Polyoxymethylene ethers as attractive hydrogen transport vectors? - Concept evaluation and steam reforming investigations

The efficient and safe transportation of renewable hydrogen remains a major challenge. Polyoxymethylene dimethyl ethers (OMEs) might be promising hydrogen transport vectors due to their liquid state at ambient conditions, low toxicity and high technical hydrogen capacity. However, two major bottlenecks for their application are identified: the direct synthesis of OMEs from CO 2 and H 2 and the catalytic steam reforming of OMEs for hydrogen release, which remains largely unexplored. A hydrogen transport cycle based on OME 1 is proposed and compared with methanol and dimethyl ether regarding technical and energetic characteristics. Experimentally, OME 1–3 steam reforming is investigated over In 2 O 3 /ZrO 2 catalysts. High OME conversion, hydrogen yield and long-term stability over 380 h on stream are achieved. OME hydrolysis is facilitated compared with dimethyl ether and requires no additional acidic catalyst. For the first time, OME 2 and OME 3 are successfully steam-reformed with comparable rates and stability to OME 1 .