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Prepn process of standard acetaldehyde gas

A technology for standard gas and acetaldehyde, applied in the field of preparation of acetaldehyde standard gas, can solve the problems of waste of standard gas, high cost, time-consuming method, etc., and achieve the effects of not easy to waste, low operating cost, and convenient measurement

Active Publication Date: 2007-12-19
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Currently commercially available acetaldehyde standard gas is stored in steel cylinders, which is prepared by the internationally accepted gravimetric method. Not only is the preparation method complex and the cost is high, but also the storage time is short. After a certain period of time, some acetaldehyde is easy to polymerize. For paraldehyde, the standard gas can no longer be used
Due to the limitation of validity period, it often causes waste of standard gas
[0004] The laboratory can prepare acetaldehyde standard gas by distillation titration method. This method first distills acetaldehyde with acid, then titrates, and then uses a vacuum bottle to prepare standard gas. The method is time-consuming and cumbersome.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] The preparation method of acetaldehyde standard gas with a concentration of 500 μL / L is as follows:

[0013] (1) Accurately calibrate the volume of a vacuum bottle (with Teflon stirring plate inside) to 1000mL by weighing method. After the bottle is dried, pump it to a negative pressure of 2mmHg, and flush it with nitrogen gas with a purity of 99.999v% for 2 to 3 After the second time, it is pumped to a negative pressure of 2mmHg.

[0014] (2) Accurately weigh 3.3483 mg of 40 wt % chromatographically pure acetaldehyde aqueous solution (containing paraldehyde) with a balance, and pour it into a vacuum bottle.

[0015] (3) Use an oven to raise the temperature to 105°C, keep the temperature constant for 2 hours, then take it out and cool it to room temperature.

[0016] (4) Fill the above-mentioned vacuum bottle with nitrogen gas with a purity of 99.999v% to normal pressure, shake the Teflon stirring plate in the bottle, mix the gas and leave it for 30 minutes to obtain t...

Embodiment 2

[0019] The preparation method of acetaldehyde standard gas with a concentration of 2500 μL / L is as follows:

[0020] (1) Use the weighing method to accurately calibrate the volume of a vacuum bottle (with Teflon stirring plate inside) to be 1000mL. After the bottle is dried, pump it to a negative pressure of 9mmHg, and flush it with helium gas with a purity of 99.999v% for 2~ After 3 times, pump again to a negative pressure of 9mmHg.

[0021] (2) Accurately weigh 16.7415 mg of 40 wt% chromatographically pure acetaldehyde aqueous solution (containing paraldehyde) (containing paraldehyde) with a balance, and inject it into a vacuum bottle.

[0022] (3) Use an oven to raise the temperature to 80°C, keep the temperature constant for 4 hours, then take it out and cool it to room temperature.

[0023] (4) Fill the above-mentioned vacuum bottle with helium gas with a purity of 99.999v% to normal pressure, shake the Teflon stirring plate in the bottle, mix the gas and place it for 30...

Embodiment 3

[0026] The preparation method of acetaldehyde standard gas with a concentration of 1000 μL / L is as follows:

[0027] (1) Accurately calibrate the volume of a vacuum bottle (with Teflon stirring plate inside) to 1000mL by weighing method. After the bottle is dried, pump it to a negative pressure of 5mmHg, and flush it with nitrogen gas with a purity of 99.999v% for 2 to 3 After the second time, it is pumped to a negative pressure of 5mmHg.

[0028] (2) Accurately weigh 6.6966 mg of 40 wt % chromatographically pure acetaldehyde aqueous solution (containing paraldehyde) with a balance, and pour it into a vacuum bottle.

[0029] (3) Use an oven to raise the temperature to 118°C, keep the temperature constant for 2 hours, then take it out and cool it to room temperature.

[0030] (4) Fill the above-mentioned vacuum bottle with nitrogen gas with a purity of 99.999v% to normal pressure, shake the Teflon stirring plate in the bottle, mix the gas and leave it for 30 minutes to obtain ...

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Abstract

The preparation process of standard acetaldehyde gas includes the following steps: feeding acetaldehyde solution into vacuumized bottle, gasifying acetaldehyde, heating to depolymerize paraldehyde in the acetaldehyde solution into acetaldehyde gas, cooling to room temperature, and diluting with inert gas to normal pressure to obtain standard acetaldehyde gas. Compared with available technology, the present invention has the advantages of being simple, fast and accurate, low cost, etc. The prepared standard acetaldehyde gas may be set stably for over 24 hr, and is used in environment atmosphere detection and acetaldehyde detection in industrial waste gas.

Description

technical field [0001] The invention belongs to the technical field of standard gas preparation methods, and specifically provides a preparation method of acetaldehyde standard gas used for monitoring and analyzing acetaldehyde in the atmosphere and waste gas. Background technique [0002] Polyester waste gas is the waste gas generated during the dehydration of ethylene glycol and thermal degradation of polyester during polyester synthesis. The main organic pollutants in the waste gas are ethylene, acetaldehyde and 2-methyl-1,3-dioxolane, etc. , where the concentration of acetaldehyde is about 2000-20000mg / m 3 , much higher than the emission limit of air pollutants from new pollution sources in GB16297 (125mg / m 3 ). In order to solve the pollution problem of waste gas from polyester plant process, Fushun Petrochemical Research Institute adopts catalytic combustion technology to treat polyester waste gas. In order to optimize the treatment process, it is necessary to analy...

Claims

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Application Information

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IPC IPC(8): C07C47/06
Inventor 闫松
Owner CHINA PETROLEUM & CHEM CORP
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