Hydrogen peroxide is now generally prepared on industrial scale by the

Industrial preparation of H2O2 :(A) By the electrolysis of 50% H2SO4 : 50% H2SO4  solution is electrolyzed at 00C between Pt electrodes. The perdisulphuric acid is formed.                  H2SO4 ⇌ H+ + HSO4-At Anode : 2HSO4- ⇌ H2S2O8+ 2e-At Cathode: 2H+ + 2e-  → H2The obtained perdisulphuric acid gives H2O2  on hydrolysis.H2S2O8  + 2H2O ⇌ H2O2 + 2H2SO4This H2O2 is separated by distillation at reduced pressure and thus, 30% solution of H2O2 is obtained.(B) By the auto-oxidation of 2-ethyl-anthraquinol (Modern method): Anthraquinol, in a mixture of benzene and n-heptanol on treatment with air gives H2O2 and 2-ethyl-anthraquinone. This 2-ethyl-anthraquinone on hydrogenation gives 2-anthraquinol in presence of Pd catalyst.