Sorption of n-butane on sulfated zirconia investigated using a combination of in-situ DRIFT spectroscopy, XPS and TAP

Abstract

The sorption of n-butane on sulfated zirconia (SZ) was investigated using in-situ Diffuse Reflection Infrared Fourier Transform Spectroscopy (DRIFTS), Photoelectron spectroscopy (XPS) and Temporal Analysis of Products (TAP) measurements. The combination of different spectroscopic techniques like XPS and DRIFTS with transient TAP experiments offer the chance to comprehensively investigate and characterize catalytic sorption sites. Using XPS, DRIFTS, and TAP it was shown that both Brønsted centers (Zr-OH) and the very reactive disulfate groups are involved in the adsorption of n-butane and thus are mainly responsible for the isomerization reaction of n-butane to iso-butane over SZ. Moreover, all methods enable to bridge the pressure gap ranging from UHV to ambient pressure. Especially, adsorption of alkanes with XPS in-situ for different adsorption times has been done for the first time.