Gas-phase oxygen oxidations of alkylaromatics over CVD Fe/Mo/borosilicate molecular sieve. V. Para-selective oxidations of methylaromatics Original Research Article

Gas-phase oxygen oxidation of methylaromatics was studied over the chemical vapor deposited (CVD) M/Mo/partially deboronated borosilicate molecular sieve (DBH) catalysts (M = Fe, Sb, Zn, Bi, Zr or Sn). The methylaromatics include toluene, xylenes, pseudocumene, mesitylene and durene. These catalysts exhibited a unique property of catalyzing oxidation of the two para-oriented methyl substituents in polymethylated benzenes to form terephthaldehyde derivatives. The para-oriented methyl substituents play a key role in defining the catalytic activity and selectivity toward aldehyde. Terephthaldehyde and monoaldehyde derivatives were formed from p-xylene, pseudocumene, and durene while toluene was converted to benzaldehyde. m-Xylene and mesitylene remained unreactive over these catalysts.