Effect of Cu modifier on the performance of CrOx/Al2O3 catalysts for isobutane dehydrogenation

Abstract

The peculiarities of active surface formation and the effect of Cu modifier on the performance of CrOx/Al2O3 catalysts in a fixed-bed isobutane dehydrogenation into isobutylene are considered using a series of model Cu-modified alumina supports (0.7–6.5% wt Cu) and CrOx catalysts on the basis thereof. The samples are characterized using a complex of physical-chemical methods, including low-temperature N2 adsorption, STA, XRF, XRD, UV–vis DR, Raman spectroscopy and H2-TPR. The modification of the alumina-chromia catalysts by a proper amount of copper is shown to enhance the catalyst activity. The catalyst with 2.6% wt Cu shows high conversion and selectivity towards isobutylene. The role of Cu modifier is connected with stabilizing of the active component mostly as monomeric and dimeric Cr(VI) species that can be reduced into the most active mononuclear and dimeric Cr3+ sites.