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Method for analyzing content of unsaturated acids in liquid phase mixture by gas chromatography

A gas chromatographic analysis and gas chromatographic technology, which is applied in the field of determination of acrylic acid content in the reaction product of acrolein prepared by propylene oxidation, can solve the problems of loss of catalyst active components, decrease in catalyst activity, aggravation of by-products, etc., and reduce column pollution. , reduce the impact, improve the reproducibility of the effect

Active Publication Date: 2016-12-21
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The gas-phase catalytic oxidation of propylene to prepare acrolein is a strongly exothermic reaction. A large amount of heat of reaction accumulates instantaneously in the reactor, forming local hot spots. The loss and detachment of components, so that the activity of the catalyst is reduced, the life is shortened, and the formation of by-products is aggravated by the excessive oxidation reaction, and even a runaway reaction is caused, which makes the catalyst sintered.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] After condensing and absorbing the 17L gas sample from the first-stage reactor sampling port of the single-tube reaction device, put it into a 1000mL volumetric flask, add water to the mark line, shake well, and use it as the test solution for later use. Finely extract 10ml of the liquid sample to be tested and add it to the Erlenmeyer flask, titrate it with a NaOH solution with a concentration of 0.0114mol / L, use phenolphthalein as an indicator, and record the volume V of the NaOH solution used NaOH = 2.23 mL. In addition to acrylic acid, there is also acetic acid in the liquid sample to be tested, so what is measured is the total acid (C 总酸 ), the content of acetic acid is very small, mainly acrylic acid. C 总酸 =C NaOH V NaOH / V 总酸 , V 总酸 = 10mL, C 总酸 = 0.00254.

[0032] Then use gas chromatography to measure acrylic acid and acetic acid: use 3 to 10 standard samples with known concentrations of acrylic acid and acetic acid, and measure the ratio of the corresp...

Embodiment 2

[0034] The determination procedure is the same as in Example 1. The acid-base titration method is used to determine the molar concentration of total acid in the liquid to be tested. The average value is measured twice. The inorganic acid is nitric acid. ℃ / min heating rate to 150 ℃, and then 20 ℃ / min heating rate to 180 ℃, measured C AA = 0.00290.

Embodiment 3

[0036] The determination procedure is the same as that in Example 1. The acid-base titration method is used to determine the molar concentration of total acid in the liquid to be tested, and the average value is measured for 3 times. The chromatographic column adopts non-isothermal segmental heating, that is, 110°C is maintained for 3min, and then the temperature is increased at a rate of 25°C / min. Raise the temperature to 150°C, and then raise the temperature to 170°C at a heating rate of 10°C / min, and measure C AA = 0.00343.

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PUM

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Abstract

The invention relates to a method for analyzing the content of unsaturated acids in a liquid phase mixture by gas chromatography. The unsaturated acids in the liquid phase mixture include acrylic acid and acetic acid. The method comprises the following determination steps: firstly, determining the total acid molar concentration in a to-be-tested liquid by an acid-base titration method; then determining the content of acrylic acid and acetic acid by the gas chromatography; and finally measuring the molar concentration of acrylic acid. The determination method has the advantages of low cost, simple and convenient operation, low requirements on a test environment, no need of large-scale analysis equipment, simple and rapid method, accurate determination results and good repeatability.

Description

technical field [0001] The invention relates to a method for analyzing the content of unsaturated acid in a liquid phase mixture by gas chromatography, in particular to the determination of the content of acrylic acid in the reaction product of acrolein prepared by oxidation of propylene. Background technique [0002] At present, acrylic acid is mainly produced in the industry by two-step oxidation of propylene, that is, a fixed-bed reactor is usually used, propylene is first oxidized to acrolein (one-stage reaction), and acrolein is oxidized to acrylic acid (two-stage reaction). [0003] In the research of catalysts for the preparation of acrolein (ACR) and acrylic acid (AA) from propylene, it is necessary to accurately detect the distribution and content of the reaction products, to screen the catalyst formula, investigate the life of the catalyst, and select the best catalyst. Process operating conditions, etc. provide reliable data. Mainly measure CO, CO in the reaction...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/02G01N31/16
Inventor 吴毅刘俊保曹帅英高杜娟何颖赵慧晖黄世英魏玉丽李晓银杜烨笪敏峰汤妍雯陈跟平贾慧青杨芳李淑萍王春龙
Owner PETROCHINA CO LTD
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