Evolution of the pore structure-transport relationship during catalyst reduction and sintering studied by integrated multi-scale porosimetry and multi-modal imaging

Abstract

Catalyst pellet fabrication parameters significantly impact final product performance. Tabletted pellets are complex, hierarchical structures that evolve differently over various levels during subsequent processing. Multi-scale porosimetry and multi-modal imaging can, together, encompass all length-scales involved, and, therefore, fully characterise the evolving pellet structure during catalyst reduction and sintering. A random pore-bond network model has highlighted the key pellet structural features determining mass transport, and, thence, was predictive of the impact on mass transfer of controlled modifications to the void space for reduced and aged catalysts. Particular macroporosity, newly induced by reduction and sintering, was critical to mass transport out of proportion to its pore volume fraction. Combined X-ray tomography imaging and percolation modelling showed that reduction and sintering leads to a change (compared to the fresh state) in the initial pellet fabrication parameter that controls mass transport in pellets formed with roll-compacted feed.