Preparation of Hollow Cu and CuO_x Microspheres with a Hierarchical Structure for Heterogeneous Catalysis

Diffusion is one of the most critical factors which affect the performance of porous catalysts in heterogeneous reactions. Hollow spheres with a hierarchical structure could significantly improve the mass transfer in the spherical catalyst. Therefore, preparation of such kind of microspheres is an important work in the field of inorganic synthesis. Herein, we combine microfluidic technology and electroless deposition to prepare hollow Cu and CuOx microspheres with a hierarchically porous structure. These microspheres have a controllable diameter (100–500 μm) and shell thickness (10–60 μm). Numerical simulation and experimental results indicate that the hollow structure is beneficial for the diffusion and utilization of the catalyst in heterogeneous reactions. The Cu and CuOx microspheres were used to catalyze the hydrogenation and Fenton-like reactions in a flow reactor, respectively. The conversion of all reactants can reach more than 95%, and catalysts can maintain their reactivity in long reaction times. Thus, the strategy in the present research should apply in the construction of other porous catalysts with high performance.