No abstract

No abstract

Ethane and methanol are converted simultaneously over Ga/H-ZSM-5, Mo/H-ZSM-5 and Ga-Mo/ H-ZSM-5 to produce light olefins and aromatics. The presence of methanol in the reactant stream is intended to facilitate activation of ethane following literature reports on co-conversion of methane and methanol. However, the conversion of ethane actually decreases significantly when methanol is present. To gain insight into mechanistic details, 13 C-labeled methanol is co-converted with unlabeled ethane. These isotopic labeling studies show that carbon atoms from ethane and methanol are mixed in the products and in the carbonaceous compounds deposited on the catalysts. This indicates that both reactants take part in the formation of the hydrocarbon pool, which is the origin of all products.

Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing amounts of ethene were produced with time on stream due to deactivation of the catalyst. We show that by use of rhenium impregnated MFI supports with very few or no acidic sites (Si/Al > 500), highly selective ethane dehydrogenation catalysts are obtained with ethene selectivities of 98%. By use of mesoporous MFI supports (Si/Al >500) the lifetime of the catalyst appears to be slightly improved compared to conventional MFI crystals. The beneficial effect of a mesoporous MFI support is convincingly demonstrated in propane dehydrogenation, where both conversion and selectivities on the mesoporous MFI (Si/Al > 500) impregnated with Re are significantly higher than on Re supported on a comparable conventional MFI support.