In-situ DRIFTs is relatively simply than other advanced in-situ reactions and is commonly used to understand reaction intermediates. The following procedure was reported by Hu et al. using in-situ DRIFTs for ICCU-DRM (https://doi.org/10.1016/j.apcatb.2020.119734).
“A combined In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS, equipment: Bruker FTIR Vertex 70 spectrometer equipped with a Harrick Praying Mantis DRIFTS gas cell, ZnSe windows and a controlled gas feed system) and Mass Spectroscopy (MS, equipment: Shimadzu, GCMS-QP2010 Ultra) was performed to monitor the possible intermediates and reactions occurred during CO2 capture and DRM steps of the CaLDRM process. The materials were ex-situ reduced by 10 vol% H2/He (50 N mL min−1) at 750 °C (with a ramping rate of 10 °C min-1) for 30 min. In the in-situ DRIFTS experiment, the reduced material was loaded into the cell and then subjected to further reduction under H2 flow at 500 °C for 1 h, followed by purging with He flow for 1 h. After taking the background scan at 550 °C and 1 bar under He, a CO2-He-CH4 sequence, composed of 10 min CO2 step, 10 min He step and 10 min CH4 step, was conducted: firstly, the CO2 feed (25 vol% CO2/He) was introduced into the cell. Subsequently, the gas feed was switched to pure He. Finally, the CH4 feed (25 vol% CH4/He) was introduced. Simultaneously, the IR spectra were collected, and the outlet products were monitored by MS. For all measurements, the flow rate of all feed gases was fixed at 24 N mL min−1, and the spectra were recorded, every 30 s, in absorbance mode between 400 and 4000 cm−1 with a resolution of 4 cm−1.”