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Method for measuring aqueous formaldehyde in isoprene synthesizing industry by adopting olefine aldehyde method

A technology of isoprene and enal method, applied in the field of analytical chemistry, can solve problems such as complex composition and achieve accurate results

Inactive Publication Date: 2017-05-31
SHANDONG YUHUANG CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This makes the composition of the water phase extremely complex. How to accurately measure the content of formaldehyde in the water phase under such complex conditions has not yet been reported in relevant patents.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Take 192g of 85wt% tert-butanol solution, 30g of 37wt% formaldehyde solution, and 30g of 88wt% phosphoric acid solution, mix the three evenly, and inject the mixed solution into the tubular reactor with a precision metering pump. The reaction temperature is 170°C and the pressure is 1.4MPa. The residence time was 20 minutes, and the obtained product was extracted with n-heptane. The oil phase was located in the upper layer, and the water phase was located in the lower layer. The yield of isoprene was 69%, and 325 g of an aqueous phase containing formaldehyde was obtained. Take 40 g of the aqueous phase, add sodium hydroxide solution, adjust the pH to 10, and filter the precipitate to obtain a colorless and clear solution. Using phenolphthalein as an indicator, reverse drip the solution to neutral with sulfuric acid, add sodium sulfite, because sodium sulfite reacts with formaldehyde to form sodium hydroxide, the solution is red at this time, titrate with sulfuric acid st...

Embodiment 2

[0024] Take 192g of 85wt% tert-butanol solution, 30g of 37wt% formaldehyde solution, and 30g of 88wt% phosphoric acid solution, mix the three evenly, and inject the mixed solution into the tubular reactor with a precision metering pump. The reaction temperature is 170°C and the pressure is 1.4MPa. The residence time was 20 minutes, and the obtained product was extracted with n-heptane. The oil phase was located in the upper layer, and the water phase was located in the lower layer. The yield of isoprene was 69%, and 325 g of an aqueous phase containing formaldehyde was obtained. Take 40g of the aqueous phase, add 6wt% formaldehyde to it, then add sodium hydroxide solution, adjust the pH to 10, filter the precipitate, use phenolphthalein as indicator, reverse drip the solution to neutrality with sulfuric acid, add sodium sulfite, and use sulfuric acid standard solution Titrate to colorless, according to the amount of consumed sulfuric acid standard solution, the calculated forma...

Embodiment 3

[0026] Take 18g of 85wt% tert-butanol solution, 41g of 37wt% formaldehyde solution, and 28g of 88wt% phosphoric acid solution, mix the three evenly, and inject the mixed solution into the tubular reactor with a precision metering pump. The reaction temperature is 160°C and the pressure is 1.0MPa. The residence time was 20 minutes, and the obtained product was extracted with n-heptane. The oil phase was located in the upper layer, and the water phase was located in the lower layer. The yield of isoprene was 59%, and 244 g of an aqueous phase containing formaldehyde was obtained. Take 50 g of the aqueous phase, add sodium carbonate solution, adjust the pH to 9, and filter the precipitate to obtain a colorless and clear solution. Using phenolphthalein as an indicator, reverse drip the solution to neutral with sulfuric acid, add sodium sulfite, because sodium sulfite reacts with formaldehyde to form sodium hydroxide, the solution is red at this time, titrate with sulfuric acid stan...

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Abstract

The invention relates to the field of analytical chemistry and particularly relates to a method for measuring aqueous formaldehyde in isoprene synthesizing industry by adopting olefine aldehyde method. With a formaldehyde-containing aqueous phase as a treatment object, the method is characterized by comprising the following steps: adding an alkaline solution into an aqueous phase to regulate the pH to alkalinity; separating the generated precipitate from aqueous phase to obtain a colorless clear solution; adding thymolphthalein into the colorless clear solution to turn the solution red, dropwise adding acid liquid to turn the solution colorless and neutral; adding a sodium sulfite solution into the neutral solution to turn the solution red, titrating with a sulfuric acid standard solution to turn the solution from red to colorless; and calculating the formaldehyde content in the aqueous phase according to consumption of the sulfuric acid standard solution. The method provided by the invention is simple and easy to implement, realizes an accurate result, eliminates influence of acid catalyst, multiple metal ions and C4 alcohol in the aqueous phase on formaldehyde measurement and is suitable for wide promotion and application.

Description

technical field [0001] The invention relates to the field of analytical chemistry, in particular to a method for measuring formaldehyde in water phase in the industry of synthesizing isoprene by enal method. Background technique [0002] Isoprene is an important raw material for the production of isoprene rubber. Isoprene rubber is used more and more widely because its structure and properties are close to natural rubber. The current production methods of isoprene include C5 fraction extraction distillation method, dehydrogenation method, and chemical synthesis method, wherein chemical synthesis method includes isobutylene-formaldehyde method, acetylene-acetone method, and propylene dimerization method. The acetylene-acetone method and the propylene dimerization method have long been used. The enaldehyde method is the most important isoprene synthesis method, which has been industrialized in Russia and Japan. [0003] The alkenal method can be divided into one-step method, ...

Claims

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Application Information

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IPC IPC(8): G01N31/16
CPCG01N31/16
Inventor 景文赵存胜何龙肖博常俊丽王胜伟
Owner SHANDONG YUHUANG CHEM CO LTD
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