1991 Volume 64 Issue 6 Pages 1926-1932
The ternary oxide system MoO3–SiO2–Al2O3 was prepared by coprecipitation method. The pH of coprecipitation has been varied from pH=2 to pH=8 and its effect on the acidic properties of the ternary oxide acidic system was studied by butylamine titration. The MoO3–SiO2–Al2O3 prepared from highly acidic solution has low acid strength. The total acid amount of the ternary oxide decreased considerably at higher pH (>6) of coprecipitation. It was found that the total acid amount of MoO3–SiO2–Al2O3 containing 9.7% (by weight) of MoO3 and silica to alumina molar ratio 16.6 is very high compared with that of SiO2–Al2O3 of the same silica to alumina molar ratio. The acid strength of SiO2–Al2O3 is reduced by the incorporation of MoO3. Increase in calcination temperature increased the acid strength. The catalytic activity of MoO3–SiO2–Al2O3 was found to be very high for the alkylation of toluene with 2-propanol. The products are found to be o-cymene, p-cymene, and three isomers of diisopropyltoluenes. Reaction temperature >200°C, higher liquid hourly space velocity, and higher alcohol content in the feed decreased the total conversion of 2-propanol to isopropyltoluenes. The acidic property and catalytic activity of MoO3–SiO2–Al2O3 are not considerably reduced up to four successive regeneration cycles.
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