Thermal Regeneration of Sn-Containing Silicates and Consequences for Biomass Upgrading: From Regeneration to Preactivation
journal contributionposted on 22.09.2020, 18:34 by Luca Botti, Daniele Padovan, Ricardo Navar, Søren Tolborg, Juan S. Martinez-Espin, Ceri Hammond
Minimizing catalyst deactivation and developing regeneration protocols are critical challenges in the area of biomass upgrading. Herein, we investigate the regeneration of Sn-containing zeolites for the continuous conversion of glucose. In doing so, we reveal that permanent changes to the properties of the catalyst occur following continuous operation and regeneration, resulting in surprising improvements to performance during subsequent operational cycles. Through a combination of characterization (119Sn CPMG MAS NMR, DRIFTS, and vapor sorption) and kinetic methodologies, we reveal that improved performance arises from restructuring of the catalyst, which causes the active-site environment to become more accessible, more hydrophobic, more reactive, and more stable. Based on these findings, we demonstrate how these positive changes can be emulated without resorting to extended operation, by optimizing pretreatment of the catalyst prior to reaction. This process, termed preactivation, involves treatment of the fresh catalyst in a flow of methanol at 110 °C for 0.5 h, prior to its heat treatment at 550 °C in air for 3 h. This relatively rapid procedure allows substantial improvements to catalyst activity and stability to be achieved in a permanent fashion prior to the first operational cycle.