The decomposition of C 3 H 8 and its reaction with CO 2 have been investigated on Au deposited on ZnO, MgO and Al 2 O 3. The reactions proceeded above 650-700 K. The conversion of C 3 H 8 was only few percents on Au/MgO and Au/Al 2 O 3 , even at 873 K, but reached $17% on Au/ZnO. The selectivity of propylene formation was about 56%. CO 2 only slightly affected the reaction of C 3 H 8 on Au/Al 2 O 3 and Au/MgO, but significantly enhanced the conversion of C 3 H 8 on Au/ZnO catalyst. The formation of large amount of CO indicates the involvement of CO 2 in the reaction of C 3 H 8. From the product distribution it was inferred that beside the oxidative dehydrogenation and dry reforming reaction, the decomposition of C 3 H 8 into CH 4 and surface carbon also occurred. The effect of ZnO is explained by an electronic interaction between n-type ZnO and Au particles leading to a formation of reactive CO 2 À .

Reaction of C 2 H 6 with CO 2 Au catalyst Effects of supports Electronic interaction between Au and oxides a b s t r a c tThe dehydrogenation of C 2 H 6 and its reaction with CO 2 have been investigated on Au deposited on various oxides. Both reactions occurred at relatively high temperatures, above 650 K. Ethylene formed in the dehydrogenation process with high selectivity, 94-98%, on most of the catalysts. The conversion of C 2 H 6 varied with the nature of support and fell in the range of 3-19%. Adding CO 2 to C 2 H 6 only slightly influenced the reaction of C 2 H 6 on Au/MgO and Au/Al 2 O 3 , but markedly increased the conversion of C 2 H 6 and changed its reaction pathways on Au deposited on n-type TiO 2 , CeO 2 and ZnO. Taking into account the properties of these oxides, we came to the conclusion that their electric behavior and not their defect structure play a dominant role in the enhanced activity of Au deposited on these supports. Based on the different work functions, an electronic interaction between Au particles and these oxides is proposed, which facilitates the formation of reactive negatively charged CO 2 .

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