Abstract

AbstractThis paper aims to describe and validate two cells designed to monitor, by in situ quick‐EXAFS, the transformation of Mo based oxidic species occurring during maturation and drying preparation steps of a single hydrodesulfurization catalyst. These transformations occur firstly upon impregnation/maturation, due to the contact of the acidic impregnation solution with the basic alumina support, and furthermore upon drying. The Mo K edge in situ quick‐EXAFS monitoring of these two elementary preparation steps is hereby reported for the first time, providing quantitative results of the Mo‐speciation. Ex situ Raman spectroscopy is used effectively as a complement. It considers an impregnation solution with a Mo concentration of 0.75 M and molar ratios of P/Mo 0.56 and Co/Mo 0.4. A two‐step drying mechanism is proposed to explain the evolution of the Mo‐speciation during in situ drying where Strandberg's, Anderson's and Dawson's HPAs are transformed into lacunary Keggin's HPA, octa‐ and monomolybdates.

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