Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2 propanol) is a colorless, flammable, organic compound with a pungent alcoholic odor. Isopropyl alcohol, an organic polar molecule, is miscible in water, ethanol, and chloroform, demonstrating its ability to dissolve a wide range of substances including ethyl cellulose, polyvinyl butyral, oils, alkaloids, and natural resins.
The main applications of Isopropyl Alcohol are as chemical intermediate and as solvent in the manufacturing of cements, primers, paints, varnishes, skin cleaners, perfumes, lotions, shampoos, and deodorants. It is also used as disinfectant and antiseptic. Also Isopropanol has many application such as raw materials to produce following chemicals:
- Acetone
- hydrogen peroxide
- Isopropyl chloride
- Fatty acid isopropyl ester
- Chlorinated fatty acid isopropyl ester
Isopropanol Production Process
Isopropyl alcohol was among the first petrochemical products to be industrially manufactured - it has been produced since 1920. At this time, Isopropanol was generated through the indirect hydration of propylene, a process that uses sulfuric acid to react with propylene and generate a compound that will react with water to produce Isopropanol. Today, it is one of the most produced lower alcohols (C1 to C5 alcohols), the third in commercial production, behind methanol and ethanol.
At present, isopropyl alcohol has achieved industrial production in the world in two categories:
- Acetone hydrogenation and
- Propylene hydration
A) Propylene water method
The present analysis approaches Isopropanol production from polymer grade (PG) propylene. The process under analysis comprehends two major sections:
- Isopropanol synthesis
- purification
Polymer grade propylene is mixed with water, vaporized, superheated to the required reaction temperature and fed to the reactor. The reaction forms, in addition to Isopropyl Alcohol, minor amounts of side products, including diisopropyl ether, n-propyl alcohol and acetone. The reactor product stream is is sent to a Washing Column, where Isopropyl Alcohol and side products are absorbed in water and separated from unreacted propylene. The washing column liquid effluent is routed to the purification, while the gaseous overhead product is compressed and recycled to the reactor.
The crude isopropanol is directed to a light ends column, where diisopropyl ether (generated in side reactions) is separated. The ether-free crude Isopropanol is transferred to the azeotrope column for removal of water and high boiling impurities. The overheads product from this column comprises an azeotropic mixture of Isopropanol and water. This mixture is separated by means azeotropic distillation using an azeotroping agent - the separated water leaves the process as wastewater.
B) Acetone hydrogenation method
Hydrogenation of acetone to produce isopropanol mainly includes three sections:
- Synthesis section of isopropanol
- Separation section
- extraction of by-products and recovery of azeotrope section
Among these three sections, only synthesis section involves chemical reactions.
The application of acetone hydrogenation method in isopropanol production process is not as wide as that of direct water method, because the method has high requirements for raw materials and large demand, which is not conducive to its economic benefits. However, this method still has advantages, low energy consumption is more important, and acetone hydrogenation has less corrosion to production equipment.
From the perspective of catalyst, nickel catalyst is expensive, but long life, and waste catalyst can be recycled, environmental protection pressure is low; The price of acidic catalyst is relatively low, but the service life is short and loss occurs in the reaction process. The catalyst needs to be continuously supplemented during the reaction, which also corrodes the reactor. Acetone hydrogenation reaction conditions are mild, and the one-way conversion rate is high, and the reaction process is not complicated. Therefore, this project adopts the acetone hydrogenation process with nickelbased catalyst.