Proposal and Evaluation of a Novel Solar Methane Carbon Cycling Reforming System for High-Purity H2 and Co Production

Abstract

Refining high-purity H2 from the gaseous product mixture in solar methane dry reforming (MDR) causes large separation energy consumption, which is derived from the high-pressure demand for H2 adsorption.To alleviate this challenge, we propose a solar methane carbon cycling reforming (MCCR) system primarily consisting of catalytic methane decomposition (CMD) and reverse Boudouard (RB) processes. This ingenious combination of the CMD and the RB can separately produce H2 and CO in different reaction stages, preventing high absorption pressure for product separation and enhancing system efficiency. In addition, we also develop a strategy that enables continuous and stable production of separated H2 and CO during a whole day with an increased solar share and study the off-design performance of the proposed system. The results show that the auto-separation decreases 72.63% of energy consumption compared with that of product refinement from a multi-component gaseous mixture in traditional solar MDR. In the daytime, solar energy is converted into fuel chemical energy with a solar-to-chemical efficiency of 18.14%, and a more impressive efficiency of 22.53% is achieved during nighttime by burning solar fuel stored in the daytime with the solar share ranging from 15.38% to 28.20%. The overall energy and exergy efficiency during a whole day can reach 67.74% and 65.31%, which are 11 and 8 percentage points higher than that of the reference system. The proposed system with excellent performance offers a promising way to efficiently utilize solar energy and fossil fuels.

Keywords: Solar thermochemical conversion, Methane carbon cycling reforming, Hydrogen production, Product auto-separation, Complementation of solar energy and fossil fuels.