Method for preparing phthalic acid through liquid phase catalytic oxidation of xylene

A technology for phthalic acid and xylene liquid, which is applied in the field of liquid phase oxidation of xylene to prepare phthalic acid, can solve the problems that three kinds of xylene cannot share oxidation, different catalyst complexing abilities, and fluctuating catalyst concentration, etc. The effect of combined deactivation, small fluctuation range of catalyst concentration, and small amount of catalyst

Active Publication Date: 2016-12-07
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Claims
  • Application Information

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Problems solved by technology

However, due to the different structures of the three xylenes, the complexing abilities of the product diacids to the catalyst are different, which directly leads to different reaction conditions. Although the current xylene oxidative esterification process is similar, the complexation caused Catalyst concentration fluctuates so that the three xylenes cannot share the oxidation technique

Method used

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  • Method for preparing phthalic acid through liquid phase catalytic oxidation of xylene
  • Method for preparing phthalic acid through liquid phase catalytic oxidation of xylene
  • Method for preparing phthalic acid through liquid phase catalytic oxidation of xylene

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Experimental program
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Effect test

Embodiment 1

[0019] A 2L continuous bubble column reactor was used, and the composition of the mixed solution was 60% dimethyl phthalate and 40% o-xylene. Wherein, the mass fraction of the catalyst is 0.012% cobalt isooctanoate, and the mass fraction of the additive 2,2-bipyridine is 0.02%. The liquid feed rate is 15g / min, the air feed rate is 10L / min, the reaction temperature is 170°C, the pressure is 1.1MPa, the residence time is 1h, the conversion rate of o-xylene is 60.2%, and the total selectivity of phthalic acid is 96.5%, tail gas oxygen concentration 3.2%, tail gas CO 2 Concentration 1.2%.

Embodiment 2～6

[0020] Embodiment 2~6: repeat the reaction process of embodiment 1, difference is to use different solvent catalyst and reaction condition. The specific raw material reaction conditions and results of each embodiment are listed in Table 1.

[0021] Table 1, embodiment 2~6 specific reaction conditions

[0022]

[0023]

Embodiment 7

[0025] A 1L batch stirred tank reactor was used, and the composition of the mixed solution was 65% diethyl terephthalate and 35% p-xylene. Wherein, the catalyst is cobalt naphthenate with a mass fraction of 0.01%, and the mass fraction of 2,2-bipyrimidine is 0.02%. The mixed liquid was 600g, the reaction temperature was 160°C, the pressure was 1.5MPa, the reaction time was 4h, the conversion rate of p-xylene was 70.2%, and the total selectivity of terephthalic acid was 97.5%.

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Abstract

The invention discloses a method for preparing phthalic acid through liquid phase catalytic oxidation of xylene, wherein the method is suitable for liquid phase oxidation reactions of p-xylene, o-xylene and m-xylene. Specifically the method comprises that phthalic acid ester or methyl benzoate is adopted as a solvent, air or oxygen is adopted as an oxidant, oil-soluble Co or Mn is adopted as a catalyst, 2,2-bipyridine and other complexing agents are adopted as additives, and oxidation is performed to obtain the phthalic acid, wherein the reaction temperature is 150-240 DEG C, and the reaction pressure is 0.5-2.0 Mpa. According to the present invention, the technology has the good universality and is suitable for the oxidation of p-xylene, o-xylene and m-xylene, the consumption of the catalyst in the method is less, the catalyst is not easily subjected to complexation inactivation, the concentration fluctuation range of the catalyst during the reaction process is small, the running period is long, the reaction effect is good, the flexible adjusting according to different reaction characteristics can be achieved, and other advantages are provided.

Description

technical field [0001] The invention relates to the field of chemistry and chemical engineering, in particular to a method for preparing phthalic acid by liquid-phase oxidation of xylene. Background technique [0002] Phthalic acid is an important chemical raw material, among which terephthalic acid is mainly used to produce polyethylene terephthalate, and has the largest demand; isophthalic acid can be used as the third monomer together with terephthalic acid Ethylene glycol is copolymerized to produce copolyesters; phthalic acid is mainly used to produce phthalate plasticizers. At present, the production methods of terephthalic acid and isophthalic acid are mainly obtained by liquid-phase oxidation of oxygen-containing gas by using their respective high-purity xylene isomers as raw materials and acetic acid as a solvent. Phthalic acid is mainly obtained by gas-phase oxidation to obtain phthalic anhydride followed by hydrolysis. In recent years, with the increasing market...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C63/16C07C63/24C07C63/26C07C51/265
Inventor 徐杰杜文强石松陈晨孙颖高进
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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