A passive and stable aerogel reactor based on Ag-loading cellulose Pickering emulsion

A pump-free, stable and efficient aerogel reactor with abundant pores is designed using Ag-loading cellulose Pickering emulsions as a template for the continuous flow catalytic reduction of 4-nitrophenol. The fabrication of the aerogel reactor entails the two-step oxidation synthesis of aldehyde-functionalized cellulose nanocrystals (ACNC), the in-situ reduction of Ag nanoparticles (NPs) on them to form Ag@ACNC, the utilization of this material to stabilize a Pickering emulsion for preparing the hydrogel, and finally the freeze-drying of the hydrogel laying on a fabric strip. The emulsion-templated aerogel features abundant pores with loading Ag NPs on inner walls, enabling reactant to flow through the pores rapidly under driving by its gravity and the capillary action of the supporting fabric strip and react on the walls. The aerogel reactor achieves efficient three-dimensional flow catalysis without an external power source and exhibits excellent conversion and stability. The conversion all remains above 91.8% during the continuous flow catalysis reaction of 6 cycles (totaling 72 h), and the conversion still reaches 94.4% at 12 h after storage in air for 60 days. This emulsion-templated aerogel reactor demonstrates great potential for advancing recyclable catalytic systems, thereby paving the way for its wide applications.