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Propylene Oxide production technology summary

 

Propylene oxide is an important basic organic chemical raw materials in the production of propylene derivatives after polypropylene and acrylonitrile. Because of propylene oxide has a great ring oxygen tension, chemically active, mainly for ( an important raw material for the production of polyurethane ) production of Polyether Polyols, Propylene Glycol, but also the production of non-ionic surfactants, oil demulsifier, pesticide emulsifier many important chemical raw material.

 

Traditional production process

 

1.      Chlorohydrin

Propylene, chlorine, alcohol and water to produce chlorine, lime and then processed to generate propylene oxide. Process is divided into chlorohydrination, saponification, refined three steps. Reaction conditions: pressure,40-90C, conversion: 97% acrylic, ~ 100% chlorine, ethylene oxide yield: > 96%

 

Byproducts: hydrochloric acid, dichloro propane dichloride, diisopropyl ether.

Epichlorohydrin production process short, mature technology, working load flexibility, without catalyst , good selectivity and high yield. However, multi -product waste, especially with CaCl2 and produce large amounts of chlorinated organic waste, chlorine and acrylic mix may explode , another serious equipment corrosion.

 

2. Indirect oxidation (Halcon Act )

Propylene oxide with an organic peroxide to obtain propylene oxide. The organic peroxide may be hydrogen peroxide or an organic percarboxylic acid compound. These peroxides peroxygen portion itself is transferred to the oxygen-selective olefin epoxide is generated, its conversion to alcohol or ketone organic percarboxylic acid is converted. There are isobutane and ethylbenzene Law Act .

 

Isobutane law: a two-step reaction . The first step: The reaction of isobutane with oxygen to give tert -butyl hydroperoxide (TBHP) and tert-butanol (TBA) reaction conditions: 137C, 3.15Mpa; Second step: the reaction of propylene oxide and TBHP (PO) . Reaction conditions: 121C, 3.61Mpa.

 

Isobutane method of propylene oxide yield> 95%, and the generation TBA, MTBE can be further reacted with methanol, or can be dehydrated to the olefin hydrogenation recycle isobutane, cogeneration ratio: PO / TBA = 1 / ( 2.43-2.67 ).

 

Ethylbenzene law: a two-step reaction. The first step: the reaction of ethylbenzene with oxygen to ethylbenzene hydroperoxide (EBHP) and benzyl alcohol (MBA), reaction conditions: 141C, 0.35Mpa; Second step: the reaction of propylene with EBHP propylene oxide (PO), the reaction conditions: 115C, 2.24Mpa.

 

Method of propylene oxide ethylbenzene yield> 95%, can be further generation of MBA styrene (SM) acetophenone is reacted with cogeneration ratio: PO/SM = 1/(2.25-2.29).

 

Advantages indirect oxidation is to produce large-scale, high yield, pollution-free; disadvantage is complex process, long process, equipment and materials for the high quality requirements, harsh operating conditions, a large co-product markets need to be considered.

 

New production process

 

1.      Cumene

This method also belongs to an indirect oxidation method. In 2003, Japan's Sumitomo Chemical Company in Chiba, Japan built the world's first industrial unit, placed in 2009 by a second suit Sumitomo and Saudi joint production.

 

The law cumene as raw material, in two steps. First step: in the air oxidation of cumene cumene hydroperoxide (CMHP), the reaction conditions :90-130C ,0.1-1 .0 Mpa; Second step: the reaction of propylene with PO and CMHP dimethylbenzyl alcohol (CMA). CMA dehydration, hydrogenation of cumene, cycle. The reaction conditions: 25-200C, 0.1-10Mpa TS-1 as catalyst byproduct is only water.

 

2.      Hydrogen peroxide method

This method is used to produce propylene oxide over the hydrogen peroxide and water, and a direct oxidation of propylene. In 2009, BASF and Dow joint development, production in Antwerp, Belgium world's first industrial unit, the production scale of 30kt/a.

 

Advantages of hydrogen peroxide law byproduct is water pollution, mild reaction conditions: pressure, 40 ~ 60 , catalyst activity, selectivity product is extremely high. Propylene conversion of substantially all the hydrogen peroxide, the PO yield > 95%. The disadvantage is that the cost of hydrogen peroxide is too high, relatively expensive catalyst TS-1, PO in the presence of large amounts of water will be hydrolyzed to produce the alcohol. Because this method requires hydrogen peroxide as raw materials, so from economic considerations, are generally produced with a combination of hydrogen peroxide.

 

According to the production process of hydrogen peroxide, and had made directly using synthetic materials for the hydrogen peroxide route step synthesis of propylene oxide, there Anthraquinone synthesis and H2-O2.

 

3.      Direct gas-phase oxidation of propylene

This method using oxygen as an oxidant to generate a direct reaction of propylene oxide with propylene. This method of ethylene oxide and ethylene oxide synthetic route similar, but the rate of complete oxidation of propylene is far greater than the rate of complete oxidation of ethylene and propylene molecule allyl very lively, prone to react with the adsorbed oxygen species, as formate and acetate generates CO2, so this route has some challenging research is still in the laboratory stage.

 

Cumene hydroperoxide route and the route is clean, efficient industrial route , has been industrialized, the next will replace the existing law, such as epichlorohydrin traditional production process, and become a major producer of propylene oxide route.

 

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