High Temperature Reactor Catalyst Material Development for Low Cost and Efficient Solar Driven Sulfur-based Processes

Recipient Greenway Energy, LLC (PI: Claudio Corgnale)

Subs University of South Carolina/UofSC (PI: John Weidner)

Water Splitting Technology STCH

Status Awarded

Abstract To make the hydrogen economy realistic at a large scale, one of the main technical issues to be overcome is relative to hydrogen production at low cost and without any greenhouse emission. The Hybrid Sulfur (HyS) process, driven by solar power, has great potential to reach high efficiency and low hydrogen production costs without greenhouse emissions. The high temperature section of the HyS cycle, which operates the catalytic decomposition of sulfuric acid into sulfur dioxide, oxygen and water, is a fundamental section affecting the overall plant efficiency and capital investment. Therefore the final hydrogen production cost is strongly dependent on the techno-economic performance of the decomposition section. Having a high performance catalyst (i.e. low cost, high catalytic activity and low degradation) is of critical importance to achieve high efficiency and low hydrogen cost.

Greenway Energy (GWE), in conjunction with the University of South Carolina (USC), proposes the development and testing of a new catalytic material to decompose sulfuric acid. A novel catalyst preparation technique, developed by USC, uses a combination of: (1) strong electrostatic adsorption (SEA), which permits formation of very small metal particles with a narrow distribution of sizes, and (2) electroless deposition (ED) to produce controlled bimetallic catalysts. The first and second phase of the project will focus on the new catalyst development, applying the technique described above. This will result in limiting the catalyst deactivation by using very small particles of a high surface free energy core metal with a catalytically-active outer metal shell deposited by ED. The new material is anticipated to have an activity degradation 60% less than that of the currently available catalytic materials to decompose sulfuric acid. In addition, the adoption of the new technique will result in decreasing the material cost and increasing the nominal catalyst activity, anticipated to be 30% higher than the current catalyst activity. A laboratory scale decomposition reactor will also be designed, based on the results obtained from a detailed transport phenomena model developed during the second phase of the project. The downselected reactor will be built at a laboratory scale and tested during the third phase of the project to assess the component performance under different scenarios and to evaluate the performance degradation. The reactor is anticipated to work with sulfuric acid flow rates on the order of 10 g/min (corresponding to hydrogen productions of about 50 mg/min). The HyS process will also be modeled, integrating the downselected reactor concept with the other HyS interfaced equipment. A large scale solar driven process configuration will be identified and optimized to achieve solar efficiencies (i.e. solar to hydrogen efficiencies) equal to (or higher than) 20% and hydrogen production costs equal to (or lower than) 2 $/kgH2.

GWE and USC will partner with INL (catalyst test), SRNL (HyS flowsheet development) and

NREL (design and assessment of the solar plant and the balance of plant equipment)