytic behavior for CO oxidation was studied at different conditions in a tubular reactor packed with catalyst using a multi-component NDIR gas analyzer (Delta 1600 S-IV). Results: The catalytic behavior of catalyst was dependent on the nano copper oxide content, reaction temperature, retention time and the particle size of the catalysts. The results show that diatomite is the promising candidate for catalytic support due to its high surface area, high porosity, low thermal conductivity, very low cost and good sorption ability of its porous media. The catalyst with 4wt % CuO content, in 0.5 l/min and at 400 °C exhibited the highest catalytic activity. Conclusion: Diatomite, which is a type of widespread natural porous material, provides a suitable support. Chemical and physical characteristics of this support are similar to cordierite. Due to the numerous fine microscopic pores, cavities and channels good sorption ability, chemical inertness, low density, high surface area, unique combination of physical and chemical properties, high permeability and excellent thermal resistance of diatomite, there is a possibility to use it as a support in automotive catalytic converters and as a cost-effective substitute of noble metals for carbon monoxide oxidation. In addition, these unique properties of diatomite can prevent sintering and agglomeration of atoms.