Coupled Raman and temperature-programmed desorption for simultaneous analysis of structure and desorbed species from powder catalysts.

Abstract

Catalyst structure and surface chemistry are often studied separately, making it challenging to establish the structure-performance relationship under real reaction conditions. To address this, we develop a coupled Raman spectrometer and mass spectrometer system to enable simultaneous Raman and temperature-programmed desorption (TPD) analysis of powder catalysts under gaseous environments (1 × 10-8 to 1 × 103 mbar) and at temperatures from 100 to 1000 K with a linear heating rate up to 10 K s-1. This system minimizes re-adsorption effects in TPD analysis to ensure accurate measurement of desorption activation energies (ΔEdes), and furthermore, catalyst structure can be directly correlated with surface adsorbates based on the coupled Raman-TPD characterizations. Studies on D2 activation on ZnO reveal the role of oxygen vacancies in stabilizing D2 adsorption. In addition, spatially resolved TPD and Raman analyses of ZnO and ZnO/ZrO2 samples highlight the enhanced adsorption capacity and stability of H species on ZnO overlayers when confined on ZrO2 support.