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domestic production gap
domestic production gapDiisopropylnaphthalene (DIPN) is an important organic chemical raw material, of which 2,6-diisopropylnaphthalene (2,6-DIPN) can also be like 2,6-DMN (2,6-dimethylnaphthalene) Naphthalene) can also be used as a raw material for the preparation of polyethylene terephthalate (PEN) and thermotropic liquid crystal polymer (LCP), and can also be used as a high value-added fine chemical product
.
Polyethylene naphthalate (PEN) is one of the new polyesters, and it has become one of the most popular polymer materials in the world with the fastest development and application
.
In various 2,6-dialkylnaphthalene liquid phase oxidation processes, due to 2,6-DMN (2,6-dimethylnaphthalene) and 2,7-DMN (2,7-dimethylnaphthalene) ) have similar physical and chemical properties, such as small differences in melting point and boiling point, difficult separation and high operating cost; while 2,6-diisopropylnaphthalene ( 2,6-DIPN) is easy to separate from isomer mixtures, Purification, lower operating cost
.
2,6-Diisopropylnaphthalene ( 2,6-DIPN ) is synthesized by direct alkylation of naphthalene, that is, naphthalene and propylene are reacted on a suitable catalyst.
Due to the use of cheap naphthalene as raw material, the source is abundant and the reaction conditions are compared.
It is mild and can directly obtain higher content of dialkylnaphthalene products
.
Process and reactor innovation to promote industrialization
Process and reactor innovation to promote industrializationThe traditional synthesis methods of diisopropylnaphthalene mostly use hydrofluoric acid, sulfuric acid or anhydrous aluminum trichloride as the catalyst.
The liquid alkylation catalyst is highly corrosive and has serious environmental pollution, and the content of 2,6-DIPN in the product is low.
, Because zeolite molecular sieves have the characteristics of high specific surface area, unique shape-selective selectivity, and easy separation from products, in recent years, the use of zeolite for naphthalene shape-selective alkylation to synthesize 2,6-DIPN, the development of environmentally friendly alkylation catalysts research is relatively active
.
2,6-Diisopropylnaphthalene production flow chart
2,6-Diisopropylnaphthalene production flow chartThe direct alkylation of naphthalene and propylene to synthesize 2,6-diisopropylnaphthalene ( 2,6-DIPN ) still has many technical problems that have not yet been solved, such as the low yield of alkylation at the 2,6 position, using Zeolite molecular shape-selective catalysis still has a large number of 2,7-isomers, molecular sieves have low activity, large pore size, high acidity, difficult to lasting activity, easy carbonization and sintering, and need to be separated by molecular sieve shape-selective separation or freezing crystallization methods.
, the separation process is complex, and the equipment investment is relatively large
.
Separation technology determines product purity
Separation technology determines product purityThe product of decalinylation is a mixture of monoisopropylnaphthalene (MIPN), diisopropylnaphthalene (DIPN), triisopropylnaphthalene (TIPN) and polyisopropylnaphthalene (PI PN), diisopropylnaphthalene only There are 10 isomers of naphthalene, and the physical and chemical properties of various isomers are very close.
The boiling point of each isomer is in the range of 308.
6-319.
6 °C.
The boiling points of the by-product 2,7-DIPN are 319.
6 ℃ and 317.
0 ℃ respectively, and the difference between the boiling points of the two is only 2.
6 ℃.
It is very difficult to obtain high-purity 2,6-DIPN by conventional rectification.
The melting points of 2,7-DIPN are 69 ℃ and -3 ℃, respectively, and the difference between the two melting points is large.
Therefore, the separation of 2,6-DIPN and 2,7-DIPN by crystallization is the direction of diisopropylnaphthalene separation research.
.
So far, the main methods for extracting dimethylnaphthalene are: supercritical extraction, pressure crystallization, adsorption separation and adsorption freezing crystallization
.
