The photo is sourced from kapital.kz
One of natural gas production risks is release of hydrogen sulfide forming an explosive mixture when in contact with the air, and it makes a negative impact on human nervous system when getting in human body. Therefore, to detect hydrogen sulfide emissions from gas wells, the sensors based on barium stannate, a transparent semiconductor made of barium oxide (a silver-white alkaline earth metal) and tin are used. This semiconductor is distinguished by thermal stability (ability to maintain properties at high temperatures) and catalytic activity affecting its sensitivity to toxic gaseous substances.
The research authors have modified barium stannate with lanthanum, a shiny, silvery-white rare earth metal used in batteries. This made it possible to increase the sensor’s sensitivity to hydrogen sulfide. At the same time, the scientists used a non-classical method for obtaining barium stannate. Typically, synthesis of this substance occurs by heating the initial components to the temperature over 500 degrees Celsius. However, the scientists heated aqueous peroxide solutions of barium and tin salts containing ammonia to the temperature of 40-50 degrees Celsius to obtain a perovskite precursor, which, when heated to the temperature of 200 degrees Celsius, decomposes and turns into barium stannate.
This also made possible solution of the problem of enlargement of crystalline particles of barium stannate, which emerges when a classical method is used, and leads to catalytic activity decrease. The new method allowed the size of crystals to be limited to 10 nanometres (one nanometre is equal to one billionth of a metre).
“The work we published contains the results of researching the composition, microstructure and sensory properties of pure and lanthanum-modified barium stannate. We have shown that the obtained materials have increased selectivity and sensitivity to hydrogen sulfide, a dangerous poisonous gas, in comparison with the sample obtained by the classical method,” IONH RAS quotes Alexei Mikhailov, Chemistry PhD candidate and senior researcher of the Laboratory of peroxide compounds and the materials based on them.
