Why hydrogen is not used as a reducing agent in metallurgy?give reactions.
Hydrogen is not used as a reducing agent in metallurgical processes because they will form hydrides when metal reacts with H2 at an elevated temperature. When hydrogen and oxygen present in the air combines , it will be explosive. The reducing power of H2 does not increase with temperature which is very important in metallurgy.
The reactions are given as follows;
H2 + FeO → Fe + H2O
H2 + PdCl2 → Pd + 2HCl
In principle, hydrogen can be applied as a reducing agent for the production of many metals. It has found commercial application for the synthesis of platinum group metals, some rare metals such as germanium and rhenium, and for the production of special grades of metals (e.g., fine nickel and cobalt powders) However, hydrogen is primarily applied for the synthesis of tungsten and molybdenum, with very pure metal powders resulting from the hydrogen reduction of their oxides.
Some years ago, our R&D Lab tried hydrogen as a replacement for carbon in the blast furnace, to reduce Fe2O3 to Fe and H2O (thus eliminating CO and CO2 release to the environment). It was a complete failure, because the Fe2O3 pellets became “sticky” and stuck to each other, forming a huge mass of partially-reduced pellets.