Mid/low-temperature solar hydrogen generation via dry reforming of methane enhanced in a membrane reactor

Dry reforming of methane (DRM) is a promising approach for hydrogen generation and decreasing CO₂ emission. However, the high reaction temperature of DRM (~800 °C) has strict requirements on materials and sealing, which also has high heat losses during the reaction process. In this study, a solar thermochemical system integrated with a parabolic trough solar collector and a membrane reactor is proposed for decreasing the reaction temperature of DRM to a mid/low-temperature range (300–500 °C). Due to the selective H₂ separation via the H₂ permeation membrane reactor, the equilibrium of the DRM reaction shifts forwards, leading to a lower reaction temperature, and high-purity hydrogen can be collected during the one-step process. The conversion rate of CH₄ in this experimental research could reach 20.47% at 400 °C and 30.00% at 425 °C, which is higher than state-of-the-art results. Besides, the thermodynamic analysis of the proposed system indicates that the first-law thermodynamic efficiency and the solar-to-fuel efficiency could reach as high as 74.73% and 38.92%, respectively. The chemical exergy of methane can be utilized efficiently by enhancing the energy level of solar thermal energy. This research provides a novel approach for efficient solar energy storage and hydrogen generation with negative CO₂ emissions.