Infrared spectroscopic studies of the adsorption of carbon dioxide and the coadsorption of carbon dioxide and water on CaY- and NiY-zeolites☆

Abstract The adsorption of carbon dioxide and the coadsorption of carbon dioxide and water on CaY- and NiY-zeolite have been studied by means of in situ infrared spectroscopy. The spectroscopic studies have been carried out systematically between 323 and 623°K in 50° steps. Physically adsorbed carbon dioxide behaves almost identically on CaY- and NiY-zeolites with absorption bands around 2360 and 2340 cm−1. However, differences are observed in the chemical adsorption. On CaY-zeolite at 373°K the monodentate carbonate species is formed with a doublet band at 1476 and 1457 cm−1. The chemisorption of carbon dioxide on NiY-zeolite produces three surface species: at 373 K the free carbonate ion (CO32−) correlated to an absorption band at 1441 cm−1, between 357 and 403°K the monodentate carbonate appears intermediary and when the temperature of 403°K is reached the bidentate carbonate with absorption bands at 1560 and 1355 cm−1 is observed. In the presence of water, the physical adsorption of carbon dioxide on CaY- and NiY-zeolite is scanty, because water is preferably adsorbed onto these surfaces. The chemisorption is influenced on CaY-zeolite by water, shifting the temperature of formation of the monodentate carbonate to 453°K. On NiY-zeolite the bidentate carbonate species is observed as in the absence of water. However, the temperature of formation for the free carbonate (CO32−) is also shifted to 453°K and the intermediary monodentate is even missed.