Interaction of the oh groups of the zeolitic support with the p-v-o active component in a redox catalyst

Abstract

The results of the measurements of the concentration changes of structural OH groups or electron acceptor centres of the following types of zeolitic catalysts are given in this article: (i) a HY zeolite either with the supported active component P-V-O (P/V = 1) or with a component containing only either vanadium or phosphorus in concentrations corresponding to the active component P-V-O; (ii) a zeolite HZSM-11 with the supported active component P-V-O. The latter catalyst,in contrast to the catalysts based on HY zeolite, makes it possible to oxidize butadiene up to maleic anhydride and not only to furan. The changes of the OH group concentrations were determined by measuring the changes in the absorbances of the stretching vibration bands of the structural OH groups and by measuring the changes of the initial reaction rates of ethylene oligomerization. In the discussion of the results, it is shown that the difference in the selective oxidation of butadiene is caused by interaction of the OH groups of the supporting HY zeolite localized in the large cavities of its skeleton with both phosphorus and vanadium present in the active component P-V-O. In the case of the zeolitic catalyst HZSM-11 supporting the same active component, no such interaction has been found; this explains the different catalytic behaviour of zeolitic catalysts (i) and (ii).