Evaluation of materials of construction for the sulfuric acid decomposition section in the sulfur–iodine (S–I) cycle for hydrogen production: Some preliminary studies on selected materials

Abstract

Water splitting by Sulfur-Iodine (S-I) cycle is one of the promising thermochemical processes for hydrogen production due to its high efficiency. The decomposition of H 2 SO 4 to produce SO 2 is the reaction with the highest energy demand in the S-I cycle and it shows a large kinetic barrier. Sulfuric acid is highly corrosive and its endothermic decomposition needs elevated temperatures ([800°C). Henceforth, before the scale-up of the process plant there is a need to explore various materials of construction under very harsh acidic environments and phase changing conditions. Corrosion studies on some of the possible materials of construction (SS-304, SS-310, SS-316, Inconel-800, Alloy-20, Inconel-600, Incoloy-800H, Hastelloy C-276) were performed in detail and the most corrosion resistant material is suggested for the construction of sulfuric acid decomposition unit. The studies were performed at low temperatures (60°C and 120°C) as well as at high temperatures (700°C, 800°C and 900°C). The corrosion rates were determined using weight loss method at low as well as high temperature and by using electrochemical method at low temperature (80°C). The phase changing condition was more severe and resulted in higher corrosion rate. Hastelloy C-276 showed the least corrosion rate.

SO3 decomposition over silica-modified β-SiC supported CuFe2O4 catalyst: characterization, performance, and atomistic insights

“…31 The sulfur-iodine (S-I) thermochemical water-splitting cycle is widely considered one of the potential mass production ways to produce hydrogen in an efficient, cost-effective and environment-friendly manner. 23,[32][33][34][35][36] The S-I cycle was originally proposed by General Atomics Co. (GA) in the mid-1970s and it is composed of the following chemical reactions: [37][38][39][40][41][42][43][44]…”

“…31 The sulfur–iodine (S–I) thermochemical water-splitting cycle is widely considered one of the potential mass production ways to produce hydrogen in an efficient, cost-effective and environment-friendly manner. 23,32–36 The S–I cycle was originally proposed by General Atomics Co. (GA) in the mid-1970s and it is composed of the following chemical reactions: 37–44 H 2 SO 4 → H 2 O + SO 2 + ½O 2 (∼1123 K) Δ H = 186(±3) kJ mol −1 H 2 SO 4 → SO 3 + H 2 O (∼673–773 K) Δ H = 97.54 kJ mol −1 SO 3 → SO 2 + ½O 2 (>1073 K) Δ H = 98.92 kJ mol −1 2HI → H 2 + I 2 (∼473–773 K) Δ H = 12 kJ mol −1 2H 2 O + I 2 + SO 2 → H 2 SO 4 + 2HI (∼373 K) Δ H = −75(±15) kJ mol −1 …”

Effect of feed impurities on catalytic performance of CuFe2O4/β-SiC for SO3 decomposition in the sulfur–iodine cycle

“…The decomposition of sulfuric acid is further subdivided into non-catalytic thermal decomposition of sulfuric acid and catalytic decomposition of SO 3 as shown in eqn (3.1) and (3.2), respectively. [34][35][36][37][38][39]…”

“…The decomposition of sulfuric acid is further subdivided into non-catalytic thermal decomposition of sulfuric acid and catalytic decomposition of SO 3 as shown in eqn (3.1) and (3.2), respectively. 34–39 2H 2 O + I 2 + SO 2 → H 2 SO 4 + 2HI (∼100 °C)2HI → H 2 + I 2 (∼200–500 °C)H 2 SO 4 → SO 3 + H 2 O (∼400–500 °C)…”

Corrosion Behavior of MoSi₂ Coated Hastelloy X Utilized in Iodine -Sulfur Cycle for Hydrogen Production Application

“…The immersion time plays a vital role in determining the corrosion rate. As the immersion is increased, the weight retainability of the sample also increases which means the corrosion rate decreases over time [13]. The immersion time was decreased as the temperature increased to study the maximum corrosion rate of the sample [14].…”