Photofluidized bed reactor maximizes photon utilization in heterogeneous photocatalysis: theory to practice

Abstract

Scaling up gas-phase heterogeneous photocatalysis requires the development of high-efficiency, cost-effective photoreactors that maximize photon capture while minimizing parasitic light losses. The integration of photocatalysis with fluidized bed technology enhances light penetration, improves particle–light interactions, and facilitates mass and heat transfer. To elucidate the mechanisms behind enhanced light absorption in a photofluidized bed reactor (PFBR), we employed CFD-DEM simulations and ray tracing to model the absorption characteristics of fluidized particles. Compared to fixed-bed systems, fluidized beds demonstrated significantly improved light absorption, particularly for particles with lower intrinsic absorptivity. The effects of particle size and gas flow rate on light absorption were also analyzed. Experimental validation was conducted using a solar-driven reverse Boudouard reaction, demonstrating the photochemistry of fluidized carbon particles in a carbon dioxide flow within an annular quartz tube reactor, and facilitating carbon monoxide production. At experimentally low gas flow rates, the PFBR exhibited enhanced photocatalytic performance. Furthermore, a comparative analysis of thermochemical and photochemical performance between fluidized and fixed beds highlighted the remarkable solar advantages of PFBRs. The results underscore the advantages of fluidized bed reactors in achieving uniform mixing of reactant gases, particles, and light under isothermal, isobaric, and isophotonic reaction conditions, demonstrating their potential for scalable solar-driven catalytic processes.