Hydrogen catalytic purification in microchannels

Abstract

This paper describes the operation of a catalytic microdevice designed by our research group to catalytically and selectively purify carbon monoxide in the presence of hydrogen. We have developed a method of successfully coating channels of only 2-4 μm in diameter with a homogenous 100 nm-thick titanium oxide layer. Novel gold nanoparticles protected with a Si-rich shell have been anchored onto this thin layer. The gold nanoparticles show great stability and activity in preferentially oxidizing carbon monoxide (CO-PrOx) in a temperature range of 363 to 473 K. The microreactor intensifies the CO selective oxidation process. Due to the scale reduction achieved in this structure (compared to conventional catalytic wall reactors), specific activities (amount of converted CO per reactor volume) that are 100 times larger were obtained, operating at the same temperature level and with the same feed mixtures. Consequently, this microreactor is very interesting for performance of the CO-PrOx reaction at microscale and for combination with a preliminary reforming stage. The connection of both processes to feed low-temperature fuel cells offers new possibilities in hydrogen technology and, particularly, in small-scale and portable applications.

Keywords: Hydrogen, fuel cells, catalysts, CO catalytic purification, gold nanoparticles.