Chemistry · Ch 4 — Hydrogen
Uses of Hydrogen
Uses of Hydrogen
Hydrogen's uses span synthesis, metallurgy, energy and beyond:
- Ammonia synthesis (Haber process). Over 90% of the hydrogen produced industrially goes into synthetic applications, the single largest of which is the Haber process, used to manufacture ammonia at large scale:
Ammonia made this way is, in turn, the feedstock for nitric acid, fertilizers and explosives.
- Methanol manufacture. Hydrogen is used to convert carbon monoxide into the industrial solvent methanol, over a copper catalyst:
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Hydrogenation of oils. Unsaturated fatty oils are converted into saturated fats -- Vanaspati (margarine) -- by catalytic reduction with Pt/H₂.
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Metallurgy. At high temperatures, hydrogen reduces many metal oxides to the free metal:
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Cutting and welding. Atomic hydrogen and oxy-hydrogen torches, which burn at very high temperatures, are used for metal cutting and welding.
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Rocket fuel. Liquid hydrogen is used as a rocket propellant (Figure 4.3), burnt with liquid oxygen to deliver a very high energy release per unit mass.
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Fuel cells and hydrogen storage. Hydrogen is used in fuel cells to generate electrical energy directly and cleanly from the H₂ + O₂ → H₂O reaction. The same reversible-uptake behaviour of hydrogen in certain metals that makes metallic (interstitial) hydrides useful for storage (Section 4.8) is also attractive for rechargeable metal-hydride batteries. …
What this figure shows. A photograph of a two-stage rocket (ISRO-style launch vehicle) lifting off its pad, with a bright orange exhaust flame at the base and a large plume of white smoke/steam billowing around the launch gantry; a clear blue sky and tree line form the background -- illustrating the use of liquid hydrogen …
Worked out. An info box arguing that the depletion of fossil-fuel reserves and the threat of global warming are pushing the world toward alternative fuels, with hydrogen a strong candidate because it is clean-burning and produces no pollutants on combustion. It can be used directly (replacing petrol/diesel/kerosene engines) or indirectly with oxygen in fuel cells to generate electricity. The box is honest about the difficulties still to be overcome: production cost is high and still relies on fossil fuels; being volatile, flammable and the smallest molecule of all, hydrogen is hard to store and transport and is prone to leakage. Alongside is a schematic of a hydrogen fuel-cell vehicle powertrain: a Hydrogen Storage Tank feeds H2 gas across a metal interface into a Fuel Cell Stack, which powers a Power C …