Ilse van Ravenhorst

PhD Candidate

Employed since: November 2015
Phone number: +31 6 33712576
Room: DDW 4th floor study area

3-D chemical imaging of coke formation in hydrotreating catalyst extrudates

With the depletion of fossil fuels and the ever increasing demand for fuels, it is important to make catalyst materials more robust for treating other, less conventional feedstocks to facilitate the gradual move of the (petro-)chemical industry from relatively clean to alternative feedstocks, i.e. the heaviest parts of crude oil, shale and bitumen tars. These alternatives are characterized by a wide variety of poisons as well as by precursor molecules for coke formation and deactivation. This especially holds for hydrotreating catalysts, which most often consist of metal sulphides, more specifically Co-Mo and Ni-Mo sulphides. [1] 

Therefore, it is of great importance to obtain insight in the type and amount of coke (precursor) deposits within Al2O3-supported Ni-MoSx and Co-MoSx hydrotreating catalysts. In order to investigate these catalysts, Au-based Shell-Isolated Nanoparticles (SHINs) will be mixed and compounded in realistic Al2O3 extrudates to enhance the signal for Raman spectroscopy (Figure 1). More specifically, SHINERS-Diagonal Offset Raman Spectroscopy (SHINERS-DORS) will be used to provide 3-D non-invasive chemical insight and obtain spatiotemporal in situ information of the catalyst bodies. [2]

The genesis of coke and related deactivation will be further investigated with soft and hard X-ray microscopy. Scanning Transmission X-ray Microscopy (STXM) employing soft X-rays and Transmission X-ray Microscopy (TXM) employing hard X-rays are used to provide spatial maps of Al, Ni, Mo, S and C. [3] Overlay of chemical maps provide unique spatiotemporal insight in where exactly coke deposits form and how they affect the structure of the metal sulphides nanoslabs.

Figure 1: Shell-Isolated Nanoparticle (SHINs) on catalyst extrudates for SHINERS-DORS measurements.

[1] J. Hagen, “Industrial Catalysis, A Practical Approach”, Wiley- VCH, Weinheim (1999).

[2] M.W. Zandbergen et al., Angew. Chem. Int. Ed., 51, 957-960 (2012).

[3] Al Samarai et al., J. Phys. Chem. C, 119, 2530-2536 (2015).