EFFECT OF ACID MODIFICATION OF NATURAL ALUMINOSILICATES ON THE ACTIVITY OF Pd(ІІ)-Сu(ІІ)-CATALYSTS FOR CARBON MONOXIDE OXIDATION

Abstract

(clinoptilolite, CLI, bentonite, Bent, and basalt tuff, BT) based on the acid modification of a natural support, by its boiling in solution (3 mol/L) of different acids (HNO3, H2SO4, Н3PO4, C6H8O7) for 30 minutes has been developed. K2PdCl4-Cu(NO3)2-KBr/S catalyst samples (S is an acid modified clinoptilolite, bentonite or basalt tuff) were tested in the reaction of carbon monoxide oxidation with air oxygen at ambient temperature, high relative humidity of a gas air mixture (GAM), and a CO inlet concentration in the GAM of 300 mg/m3 (15 MPCCO). It has been found that the acid modification of clinoptilolite, bentonite, and basalt tuff does not result in significant changes in the structures of these natural aluminosilicates. The treatment of the natural sorbents with acids of the different nature leads to a considerable decrease in pH values of their aqueous suspensions, i.e. to 4.0-5.5. It has been found that the catalytic activity of Pd(II)-Cu(II)/S— compositions in the reaction of CO oxidation with air oxygen significantly increases after modification of the supports with nitric, sulfuric, phosphoric, and citric acid. A value of CO conversion in the steady-state mode (ηst, %) was chosen as a measure of activity for the above mentioned compositions and their dependence on acid modified supports can be presented as the following orders: 3НNO3-CLI-0.5 > 3Н2SO4-CLI-0.5 > 3Н3PO4-CLI-0.5> 3C6H8O7-CLI-0.5, 3НNO3-Bent-0.5 > 3Н3PO4-Bent-0.5 > 3Н2SO4-Bent-0.5 > 3C6H8O7-Bent-0.5, and 3НNO3-BT-0.5 · 3Н3PO4-BT-0.5 · 3C6H8O7-BT-0.5 · 3Н2SO4-BT-0.5. It has been determined that regardless of the acid nature an activity of the catalytic compositions decreases in the order 3HX-BT-0.5 > 3HX-CLI-0.5 > 3HX-Bent-0.5. The catalytic compositions based on such active components as palladium(II) and copper(II) are promissory for air purification from CO in collective and personal respiratory protective devices.

Keywords

• монооксид карбону
• низькотемпературне окиснення
• каталізатори
• кислотне модифікування
• алюмосилікати