Method for synthesizing 2,6-dimethylnaphthalene with 2-methylnaphthalene and C10 aromatics by transferring alkyl group

Abstract

The invention relates to a method for synthesizing 2,6-dimethylnaphthalene with 2-methylnaphthalene and C10 aromatics by transferring an alkyl group, in particular to a method for synthesizing the 2,6-dimethylnaphthalene by transferring the alkyl group through a molecular sieve based catalyst by using the 2-methylnaphthalene and the C10 aromatics (which is an aromatics mixture using tetramethylbenzene as a main component, wherein the carbon atom number of the mixture is 10, and the mixture is a by-product of a petrifaction aromatics device) as raw materials. The method comprises the following steps of: blending the C10 aromatics a and the 2-methylnaphthalene b which are used as the raw materials into a mixture raw material by a weight ratio of a:b=1-5:1; keeping the reaction airspeed to be 0.1-3 h<-1> at a reaction temperature of 360-540 DEG C and a reaction pressure of 0-7.0 MPa; and realizing an alkyl group transfer reaction through the molecular sieve based catalyst to synthesize the 2,6-dimethylnaphthalene. In the invention, the catalyst has low inactivation speed and longer service life, and meanwhile, the reaction selectivity and the yield of the 2,6-dimethylnaphthalene can be effectively improved; in addition, the mixture of the C10 aromatics is used as the raw material, and thus the production process of the 2,6-dimethylnaphthalene is effectively simplified; and the utilization of the C10 aromatics resource which is a byproduct and has low carbon value is also beneficial to the reducing of the production cost.

Description

technical field [0001] The invention relates to a method for synthesizing 2,6-dimethylnaphthalene through the transalkylation reaction of 2-methylnaphthalene and carbon ten aromatic hydrocarbons. Background technique [0002] 2,6-Dimethylnaphthalene (2,6-DMN) is the raw material for the production of a new high-performance polyester material, polyethylene naphthalate (PEN), and its oxidation and esterification produces 2,6-naphthalene As a monomer, dimethyl dicarboxylate (NDC) is polycondensed with ethylene glycol to generate polyethylene naphthalate (PEN). Compared with polyethylene terephthalate (PET), PEN has better performance. PEN has superior heat resistance, mechanical properties, chemical stability, gas barrier and UV and radiation resistance, and also It has good transparency; the use temperature of PEN is 35-55°C higher than that of PET, the tensile strength is 50% higher, and the heat insulation performance is 5 times higher; in addition, in the production of lam...

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Problems solved by technology

While the process obtains 2,6-dimethylnaphthalene, it still produces a large amount of various isomers that need to be separated. The process steps are many, the material consumption is large, and the cost is also very high.

US4795847 (J weitkamp et al.) reported the alkylation reaction of methylnaphthalene and methanol on ZSM-5. After 0.5 hour of reaction, the selectivity of 2,6-dimethylnaphthalene was 32%, but methylnaphthalene The conversion rate of the 2,6-dimethylnaphthalene has only 7%; As the reaction time prolongs, the methylnaphthalene conversion rate does not change substantially, but the selectivity of 2,6-dimethylnaphthalene will reduce

WO02060581 (Lillwita et al.) reported that FeF 3 and NH 4 HF 2 On the modified HZSM-5 molecular sieve, the alkylation reaction of methylnaphthalene and methanol can obtain 60% 2,6-dimethylnaphthalene selectivity, and the ratio of 2,6- / 2,7-dimethylnaphthalene is also It can reach 1.8-2.2, but the reaction conversion rate of methylnaphthalene is low, and the yield of synthetic 2,6-dimethylnaphthalene is low

Literature reports (C. Zhang, X. W. Guo, C. S. Song et al. Catalysis Today 149 (2010) 196-201.) HZSM-5 molecular sieves were modified by ethyl orthosilicate and water vapor treatment, the two modified The yields of 2,6-dimethylnaphthalene on molecular sieves are 5.3% and 7.6%, respectively, and it is considered that the acidity adjustment of zeolite molecular sieves is more conducive to improving the 2,6- / 2,7-dimethylnaphthalene than the control of pore size. The ratio of methylnaphthalene isomers, but the side reaction is serious, and the catalyst stability is not good

[0003] At present, although the selectivity of the synthesis of 2,6-dimethylnaphthalene by the alkylation reaction of methylnaphthalene and methanol on molecular sieves can be improved by adjusting the acidity and pore size of zeolite molecular sieves, the synthesis of 2,6-dimethylnaphthalene The yield is low, and the side reaction is serious, and the stability of the catalyst is not ideal, which limits the industrial application of this process

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