SULPHURREAL · An innovative thermochemical cycle based on solid sulphur for integrated long-term storage of solar thermal energy

SULPHURREAL aims at demonstrating and validating a breakthrough approach for next generation, carbon-free, direct conversion of solar energy into chemicals storable for a virtually unlimited time, based on elemental sulphur produced and consumed on-demand via a solar-aided thermochemical cycle. The project is targeted on the one hand to develop disruptive catalytic technologies for the two catalytic steps of this solid sulphur thermochemical cycle, namely the high- (800-850 C) and medium- (600-650 C) temperature catalytic SO3 splitting to SO2 and oxygen and the subsequent disproportionation of SO2 to solid sulphur and sulphuric acid. The research line involves identifying, developing and testing novel catalysts and reactor designs under operating conditions so that these two, less developed steps of the cycle cf. sulphur combustion, can be integrated and performed in sequence with maximum compatibility in a first-of-its kind integrated approach. Innovations to be introduced concern not only novel catalyst compositions but also novel reactor designs and methods of applying and distributing the catalysts within the reactors, to achieve maximum utilisation of the active catalytic materials and optimal combination of improved performance, conversion efficiency and process cost reduction. On the other hand, SULPHURREAL will further develop and upscale a first-of-its-kind sulphur burner operating at power density > 5 MW/ m³ at ambient pressure and having demonstrated potential for prolonged operation at power densities of > 75 MW/cbm for typical operating pressure of 15 bar by simulations. The proposed combination integrates renewable energy sources (solar energy) with valorisation of non-CRM substances currently produced as industrial by-products from oil and gas (solid sulphur) and steel industries (Fe-containing slags) and industrial-scale chemicals production (sulphuric acid industry) in absolute accordance with a circular economy environment and industrial symbiosis.