Feedstock applications

	methane and ethane (ie. C1 and C2, or gas-based) or from;
	propane or butanes (C3 and C4, or naphtha or oil-based).

Petrochemicals can be broadly broken down into two groups - derived from methane and ethane (gas-based) and from propane and butane (oil-based).

	Methane is the largest component of natural gas (typically 90 per cent) and is used after conversion to the more flexible synthesis gas (syngas). It can produce a broad range of chemicals including methanol, formaldehyde and chemical intermediates and the fertilisers, ammonia, urea, ammonium nitrate and ammonium nitrate.
	Ethane is the second most common component of feedstocks used to produce polyethylenes and PVC. Via a chloralkali plant, (used to produce the chlorine primarily required for PVC) ethane feedstock may thereby be linked to the production of titanium dioxide pigment, silicones and titanium metal that require chlorine in the production chain.
	Propane is a component of LPG but is commonly produced at petroleum refineries and by the cracking of naphtha. Propanes (or C3) are used to produce polypropylene, acrylics, and with ammonia and via cyclohexane (from benzene), acrylonitrile and caprolactam (to produce nylons).
	Butanes (C4) is available from LPG gas but commonly produced from naphtha cracking. It provides the butyl component in ABS, rubbers and MTBE (an antiknock fuel additive).

The breakdown provides some indication of potential relationships, such as between ammonia used in fertiliser plants (to produce ammonium nitrate, phosphates, urea etc.) and its use to produce acrylonitrile, caprolactams etc. Oxygen plays a part in such petrochemicals as ethylene and propylene oxide, glycols, non ionic surfactants, acrylics etc.