Highly active and stable Co (Co3O4)_Sm2O3 nano-crystallites derived from Sm2Co7 and SmCo5 intermetallic compounds in NH3 synthesis and CO2 conversion

Intermetallic compounds (IMCs) are interesting materials in the field of heterogeneous catalysis due to their ordered structure and tunable electronic properties. These IMCs can act as precursor to synthesize metal/metal oxide composite catalysts that are more active than just the starting IMCs. In this work, Sm2Co7 and SmCo5 IMCs were used as precursors to prepare highly active and stable Co_SmO, Co_Sm2O3 and Co3O4_Sm2O3 catalysts via controlled modification. Transmission electron microscopy (TEM) demonstrated that Co and Sm2O3 Nano crystallites were formed after the modification of the IMC. IMCs derived Co_SmO and Co_Sm2O3 were stable and active in NH3 synthesis with very low activation energy of 55 and 77 kJ mol−1 respectively. The structural, morphological and surface characterization revealed that a strong metal support interaction existed between Co and Sm2O3 (electronic effect) along with the presence of surface steps and edges of Co nano crystallites (structural effect) that activate the N2 at low temperature (360 °C). Similarly, Co3O4_Sm2O3 derived from the IMC were found to exhibit high CO2 and butane conversion in butane dry reforming at low temperature (550 °C) with excellent stability. The study revealed that the presence of Co3O4 and Sm2O3 active sites in close proximity (geometrical effect) promoted the simultaneous adsorption or activation of butane and CO2. The Co_Sm2O3 and Co3O4_Sm2O3 derived from IMCs exhibited superior catalytic performance in both NH3 synthesis and butane dry reforming compared to similar compositional catalyst synthesized by hydrothermal route. These studies pave the way to potential uses of IMCs as precursors to derive composite metal/metal oxide catalysts that are highly stable and active despite their low surface areas.