CNx stabilized Ni-Ga nanoparticles for CO 2 hydrogenation: Role of preparation methods

Carbon based framework are believed to be adsorbed large amount of hydrogen reversibly on its surface and this adsorbed active H-species can increase the rate of surface hydrogenation reactions. The basic nitrogen functionality if present can provides additional sites for adsorption of CO 2 molecule. On this regard, CO 2 hydrogenation has been investigated on multifunctional nitrogen doped carbon (CNx) consisting of Ni-Ga nanoparticles. Alloy nanoparticles (2–10 nm) of Ni 3 Ga and Ni 3 Ga 5 has been identified from HR-TEM in combination of d value calculation form XRD. Whereas, mix Ni and Ni-Ga phase appears in case of higher loading catalyst i.e. NG-CNx-3. Under experimental conditions (2 MPa, 280 °C), the CO 2 hydrogenation products are CH 4 , CO (major) and methanol. The activity of the synthesised catalysts strictly depends on the synthesis method and support. The catalyst consisting 14 and 9 (wt %) of Ni and Ga on CNx (NG-CNx-2) shows highest catalytic activity in terms of CO 2 conversion. While NGBCNx-2 with 14 and 9 (wt %) of Ni and Ga on BCNx is found to be active towards methanol selectivity which may be due to the finely dispersed Ni-Ga alloy nanoparticles with size distribution between 2–5 nm.