Preferential oxidation of CO over Pt–Sn/AC catalyst: Adsorption, performance and DRIFTS studies

Abstract

Preferential CO oxidation over 1% Pt–0.25% Sn supported on nitric acid treated activated carbon (AC-N) was studied for various feed compositions including fully realistic feed. The real time performance of the catalyst and the effect of reaction parameters on its PROX activity and selectivity were investigated. Factors leading to high performance of the Pt–Sn/AC-N catalyst were scrutinized by CO and O2 adsorption and PROX tests conducted on an in situ diffuse reflectance IR Fourier transform spectroscopy system connected to a mass spectrometer (FTIR-DRIFTS-MS). CO and CO2 adsorption properties of Pt–Sn/AC-N and Pt/AC-N samples were also studied by a gravimetric analyzer. FTIR-DRIFTS-MS and adsorption studies confirmed enhanced CO chemisorption on Pt–Sn/AC-N catalyst compared to that on Pt/AC-N. The performance results showed that the presence of CO2 and H2O in the feed does not significantly affect the CO conversion performance and CO selectivity of the catalyst. In all tests, CO conversion increased with the decrease in temperature within 135–110°C range, indicating enhancement in CO selectivity as the temperature decreases. The CO conversion of the catalyst reached for the W/F value tested was ca. 90% at 110°C for the H2-rich feed including CO2, water vapor and methane.