Hard X-ray-based techniques for structural investigations of CO2 methanation catalysts prepared by MOF decomposition. Issue 29 (21st July 2020)

• Record Type: Journal Article
• Authors: Prinz, Nils; Schwensow, Leif; Wendholt, Sven; Jentys, Andreas; Bauer, Matthias; Kleist, Wolfgang; Zobel, Mirijam
• Is Part Of: Nanoscale. Volume 12:Issue 29(2020)
• Page Start: 15800
• Page End: 15813
• Publication Date: 2020-07-21
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d0nr01750g
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : We investigate the structure-activity correlations of methanation catalysts obtained by thermal decomposition of a Ni-based metal-organic framework, using pair distribution function, X-ray absorption spectroscopy and X-ray diffraction. Abstract : Thermal decomposition of metal–organic framework (MOF) precursors is a recent method to create well-dispersed metal centers within active catalyst materials with enhanced stability, as required for dynamic operation conditions in light of challenges caused by the renewable energy supply. Here, we use a hard X-ray-based toolbox of pair distribution function (PDF) and X-ray absorption spectroscopy (XAS) analysis combined with X-ray diffraction and catalytic activity tests to investigate structure–activity correlations of methanation catalysts obtained by thermal decomposition of a Ni(BDC)(PNO) MOF precursor. Increasing the decomposition temperature from 350 to 500 °C resulted in Nifcc nanoparticles with increasing particle sizes, alongside a decrease in Ni 2+ species and strain-induced peak broadening. For lower temperatures and inert atmosphere, Ni3 C and NiO phases co-existed. A graphitic shell stabilized the Ni particles. Compared to an inert atmosphere, reducing conditions led to larger particles and a faster decomposition of the MOF precursor. Catalytic studies revealed that the decomposition at an intermediate temperature of 375 °C in 5% H2 /He is the best set of parameters to obtain high specific surface areas while maintaining particle sizes that feature many active Ni centers for the formation of CH4 .