Vìsnik Odesʹkogo Nacìonalʹnogo Unìversitetu: Hìmìâ (May 2019)
EFFECT OF DURATION OF THE BENTONITE ACID MODIFICATION ON THE ACTIVITY OF PD(II)-CU(II) CATALYTIC COMPOSITIONS IN THE REACTION OF CARBON MONOXIDE OXIDATION
Abstract
The effect of duration of the bentonite acid modification on its physicochemical and structural parameters and also on the catalytic properties of bentonite anchored palladium-copper complexes in the reaction of low-temperature carbon monoxide oxidation with air oxygen has been studied. For all acid modified bentonite samples, 1H-Bent-τ (τ = 0.5, 1.0, 3.0, 4.0, and 6.0 h), some regularities of changes as compared with natural bentonite, N-Bent, in the bentonite phase composition and X-ray spectral parameters of montmorillonite that is a samples, regardless a contact time, τ, the montmorillonite crystalline structure does not change however its aluminosilicate layers constrict for both bentonite acid modified samples and Pd(II)-Cu(II)/1H-Bent-τ compositions. After acid treatment, the number and positions of IR bands characterizing structural groups Al-Al-OH, Al-Fe3+-OH, Si-O-Si, and Si-O-Al of Mont phase do not change however their intensities, except for Si-O-Si, decrease pointing to the loss of Al3+ and Fe3+ cations. Palladium-copper complexes can be anchored not only on Mont structural groups but also on surfaces of quarts, amorphous SiO2, and calcite if any. It has been found that the changes in physicochemical and structural parameters of the bentonite samples result in alterations in the catalytic activity of Pd(II)-Cu(II)/S— compositions (S— is N-Bent or 1H-Bent-τ) in the reaction of carbon monoxide oxidation with air oxygen. The composition based on 1Н-Бент-0.5 characterizing by the minimum pH value of its aqueous suspension shows the maximum catalytic activity: CO conversion is 78 %.
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