Question

Commercial hydrogen is obtained from (1) coal gas (2) water gas (3) air (4) producer gas

Short answer

Water gas

Step-by-step solution

Identify the Question

Determine what the question is asking: Where is commercial hydrogen obtained from?

List the Options

The given options are coal gas, water gas, air, and producer gas.

Analyze Each Option

Evaluate each option to determine which one is a commonly used source of commercial hydrogen: - Coal gas: Mainly contains methane and other hydrocarbons with a lower concentration of hydrogen.- Water gas: Consists of carbon monoxide and hydrogen and is a significant source for commercial hydrogen.- Air: Primarily contains nitrogen and oxygen, with negligible hydrogen.- Producer gas: Made from partial combustion of carbonaceous material and contains carbon monoxide and nitrogen, with a smaller amount of hydrogen.

Conclusion

Water gas is the primary source among the given options used for commercial hydrogen production.

Key concepts

coal gas

Coal gas is one of the earliest sources of fuel and energy. It is produced by the gasification of coal. This process heats coal in the absence of air, creating a variety of gaseous products. The main components of coal gas are methane (CH4), carbon monoxide (CO), and hydrogen (H2), along with other hydrocarbons. However, coal gas contains a lower concentration of hydrogen compared to other gases, making it less efficient for commercial hydrogen production. Its primary use is in heating and as a fuel for gas-powered appliances, not typically for extracting hydrogen due to its lower yield.

water gas

Water gas is a synthesis gas, or syngas, primarily composed of carbon monoxide (CO) and hydrogen (H2). It is produced by passing steam over hot coal, a process known as coal gasification. The chemical reaction can be represented as:
C (s) + H2O (g) → CO (g) + H2 (g)
Water gas is highly significant as a source of commercial hydrogen. It contains a higher concentration of hydrogen relative to other gases like coal gas and producer gas. It is used in various chemical processes, including the production of ammonia for fertilizers and in fuel cells, making it a crucial component in hydrogen production.

producer gas

Producer gas is a type of syngas generated from the partial combustion of carbonaceous materials, such as coal or biomass, in an environment with a limited supply of air. The gas primarily consists of carbon monoxide (CO) and nitrogen (N2), with a smaller amount of hydrogen (H2) and methane (CH4). The overall composition of producer gas makes it less ideal for hydrogen production compared to water gas. Its primary use is as a fuel for industrial heating and in internal combustion engines, rather than as a source for commercial hydrogen.

sources of hydrogen

There are several sources from which commercial hydrogen can be produced. Some of the primary sources include:

• Natural gas: The most common source, accounting for around 75% of the world's hydrogen production. The process is known as steam methane reforming (SMR).
• Coal: Through gasification, coal can produce syngas (a mix of CO and H2).
• Water: Electrolysis of water is a clean method, although currently more expensive, where water is split into hydrogen and oxygen using electrical energy.
• Biomass: Organic materials undergo gasification to produce hydrogen.

While air and producer gas contain negligible amounts of hydrogen, water gas, due to its higher hydrogen concentration, is a significant source for commercial hydrogen production. Understanding these sources is vital for technologies that aim to utilize hydrogen as a clean energy carrier.