| Research Abstract |
It has been known that Mo on HZSM-5 catalyst promotes the dehydro-aromatization of methane to benzene and naphthalene with far higher activity and selectivity than the other catalysts. In searching central metal of the catalyst from 17 elements, we found a new Re/HZSM-5, which is an equally active and selective catalyst as Mo/HZSM-5 in the dehydro-aromatization of methane. The active phase to the reaction on Re/HZSM-5 was revealed to be Re metal from XAFS and TPR (temperature programmed reaction)/TG/Mass studies, in contrast to Mo carbide on Mo/HZSM-5 catalyst. Further, we looked for new supporting materials, which are equally effective to the reaction as HZSM-5. Among tested materials, those zeolites having pore size of 5.3-5.6Å such as MCM-22, ZPR-1, ZSM-11 similar to the size of aromatic ring exerted high activity and selectivity. In summary, the dehydro-aromatization reaction of methane is promoted with high activity and selectivity to benzene and naphthalene on the unique catalysts, whose central metal comprised of Re or Mo and whose support is selected from zeolites with pore size of 5.3-5.6Å.
Effect of second metal added in Mo or Re was tested. As a result, bimetallic catalysts of Mo or Re with La supported on the selected zeolite found to increase the activity and the stability in the reaction.
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