fes catalysts are used in a variety of applications, including:

hydrodesulfurization (hds): fes is used as a catalyst in the hds process to remove sulfur from petroleum products.
hydrodenitrogenation (hdn): fes is used as a catalyst in the hdn process to remove nitrogen from petroleum products.
hydrocracking: fes is used as a catalyst in the hydrocracking process to convert heavy hydrocarbons into lighter hydrocarbons.
fischer-tropsch synthesis: fes is used as a catalyst in fischer-tropsch synthesis to convert synthesis gas to hydrocarbons.
coal gasification: fes is used as a catalyst in the coal gasification process to convert coal into synthesis gas.
water splitting: fes is used as a catalyst in the process of water splitting to split water into hydrogen and oxygen.
fes is a versatile catalyst that can be used in a variety of applications. it is a relatively cheap catalyst and easy to handle. fes is also a safe catalyst that does not produce any harmful by-products.

however, fes is not without its drawbacks. it is a relatively active catalyst and is easily poisoned by impurities in the raw materials. fes is also a relatively unstable catalyst that deactivates over time.

overall, fes is a valuable catalyst that can be used in a variety of applications. it is a relatively cheap catalyst that is easy to handle and safe to use. however, fes is a relatively active catalyst that is easily poisoned and deactivated.