The effect of Al-doping on ZnO nanoparticles applied as catalyst support.

A pure ZnO sample and a sample containing 3 mol% Al were prepared by (co)-precipitation as model materials for the oxidic support phase in Cu/ZnO/Al(2)O(3) methanol synthesis catalysts. The samples were characterized with respect to their crystal, defect and micro-structure using various methods (XRD, TEM, XPS, UV-vis spectroscopy, EPR, NMR). It was found that a significant fraction of the Al is incorporated into the ZnO lattice and enhances the defect chemistry of the material. The defect structure, however, was not stable under reducing conditions as applied in catalytic reactions. Al ions migrated towards the surface of the ZnO nanoparticles leading to formation of an Al-rich shell and an Al-depleted core. This process proceeds during the first 10-20 hours on stream and is associated with strong modification of the optical bandgap energy and the EPR signal of donor sites present in ZnO.

Evidence for C-C bond cleavage by H2O2 in a mesoporous CMK-5 type carbon at room temperature.

We reported an evidence for C-C bond cleavage by milder oxidizing agent H2O2 in a mesoporous CMK-5 type carbon at room temperature.