ABSTRACT
Ethanolamines were initially prepared from ethylene chlorohydrin and ammonia, but this route was replaced when ethylene oxide became readily available after World War II. The ratio of end products formed depends on the molar excess of ammonia present. All plants produce a mixture of ethanolamines, the ratio depending upon the product composition required. Monoethanolamine is the most important of the ethanolamines, accounting for around half of total production, followed by diethanolamine with 30–35%. Liquid ammonia and water, which acts as a catalyst, are mixed to give an ammonia concentration of 50–100%. Ethylene oxide is metered into the ammonia-water mixture to avoid the risk of explosive polymerization; the feed then passes into a tubular reactor containing an ion exchange resin. Ethanolamines can be absorbed by the skin in toxic amounts, repeated contact leading to redness and swelling. Ammonia and water are removed from the end products. The mixture of ethanolamines is then separated in a series of vacuum distillation columns.
