Yellow tungsten oxide in coulometric tiltration of testing sulfur is used as catalyst. In the testing process, catalytic sulfur compounds completely decomposed, thereby improving accuracy of sulfur determination results. Sulfur in coal can be decomposed completely with premiere condition of high temperature in furnace. However, under heating and oxygen environment, sulfur compound decomposition still has reversible reaction between sulfur dioxide and sulfur trioxide. Sulfur trioxide is involved in coulometric titration of sulfur reaction, it will reduce sulfur determination results.
Yellow tungsten oxide during test process will change chemical reaction of sulfur, reducing activation energy of reaction, making the chemical reaction occurs only through the lower energy barrier in a relatively harsh environment. As a result, in the process of sulfur testing, only cover a layer of yellow tungsten oxide catalyst on the surface of coal will be enough.