KOH-promoted Pt/Al2O3 catalysts for water gas shift and methanol steam reforming: An operando DRIFTS-MS study

The performance of KOH-modified Pt/AlO catalysts has been investigated under the conditions of the water-gas shift (WGS) reaction and methanol steam reforming (MSR) with diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) coupled with online quadrupole mass spectrometry (QMS). We demonstrate that both the activity and the selectivity are enhanced in comparison to the uncoated catalyst by applying a thin coating of KOH. By means of IR spectroscopy, we were able to follow the formation of surface species on two different types of catalysts. During reaction, primarily formates are observed on the uncoated catalyst while a film of hydroxides and carbonates is observed on the KOH-coated sample. Additionally, the vibrational bands of CO adsorbed on Pt suggest a strong modification of the electronic structure of the Pt particles by K-coadsorption, leading to a weakening C[sbnd]O bond and a strengthening of the Pt[sbnd]C bond. As a result, we observe an increased selectivity to CO on the KOH modified system.