Industrial ethanol production methods mainly fall into two categories: fermentation and ethylene hydration. Fermentation, as a traditional process, was long the primary source of ethanol in various countries, and currently, all alcoholic beverages and approximately 75% of industrial ethanol worldwide are still produced using this method. However, in the last forty years, with the development of ethylene hydration technology, fermentation has gradually been replaced.
Fermentation consumes large amounts of grain; approximately 4 tons of grain or 12 tons of potatoes are needed to produce 1 ton of ethanol, resulting in high costs, and therefore it has been phased out. Wood hydrolysis, due to its large investment and high costs, is only suitable for a few countries with abundant forestry resources. Using byproducts from the sugar or paper industry-such as molasses (sugar residue) and sulfite pulp waste-to produce ethanol is still used in some countries, but the yield is low due to limited raw material sources; for example, only 1 ton of ethanol can be produced from 15-20 tons of pulp waste, which cannot meet large-scale industrial needs. Although agricultural byproducts and wild plants (such as rice straw, corn stalks, or wild fruits) can also be used as raw materials, problems such as collection, transportation, and limited available resources remain. Overall, fermentation methods, limited by raw material availability and economic efficiency, have become insufficient to meet the demands of large-scale production.
Against this backdrop, the ethylene hydration method gradually emerged. Shell Chemical Company in the United States industrialized direct hydration in Houston in 1948, building an ethanol plant with a capacity of 60,000 tons per year. Subsequently, in 1951, they built another ethanol plant in Scottscou with an annual capacity of 35,000 tons, marking the maturation and widespread application of ethylene hydration technology.
