A low-temperature hydrogen production process based on H2S splitting cycle for sustainable oil sands bitumen upgrading

The following reactions:equation(1)H2S + H2SO4 → SO2 + S + 2H2Oequation(2)S + O2 → SO2equation(3)2SO2 + 4H2O + 2I2 → 2H2SO4 + 4HIequation(4)4HI → 2 H2 + 2I2form a H2S chemical splitting cycle that converts 1 mol H2S into 2 mol of H2. This makes it possible to provide hydrogen in upgrading the Canadian oil sands bitumen from processing its waste product H2S. To engineer the chemistry, process design and experiments on reactions and separations are under investigation. In this paper, efforts have been made in order to have reactions 1, 3 and 4 be conducted at ambient temperatures and in fluid medium, thus minimizing side reactions, corrosiveness and other process difficulties and making the separations of products easier. The results show that the separation of the elemetal sulfur from the spent sulfuric acid after reaction 1 can be done by phase separation, that using the I2-toluene solution can make the Bunsen reaction (reaction 3) take place below the melting point of iodine, and that the direct electrolysis of HI solution from the product of reaction 3 leads to the production of H2 at room temperature through reaction 4.

► We studied the low-temperature H2 production based on the H2S chemical splitting cycle.
► The SO2 production from the reaction between H2S and sulfuric acid is optimized.
► The separation of elemental sulfur from the spent sulfuric acid is technically possible.
► Using the I2-tolunen solution allows the Bunsen reaction to be run at room temperature.
► The direct electrolysis of HI in the Bunsen reaction products is also technically feasible.