DEHYDROCYCLIZATION AND POSITIONAL ISOMERIZATION OF PIPERYLENE - NEW METHOD FOR PRODUCING 1,4-PENTADIENE

A study has been made of the conversion of piperylene on oxide catalys ts based on group II metal oxides containing Fe2O3. It has been found that, on these catalysts at 630 degrees C, piperylene forms cyclopente ne, cyclopentadiene, 1,4-pentadiene, cracking products and products of hydrogen transfer (n-pentenes). The highest yield of C-5 cyclic hydro carbons is achieved by Fe2O3-MgO (11%). Cyclizing activity is also exh ibited by individual oxides, and here the yield of cyclic hydrocarbons increases with increasing basicity of the oxide, while the 1,4-pentad iene yield increases in reverse order. The highest 1,4-pentadiene yiel d is observed on BeO and its compounds with magnesium oxide. The highe st yields and selectivity (6 and 77% respectively) were obtained on a catalyst containing 80% BeO and 20% MgO at a temperature of 575 degree s C with a volume feed rate of piperylene of 1.0 h(-1) and a steam dil ution molar ratio of 1:10. The yield obtained amounts to two thirds of the thermodynamically possible yield.