Invention

Part 4 - Oil Refining

Carbon has 4 electrons in the outer (valence) shell and this allows it to form long chains of stable carbon–carbon bonds that are the essential basis for all life on Earth. There are about ten million known compounds, and this is only a fraction of the possible combinations.

Combined with hydrogen, carbon forms a large range of chemical compounds, the simplest of which include;- methane (CH4),  ethane (C2H6),  propane (C3H8),  butane (C4H10) and ethylene (C2H4) used to make polyethylene plastic.  The hydrate of ethylene is ethanol (drinking alcohol) (C2H6O).  Benzene (C6H6) is a ring shaped molecule formerly used in gasoline. 

A typical mixture of gasoline contains butane (C4H10),  pentane (C5H12),   isopentane (C5H12), benzene (C6H6),  ethylbenzene (C8H10),  toluene(C7H8) and xylene (C8H10).   Kerosene-type jet fuels have between 8 and 16 carbon atoms per molecule.

An oil refinery, transforms crude oil into products such as:-  hydrogen,  naphtha,  gasoline,  diesel fuel,  asphalt base,  heating oil,  kerosene,  liquefied petroleum gas,  jet fuel and fuel oils. Ethylene, propylene and butadiene are used as feedstocks for the production of ammonia, synthetic rubber and glycol and plastics (including polyethylene and nylon and polyesters fibres). 

Benzene, toluene, xylene, hexane and heptane are used as solvents and paint thinners, dry-cleaning fluids, degreasers, industrial and pesticide solvents. 

Large aromatic hydrocarbon molecules with more than 15 carbon atoms, are used as feedstocks for lubricants, waxes, detergents and elastomers. Heavier (less volatile) fractions can also be used to produce asphalt, tar, paraffin wax, lubricating and other heavy oils. 

Carbon, in the form of petroleum coke, and hydrogen may also be produced. Hydrogen is often used as an intermediate product for other oil refinery processes such as hydro-cracking and hydro-desulfurization.

Lubricating oils are low-volatile, medium- to high-viscous mixtures of oils, with boiling ranges from 371 °C to 538 °C. Additives, such as demulsifiers, anti-oxidants and viscosity improvers, are blended for motor oils, turbine and hydraulic oils, industrial greases, lubricants, gear oils and cutting oils. Detergents may be added to keep in suspension any sludge formed during the use of the oil.

Greases are mixtures of lubricating oils and metallic soaps, with the addition of special-purpose materials such as asbestos, graphite, molybdenum, silicones and talc to provide insulation or lubricity. Cutting and metal-processing oils are lubricating oils with special additives such as chlorine, sulphur and fatty-acid additives which react under heat to provide lubrication and protection to the cutting tools. Emulsifiers and bacteria prevention agents are added to water-soluble cutting oils.

Crude oil may contain a few percent of sulfur-containing compounds which must be extracted but it has industrial uses, principally in the form of sulfuric acid. 

Other materials produced from crude oil include bulk tar used for packaging and some types of roofing, and asphalt, used as a binder for gravel to form asphalt concrete for road paving. Over 6,000 items are made from petroleum by-products including: fertilizer, floor coverings, perfume, insecticide, petroleum jelly, soap and vitamin capsules.

The energy density of fuels (MJ/kg = megaJoules per kilogram) is the amount of energy available from one kilogram. This varies from about 18 for wood, 30 for the best coal to over 40 for gasoline, diesel and jet fuel. Natural gas is over 50.

Hydrogen has a energy density between 120 and 142 MJ/kg and the only combustion product is water (H2O), which makes it idea as a fuel for transportation.  However it is a highly flammable gas and dangerous to store and pump.

For comparison, a lithium-ion battery can hold up to 0.8 MJ/kg while uranium (fissioned in nuclear reactors) contains 80,000,000 MJ/kg and also does not release carbon dioxide into the atmosphere.