Temperature-programmed reduction (TPR) was used for examining the catalyst reducibility, and performed on the AMI1 system from Altamira Instruments, USA, equipped with TCD. Before the measurements, the calcined catalysts were in-situ heated up to 300 °C for 30 min in a mixture of 2 vol% O2 and 98 vol% Ar at a space velocity W/F = 1.11 × 10 -5 g/h cm 3 (10 °C/min heating rate) to remove impurities from the sample surface. The TPR profiles were recorded from 35 °C up to 800 °C, with a heating rate of 7°C/min, using a mixture of 5 vol% H2 and 95 vol% Ar at a similar space velocity.