Explain with chemical equations the industrial production of dihydrogen gas.Answer the given question in detail.
Answers
Fossil fuels are the dominant source of industrial hydrogen. Carbon dioxide can be separated from natural gas with a 60-70% efficiency for hydrogen production and from other hydrocarbons to varying degrees of efficiency.Specifically, bulk hydrogen is usually produced by the steam reforming of methane or natural gas.
Hydrogen can be produced using a number of different processes. Thermochemical processes use heat and chemical reactions to release hydrogen from organic materials such as fossil fuels and biomass. Water (H2O) can be split into hydrogen (H2) and oxygen (O2) using electrolysis or solar energy.
By the electrolysis of water
Water is a weak electrolyte .When an electrolyte(acid, base or a salt) is added to water, it conducts electricity. When electric current is passed, water dissociates into positive and negative ions. Hydrogen is collected at cathode and oxygen at anode.
2H2O è 2H2 + O2
Advantage:
Hydrogen gas obtained by the electrolysis of water is 100% pure.
Disadvantage:
It is an expensive method due to electricity cost.
By the cracking of methane
When natural gas is heated in the absence of air up to 700C, it decomposes to produce hydrogen.
CH4 è C (solid) + 2H2
Byproduct:
During cracking of methane "Carbon Black" is obtained as byproduct.
Uses of Carbon Black :
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4) Paints.
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6)Carbon papers.
By thermal decomposition of ammonia
When liquid ammonia is vaporized and heated up to 1000C in the presence of a catalyst .It decomposes to produce nitrogen and hydrogen.
2NH3 è N2 + 3H2
Separation of Nitrogen :
Mixture of N2 and H2 is cooled to -196C .At -196C, N2 liquefies and H2 is separated in gaseous state.
Steam/ alcohol method
When methyl alcohol is passed over steam at 250C, a mixture of hydrogen and CO2 is obtained.
CH3OH + H2O è CO2 + 3H2
Separation of C02 :-
When the mixture of H2 and CO2 is introduced in to water at high pressure, CO2 is dissolved in water and H2 gas is separated.
Coke and Steam Process
When steam is passed over red-hot coke, mixture of CO and H2 known as Water Gas is obtained.
H2O + C è CO + H2
Separation of CO
Method No. 1:
Water gas is cooled to -200C .At -200C temperature CO liquefies and H2 is separated.
Removal of traces of CO
H2 so obtained contains few particles of CO. In order to remove these particles H2 gas is treated with NaOH.
CO + NaOH è HCOONa (Sodium formate)
Method No. 2
Water gas is heated with steam in the presence of iron oxide or cobalt oxide. Due to this reaction CO is converted in to CO2.
H2 + CO + H2O è CO2 + 2H2
Separation of CO2
When a mixture of H2 and CO2 is dissolved in water at high pressure, CO2 is dissolved in water and H2 gas is separated.
Steam / Natural gas method
CH4 + H2O è CO + 3H2