Comments on the characterisation of oxidation catalysts using TPR/TPO

Abstract

Temperature programmed reduction (TPR) and oxidation (TPO) are used extensively in catalyst characterisation. In this paper, we examine the use of TPR/TPO cycles for the characterisation of a range of molybdates and single oxides. In particular we observe that the first cycle differs from that of subsequent analyses, even when the maximum temperature is limited to that used in the catalytic reaction. The effect is independent of heating rates and cooling atmospheres and has been demonstrated using different bed configurations. This observation has significance when these oxides are used in periodic flow reactors that involve many cyclical reduction/oxidation.

Temperature‐Programmed Reduction and Oxidation1A list of symbols used in the text is provided at the end of the chapter.

“…Song et al [16] recently examined the use of TPR/TPO cycles for the characterization of a range of molybdates including BiMoO 6 , CoMoO x , CoBiMoO x and BiMo 12 Fe 2 NiCo 7 MgSb 0.9 Ti 0.1 Te 0.02 O x and single oxides MoO 3 , Bi 2 O 3 and Co 3 O 4 . The results of this investigation demonstrated that for complex molybdates, and also less complex materials, the first and subsequent TPR/TPO cycles are clearly different, the first cycle being unique.…”

“…Fig 16. H 2 consumption and H 2 O evolution profiles measured during H 2 temperature-programmed reduction of a passivated Mo nitride (4 m 2 g −1 ) (adapted from Ref [101]…”