Hydrogen: Types & Methods of Preparation

In the whole universe, the lightest and the most abundant element is none other than Hydrogen (H₂). It plays quite an important role in many sectors like industries, energy systems, and chemical processes, as a diatomic molecule. Hydrogen is used in the Haber process (NH₃), hydrogenation of oils, rocket fuel, welding, and fuel cells.

Let us understand more about hydrogen. Read on to learn what its types are, and also the methods of preparation.

What is Hydrogen?

In the free state, hydrogen is present on Earth in trace amounts, but in reality, it is abundant in compounds such as water (H₂O), hydrocarbons, and organic molecules. The gas is colourless, odourless, and tasteless, along with being flammable.

H 2 Molecule structure

Breakdown of Types of Hydrogen

Hydrogen can be classified on the basis of two parameters: one based on isotopes and the other on its production methods. Here is a complete understanding of its types.

Based on Isotopes

Protium (¹H) → has no neutrons in its nucleus and is the most abundant isotope.
Deuterium (²H or D) → has one neutron in the atom and is used in nuclear reactors.
Tritium (³H or T) → has two neutrons, is radioactive (β-emitter), used in nuclear fusion research

Note: Protium = 99.98% abundant

Based on Production (Energy Source)

Grey Hydrogen → These are produced from natural gas / coal without carbon capture (CO₂ released)
Blue Hydrogen → These are produced the same way as grey but with CO₂ captured & stored.
Green Hydrogen → These types are produced from water electrolysis using renewable energy.
Brown/Black Hydrogen → These are from coal gasification (brown = lignite coal, black = bituminous coal).
Pink Hydrogen → Nuclear energy (electrolysis powered by nuclear energy) produces pink hydrogen.

Preparation of Hydrogen

Hydrogen can be prepared on both small and large scales. Small-scale preparation is usually done in the laboratories, whereas large-scale productions are done on industrial level.

1. Laboratory Preparation

Reaction of Metals with Dilute Acids
- Example: Zn + 2HCl → ZnCl₂ + H₂↑
- Hydrogen is liberated when dilute HCl or H₂SO₄ reacts with metals (like zinc, iron, and magnesium)
Reaction of Metals with Alkali
- Example: 2Al + 2NaOH + 6H₂O → 2Na[Al(OH)₄] + 3H₂↑
- Hydrogen is liberated when strong bases react with amphoteric metals (like Al, Zn)
Electrolysis of Water
- H₂ and O₂ are produced after decomposition of acidified or alkaline water by passing electricity through it.

2. Industrial Preparation

Steam Reforming of Natural Gas
- CH₄ + H₂O → CO + 3H₂
- This is the most common method of large-scale hydrogen production. CO further reacts with H₂O in water–gas shift reaction:
Coal Gasification
- C + H₂O → CO + H₂
- H₂ and CO (water gas) mixture is formed.
Electrolysis of Water (for green hydrogen)
- 2H₂O → 2H₂ + O₂
- This method is powered by renewable or nuclear energy.
Partial Oxidation of Hydrocarbons
- CH₄ + ½O₂ → CO + 2H₂

Details At A Glance

Property	Details
Symbol	H
Atomic Number	1
Atomic Mass	1.008
Isotopes	Protium (¹H), Deuterium (²H), Tritium (³H)
Types (by source)	Grey, Blue, Green, Brown/Black, Pink
Common Lab Methods	Metals like Zn, Fe, Mg + dilute HCl/H₂SO₄ (not HNO₃)
Industrial Methods	Steam reforming, Coal gasification, Electrolysis

Summing Up

We have understood that hydrogen is the fuel for the future and a versatile energy source. It can be easily produced on both industrial and laboratory levels using various methods. Regarding the growing requirement for renewable energy technologies, green hydrogen is gaining much importance in this sustainable sector.