Scale up analysis of a plasmon-enhanced ethylene oxide production process

Abstract

Geometric modeling of hourly solar irradiance combined with Markov chain descriptions of cloud cover dynamics is shown to be an effective tool for the design and analysis of solar-assisted catalytic processes. A key finding of this study is that because of the large area needed to collect incoming irradiation, even at modest reactor operating temperatures, radiative thermal losses can greatly exceed the incoming solar irradiance - for the ethylene oxide process of this study, the most significant source of thermal power was found to be that released by the competing exothermic ethylene oxidation reaction. The net result of the radiative losses is that a fixed Earth-tangent solar chemical reactor, under representative annual weather and irradiance conditions, can only operate in the hours surrounding solar noon and would be idle on days between the fall and spring equinoxes. It is further shown that if a sun-tracking reactor configuration is used, the thermodynamic feasibility of the process improves considerably, even with no irradiance concentration. Significant gains are found for modest levels of solar irradiance concentration; however, while the illuminated catalyst surface area will decrease with increasing irradiance concentration for fixed production levels, the projected area of the concentrating system also will increase proportionally, offsetting the reactor performance gains.