A near-ambient pressure flow reactor coupled with polarization-modulation infrared reflection absorption spectroscopy for operando studies of heterogeneous catalytic reactions over model catalysts

Rev Sci Instrum. 2022 May 1;93(5):054105. doi: 10.1063/5.0081102.

Abstract

The model catalyst approach is often used for fundamental investigations of complex heterogeneous catalysis, in which operando characterizations are critical. A flow reactor is usually adopted for gas-solid heterogeneous catalytic reactions. Herein, we report a home-designed near-ambient pressure (NAP) flow reactor coupled with polarization-modulation infrared reflection absorption spectroscopy (PM-IRAS) and an online quadrupole mass spectrometer for operando studies of heterogeneous catalytic reactions over model catalysts. A unique gas supply system is designed and manufactured to enable a stable gas inlet to the NAP flow reactor at pressures up to ∼100 mbar. An ultrahigh vacuum chamber equipped with the facilities for x-ray photoelectron spectroscopy, low-energy electron diffraction, thermal desorption spectroscopy, E-beam evaporation source, and ion sputtering gun is connected to the NAP flow reactor via a gate valve for preparations and routine characterizations of model catalysts. The functions of the system are demonstrated by in situ PM-IRAS characterization of CO adsorption on Pt(111) and operando characterizations of CO oxidation on Pt(111) under NAP conditions.