Complex sentence: The effectiveness of HDS is determined by the type of catalyst employed, typically a catalyst containing transition metals such as cobalt and molybdenum, and the severity of the reactor conditions, notably, temperature, hydrogen pressure and residence time.
Split into simpler sentences: The effectiveness of HDS is determined by the type of catalyst employed. Typically, a catalyst containing transition metals such as cobalt and molybdenum, and the severity of the reactor conditions, notably, temperature, hydrogen pressure, and residence time.