CN1106371A - Catalytic degradation of waste polystyrene into phenylethylene - Google Patents

Abstract

The direct catalytic degradation of molten waste polystyrene is conducted in the presence of catalyst that is prepared with specially modified Y molecular sieve and high-purity alumina with high specific surface area to obtain styrene and small amount of benzenes product. The styrene is then separated out by catalytic distillation. Said two steps are a combined whole procedure.

Description

Catalytic degradation of waste polystyrene into phenylethylene

The present invention is that waste plastics recovery method, particularly waste and old polystyrol are recovered as the cinnamic method of raw material in the environmental science.

In recent years along with the developing rapidly of plastics industry, the widespread use of polystyrene plastic, turnout increases fast, and foam package material, daily life are very big with the disposable product amount, have caused the white pollution source that attracts people's attention and the imbalance of ecotope.Also have at present its regeneration, but treatment capacity is little, poor quality, does not obtain promoting.Thereby need a kind of science, rational, high-caliber processing recovery technology.Catalyzed degradation is two kinds of new technologies that grow up in the world in recent years in conjunction with catalytic distillation.No. 4175211, United States Patent (USP), be for No. 4851601 with polystyrene and other polyolefin plastics all as unified raw material and catalytic pyrolysis is oil fuel, paraffin and refinery coke, its main technique is to adopt heavy cycle oil that plastics are fused, and then carries out catalytic cracking and handle.Its main drawback is to need a large amount of high boiling point heavy oil, has increased the complicacy of technological process as thermal cycling oil.No. 5079385 (1992) years of U.S. Pat have been reported a kind of novel method, adopt acid molecular sieve catalyst such as laboratory sinteticses such as ZSM4～50 and β-molecular sieve, plastics such as polyolefine have been carried out catalytic pyrolysis, but these catalyzer are laboratory sintetics in a small amount, still can not suitability for industrialized production, and product is distributed more widely, from lubricating oil to various saturated and unsaturated hydro carbons.The shortcoming of above-mentioned patented method is that technical process is complicated, and final product will be condensed into liquid state, reheats distillation again, and power consumption is high.

The objective of the invention is environmental pollution growing at China's plastics industry, the universal day by day particularly polystyrene plastic of plastic prod is extensive use of generation in fields such as industry, electronics, chemical industry, under the situation that supply falls short of demand of the vinylbenzene as raw material, adopt catalyzed degradation and catalytic distillation new technology to solve the problem that recycles of polystyrene plastic simultaneously.This technical process is advanced simply, efficient is high.

The aluminum oxide that the present invention adopts a kind of Y zeolite of special modification and high purity, high-ratio surface is the catalyzer that forms of Compound Machining under given conditions, with this catalyzer in reactor, temperature be under 350～410 ℃ the condition directly catalyzed degradation fusion be that the polystyrene plastic of liquid is the steam state hydrocarbon, enter in the distillation tower by the road and separate.This catalytic distillation system is that the theoretical tray design that the boiling point according to product carries out mass-and heat-transfer forms, its product is distributed as vinylbenzene, alpha-methyl styrene, toluene, ethylbenzene and 200～350 ℃ of raffinates, thereby up-to-date catalytic distillation technology be applied to the invention in, the two-step process of prior art catalytic pyrolysis and thermo-cracking change into one the step carry out.This catalyzer has the higher active and long life-span.This catalyzer is the special-purpose catalyst of this invention, and its detailed content is open in the catalyst prod patent application that proposes simultaneously with the application.

Advantage of the present invention is:

1. changing the thermo-cracking of prior art and the two-step approach of catalytic pyrolysis is the single stage method of direct catalytic distillation, makes the main technique process simplification, saves the facility investment and the energy.

2. in catalyzed degradation, the steam state hydrocarbon of generation directly enters in the distillation tower through pipeline and effectively separates, and directly obtains product.Not as existing technology, earlier the liquid product condensation to be got off, desired product is isolated in the reheat distillation, has simplified a back step process, and has saved the energy.

3. the product that processes all is the lightweight fraction below 350 ℃, and its yield is: the fraction below 200 ℃ 〉=85%, wherein:

Vinylbenzene: 62～65%

Alpha-methyl styrene: 10～13%

Toluene: 8～10%

Ethylbenzene: 12～15%

200～350 ℃ contain (solar oil) below 10%.

Details are as follows to the present invention below in conjunction with process flow sheet:

Fig. 1 is a process flow sheet of the present invention, numbers among the figure: 1. hopper; 2. electric heater; 3. feeding screw; 4. melt still; 5. pump; 6. reactor; 7. distillation tower; 8. vapour liquid separator; 9. water cooler; 10. product jar.

1. charging melt system: waste polystyrene plastic enters the screw conveying feeding device (3) of external heat device (2) through pulverizing, rinsing, after dry from feed hopper (1), enters crucible (4) again, and temperature in the kettle is 250～300 ℃. Keep this temperature, the air-isolation heating to reduce melt viscosity, is finished infall process, makes the solid impurity sedimentation separation, in order to avoid enter reactor (6).

2. catalytic reaction system: with pump (5) liquid plastics after the sedimentation is entered reactor (6) simultaneously from bottom, the middle part of reactor, fused mass is fully contacted with catalyst. According to the speed control amount of pumping into of catalytic reaction, take full advantage of the effect of catalyst and the activity of maintenance catalyst. The catalytic reaction temperature is 320～390 ℃, generates the steam state hydrocarbon through the catalyst degradation reaction.

3. catalytic distillation piece-rate system: the steam state hydrocarbon after catalytic reaction enters destilling tower, distillates through the never level side line of each component behind the mass-and heat-transfer and mouthful separates. Raffinate after the fractionation i.e. 200～350 ℃ fraction is collected at the bottom of tower. Each fraction enters vapour liquid separator (8), enters products pot (10) then after cooler (9) cooling. During fractionation, 10～40 ℃ steam state hydrocarbon and the heavy fraction at the bottom of the tower can be used as the heating fuel of this equipment.

Embodiment: get a certain amount of catalyzer and 2 times of amount styrofoam plastics after activated and aging and heat jointly, during heating temperature rise rate should be controlled 10 ℃/5 minutes, until the complete fusion of plastics, and it is temperature required to be heated to catalyzed degradation with 5 ℃/10 minutes speed, when distillating when mouthful having liquid to distillate, remain on and stop under this temperature heating up, until reaction all finish its product fraction distribute, as table 1.

Table 1. product fraction distribution (using this invention special-purpose catalyst)

Boiling point ℃ weight %

Put and heat up in a steamer 128

136 10

139 20

141 30

143 40

145 50

152 70

168 80

200 85

350 95

Product distributes as shows 2(200 ℃ with foreshot).

Table 2. product distribution (using this invention special-purpose catalyst)

Component content %

Toluene 8.85

Ethylbenzene 12.98

Vinylbenzene 62.54

Alpha-methyl styrene 11.43

Heavy fraction at the bottom of the still promptly 200～350 ℃ be solar oil, after being in harmonious proportion, can sell or of the fuel use of this fraction as this device.

Claims (5)

1, the present invention is that a kind of catalytic degradation of waste polystyrene plastics is the method for vinylbenzene and benzene class byproduct, it is characterized in that: the catalyzer that adopts the aluminum oxide of the Y zeolite of special modification and high purity, high-ratio surface under special conditions, to process, in reactor, being melt into liquid polystyrene plastic with the direct catalyzed degradation of this catalyzer is main productss such as vinylbenzene, alpha-methyl styrene, toluene, ethylbenzene, and temperature of reaction kettle remains on 320～390 ℃.

2, according to claim 1 is cinnamic method with catalytic degradation of waste polystyrene plastics, it is characterized in that the described liquid polystyrene plastic that enters reactor is to send in the feeding screw (3) of band well heater (2) through pulverizing, cleaning, exsiccant waste and old polystyrene plastics, carry out pelletizing regeneration after the fusion, polystyrene after the fusion can also be sent in the melt still (4), the secluding air heating, temperature remains on 250～300 ℃, pumps into reactor (6) behind standing sedimentation.

3, according to claim 1 is cinnamic method with catalytic degradation of waste polystyrene plastics, it is characterized in that described liquid polystyrene plastic is to enter reactor with liquid-solid form catalyzed degradation by reactor bottom and middle part.Catalyzer is multi-layer fixed-bed type.

4, catalytic degradation of waste polystyrene plastics according to claim 1 is cinnamic method, it is characterized in that described finishing with catalytic distillation technology separate each component, controls treatment capacity according to the loading level and the speed of response of catalyzer.

5, according to claim 1 is cinnamic method with catalytic degradation of waste polystyrene plastics, it is characterized in that carrying out rectifying separation again after described steam state hydrocarbon behind reactor (6) catalyzed degradation can cool off.This invention has the function of patent of invention CN1077479A equally.

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