Activation of Co−Mo−S Hydrodesulfurization Catalysts Under Refinery Conditions‐A Combined SAXS/XAS Study. Issue 20 (20th September 2019)

• Record Type: Journal Article
• Authors: van Haandel, Lennart; Longo, Alessandro; Bras, Wim; Hensen, Emiel J. M.; Weber, Thomas
• Is Part Of: ChemCatChem. Volume 11:Issue 20(2019)
• Page Start: 5013
• Page End: 5017
• Publication Date: 2019-09-20
• Subjects: Heterogeneous catalyst -- Nanoparticle formation -- Hydrodesulfurization -- SAXS -- EXAFS; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201901390
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The activation of heterogeneous catalysts is challenging to follow experimentally and poorly understood in many cases. We combine in situ and time‐resolved X‐ray absorption spectroscopy and small‐angle X‐ray scattering to study the activation of Co‐Mo−S hydrotreating catalysts under conditions close to a refinery start‐up, i. e., 20 bar H2 pressure and gaseous H2 S or liquid sulfiding agents. Formation of MoS2 nanoparticles involves three stages, namely aggregation (50–150 °C) and self‐assembly (150–250 °C) of two distinct amorphous MoSx intermediates, followed by a transition into layered structures that closely relate to the MoS2 structure. In stage III, these nuclei coalesce into the final MoS2 nanoparticles. Their growth distribution and stacking degree can be tailored by controlling the aggregation step, paving the way for the synthesis of better hydrotreating catalysts. Our experimental approach enables studying a broad range of supported amorphous nanomaterials at various length scales and operating conditions relevant to important catalytic processes. Abstract : Take a closer look : Small angle X‐ray scattering, and X‐ray absorption spectroscopy were combined to observe the birth of a hydrodesulfurization catalyst under industrial conditions. It is shown that MoS2 stacking, an important property of these catalysts, is determined by aggregation of meta‐stable MoSx intermediates and can be controlled during catalyst activation