Abstract: MoO_3-SnO_2 catalysts prepared by precipitation, impregnation and high temperature calcination of the relevant mixtures have been investigated by using XRD, IR and ESR, It is shown that there is a strong interaction between MoO_3 and SnO_2. An electron transfer process occurs between two components and leads to the formation of Mo~(5+) from Mo~(6+), surface acid site with pKα≤+3.3 as well as active center for methanol selective oxidation.
The preparation method has significant effect on the interaction between MoO_3 and SnO_2 and the catalytic behavior of the catalysts. MoO_3 can dissolve in SnO_2 forming solid solution in the catalyst prepared by precipitation method, while Mo ions diffuse into the bulk of SnO_2 in hte catalyst prepared by impregnation. Below a certain level, MoO_3 can disperse as a monolayer on the SnO_2 surface in the ctalyst prepared by high temperature calcination.
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