The starting material was a montmorillonite from Tsukinuno,
supplied by the Clay Science Society of Japan. The raw clay was
pillared with alumina according to a conventional pillaring procedure [17], then used as catalytic support. The supported palladium
catalyst was prepared by wet impregnation of the support with
a solution of palladium (Pd(NO3)2, palladium(II) nitrate solution,
10 wt.% in 10 wt.% HNO3, Sigma–Aldrich) to obtain a material with
a metal loading of 0.1 wt.%. The metal salt/clay slurry was evaporated under reduced pressure in a rotavapor and the resulting solid
dried at 120
◦
C for 16 h before being calcined in air at 500
◦
C for 4 h
to form the final supported catalyst. The modified catalysts were
prepared by treating 5 g of the Pd catalyst with 50 cm
3
of aqueous
Ce(NO3)3·6H2O solutions (99.99%, Sigma–Aldrich) to obtain loadings of between 0 and 1 wt.%. The metal salt/catalyst slurries were
evaporated under reduced pressure in a rotavapor and the resulting
solids dried at 120
◦
C for 16 h before being calcined in air at 500
◦
C
for 4 h to form the final modified catalysts. The catalytic series are
referred to as wt. CePd, where wt. indicates the cerium content.