Abstract:
This study is focused on the influence of Co and Cu ions located in Zn/Ni/Al matrix on the structural, textural and catalytic
properties of layered double hydroxides (LDHs). The samples were prepared by co-precipitation (Ni2+/Co2+(Cu2+)=0.25;
M2+/M3+=2)) at low super-saturation and afterwards characterized by XRD, nitrogen physisorption, thermogravimetry, FT-IR, DR
UV-Vis and TPR. The XRD results show that the resulted solids are well crystallized and contain only pure phases of LDHs.
Also, the spectral techniques indicated that both Co and Cu species are successfully introduced in the brucite-like layers. The
catalysts have been simply activated under hydrogen flow at 150°C for 2h and tested in the liquid-phase hydrogenation of transcinnamaldehyde.
The results indicated that the nature of the substituted cations exerts great influence on the activity and
selectivity of catalysts. Thus, Cu-containing LDH was very active but less selective to cinnamyl alcohol, while Co-containing
LDH was less active but very selective to unsaturated alcohol. Their catalytic activities have been explained taking into account
the reducibility of cations at low temperatures, while the catalytic selectivities have been explained on the basis of the width of dband.