Hydrogen production and decarbonization with hydrogen absorption-enhanced methanol steam reforming

Abstract

Methanol, as a promising liquid hydrogen carrier, has attracted considerable interest in sustainable energy applications due to its renewability and ease of storage and transportation. Although methanol steam reforming for hydrogen production has been extensively studied, it faces several challenges, including high energy consumption at elevated temperatures, low hydrogen purity, and substantial CO₂ emission. We propose a four-step H₂ absorption-enhanced methanol steam reforming method that includes reforming/absorption, vapor purge, vacuum desorption, and pressurization steps. A two-dimensional, axisymmetric transient numerical model is developed, accounting for flow, heat transfer, mass transfer, chemical reactions, and hydrogen absorption/desorption. All components of the established model, including methanol steam reforming and H₂ absorption/desorption, are separately validated through experimental data, confirming the reliability of the model. Results indicate that under baseline conditions of 463 K and 3 bar, the reforming/absorption step achieves a methanol conversion of 98.88% and a hydrogen production rate of 0.87 mmol g⁻¹ min⁻¹, representing an improvement of 17.43 percentage points and 0.17 mmol g⁻¹ min⁻¹ compared with conventional methanol steam reforming, respectively. Additionally, a CO₂ stream with a concentration of 98.87% is obtained from the reactor outlet, which is comparable to the concentrations achieved by specialized CO₂ capture technologies and can be directly sequestered or reused. In the four-step cycle, incorporating the vapor purge enhances hydrogen purity, achieving levels exceeding 99.9%, compared with only 96.89% purity in the direct vacuum desorption method. Moreover, the four-step method obtains a hydrogen recovery rate of 98.92%. The proposed method provides a clean, straightforward, and highly integrated approach to sustainable hydrogen production and presents a novel option for accelerating the decarbonization of fossil fuel-dominated energy systems.