Table 1

Direct hydroxylation of benzene to phenol and toluene to cresol with oxygen and hydrogen catalyzed by a palladium membrane. “Inner” and “outer” mean that a gaseous mixture containing a hydrocarbon was flowed inside or outside of the palladium membrane tube, respectively. Selectivity was based on the amount of benzene or toluene consumed.

CatalystReaction temp. (°C)Reaction system (volume ratio)Results
Aromatic/O2/He (28 ml/min)H2/He (14 ml/min)Reactant conversion (%)Product selectivity (%)
Benzene
Pd membrane (inner)1500.40/1.29/24.62.43/20.013.2585.3
Pd membrane (inner)1600.45/4.70/29.86.72/28.21.6096.3
Pd membrane (inner)2501.80/8.51/24.610.06/24.92.0592.7
Pd membrane (outer)1502.00/1.29/24.62.43/20.02.1194.8
Pd membrane (outer)2002.00/1.29/24.62.43/20.03.0093.3
Toluene
Pd membrane (inner)1500.40/1.29/24.62.43/20.03480