A method for preparing triphenyl phosphate by extracting phenol from aryl phosphate production wastewater

Abstract

The invention discloses a method for preparing triphenyl phosphate through phenol extraction in aryl phosphoric ester production waste water. The method comprises the following steps of adding acid into the aryl phosphoric ester alkali washing waste water for regulating the pH value to 6 to 7; stirring and still standing layering to obtain an oil layer and waste water with the phenol content beinglower than 25000 ppm; adding triphenyl phosphate extraction agents into the waste water for stirring extraction; transferring an extraction phase into a distillation kettle for reduced pressure distillation dewatering; putting the dewatered extracts into an esterification kettle; next, adding phosphorus oxychloride and anhydrous magnesium chloride for esterification reaction to obtain triphenyl phosphate coarse products; sequentially performing acid washing, alkali washing, water washing and distillation treatment to finally obtain the qualified triphenyl phosphate finished product. Through the unified use of the triphenyl phosphate with the most simple phenol reuse process and least links as the extraction agents, one set of equipment can be used for solving the phenol recovery problem of various aryl phosphoric ester waste water in a concentrated way.

Description

technical field [0001] The invention relates to a method for preparing triphenyl phosphate by extracting phenol from aryl phosphate production wastewater. Background technique [0002] Aryl phosphate flame retardant is an important environmentally friendly halogen-free flame retardant, mainly used in engineering plastics flame retardant, common bisphenol A-bis (diphenyl phosphate), resorcinol-bis (diphenyl base phosphate), hydroquinone bis(diphenyl phosphate), tert-butylated aryl phosphate, etc. Due to the increasingly stringent restrictions on the use of halogen-containing flame retardants in European and American countries, the market demand for halogen-free aryl phosphate flame retardants is increasing year by year. [0003] Since the production of aryl phosphate flame retardants mostly uses phenol as the final phosphorus oxychloride capping reagent, in order to ensure that the esterification reaction reaches the end and obtain a higher conversion rate, an excess of phen...

AI Technical Summary

Problems solved by technology

This method is based on the adsorption of phenol by macroporous adsorbent, combined with the high-efficiency extraction effect of complex extractant on phenol to adsorb phenol. Compared with liquid complex extractant, no container is needed, only a fixed bed is needed, and relatively liquid Extractant, solid particles are easier to recover, but it is only tested for low-concentration phenol wastewater, and the effect is not good for wastewater with a concentration above 10,000ppm

[0008] Patent 4: In the document "Complex Extraction of Tributyl Phosphate TBP to Phenol" in Volume 14, Issue 5 of September 1995, Environmental Science described the extraction principle of dilute phenol solution with TBP+kerosene complex extractant Experimental analysis, comparing the extraction effect of other organic solvent extractants on phenol, proves that the TBP+kerosene complex extractant is better than a single solvent extraction effect. According to the analysis, it is considered that the waste water cannot be discharged up to the standard through a single extraction operation

Phosphate ester + high boiling point solvent mixed extraction agent is an extraction agent with a relatively high extraction rate, but there is still a problem that a large amount of alkaline or neutral saline wastewater will be generated when the mixed extraction agent is regenerated, and the quality of the finished product made from phenol dehydration is poor

[0009] For similar literature reports on mixed complexing extractants using phosphate ester + solvent, there are "Shandong Chemistry" 2015 Volume 44 "Complexation Extraction Method for High Concentration Phenol Wastewater", "Guangdong Chemistry" 2018 Issue 4 Volume 45 Reports such as "Research on the Process of Complex Extraction of High-Concentration Phenol-Containing Wastewater" mainly focus on the research on the factors affecting the extraction efficiency of phenol, but there is not much research on the problem of wastewater generated during the treatment process that enterprises are more concerned about.

[0010] The extraction method has the following common disadvantages: most extractants need to be regenerated by eluting phenol with alkaline aqueous solution, and the eluted phenol needs to be neutralized to neutral and then layered and dehydrated to obtain phenol. This process will produce a large amount of The wastewater containing sodium chloride and a small amount of phenol increases the amount of wastewater treatment

Repeated elution will gradually reduce the extractant, and it is necessary to purchase supplementary extractant regularly

The phenol obtained at the same time is very easy to change color due to high-temperature dehydration and other operations, and generally can only be used in a downgraded manner, which affects the scope of use of the extraction method.