sec-butyl acetate; C4; reactive distillation; esterification reaction
Sec-butyl acetate, also known as sec-butyl acetate, is a colorless, fruity flammable liquid. Sec-butyl acetate has many uses as a fragrance, medicine, solvent, metal cleaner, reaction medium and extractant. In recent years, due to the increasingly stringent requirements for environmental protection around the world, people tend to reduce the amount of solvents such as toluene, xylene, and ketones. The development direction is the development and utilization of tree ester coatings and the replacement of aromatics and ketones in volatile coating formulations with oxygenated solvents such as acetates. Sec-butyl acetate meets this trend.
At present, there are two main methods for the production of sec-butyl acetate: alcohol esterification and olefin-acetic acid addition.
The addition process of butene-acetic acid to synthesize sec-butyl acetate is the addition reaction of the remaining olefins after the removal of isobutylene from the C4 olefin isomer and glacial acetic acid under the action of acid catalyst to directly synthesize sec-butyl acetate. The acid ester is separated by rectifying to obtain high-purity sec-butyl acetate products. The C4 light hydrocarbon fraction contains a large amount of isobutylene, which can be used to produce methyl tert-butyl ether (MTBE) and polyisobutylene (PIB) and other petrochemical products. After rectifying, the C4 component contains a large amount of 1-butene, which provides an ideal raw material for the production of sec-butyl The catalysts used in the reaction process are roughly divided into two categories, namely solid acid catalysts and liquid acid catalysts. The former includes cation exchange resins, solid phosphomolybdic acid, etc.; the latter includes sulfuric acid, p-toluenesulfonic acid, etc. The process involved in this case can be divided into reaction units and rectification units.
Feedstock : C4 fraction (total butene content over 55%), acetic acid, hydrogen after distillation from MTBE unit.
Catalyst : Acid catalyst.
Technical solution : The reaction unit includes hydrogenation reaction to remove butadiene, distillation to remove excess hydrogen, and addition of butene and acetic acid to produce sec-butyl acetate; the rectification unit includes removal of C4 fraction, azeotropic distillation, acetic acid refining, removal of light fraction and removal of heavy fraction.
Main equipment : several sets of distillation towers, fixed bed reactors, storage tanks, heat exchangers and matching pipelines and meters.
1. Adopt the process of reactive distillation to synthesize the reactor and distillation column into one equipment, reducing investment and saving costs;
2. The process uses simple methods such as C4 multi-point feeding, reaction external circulation heat extraction, acetic acid recycling, etc., to effectively optimize the reaction conditions and reduce energy consumption;
3. The yield of sec-butyl acetate is high and the capacity is large. Acetic acid can also be recycled, which further improves the economy of the whole process and has a better industrial application prospect;
4. Compared with the alcohol esterification method, the olefin-acetic acid addition method can reduce the raw material price by about 2300 yuan per ton, and the economic benefit is significantly higher than that of the alcohol esterification method.
