High-efficiency microreactor design for hydrogen peroxide decomposition: impact of concentration and flow rate on two-phase flow instability and conversion

Microreactors have been widely applied in various fields involving gas-liquid two-phase reactions. However, there is still a need to achieve stable and high conversion rates in microreactors because the complex interactions between the gas and liquid phases can lead to unstable flow patterns, resulting in inefficient mass transport and reduced conversion rates. This work designs a novel radial channel microreactor for hydrogen peroxide decomposition. By integrating fast Fourier transform (FFT) and wavelet transform (WT) methods for time-frequency analysis with visual experiments, this study reveals the impact of reactant flow rate and concentration on flow instability, as well as flow pattern transitions. The radial channel reactor attains a conversion level that remains unaffected by variations in reactant flow rate by employing periodic flow pattern transitions when using 3 wt.% H₂O₂. In the case with 10 wt.% and the case with 30 wt.% H₂O₂, the radial channel reactor can stabilize the flow pattern transition to achieve a high conversion. The highest conversion rate for H₂O₂ decomposition is 92.7 % in the case with 30 wt.% H₂O₂, surpassing the previously reported values in the literature. Through multiple linear regression (MLR) method, a predictive model is proposed and helps to elucidate the effects of reactant flow rate and concentration. This work proves an improved reactor design to utilize and alleviate two-phase flow instability can enhance reactor performance and achieve high conversion rates.