WO2023108859A1

WO2023108859A1 - Pyrolysis recycling method for organic component in waste light-emitting diode

Info

Publication number: WO2023108859A1
Application number: PCT/CN2022/072847
Authority: WO
Inventors: 李彬; 陶然; 吴玉锋; 张炜
Original assignee: 北京工业大学
Priority date: 2021-12-17
Filing date: 2022-01-20
Publication date: 2023-06-22
Also published as: CN114317973A

Abstract

A pyrolysis recycling method for an organic component in a waste light-emitting diode, relating to the technical field of photoelectric device recycling. In the present invention, firstly, pyrolysis is performed for a waste light-emitting diode, a volatile component is collected, and metal is enriched; the volatile component is condensed to obtain a pyrolytic gas and a pyrolytic oil, and the pyrolytic gas is purified and then combusted for heat reuse; ammonia water is added into the pyrolytic oil, heating is carried out for reaction, the liquid is left standing for layering, a separated water layer is heated to recycle ammonia gas, and an oil layer is subjected to high-speed centrifugation to separate out a black oil layer and crude silicone oil; the black oil layer is subjected to water washing, drying, extraction by an organic solvent, and distillation under reduced pressure to prepare crude phenol. According to the present invention, by using pyrolysis, metal in a waste light-emitting diode is effectively enriched, thereby facilitating comprehensive recycling of the metal, and the effect of 20%-25% volume reduction of the waste light-emitting diode is achieved in the pyrolysis process. According to the present invention, the pyrolytic gas is directly reused after being purified, such that energy consumption is reduced. According to the present invention, phenol separated using ammonia water is used, and the use of a strong alkali and a strong acid is avoided.

Description

A method for pyrolysis recovery of organic components of waste light-emitting diodes

technical field

The invention belongs to the technical field of photoelectric device recycling, and in particular relates to a pyrolysis recycling method for organic components of waste light-emitting diodes.

Background technique

Light emitting diode (Light Emitting Diode, LED) due to its outstanding advantages of energy saving, small size, long service life, impact resistance, high reliability, fast response, etc. The fourth generation of lighting sources, also known as green light sources. Widely used in lighting lamps, LED displays, OLEDs, traffic lights, automotive lamps, LCD backlights, etc.

As the use of LEDs has grown massively, so has the volume of waste. Light-emitting diodes not only contain a large amount of base metals such as iron, aluminum, and copper, but also rare and precious metals such as gallium, indium, gold, and silver, which are of great recycling value; Safety poses a great hazard. Therefore, it is of great significance to harmlessly treat waste light-emitting diodes and to recycle organic matter and metals therein.

Pyrolysis, also known as dry distillation, refers to the process of heating macromolecular organic matter or polymers to break their chemical bonds under anaerobic or anaerobic conditions, and forming new solid, liquid, and gaseous phase products after condensation and other treatments. In the process of processing electronic waste, pyrolysis can not only recover metals, but also realize the resource recovery and reuse of non-metallic substances such as glass fibers and resins. In recent years, researchers have done a lot in the pyrolysis of electronic waste A lot of exploration work, patent CN108413400A discloses a method of co-pyrolysis of alkali slag and waste circuit boards, patent CN112759731A discloses a method for separation and reuse of pyrolysis oil in waste circuit boards and electronic component packaging materials, patent CN109719117A discloses A method of pyrolysis in the process of recycling waste lithium batteries, but there are few reports on the pyrolysis treatment of waste light-emitting diodes. The main reason is that the types of non-metallic components in light-emitting diodes are complex, not only containing a variety of epoxy resins, It also contains a large amount of silicon substances, acid anhydride substances, high light diffusing fillers and thermal stability dyes, etc., and the pyrolysis recovery process is complicated.

There are few patents and reports on the recycling of waste light-emitting diodes, which mainly focus on the separation and extraction of metals from waste light-emitting diodes. The article "Recycling of metals (Ga,In,As and Ag) from waste light-emitting diodes in sub/ Supercritical ethanol" proposed a method for metal enrichment of waste light-emitting diodes. This process first uses absolute ethanol to dissolve the adhesive at 250°C, and then uses a subcritical water-ethanol mixture to degrade the encapsulation resin at 300°C to achieve metal enrichment. Enrichment, patent CN104576848A discloses a method for recovering gallium from waste gallium nitride-based light-emitting diodes. The process uses vacuum metallurgy. The vacuum metallurgy is based on the different saturated vapor pressures of different metals at the same temperature. Evaporation and condensation realize the separation of metals. This process has high energy consumption and high equipment requirements, which is not conducive to industrial application and promotion. Patent CN109055782A discloses a leaching method for recovering gallium from waste light-emitting diodes. The process is to pyrolyze the light-emitting diodes at 450-500°C, and then ball mill and sieve to obtain gallium-enriched bodies. Gallium is leached with oxalic acid to realize Recovery of scattered gallium metal from e-waste to leachate. However, this process only recovers gallium metal, without considering the recovery of organic components.

The present invention proposes to pyrolyze waste light-emitting diodes, recover pyrolysis gas for reuse, add ammonia water to remove phenol from pyrolysis oil, separate liquid after reaction, and recover ammonia gas by heating the separated water layer, and the separated oil layer will appear black after standing still Centrifuge the oil droplets and separate the liquid again. The white oil layer is crude silicone oil, and the black oil layer is phenol enrichment, 80% of which are phenolic compounds. Crude phenol can be obtained by washing with water, drying, organic solvent extraction, and vacuum distillation. , so as to realize the recovery of waste light-emitting diode pyrolysis oil, the recovery of phenol and the enrichment of metals.

Contents of the invention

The purpose of the present invention is to provide a method for pyrolysis recovery of organic components in waste light-emitting diodes, which can properly recover the organic components in waste light-emitting diodes to obtain crude phenol and crude silicone oil, and also enrich the metals in waste light-emitting diodes. Contributes to further recycling processing.

A method for pyrolyzing and recovering organic components of waste light-emitting diodes according to the present invention comprises the following steps:

(1) Put the waste light-emitting diodes into the pyrolysis furnace, and continuously feed argon;

(2) The waste light-emitting diodes are pyrolyzed under an inert gas atmosphere to obtain volatile matter and pyrolysis slag;

(3) condensing the volatile matter obtained in step (2) to obtain pyrolysis oil and pyrolysis gas;

(4) Purify and burn the pyrolysis gas obtained in step (3), which can be used as energy to provide heat for step (2);

(5) adding ammonia water to the pyrolysis oil obtained in step (3), stirring, heating, standing, and liquid separation to obtain a water layer and an oil layer A;

(6) heating the water layer that step (5) obtains, collects volatilized ammonia, and can return to step (5) for reuse;

(7) centrifuging the oil layer A obtained in step (5), and obtaining black oil layer B and crude silicone oil after liquid separation;

(8) The black oil layer B obtained in step (7) was washed with water, dried, extracted with an organic solvent, and distilled under reduced pressure to obtain crude phenol.

Further, in step (2), the pyrolysis temperature is 300-600° C., and the holding time is 20-60 min.

Further, in step (5), the concentration of ammonia water is 10-15mol/L, the ratio of alkali to oil (the volume ratio of alkali liquor to oil liquid, that is, the volume ratio of ammonia water to pyrolysis oil) is 0.5-2, and the reaction temperature is 20 -80°C, the reaction time is 10-20min.

Further, in step (8), the organic solvent is benzene, and the number of extractions is 1-3 times.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The present invention uses pyrolysis to effectively enrich the metals in the waste light-emitting diodes, which is beneficial to the comprehensive recovery of metals. During the pyrolysis process, the effect of reducing the capacity of waste light-emitting diodes by 20-25% is achieved.

(2) The present invention directly reuses the pyrolysis gas after purification, reducing energy consumption.

(3) The present invention uses ammonia water to separate the phenols in the pyrolysis oil, avoiding the use of strong alkalis such as sodium hydroxide.

(4) The present invention uses ammonia water to separate phenol, and does not need to use strong acid neutralizing solution in the process of making crude phenol, avoiding the use of strong acids such as sulfuric acid.

Description of drawings

Fig. 1 is a process roadmap provided by an embodiment of the present invention.

Detailed ways

Example 1

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously feed argon; under the condition of argon atmosphere, heat up to 300°C and keep it warm for 60 minutes to obtain volatile matter and pyrolysis residue; condense the volatile matter to obtain pyrolysis oil and pyrolysis gas; after purification and combustion, the pyrolysis gas can be used as an energy source to provide heat for pyrolysis; add 15mol/L ammonia water to the pyrolysis oil, the ratio of alkali to oil is 2:1, stir and react at 20°C for 12 minutes, then stand for separation liquid to obtain water layer and oil layer A; the water layer is heated to collect volatilized ammonia gas, which can be reused; oil layer A is centrifuged, and black oil layer B and crude silicon oil are obtained after liquid separation; black oil layer B is washed with water and dried , extracted 3 times with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes is 83.98%, and the removal rate of phenol is 98.56%.

Example 2

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously pass in argon; under the condition of argon atmosphere, heat up to 350°C and keep it warm for 60 minutes to obtain volatile matter and pyrolysis residue; condense the volatile matter to obtain pyrolysis oil and pyrolysis gas; after purification and combustion, the pyrolysis gas can be used as an energy source to provide heat for pyrolysis; add 15mol/L ammonia water to the pyrolysis oil, the ratio of alkali to oil is 1:2, stir and react at 80°C for 15 minutes, then stand and separate liquid to obtain water layer and oil layer A; the water layer is heated to collect volatilized ammonia gas, which can be reused; oil layer A is centrifuged, and black oil layer B and crude silicon oil are obtained after liquid separation; black oil layer B is washed with water and dried , extracted twice with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes was 86.63%, and the removal rate of phenol was 95.31%.

Example 3

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously pass in argon; under the condition of argon atmosphere, heat up to 400°C and keep it warm for 50 minutes to obtain volatile matter and pyrolysis slag; condense the volatile matter to obtain pyrolysis oil and pyrolysis gas; after purification and combustion, the pyrolysis gas can be used as an energy source to provide heat for pyrolysis; add 13mol/L ammonia water to the pyrolysis oil, the ratio of alkali to oil is 3:2, stir and react at 50°C for 18 minutes, then stand for separation liquid to obtain water layer and oil layer A; the water layer is heated to collect volatilized ammonia gas, which can be reused; oil layer A is centrifuged, and black oil layer B and crude silicon oil are obtained after liquid separation; black oil layer B is washed with water and dried , extracted twice with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes was 90.07%, and the removal rate of phenol was 97.40%.

Example 4

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously pass in argon; under the condition of argon atmosphere, heat up to 450°C and keep it for 45 minutes to obtain volatile matter and pyrolysis slag; condense the volatile matter to obtain pyrolysis oil and pyrolysis gas; after purification and combustion, the pyrolysis gas can be used as an energy source to provide heat for pyrolysis; add 12mol/L ammonia water to the pyrolysis oil, the ratio of alkali to oil is 1:1, stir and react at 60°C for 20 minutes, then let it stand for separation liquid to obtain water layer and oil layer A; the water layer is heated to collect volatilized ammonia gas, which can be reused; oil layer A is centrifuged, and black oil layer B and crude silicon oil are obtained after liquid separation; black oil layer B is washed with water and dried , extracted once with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes was 92.16%, and the removal rate of phenol was 97.09%.

Example 5

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously pass in argon; under the condition of argon atmosphere, heat up to 480°C and keep it for 30 minutes to obtain volatile matter and pyrolysis slag; condense the volatile matter to obtain pyrolysis oil and pyrolysis gas; after purification and combustion, the pyrolysis gas can be used as an energy source to provide heat for pyrolysis; add 10mol/L ammonia water to the pyrolysis oil, the ratio of alkali to oil is 1:2, stir and react at 80°C for 10 minutes, then stand for separation liquid to obtain water layer and oil layer A; the water layer is heated to collect volatilized ammonia gas, which can be reused; oil layer A is centrifuged, and black oil layer B and crude silicon oil are obtained after liquid separation; black oil layer B is washed with water and dried , extracted once with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes was 94.37%, and the removal rate of phenol was 95.80%.

Example 6

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously pass in argon; under the condition of argon atmosphere, heat up to 500°C and keep it warm for 25 minutes to obtain volatile matter and pyrolysis slag; condense the volatile matter to obtain pyrolysis oil and pyrolysis gas; after purification and combustion, the pyrolysis gas can be used as an energy source to provide heat for pyrolysis; add 13mol/L ammonia water to the pyrolysis oil, the ratio of alkali to oil is 2:3, stir and react at 30°C for 12 minutes, then stand for separation liquid to obtain water layer and oil layer A; the water layer is heated to collect volatilized ammonia gas, which can be reused; oil layer A is centrifuged, and black oil layer B and crude silicon oil are obtained after liquid separation; black oil layer B is washed with water and dried , extracted twice with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes was 97.72%, and the removal rate of phenol was 96.40%.

Example 7

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously pass in argon; under the condition of argon atmosphere, heat up to 550°C and keep it for 20 minutes to obtain volatile matter and pyrolysis slag. Condensate the volatile matter to obtain pyrolysis oil and pyrolysis gas; the pyrolysis gas can be used as energy to provide heat for pyrolysis after purification and combustion; add 14mol/L ammonia water to the pyrolysis oil, and the ratio of alkali to oil is 2:1 , stirred and reacted at 40°C for 15 minutes, then left to separate liquids to obtain water layer and oil layer A; heated the water layer to collect volatilized ammonia gas, which can be reused; centrifuged oil layer A, and obtained black oil layer B and oil layer A after liquid separation Crude silicone oil; the black oil layer B was washed with water, dried, extracted 3 times with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes is 98.38%, and the removal rate of phenol is 98.87%.

Example 8

Follow the steps below to recycle:

Put the waste light-emitting diodes into the pyrolysis furnace, and continuously pass in argon gas; under the condition of argon gas atmosphere, heat up to 600°C and keep it warm for 30 minutes to obtain volatile matter and pyrolysis slag; condense the volatile matter to obtain pyrolysis oil and pyrolysis gas; after purification and combustion, the pyrolysis gas can be used as an energy source to provide heat for pyrolysis; add 15 mol/L ammonia water to the pyrolysis oil, the ratio of alkali to oil is 3:2, stir and react at 80°C for 20 minutes, then stand for separation liquid to obtain water layer and oil layer A; the water layer is heated to collect volatilized ammonia gas, which can be reused; oil layer A is centrifuged, and black oil layer B and crude silicon oil are obtained after liquid separation; black oil layer B is washed with water and dried , extracted twice with benzene, and distilled under reduced pressure to obtain crude phenol. The pyrolysis rate of waste light-emitting diodes is 99.56%, and the removal rate of phenol is 99.20%.

Claims

A method for pyrolyzing and recovering organic components of waste light-emitting diodes, characterized in that it comprises the following steps:

(1) Put the waste light-emitting diodes into the pyrolysis furnace, and continuously feed argon;

(2) The waste light-emitting diodes are pyrolyzed in an argon atmosphere to obtain volatile matter and pyrolysis slag; the pyrolysis temperature is 300-600°C, and the holding time is 20-60min;

(3) condensing the volatile matter obtained in step (2) to obtain pyrolysis oil and pyrolysis gas;

(4) purify the pyrolysis gas of step (3);

(5) Add ammonia water to the pyrolysis oil obtained in step (3), stir, heat, stand, and separate liquids to obtain a water layer and an oil layer A; the concentration of ammonia water is 10-15mol/L, and the ratio of alkali to oil is ammonia water to heat The volume ratio of oil separation is 0.5-2, the reaction temperature is 20-80°C, and the reaction time is 10-20min;

(6) heating the water layer that step (5) obtains, collects volatilized ammonia;

(7) centrifuging the oil layer A obtained in step (5), and obtaining black oil layer B and crude silicone oil after liquid separation;

(8) The black oil layer B obtained in step (7) was washed with water, dried, extracted with an organic solvent, and distilled under reduced pressure to obtain crude phenol.
A method for pyrolyzing and recovering organic components of waste light-emitting diodes according to claim 1, wherein the pyrolysis gas obtained in step (3) is purified and burned to provide heat for step (2) as an energy source.
A method for pyrolyzing and recovering organic components of waste light-emitting diodes according to claim 1, characterized in that, in step (8), the organic solvent is benzene, and the number of extractions is 1-3 times.