A review on hydrogen production from hydrogen sulphide by chemical and photochemical methods

The production of hydrogen from hydrogen sulphide has a twofold goal as it can be seen as a challenging opportunity for combining hydrogen recovery with the abatement of a highly toxic pollutant. Despite the thermodynamics encourage hydrogen sulphide splitting with respect to water splitting, no hydrogen sulphide dissociation process proving a net superiority with respect to others has been exploited at large scale yet. This paper aims at surveying the most important techniques being proposed for hydrogen sulphide splitting, with a particular attention to chemical methods that seem to be promising candidates for real industrial applications. Several processes based on thermal dissociation, catalytic cracking, multistep thermochemical methods and photocatalytic splitting are compared and critically analysed pointing out merits and drawbacks having a basic role in technology transfer. The main objective of this short review consists of collecting new process trends and improvements in pre-existing strategies in matter of hydrogen sulphide dissociation during the last two decades. Some new techniques here reported are inspired to recent issues in material science and nanotechnology bringing basic innovations for a non-conventional hydrogen production from such a waste.