Quantitative imaging of carbon in heterogeneous refining catalysts

Abstract

Heterogeneous catalyst materials are the core of crude oil purification process performance. Catalyst deactivation, which is a result of crude impurity deposits into catalyst pores during this process, is therefore a major concern during refining. However, deactivation mechanisms are not easily investigated, as they involve carbon transport phenomena over a large range of concentrations, typically from hundreds of ppm to tens of mass%. Spatially resolved analysis of carbon conducted at the entire grain scale (∼mm²) with a micrometric resolution is therefore of primary importance to better predict, control, and further improve the purification processes. However, usual spatially resolved approaches are not easily suitable for mm²-scale analysis and/or not adequate in terms of carbon detection limits. In this work, we propose a quantitative methodology dedicated to carbon spatially resolved analysis and the evaluation of its analytical performance. This approach, based on laser-induced breakdown spectroscopy (LIBS), allows for the first time 2D imaging of carbon at different process times as well as quantitative profiling of carbon diffusion over more than two orders of magnitude in concentration.