Acid-modified clinoptilolite as a support for palladium–copper complexes catalyzing carbon monoxide oxidation with air oxygen
Samples of natural clinoptilolite were modified by an acid–thermal method at nitric acid concentrations of 0.25, 0.5, 1.0, and 3.0 M and a contact time of 30 min. A series of catalysts, K2PdCl4–Cu(NO3)2–KBr/S (S = 0.25H-CLI, 0.5H-CLI, 1H-CLI, and 3H-CLI) was obtained. All samples were investigated by X-ray phase and thermogravimetric analysis, FT-IR spectroscopy, water vapor ad/desorption and pH metric method. Besides, K2PdCl4–Cu(NO3)2–KBr/S samples were tested in the reaction of low-temperature carbon monoxide oxidation. It have been found that, owing to special physicochemical and structural-adsorption properties of 3H-CLI, it promotes formation of the palladium–copper catalyst providing carbon monoxide oxidation at the steady-state mode down to CO concentrations lower than its maximum permissible concentration at air relative humidity varied within a wide range.
Physicochemical and structural characteristics of HEU-type zeolitic tuff treated by hydrochloric acid
Samples of natural HEU-type zeolites - clinoptilolite-Ca, from the Nova- kovici deposit (near Prijedor, Bosnia and Herzegovina) were treated with the hydro- chloric acid of various concentrations (from 10 -3 M to 2 M). Zeolitic tuffs before and after the acid treatment were examined using IR, XRPD, and chemical analyses. The changes in the crystal structure of acid treated samples showed a significant reduc- tion in the crystallinity of zeolitic tuffs (60-70 %), which were effected by hydro- chloric acid with concentrations of 1 M and above.
The analysis of group contingency data.
The data analyses utilized in group contingency projects are reviewed. Previous studies are cited to emphasize advantages of nonconsolidated ("individual") over consolidated analyses. Several procedures are described that enable applied researchers to incorporate nonconsolidated data analyses in group contingency studies.