Maleic anhydride has traditionally been produced by the oxidation of benzene, but more recently, n-butane has replaced benzene as the main feedstock. Maleic anhydride is a versatile molecule that lends itself to many applications requiring multi-functionality. The main applications for refined Maleic anhydride are unsaturated polyester resins and fine chemicals (alkenyl succinic anhydrides, fumaric acid, polyaspartic acid).
Medium Crude is a term used to define a crude oil part way between Light Crude and Heavy crude.
Melamine is a white crystaline solid produced by the reaction of ammonia and urea over a catalyst. It is typically shipped in bags and is used mainly as a raw material in the production of melamine formaldehyde resins. These resins are used to produce wood laminates, in textile and paper treatment and as leather tanning agents. Melamine itself also finds applications in flame retardants, speciality fertilizers, ion exchange resins and as a concrete additive.
Methanol, the simplest of the alcohol compounds, is a toxic, flammable liquid with a distinctive odour. Methanol is mainly produced by the reforming of hydrocarbon feedstock syngas, which is mainly derived from natural gas, but can also be derived from coal or refinery residues. As methanol is relatively simple to ship, it provides a means to exploit natural gas reserves which are too remote to be connected to consumers by pipeline, so called "stranded gas". For this reason most of the world's methanol is now produced in remote areas and shipped to consumers in large dedicated methanol carriers. Methanol is a bulk commodity chemical and its major derivatives are formaldehyde, methyl tertiary butyl ether (MTBE), acetic acid, methyl methacrylate (MMA), and di methyl terephthaliate (DMT).
Methyl Tertiary Butyl Ether (MTBE)
Methyl tertiary butyl ether (MTBE) is a volatile, combustible, colourless liquid that is categorised as an oxygenate due to its ability to boost the oxygen content and octane rating of gasoline. It is relatively water soluble and exhibits an unpleasant taste and odour in solution. MTBE is produced from methanol and isobutylene, as is produced both by refiners to meet their own requirements and by major export-based producers in the Middle East, Europe and the United States. MTBE has marginal outlets as a solvent in chemical and medical applications, although its dominant end-use is as a gasoline additive. It is currently being phased out of the gasoline market in the USA due to concerns over groundwater contamination.
Mixed C4 is the term used to describe the mixture of four carbon compounds that are commonly produced from a steam cracker. Four carbon compounds differ from the shorter olefins in that they can be formed in a variety of structures, being straight or branched and with one or two double bonds. These separate chemicals can either be separated within the steam cracker, or alternatively at separate dedicated extraction units.
Mixed xylenes refers to a mixture of xylene isomers, meta-xylene, ortho-xylene and para-xylene, which are obtained from various sources within a refinery or steam cracker. Although they can be used in a mixture for solvents, they are usually separated and used as feedstock for a limited range of intermediates. They are one of the "aromatic" compounds, along with benzene and toluene. The largest use is para-xylene for polyester production.
Mono Ethylene Oxide (MEG)
Mono ethylene glycol (MEG) is the main constituent of anti-freeze, although consumption of MEG in the production of PET has now overtaken this as the main end-use, and MEG is therefore classed as a polyester intermediate. MEG is produced by the reaction of ethylene oxide and water, and most modern plants are combined EO/MEG units. MEG is produced in all regions, although to an increasing extent in the Middle East.