Understanding effects of activation-treatments in K-free and K-MoVSbO bronze catalysts for propane partial oxidation

• Studying the effect of different activation protocols on K-free and K-MoVSb oxides.
• Determining their catalytic behavior for propane oxidation into acrylic acid.
• Bulk, surface and catalytic properties depend on composition and activation treatment.
• Sb is the most affected species by the activation treatment and the presence of K.
• K is selectively incorporated in M1-phase structure, reducing its surface acidity.

The effect of activation treatments of K-free and K-MoVSbO bronzes on either their physico-chemical characteristics or catalytic properties for propane partial oxidation have been studied. The as-synthesized materials, hydrothermally prepared and presenting (SbO)2M20O56 type structure (the so called M1-phase), were activated by different heat-treatments, characterized (XRD, SEM-EDS, HRTEM, V K-edge, Sb L1- and K-edges XANES, EPR, XPS, NH3-TPD) and tested in propane partial oxidation. In general, the selectivity to acrylic acid (the most valuable product) was higher in K-containing MoVSbO catalysts. In addition, different trend in the catalytic behavior was found between K-free and K-containing MoVSbO series, mostly related to different changes in crystalline phases distribution and catalysts surface characteristics (composition and acid properties) induced by the several activation treatments which also modified the average Sb oxidation state.

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