Hydrochlorofluorocarbon in the context of "Propellants"

This article is a list of locations and entities by greenhouse gas emissions, i.e. the greenhouse gas emissions from companies, activities, and countries on Earth which cause climate change. The relevant greenhouse gases are mainly: carbon dioxide, methane, nitrous oxide and the fluorinated gases bromofluorocarbon, chlorofluorocarbon, hydrochlorofluorocarbon, hydrofluorocarbon, nitrogen trifluoride, perfluorocarbons and sulfur hexafluoride.

The extraction and subsequent use of fossil fuels coal, oil and natural gas, as a fuel source, is the largest contributor to global warming.

Hydrofluorocarbons (HFCs) are synthetic organic compounds that contain fluorine and hydrogen atoms, and are the most common type of organofluorine compounds. Most are gases at room temperature and pressure. They are frequently used in air conditioning and as refrigerants; R-134a (1,1,1,2-tetrafluoroethane) is one of the most commonly used HFC refrigerants. In order to aid the recovery of the stratospheric ozone layer, HFCs were adopted to replace the more potent chlorofluorocarbons (CFCs) such as R-12, which were phased out from use by the Montreal Protocol, and hydrochlorofluorocarbons (HCFCs) such as R-21 which are presently being phased out. HFCs are also used in insulating foams, aerosol propellants, as solvents and for fire protection.

HFCs may not harm the ozone layer as much as the compounds they replace, but they still contribute to global warming – with some like trifluoromethane (CHF₃ or R-23) having 11,700 times the warming potential of carbon dioxide. HFC atmospheric concentrations and contribution to anthropogenic greenhouse gas emissions are rapidly increasing – consumption rose from near zero in 1990 to 1.2 billion tons of carbon dioxide equivalent in 2010 – causing international concern about their radiative forcing.

Dichlorofluoromethane or Freon 21 or R 21 is a halomethane or hydrochlorofluorocarbon with the formula CHCl₂F. It is a colorless and odorless gas. It is produced by fluorination of chloroform using a catalyst such as antimony trifluoride: