Reduction of Cu2+ cations supported on Y zeolites

Abstract

The reduction of Cu²⁺ cations supported on a range of Y zeolites, enriched to various levels with different alkalimetal cations, has been investigated. The location of Cu²⁺ cations within the zeolite framework has been monitored after various stages of thermal treatment and the reduction of the Cu²⁺ ions in a flowing hydrogen atmosphere has been correlated with such diverse factors as the reduction temperature, reduction time, heating rate and NH₃ pretreatment. Cation location has been probed by means of Cs⁺ back-exchange. Iodometric titrations and Na⁺ back-exchange techniques have been used to measure the levels of Cu²⁺ reduction. From the data generated it is shown that the nature of the alkali-metal co-cation strongly influences the degree of Cu²⁺ reduction. The levels of Cu²⁺ reduction are compared to those exhibited by Ni²⁺ ions supported on a range of Y zeolites reduced under the same experimental conditions.