Effective encapsulation of Ni nanoparticles in metal-organic frameworks and their application for CO2 methanation

Ni(10 wt%)@UiO-66 and Ni(10 wt%)@MIL-101 composites were prepared by the classical impregnation method (IMP) and the double solvent method (DS), followed by the rapid and simple reduction of Ni2+ to Ni-0 by aqueous solution of NaBH4. Structural characterization by BET, XRD, TGA, SEM/EDX, EELS, XPS showed that Ni nanoparticles of maximum 4 nm are uniformly dispersed on the microporous UiO-66 or the mesoporous MIL-101 support, regardless of the deposition method, without any significant difference in crystallinity and morphology of the MOF support. Functional characterization through temperature programmed desorption of CO2 (CO2-TPD) reveals an important contribution of the Ni-MOF interaction in the CO2 adsorption capacity. The best catalytic performance in CO2 hydrogenation reaction was obtained in case of the Ni MIL-101 (IMP) sample: X-CO2 of 56.4%, and S-CH4 of 91.6% at 320 degrees C, 4650 h(-1) and CO2:H-2 = 1:8. All catalyst samples show stable catalytic performance parameters over a 10 h time on stream. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.