The thermal cracking reaction is highly endothermic and is usually carried out in a powered heater. Although residence time and temperature are carefully controlled, significant quantities of chlorinated hydrocarbon by-products are produced. In practice, EDC conversion efficiency is relatively low (50-60%). The furnace effluent is immediately soaked with cold EDC to minimize adverse side reactions. The resulting vapor-liquid mixture then enters a cleaning system. Some processes use an absorber system to separate HCl from chlorinated hydrocarbons, while other processes use a cooled continuous distillation system. [2] Ethan is readily available, especially on the U.S. Gulf Coast. Ethylene is made from ethane by cracking ethane, and then ethylene is used to make vinyl chloride. In order to save processing costs for ethylene production, many attempts have therefore been made to convert ethane directly to vinyl chloride.

Direct ethane supply to vinyl chloride plants could thus significantly reduce raw material costs and make plants less dependent on cracking capacity. The conversion of ethane to vinyl chloride can occur in several ways:[12] Vinyl chloride is a mutagen with clastogenic effects that affect the chromosomal structure of lymphocytes. [19] [21] Vinyl chloride is a Group 1 human carcinogen with an increased risk of rare angiosarcomas, brain and lung tumours, and malignant hematopoietic lymphatic tumours. [22] Chronic exposure leads to frequent forms of respiratory failure (emphysema, pulmonary fibrosis) and focused hepatotoxicity (hepatomegaly, hepatic fibrosis). Continued exposure can cause CNS depression, including euphoria and disorientation. Decreased male libido, spontaneous abortions, and birth defects are known serious reproductive abnormalities associated with vinyl chloride. Vinyl chloride is an organochloride with the formula H2C = CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. This colorless compound is an important industrial chemical primarily used to produce polyvinyl chloride (PVC) polymer. About 13 million tonnes are produced each year. VCM is among the twenty largest petrochemicals (petrochemicals) in global production.

[2] The United States is currently still the largest production region for MCV due to its low production costs of chlorine and ethylene feedstocks. China is also a major manufacturer and one of the largest consumers of VCMs. [3] Vinyl chloride is a sweet-smelling gas. It is highly toxic, flammable and carcinogenic. It can form in the environment when soil organisms break down chlorinated solvents. Vinyl chloride released from industry or formed by the decomposition of other chlorinated chemicals can leach into air and drinking water. Vinyl chloride is a common contaminant near landfills. [4] In the past, VCM was used as a refrigerant. [5] A major disadvantage of using ethane is the constraints required for its use, which are due to its lack of molecular functionality. Unlike ethylene, which readily adds chlorine, ethane must first be functionalized through substitution reactions, resulting in a variety of downstream and side-chain reactions.

The reaction must therefore be controlled kinetically in order to obtain maximum vinyl chloride yield. Vinyl chloride provides an average of 20-50% per pass. Ethylene, ethyl chloride and 1,2-dichloroethane are the main by-products. However, with special catalysts and under optimized conditions, ethane conversions of over 96% have been reported from oxychlorination reactions. The ethylene formed can be recycled or oxychlorinated and cracked conventionally. Many of these ethane-based methods have been and are being developed. [2] According to the EPA, vinyl chloride emissions from polyvinyl chloride (PVC), ethylene dichloride (EDC) and vinyl chloride monomer (VCM) plants cause or contribute to air pollution that can reasonably be expected to result in increased mortality or increased irreversible or invalid reversible diseases. Vinyl chloride is a known human carcinogen that causes rare liver cancer. [34] The EPA`s updated toxicological profile in 2001 and the summary of the health assessment of the MCV in its Integrated Risk Information System (IRIS) database, reduce the EPA`s previous estimate of risk factors by a factor of 20 and conclude that «based on consistent evidence of liver cancer across studies. And the weaker association for other sites concludes that the liver is the most sensitive site, and protection against liver cancer protects against possible induction of cancer into other tissues. [35] In the United States, OSHA lists vinyl chloride as a Class IA flammable liquid with a National Fire Protection Association flammability rating of 4.

Due to its low boiling point, liquid VCM undergoes instant evaporation (i.e. cooling of the car) when released into atmospheric pressure. The vaporized part forms a dense cloud (more than twice as heavy as the surrounding air). The risk of a subsequent explosion or fire is considerable. According to OSHA, the flash point of vinyl chloride is -78°C (-108.4°F). [15] The flammability limits in air are as follows: 3.6% by volume and 33.0% by volume.