Pd/oxide/cordieritemonolithic catalysts (oxide=Al

2

O

3

SiO

2

and SiO

2

-Al

2

O

3

)were prepared by the impregnation method. The results of ICP

XRD

SEM-EDX

XPS and N

2

adsorption-desorption measurements revealed that the Pd penetration depth increased with increasing the thickness of oxide layer

and the catalysts with Al

2

O

3

layers had the larger pore size than those with SiO

2

and SiO

2

-Al

2

O

3

layers. Catalytic hydrogenation of 2-ethylanthraquinone (eAQ)

a key step of the H

2

O

2

production by the anthraquinone process

over the various monolithic catalysts (60℃

atmosphere pressure) showed that themonolithic catalystwith the moderate thickness of Al

2

O

3

layer (about 6 μm) exhibited the highest conversion of eAQ (99.1%) and hydrogenation efficiency (10.0 g·L

-1

). This could be ascribed to the suitable Pd penetration depth and the larger pore size

which provides a balance between the distribution of Pd and accessibility of active sites by the reactants.