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FTi.r. spectroscopy has been applied in studying the reaction between methanol and hydrogen sulfide on NaX and NaY zeolites. Hydrogen-bonded methanol and methoxy and carbonate species were found on both of the zeolites after methanol adsorption. Pyrrole and pyridine preadsorption experiments have shown that methanol is chemisorbed on basic and/or cationic sites on the zeolites used. H2S is adsorbed on the same sites. In the reaction between methanol and hydrogen sulfide on sodium zeolites methoxy species or HS−ions are involved. Carbonate species can also react with H2S producing hydrogenthiocarbonates or thiocarbonates. However, this reaction does not play any role in the interaction between CH3OH and H2S under the conditions used.

Low-temperature CO adsorption on TiO2 (anatase) has been investigated by FTIR spectroscopy on (i) a pure sample, (ii) a sample on which the sites for CO adsorption at room temperature are blocked by ammonia, and (iii) anatase whose surface is covered by ammonia. Adsorption of small amounts of CO at 100 K on anatase leads to the appearance of two bands at 2210 and 2192 cm^-1 due to CO adsorbed on two kinds (α and β‘, respectively) of Ti⁴⁺ sites (the same species are also observed when adsorbing CO at room temperature). The increase of the introduced CO amount involves sites (β‘‘-sites) that are inert at room temperature. The CO molecules adsorbed on β‘‘-sites interact with CO molecules preadsorbed on β‘ sites, as a result of which the two adsorption forms produce a common absorption band whose maximum is shifted to 2179 cm^-1 at higher coverage. With increasing amount of adsorbed CO, one more kind (γ) of Ti⁴⁺ site with very weak acidity is detected, the corresponding absorption band being at 2165 cm^-1. Under CO equilibrium pressure two additional reversible adsorption forms appear:  CO H-bonded to surface hydroxyl groups (ν(CO) at 2155 cm^-1) and physically adsorbed CO (band at 2138 cm^-1). Simultaneously with the appearance and increase in intensity of the band at 2155 cm^-1, a broadening and shift by about −115 cm^-1 of the bands for the surface hydroxyl groups occur. Adsorption of a ¹³CO shows that the shifts of the bands at 2210 and 2192 cm^-1 are mainly of a static type (−4 and −17 cm^-1, respectively), the dynamic components being only +4 cm^-1 for the β-carbonyls and not measurable for the α-carbonyls. CO adsorption on reduced anatase indicates the formation of the same types of carbonyls. However, in this case, part of the introduced CO probably dissociates and oxidizes the Ti³⁺ ions into Ti⁴⁺. Low-temperature CO adsorption on anatase on which the sites for CO adsorption at room temperature (the α and β‘ sites) are preliminary blocked by ammonia leads to the formation of carbonyls on β‘‘ and γ sites (ν(CO) at 2177 and 2156 cm^-1, respectively), as well as of CO adsorbed on OH groups and physically adsorbed CO. In this case the shift of the OH stretching modes is still −115 cm^-1. Low-temperature CO adsorption on anatase fully precovered with ammonia shows the appearance of weakly bound forms only:  a part of the carbonyls on γ-sites (ν(CO) shifted to 2151 cm^-1), CO adsorbed on hydroxyl groups, and physically adsorbed CO. However, in this case the shift of the ν(OH) stretching modes is only −65 cm^-1. The nature of the different kinds of active sites for adsorption of ammonia and CO on anatase is discussed.

Comparative adsorption of CH316OH and CH318OH on thoria shows the formation of four types of methoxy species resulting from methanol O−H dissociation. Species I, characterized by the highest ν(C−O) wave-number, reacts with CO2 at room temperature, leading to the formation of methyl carbonate species while the others are almost unreactive. Species I is considered as monodentate, the others as bi or tridentate. Their structure is related to the local arrangement of the exposed faces.