Laboratory scale demonstration of the magnesium-sulfur-iodine cycle for thermochemical hydrogen production

Abstract

The Mg-S-I thermochemical water-splitting cycle was demonstrated on a laboratory scale. The process design was canied out to a h at the veriflcatbn of repeated H2 and O2 production through pwety thermochemical processes below 1273 K (1000 "C). An experimental apparatus was made of quartz and Pyrex glass, and electric furnaces were used. Owing to tbe avoldance of MgSO4-MgI2 separation and of solid transportation processes, the whole system was so simplMe$ as to CMpTISB only three reactors operated in three stages. with satisfactory performance of the system, 30 cycle Operations were successfully repeated with roughly constant production of 0.3 dm3 (0.3 L) of H, and 0.15 dm3 (0.15 L) of O2 per cycle. The tlme requirement for one cycle operation was about 1 h, where all the chemical reactions proceeded and all the reactants were circulated.This paper presents new analysis tools and a design methodology which systematically develops plant designs with improved dynamk: operability. When the proposed techniques are used, the conservatism associated with existing methods can be remedied and the effect of uncertainty on dynamic operabHtly can be analyzed in a more effective design setting. The analytical tools are incorporated into a computgr-aided analysis and design software which makes use of the symbolic logic languages and the recent computational techniques in singular value decomposition and optimization. The physical examples illustrate that wlthin the proposed analysis and design framework, valuable insight into the dynamic operabilii of chemical plants can be gained; crucial design variables can be easily identified, and robustness of the plant operation can be accordlhgly improved upon.

Pt/graphite catalyst for hydrogen generation by HI decomposition reaction in S-I thermochemical cycle

“…S–I cycle has a few advantages over other thermochemical cycles such as only liquid/fluid handling, no electrolysis step etc. Not only HI decomposition step is an integral part of this thermochemical cycle, but also for some other iodine based thermochemical cycles like magnesium iodide thermochemical cycle . HI decomposition reaction as such is thermodynamically limited with very low thermodynamic conversions, and it requires a catalyst to achieve workable reaction rates .…”

Pt/zirconia catalyst for hydrogen generation from HI decomposition reaction of S-I cycle

“…As one can see from the reaction earlier, HI decomposition step is an integral part of this cycle as well as some other iodinebased cycles like magnesium iodide cycle [18,19]. These two acids are separated and decomposed into two different steps, that is, HI and H 2 SO 4 decomposition reactions, respectively.…”

“…S-I cycle has certain advantages over other competitors like no solid handling and no electrolysis step. As one can see from the reaction earlier, HI decomposition step is an integral part of this cycle as well as some other iodinebased cycles like magnesium iodide cycle [18,19]. HI decomposition reaction as such is thermodynamically limited to very low thermodynamic conversions, and it requires a catalyst to achieve workable reaction rates [20].…”