A significant percent of America’s need for electric power will, for many years into the future, be supplied by coal from our massive reserves in Appalachia and the Western states. But coal is an expensive and more polluting way to make chemicals – though technology is available and continues to be developed in China. In our country, chemical feedstocks are and will be produced from hydrocarbons, with natural gas and gas liquids (separated from the gas), predominating over naphtha and heavier oils. Biomass-based chemicals will have an increasing role, though largely as low volume “specialty chemicals”. But we can forget about coal chemicals.
Not so the Chinese. That country is building a large number of plants that are producing various “petrochemicals” from coal in many regions. Coal is China’s main resource for both energy and chemicals, though the country is extremely concerned about pollution and is working on becoming “greener”. But the government evidently felt some years ago that it had no choice but to use coal to make chemicals, thus reducing its needs for imports. Using coal as a feedstock is an expensive way to go. First, there is a large infrastructure for coal handling. Then, the coal must be pulverized and fed into large gasifiers, using oxygen, where so-called synthesis gas, a mixture of carbon monoxide and hydrogen is eventually produced, with carbon dioxide and water as a co-product. The gas is then passed over different catalysts to produce various types of chemicals.
The January 30-February 12, 2012 issue of ICIS Chemical Business provides a rundown of the many coal-to-chemical plants that have been or are being built in China. Products
include ammonia, methanol, and methanol-derived chemicals, including ethylene and propylene, ethylene glycol and allegedly even p-xylene and terephthalic acid (which are raw materials for polyester fibers and plastic bottles). Chinese chemical companies also make acetylene from coal and convert it into vinyl acetate, as well as vinyl chloride and PVC. That technology was actually used in the U.S., Europe and Japan until ethylene from hydrocarbons became much cheaper than acetylene from coal.
China is still importing large amount of “petrochemicals” from the U.S., the Middle East and Southeast Asia. Both Chinese and multinational firms are building huge petrochemical complexes in China, based on naphtha feedstocks. All of which means that China will sooner or later have enough internal production from both hydrocarbon- and coal-based feedstocks to become somewhat more self-sufficient. But neither coal-based or, particularly naphtha-based Chinese chemicals, which predominate. will have production costs as low as American producers from natural gas(!)