XRD patterns were recorded on a Bruker D8 Focus instrument
by using Ni filtered Cu Karadiation. The crystallite size was calculated from the XRD spectra by using the Scherrer equation. Full
nitrogen adsorption/desorption isotherms at 77 K were obtained
after outgassing of the sample under vacuum at 473 K for 3 h, using
a Micromeritics ASAP2020 M+C adsorption apparatus. The active
surface area of Cu (SCu) was determined by the technique of N2O
reactive frontal chromatography at 333 K assuming a Cu:N2O=2
titration stoichiometry and a surface atomic density of
1.4610
19 copper atoms per m
2
, respectively [5].H2-TPR measurement was carried out by using 10% H2/N2as a reducing gas
in a quartz microreactor with 30 mg catalyst. The flow rate of the
reducing gas was kept at 30 ml/min and the temperature was
raised from 373 to 673 K at a rate of 5 K/min. The amount of consumed H2was measured by a TCD.