Zinc oxide was examined as a high-temperature desulfurization sorbent.
At high temperature (>ca. 600-degrees-C), the zinc oxide sorbent is r
educed to metallic zinc with reductive gas in a coal derived gas, and
then the metallic zinc evaporates. This reduction and vaporization was
not completely prevented by the additions of ZrO2, TiO2, and Al2O3 to
the zinc oxide. There duction and vaporization tendencies of zinc oxi
de were studied by the temperature-programmed reduction (TPR) method u
sing thermobalance, under different conditions which simulated practic
al desulfurization of hot coal-derived gases. From these results, the
stability of zinc oxide for reduction followed by vaporization could b
e expressed by an experimental equation using concentrations of H-2, C
O, H2O, and CO2 in coal-derived gases and temperature as functions. Fr
om the measurements of TPR profiles and reactivities of the zinc oxide
sorbents containing the additives, it is suggested that stabilization
of zinc oxide by additives without a decrease of the reactivity of zi
nc oxide is a very difficult problem.