Diethanolamine is derived from the dehydration of sulfuric acid. The diethanolamine was added into the water reaction pot, and sulfuric acid was added dropwise below 60° C., and the temperature was increased at 185-195° C. and incubated for 30 min. Cold to below 60 °C, sodium hydroxide solution was added dropwise to pH = 11, cooling, filtration, filtrate distillation, collecting fractions below 130 °C, the content of refined morpholine up to 99.5%. The raw material of this method is readily available and it has become the main method of producing morpholine in the world. The morpholine can be prepared by gas phase catalytic reaction of dioxane and ammonia.
The morpholine can also be prepared using diethylene glycol and ammonia in the presence and pressure of the catalyst. The method is easy to obtain raw materials and has become the main method for producing morpholine in the world.