What is ethane gas and what is its use?

The Accidental Discovery of a Gas

Ethane was discovered for the first time in 1834 by the English chemist Michael Faraday. During his studies on various hydrocarbon gases, he identified this gas as a new compound. Faraday was attempting to liquefy different gases and analyze their properties. He observed that one of the simple hydrocarbon compounds, obtained from the decomposition of certain organic materials, exhibited distinct chemical characteristics. Upon further investigation, he identified this gas as a new saturated hydrocarbon. Later, in the late 19th century, the chemical formula of ethane was determined by other scientists.

Ethane: The Second Member of the Alkane Family

The name “ethane” originates from Greek, meaning “to shine or burn,” as ethane gas burns easily and produces a bright flame. As the second member of the alkane family, ethane is a saturated gaseous hydrocarbon with the chemical formula C2​H6​. It is the second major component of natural gas after methane. Under standard temperature and pressure (STP), ethane exists in gaseous form and consists of two carbon atoms and six hydrogen atoms. All bonds in the chemical structure of this molecule are single bonds.

Physical and Chemical Properties

Applications of Ethane

• Production of Ethylene: Ethane is used as a feedstock for the production of ethylene, one of the most important base compounds in the petrochemical industry. Ethylene itself is the primary material for manufacturing plastics, resins, and synthetic fibers.
• Industrial Fuel: Ethane is sometimes used as a fuel in various industries. When burned, it generates a high amount of thermal energy, making it suitable for industrial processes.
• Use in Cooling Processes: Due to its low boiling point, ethane is utilized in industrial refrigeration systems and natural gas liquefaction (LNG) processes as a refrigerant at extremely low temperatures.
• Research and Development in Laboratories: Ethane is employed as a standard gas for scientific experiments and research in the fields of gas chemistry and physics. Its well-known properties help researchers study chemical reactions effectively.

Four Reasons Why Isobutane is Superior to Ethane as a Household Refrigerant

• Boiling Point: Isobutane has a boiling point of −11.7°C, which is ideal for household cooling systems like refrigerators and freezers. In contrast, ethane, with its much lower boiling point of −88.5°C-88.5°C−88.5°C, is more suited for industrial refrigeration applications requiring extremely low temperatures.
• Energy Efficiency: Isobutane offers higher energy efficiency, allowing it to provide optimal cooling for household appliances with lower energy consumption. This makes it more economical for use in refrigerators and home air conditioners.
• Safety: While both gases are flammable, isobutane is less flammable and operates at a lower working pressure, which enhances its safety compared to ethane in household applications.
• Environmental Friendliness: Isobutane is a natural gas that is environmentally friendly, with very low greenhouse effects and no ozone depletion potential. Compared to ethane, it better meets stringent environmental standards required in the design of household cooling systems.

Steps in Ethylene Production from Ethane

Ethylene, or ethene, is an unsaturated hydrocarbon that is highly reactive due to its double bond and is widely used in the production of plastics and polyvinyl chloride (PVC). The production of ethylene from ethane involves four main stages:

Stage 1: Feedstock Preparation

For ethylene production, the ethane feedstock must be purified before entering the steam cracking process to avoid operational issues and ensure high efficiency. This preparation includes the removal of impurities such as sulfur, carbon dioxide, water, and other unwanted compounds. The purification process typically involves passing ethane gas through chemical absorbents or gas filters to absorb sulfur and carbon dioxide, as well as using dryers to remove moisture. These steps help prevent equipment corrosion, unwanted reactions in the cracking furnace, and optimize the feedstock quality for ethylene production.

Stage 2: Steam Cracking

Steam cracking is the core step in producing ethylene from ethane, involving the thermal decomposition of ethane molecules at high temperatures and low pressure. In this process, ethane is mixed with steam and fed into the cracking furnace, where it is heated to temperatures between 850°C and 950°C under a pressure of less than 2 atmospheres. Steam acts as a diluent to prevent carbon formation and unwanted side reactions.

Under the intense heat, the carbon-hydrogen bonds in the ethane molecule break, converting it into ethylene and hydrogen. The chemical reaction is as follows:

C2​H6​→C2​H4​+H2​

The furnace output consists of a gas mixture containing ethylene, hydrogen, trace amounts of methane, propane, and heavier hydrocarbons. To prevent further reactions, the products are immediately subjected to rapid cooling after leaving the furnace.

Steam cracking is widely used in the petrochemical industry due to its high yield in ethylene production and the abundant, cost-effective availability of ethane feedstock.

Stage 3: Rapid Cooling

The gas mixture exiting the cracking furnace is rapidly cooled to prevent side reactions and carbon formation. This cooling is achieved using water or cooling oils. The primary goal of this stage is to halt unwanted reactions and minimize ethylene losses.

Stage 4: Separation and Final Purification

After cooling, the gas mixture containing ethylene, hydrogen, methane, and other hydrocarbons is transferred to separation towers. In these towers, heavier components such as propane and butane are separated first. Then, using cryogenic distillation (at extremely low temperatures), ethylene is separated from lighter gases like hydrogen and methane. In the final step, any remaining impurities are removed from the ethylene to achieve a purity level of over 99.9%, making it ready for use in the petrochemical industry.

Is Ethane a Threat to the Environment?

Ethane is a relatively weak greenhouse gas compared to methane and carbon dioxide, having a much smaller impact on global warming. One reason for this is the short lifespan of ethane in the atmosphere, which lasts only a few months, whereas methane and carbon dioxide can persist for years or even decades. As a result, the greenhouse effect of ethane is significantly less pronounced, and its impact on climate change is relatively limited.

However, ethane has the potential to convert into methane, thereby having a notable indirect impact on the environment. Ethane reacts with hydroxyl radicals in the atmosphere, breaking down into methane, which is a potent greenhouse gas that plays a significant role in accelerating global warming. Additionally, emissions of ethane from various sources, such as natural gas leaks and industrial processes, can contribute to the increase in ozone levels in the troposphere. Ozone in this layer is considered a dangerous pollutant, posing risks to human health and plant life.

Therefore, while ethane itself is a weak greenhouse gas, its indirect effects can significantly influence climate change and air quality.