CO adsorption on the Na,K-Ferrierite zeolite at 77 K and 193 K: New IR insights and consequences on the previously endorsed assignments of adsorbed species

• IR spectra of CO adsorption are reported for both pressure and temperature as independent influences.
• We outline the abnormal thermodynamic behavior of the so-called dual sites.
• We evidence Silanol also interact and describe how SiOH impact CO adsorption.
• Attributions of surface adsorbed species endorsed in the literature are called into question.

We survey CO adsorption on the Na,K-Ferrierite zeolite throughout two in-depth IR investigations at the 77 K and 193 K temperatures. For the large range of CO pressures we considered, we newly evidence CO interacts with silanol groups at the 77 K but not at the 193 K temperature. Discrepancy of the as-resulting IR bands both in their shape and positions we obtain for the two temperatures sets strongly indicate that carbonyl adsorbed species develop differently with temperature. Moreover, we highlight for the two temperatures how the different carbonyl adsorbed species influence on their mutual development. Results newly reported here are discussed in connection with assignments of the CO-complexes formed in the K-FER as previously reported in the literature. Our conclusions strongly suggest they should be reconsidered.

IR spectra of CO adsorbed on K-FER with both temperature and pressure dependence: the abnormal behaviour of the bridged adsorbed species.Figure optionsDownload as PowerPoint slide