The conversion of methanol to hydrocarbons using composite catalysts comprising physical mixtures of the zeolite H-ZSM-5 with group 13 oxides (gamma-Al2O3, beta-Ga2O3, In2O3, Tl2O3) is reported and discussed. The addition of beta-Ga2O3 at 400degreesC gives a marked enhancement in the yield of C-8 and C-9 aromatic compounds, whereas the addition of gamma-Al2O3 has no effect and both the In2O3/H-ZSM-5 and Tl2O3/H-ZSM-5 are inactive. At 300degreesC, a marked enhancement in the yield of aromatic hydrocarbons is observed for beta-Ga2O3 and In2O3, and a less marked enhancement is observed with Tl2O3 and gamma-Al2O3. In particular, the addition of In2O3 to H-ZSM-5 as a simple physical mixture gives a significant enhancement in catalyst activity at 300degreesC. The effect of the Si:Al atomic ratio of H-ZSM-5 is also investigated for the beta-Ga2O3/H-ZSM-5 ratio is dependent upon the Si:Al ratio. Pretreatment or co-feeding of hydrogen decreases the yield of the aromatic products. The results are explained in terms of an active site formed by the interaction between the oxide and the zeolite.
- promotion in heterogeneous catalysis
- methanol conversion
- aromatic hydrocarbon synthesis
- group 13 oxides
- beta-Ca theta O-2(3)/H-ZSM-5 composite catalysts