Deactivation of π-Complexation Adsorbents by Hydrogen and Rejuvenation by Oxidation

Abstract

The π-complexation sorbents are the best sorbents for bulk olefin/paraffin separation and purification of normal α-olefins. Hydrogen produced during cracking operations would remain in small or trace amounts in the process streams. The effect of hydrogen exposure on Ag + -exchanged Y zeolite (AgY) and monolayer-dispersed AgNO 3 /SiO 2 (π-complexation sorbents) on olefin adsorption was studied by using accelerated tests. Hydrogen exposure could severely deactivate the π-complexation sorbents for adsorption of ethylene, 1,3-butadiene, and 1-butene. XPS analysis indicated that the Ag + ion responsible for π-complexation was partially reduced, hence, the deactivation. It was found that the deactivated sorbents could be rejuvenated by mild oxidation. The reoxidation of the H 2 -exposed AgY samples were carried out under different oxidation conditions to locate the optimum conditions. The treatment of the H 2 -exposed samples to 0.13 atm of O 2 in He at 350 °C for 0.5 h was the best reoxidation condition achieved in this study.