Samples of natural clinoptilolite were modified by an acid–thermal method at nitric acid concentrations of , , , and M and a contact time of 30 min. A series of catalysts, K2PdCl4–Cu(NO3)2–KBr/S (S = , , 1H-CLI, and 3H-CLI) was obtained. | Acid-modified clinoptilolite as a support for palladium copper complexes catalyzing carbon monoxide oxidation with air oxygenth air oxygen