How does CO capture process on microporous NaY zeolites? A FTIR and DFT combined study

Abstract

Reliable experimental IR and theoretical approaches, both investigating CO adsorption on NaY faujasites, are supporting that CO capture occurs through the completion of the vacant coordination of Na(+) cations located in the accessible S(II) sites. As a result, carbonyl adsorbed species are formed by the capture of one, two or three CO molecules and are experimentally discernable by their respective IR positions that are down-shifted by an average 11-12 cm(-1) value for each captured CO molecule. DFT analysis is proposed for comparison and reproduces well the observed experimental shift of the ν(CO) positions of the different polycarbonyls of interest. In addition, the effect of Si or Al composition surrounding the SII Na(+) cation is investigated and results suggest that polycarbonyls that are formed might be in connection with the acidic strength of the cationic sites. This combined study completes and improves the understanding of the complex issue of CO adsorption at 80 K widely used as a model to explain how physical adsorption takes place in NaY faujasites working as an efficient industrial adsorbent in gas separation or gas purification processes.

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

“…CO, H2, NO and O2) in the aim of improving the catalytic properties of the material. 6,28,[31][32][33][34] CO is typically used as a probe molecule for specifying the properties of adsorption on solid materials 32,35 and it is known for inducing morphological changes to the catalytic surface when adsorbed thereon. For example, highly mobile carbonyl species on Pt-and Pd-doped Fe3O4(001) are observed with scanning tunnelling microscopy (STM) after exposure of the surfaces to CO gas at low PCO (e.g.…”

DFT study of the structure, chemical ordering and molecular adsorption of Pd–Ir nanoalloys

“…Surface segregation of Pd has been reported to occur in the presence of reactive gases such as CO and O 2 , 21,22 and the binding of CO molecules is commonly used as a probe to identify the nature of metal surface adsorption sites. 23,24 Pd-Ir nanoalloys are often used as catalysts in the preferential oxidation of CO (PROX). 8,10 The Pd-Ir system has rarely been studied computationally, [25][26][27][28][29] and relatively few catalytic studies have been devoted to Pd-Ir nanoalloys.…”

Evidence of Pd segregation and stabilization at edges of AuPd nano-clusters in the presence of CO: A combined DFT and DRIFTS study

“…In surface science and catalysis, the CO molecule is commonly used as an indirect probe to identify the nature of metal surface sites [1][2]. Its application is based on the statement that IR bands of carbonyl adsorbed species recorded after CO introduction are relevant to specific CO/metal interactions and serve as a fingerprint of the adsorption site.…”