Question

Explain the chemical reactions that take place in Bosch's process.

Answer 1

The Bosch process is used in the production of hydrogen gas.

In the first step of the Bosch process water gas(CO+H₂) is prepared by passing steam(H₂O) over red hot coke(C)

$$\begin{gathered} \mathrm{C}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)\to \mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Coal}\mathrm{Steam}\mathrm{Carbon}\mathrm{Hydrogen} \\ \mathrm{Monooxide} \end{gathered}$$

In the second step, this water gas is mixed with an excess of steam

In this reaction Ferric oxide (Fe₂O₃) is used as a catalyst and Chromium oxide(Cr₂O₃) is used as a promoter.

$$\begin{gathered} \mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)\underset{{\mathrm{Cr}}_2{\mathrm{O}}_3}{\overset{{\mathrm{Fe}}_2{\mathrm{O}}_3}{\to }}2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ \mathrm{Carbon}\mathrm{Hydrogen}\mathrm{Steam}\mathrm{Hydrogen}\mathrm{Carbondioxide} \\ \mathrm{Monooxide} \end{gathered}$$

This hydrogen can be separated from CO₂ by passing the above mixture from KOH (potash solution)

CO₂ gas will dissolve in potash solution and hydrogen is separated

$$\begin{gathered} \mathrm{KOH}\left(\mathrm{aq}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)\to {\mathrm{K}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{Potash}\mathrm{Carbonmonoxide}\mathrm{Potassium}\mathrm{Water} \\ \mathrm{solution}\mathrm{Carbonate} \end{gathered}$$

Separation of H₂ from water gas (CO+ H₂)

Water gas is passed through an ammonical mixture of cuprous chloride (CuCl)

CO (Carbon monoxide from water gas) gets dissolved in CuCl and hydrogen gas is obtained.

$$\begin{gathered} \mathrm{CO}\left(\mathrm{g}\right)+\mathrm{CuCl}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to \mathrm{CuCl}.\mathrm{CO}.2{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Carbon}\mathrm{Cuprous}\mathrm{Water}\mathrm{Adduct} \\ \mathrm{Monooxide}\mathrm{Chloride} \end{gathered}$$