In-situ generation of gas bubbles in porous gel spheres for multiphase catalysis

Capturing gas bubbles in liquid is vital for the gas-liquid-solid (GLS) three-phase reactions due to the limited gas solubility. Constructing the special porous skeleton for bubble accommodation opens an opportunity to drag bubbles in liquid. Herein, mm-sized Pd-anchored cellulose/agarose (PCA) spheres with a highly porous architecture have been fabricated using a liquid nitrogen-freezing method. PCA particles could act as gas carrier to accommodate a variety of gas bubbles in liquid, including H 2 , O 2 , air, and CO 2 via an in-situ nucleation route. Moreover, these PCA beads enabled efficient multiphase catalysis as demonstrated by cascade reduction of a series of substances, such as aldehydes, nitroarenes, and alkenes. Their catalytic activities remarkably surpassed Pd-deposited solid glass spheres (PG) and sole Pd nanoparticles, manifesting the important role of their porous texture in gas harvesting and storage. A gas (H 2 ) utilization of 98.0 % was attained for multiphase reaction over PCA beads. During multiphase reaction process, a controllable motion of PCA spheres was achieved via gas reservation or consumption. This work provides a profound inspiration for bubble arresting and stabilization toward regulable movement and multiphase processes.