Kinetics of carbon monoxide oxidation on a copper oxide/titania catalyst.

摘要

Mixed metal oxide catalysts are developed and evaluated for selective carbon monoxide combustion at atmospheric pressure and temperatures from 25°C to 700°C. There are a considerable number of literature references dealing with the combustion of carbon monoxide using mixed metal oxides. Only a very few of these reported studies have dealt clearly with catalysts that are: (1) inexpensive, for non-recyclable process; (2) highly reactive, because of the low contact time of the gas and the catalyst; (3) selective, because of the presence of other gaseous components; (4) resistant to fouling and/or poisoning due to, for instance, moisture, and (5) reactive only at a temperature substantially higher than room temperature. The latter property is desired to ensure catalytic activity over specific ranges of temperature only. Most of the promising catalysts reported in the literature incorporate precious metals such as gold or palladium. There is a need for an inexpensive catalyst that exhibits the five favorable properties listed.; In preliminary experiments, mixtures of commercial copper oxide-titanium oxide nanoparticles showed extremely high reactivity. Neither copper oxide nor titanium oxide is expensive compared to catalysts containing precious metals. Several copper oxide/titanium oxide catalyst formulations were prepared using various synthesis methods and one synthesis method was selected based on CO oxidation catalytic reactivity and retention of catalytic properties after sintering at 600°C. The catalyst formulation of choice is designated as (40 wt% CuO)/(60wt% TiO2) which shows 100% CO conversion in a gas containing 3.6 vol% CO and a gas residence time of 0.004 second.; A model based on Langmuir-Hinshelwood kinetics is developed to explain the observed CO oxidation performance of the (40 wt% CuO)/(60wt% TiO 2) catalyst. Several parameters, including CO and O2 partial pressures, total reactive gas flow rate, catalyst bed weight, and reaction temperature, were systematically changed to investigate the performance of the catalyst. The results of this research provide a fundamental reaction engineering foundation for the interpretation of catalytic combustion of CO on mixed metal oxide catalysts.