E L E C T R O N I C S T R U C T U R E , M A G N E T I S M A N D D Y N A M I C S

S C I E N T I F I C H I G H L I G H T S

1 0 8 H I G H L I G H T S 2 0 2 1 I

and Figure 87b, respectively. The formation of the Co2C was confirmed by XRD, as shown in Figure 87c. For the FTS reaction, the Co L3-edge presented the characteristic shift produced by the formation of Co2C, again monitored simultaneously by XRD. The C K-edge spectrum confirms the evolution of graphitic carbon species in the catalyst during the FTS reaction. The C K-edge spectra were fitted

to different standard reference measurements to identify and quantify the different carbon species presented in the catalyst during the reaction.

Significant correlation was observed between the conversion of metallic Co to Co2C and the spatial position along the bed of the capillary reactor for the control

Fig. 87: a) In-situ Co L2,3-edges for the control experiment (carburisation reaction), the spectrum of metallic Co in red and the spectrum after carburisation in black. b) In-situ C K-edge for the control experiment, spectrum at the beginning of the carburisation reaction in blue and carburised spectrum in dark red. c) In-situ XRD patterns collected during the control experiment. From bottom to top: reduced cobalt, carburisation steps of 2h, 4h and 6h, and after re-hydrogenation. Diffraction peaks of fcc- Co are marked with % and hcp-Co with & , Co2C peaks are marked with # , and boron nitride peaks are marked with $ .

Fig. 88: Left: Image of the capillary reactor recorded during the in-situ XRS experiments using the spectrometer s imaging capability. The thermocouple can be seen at the top of the reactor. Right: In-situ XRD measurements performed at different positions of the bed of the capillary reactor. Diffraction peaks of fcc-Co are marked with % and hcp-Co with & , Co2C peaks are marked with # , and boron nitride peaks are marked with $ .