Sulfur–iodine cycle

The sulfur–iodine cycle (S–I cycle) is a three-step thermochemical cycle used to produce hydrogen. The S–I cycle consists of three chemical reactions whose net reactant is water and whose net products are hydrogen and oxygen. All other chemicals are recycled. The S–I process requires an efficient source of heat. The three reactions that produce hydrogen are as follows: I2 + SO2 + 2 H2O 2 HI + H2SO4 (); Bunsen reaction The HI is then separated by distillation or liquid/liquid gravitic separation. 2 H2SO4 2 SO2 + 2 H2O + O2 () The water, SO2 and residual H2SO4 must be separated from the oxygen byproduct by condensation. 2 HI I2 + H2 () Iodine and any accompanying water or SO2 are separated by condensation, and the hydrogen product remains as a gas. Net reaction: 2 H2O → 2 H2 + O2 The sulfur and iodine compounds are recovered and reused, hence the consideration of the process as a cycle. This S–I process is a chemical heat engine. Heat enters the cycle in high-temperature endothermic chemical reactions 2 and 3, and heat exits the cycle in the low-temperature exothermic reaction 1. The difference between the heat entering and leaving the cycle exits the cycle in the form of the heat of combustion of the hydrogen produced. All fluid (liquids, gases) process, therefore well suited for continuous production High thermal efficiency predicted (about 50%) Completely closed system without byproducts or effluents (besides hydrogen and oxygen) Suitable for application with solar, nuclear, and hybrid (e.g.

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts (18)

Related lectures (9)

Thermochemical cycle

Thermochemical cycles combine solely heat sources (thermo) with chemical reactions to split water into its hydrogen and oxygen components. The term cycle is used because aside of water, hydrogen and oxygen, the chemical compounds used in these processes are continuously recycled. If work is partially used as an input, the resulting thermochemical cycle is defined as a hybrid one. This concept was first postulated by Funk and Reinstrom (1966) as a maximally efficient way to produce fuels (e.g.

Hydrogen production

Hydrogen production is the family of industrial methods for generating hydrogen gas. As of 2020, the majority of hydrogen (~95%) is produced from fossil fuels by steam reforming of natural gas and other light hydrocarbons, partial oxidation of heavier hydrocarbons, and coal gasification. Other methods of hydrogen production include biomass gasification, methane pyrolysis, and electrolysis of water. Methane pyrolysis and water electrolysis can use any source of electricity including solar power.

Copper–chlorine cycle

The copper–chlorine cycle (Cu–Cl cycle) is a four-step thermochemical cycle for the production of hydrogen. The Cu–Cl cycle is a hybrid process that employs both thermochemical and electrolysis steps. It has a maximum temperature requirement of about 530 degrees Celsius. The Cu–Cl cycle involves four chemical reactions for water splitting, whose net reaction decomposes water into hydrogen and oxygen. All other chemicals are recycled.

Solar Thermochemistry: Solar Fuels and Redox Cycles ME-468: Solar energy conversion

Delves into solar-driven thermochemistry for fuel production and the principles of solar thermochemical conversion devices.

Solar Fuels: Conversion Pathways and Reactor Concepts

Explores solar energy conversion into fuels, reactor concepts, stringent material requirements, proposed devices, efficiency considerations, and net value per energy.

Solar Fuels: Conversion Pathways and Reactor Concepts ME-460: Renewable energy (for ME)

Explores solar energy conversion into fuels, reactor concepts, and material requirements for efficient photoelectrochemistry.