Petrochemicals

Petrochemicals are chemical products made from raw materials of petroleum or other hydrocarbon origin. Although some of the chemical compounds that originate from petroleum may also be derived from coal and natural gas, petroleum is the major source. The largest petrochemical industries are to be found in the USA and Western Europe, though the major growth in new production capacity is in the Middle East and Asia. There is a substantial inter-regional trade in petrochemicals of all kinds. World production of ethylene is around 110 million tons per year, of propylene 65 million tons, and of aromatic raw materials 70 million tons.

C1- Groups.
Methanol: Production.
Today, synthesis gas is most commonly produced from the methane component in natural gas rather than from coal. Three processes are commercially practiced. At moderate pressures of 4 MPa (10–20 atm) and high temperatures (around 850 °C), methane reacts with steam on a nickel catalyst to produce syngas according to the
chemical equation:
CH4 + H2O → CO + 3 H2
This reaction, commonly called steam-methane reforming or SMR, is endothermic and the heat transfer limitations place limits on the size of and pressure in the catalytic reactors used. Methane can also undergo partial oxidation with molecular oxygen to produce syngas, as the following equation shows:
2 CH4 + O2 → 2 CO + 4 H2
this reaction is exothermic and the heat given off can be used in-situ to drive the steam-methane reforming reaction. When the two processes are combined, it is referred to as autothermal reforming. The ratio of CO and H2 can be adjusted to some extent by the water-gas shift reaction,
CO + H2O → CO2 + H2,
to provide the appropriate stoichiometry for methanol synthesis.
The carbon monoxide and hydrogen then react on a second catalyst to produce methanol. Today, the most widely used catalyst is a mixture of copper, zinc oxide, and alumina first used by ICI in 1966. At 5–10 MPa (50–100 atm) and 250 °C, it can catalyze the production of methanol from carbon monoxide and hydrogen with high selectivity
CO + 2 H2 → CH3OH
It is worth noting that the production of synthesis gas from methane produces 3 moles of hydrogen for every mole of carbon monoxide, while the methanol synthesis consumes only 2 moles of hydrogen for every mole of carbon monoxide. One way of dealing with the excess hydrogen is to inject carbon dioxide into the methanol synthesis reactor, where it, too, reacts to form methanol according to the chemical equation:
CO2 + 3 H2 → CH3OH + H2O
Although natural gas is the most economical and widely used feedstock for methanol production, other feedstocks can be used. Coal is increasingly being used as a feedstock for methanol production, particularly in China. In addition, mature technologies available for biomass gasification are being utilized for methanol production.