WO2001005908A1

WO2001005908A1 - A process for producing gasoline and diesel from waste plastics and/or heavy oil

Info

Publication number: WO2001005908A1
Application number: PCT/CN2000/000196
Authority: WO
Inventors: Li Xing
Original assignee: Enercon Technologies, Inc.
Priority date: 1999-07-16
Filing date: 2000-07-13
Publication date: 2001-01-25
Also published as: AU5801500A; EP1228165A1; CN2408118Y; CA2379529A1; KR20020052168A; EP1228165A4; JP2003528937A; BR0012623A

Abstract

The invention relates to a process for producing gasoline and diesel from waste plastics and/or heavy oil and comprises the steps of: (a) mixing waste plastics and/or heavy oil with a first catalyst in a pyrolysis reactor at a high temperature to carry out a pyrolysis and a first catalytic cracking; and (b) introducing the products in step (a) into a fixed bed to perform a second catalytic cracking with a second catalyst. The process further comprises the step (c) recycling the first catalyst in the reaction.

Description

A PROCESS FOR PRODUCING GASOLINE AND DIESEL FROM

WASTE PLASTICS AND/OR HEAVY OIL

Field of the Invention

The present invention relates to a process for producing low-boiling

point hydrocarbons from waste plastics and/or heavy oil, and more

particularly to a process for producing gasoline and diesel through

pyrolysis and catalytic cracking of waste plastics and/or heavy oil.

Background of the Invention

Many methods for preparing low-boiling hydrocarbons from waste

plastics and high-boiling hydrocarbons are known. U.S. Patent No.

4,851,601 and EP-A-0607862 (Applicant: MAZDA MOTOR

CORPORATION) disclose a reaction of pyrolysis in a reactor kettle

(vertical or horizontal), wherein the outside wall of the kettle is heated at

a high temperature while the materials therein are heated indirectly.

In this method, the outside wall is apt to be deformed when the

reactor is heated directly at a high temperature. The materials are readily

sintered on the inside wall because of local over-heating so that the

conversion yield of the reaction and the life of the reactor are greatly

decreased. In addition, the coefficient of the reactor's heat transfer is

relatively low, it is difficult to drain the reaction residues, and the catalytic reaction in the fixed bed needs a separate heat supply. These are

the common drawbacks of the reactor kettle in the prior art.

A spiral reactor utilized in some special fields is similar to the above.

Heat is indirectly transferred when it works. The outside wall of the

reactor is heated directly at a very high temperature, making the materials

in the reactor indirectly heated. Therefore, the heat transfer coefficient is

not satisfactory. Particularly, because the screw therein is apt to be

deformed at a high temperature, making it hard to seal the two ends of the

screw so that gas generated in the reaction may be exhausted.

Summary of the Invention

Accordingly, an object of the invention is to provide a process for

producing gasoline and diesel from waste plastics and/or heavy oil

(including high-boiling hydrocarbons) to overcome the shortcomings in

the prior art as described above.

The process of the present invention comprises the steps of:

(a) mixing waste plastics and/or heavy oil with a first catalyst at a

high temperature in a pyrolysis reactor to carry out a reaction of pyrolysis

and first catalytic cracking simultaneously; and

(b) introducing the products in step (a) into a fixed bed to perform a

reaction of second catalytic cracking. Said first catalyst is made as follows: powder A1₂0₃ is mixed with

water glass to obtain a slurry, and the resultant slurry is then mixed with

catalyst HZSM-5. The resultant mixture is dried, formed, granulated, and

heated to obtain the first catalyst.

The ratio between powder A1₂0₃ and water glass is 1 :3-5 by weight

and that between the slurry and HZSM-5 is 1 :0.2-0.5 by weight.

According to the process of the invention, the materials can be

converted to gasoline and diesel with a high yield, and the requirements

for the reactor are not strictly defined because the first catalyst is used to

heat the materials directly.

Brief Description of the Drawing

Figure 1 is an operational flow chart of the process in the invention.

Detailed Description of the Invention

The process of the present invention comprises the steps of:

(a) mixing waste plastics and/or heavy oil with a first catalyst at a

high temperature in a pyrolysis reactor to carry out a reaction of pyrolysis

and first catalytic cracking simultaneously; and

(b) introducing the products in step (a) into a fixed bed to perform a

reaction of second catalytic cracking.

The process of the invention further comprises a step of: (c) recycling the first catalyst in the reaction.

The reaction of pyrolysis and first catalytic cracking may be

conducted under the standard atmosphere or higher, and the temperature

of the first catalyst may be controlled at 500-l,000°C, preferably 600-

700°C.

The reaction of second catalytic cracking is carried out with a

second catalyst in the fixed bed at 300-600°C, preferably 300-450°C.

The second catalyst used in the invention may be the commonly

used catalyst in the reaction of catalytic cracking in the art.

In the invention, the first catalyst after being heated to a high

temperature in the combustion chamber the first catalyst is charged into a

pyrolysis reactor by using a spiral conveyor. Waste plastics (or heavy oil)

are charged into the sealed pyrolysis reactor, and there they are directly

mixed with the hot first catalyst to perform a reaction of pyrolysis and

first catalytic cracking. The materials are decomposed into gaseous

hydrocarbons and residues. The gaseous hydrocarbons then enter a fixed

bed in the reactor and are further decomposed into smaller molecules via

a second catalytic cracking. Gaseous substances from the reaction are

collected by means of the conventional process in the prior art so as to

obtain gasoline and diesel. Said first catalyst and residues in the reaction

are introduced into a gasification chamber by a screw, and further into a

separator by a spiral conveyor. Hot flue gas is led into the separator with a blower, which blows said mixture into a cyclone separator so as to

collect a solid mixture. Said mixture is introduced into a combustion

chamber by a spiral conveyor. In the combustion chamber, organic

substances in the mixture are burnt out, while the first catalyst is heated

and delivered to the spiral reactor again.

In the above-mentioned process, the feedstock is mixed directly with

hot first catalyst, and pyrolysis and the first catalytic cracking take place

at the same time. The first catalyst is not only used as a heating medium

but also as a catalyst, which can be recycled.

Said first catalyst is made as follows: powder A1₂0₃ is mixed with

water glass to obtain a slurry, and the resultant slurry is then mixed with

catalyst HZSM-5; and the resultant mixture is dried, formed, granulated,

and heated at a temperature of 550-800°C. The ratio between powder

A1₂0₃ and water glass to be used is 1 :3-5 by weight and that between the

slurry and HZSM-5 is 1 :0.2-0.5 by weight. Said first catalyst used in the

invention is generally of a Mo is' scale of hardness of 7-9 and a diameter

of 0.2-0.5mm.

In the above process, said pyrolysis and first catalytic cracking may

be conducted under standard atmosphere or higher. The reaction

temperature, when the first catalyst is transmitted from the combustion

chamber to the pyrolysis reactor, is controlled at 500-1000C, preferably

600-700°C. The temperature of the first catalyst is kept at 400-800°C, preferably 500-600°C when it leaves the pyrolysis reactor.

Said second catalytic cracking is carried out in the fixed bed

inside the gasification chamber. Heat required in the second catalytic

cracking is provided by the gasification chamber itself. The second

catalytic reaction is undertaken at 230-600°C, preferably 300-450°C. A

particular catalyst DL-1 being composed of (Wt. %): 8% of CHO-l(a

commodity produced by China Qilu Petrochemical Factory), 24% of

REY, 25% of flokite (silicon/aluminum =12/1) and 43% of catalyst ZSM-

5 is used in the second catalytic cracking after being thoroughly mixed

and calcined.

The present invention will be more distinct with reference to the

accompanying drawings.

Referring to Fig. 1, a first catalyst 16 in the granular form is charged

into a combustion chamber 21 from a storage tank 26 with a spiral

conveyor 27. Fuel oil (or recuperated pyrolysis gas) and air are sprayed

into the combustion chamber 21 simultaneously via nozzles 18, 19 and 20.

The first catalyst 16 in the combustion chamber 21 is heated to 500-

1,000°C and subsequently led into a storage tank 17. A spiral conveyor

29 is started by a motor 1 to push the first catalyst 16 continuously into a

pyrolysis reactor 14. At the same time, the materials to be treated are

pushed by a screw (or reciprocating) extruder 4 into a spiral reactor 14. If

the materials are heavy oils, they may be pumped into the sealed pyrolysis reactor 14 via an inlet 28. The materials are mixed directly with

the first catalyst 16 in the reactor 14 to undergo a pyrolytic reaction and a

first catalytic cracking. Rotated and pushed by the spiral conveyor 2,

gaseous hydrocarbons generated from the reaction and residues move

forward to enter a vaporizer 13. Gaseous hydrocarbons enter a fixed bed

12 in the vaporizer 13 through the vaporization region, and react with a

second catalyst to generate gaseous hydrocarbons with small molecules,

which will be fractionated in a fractional column 9 to obtain gasoline and

diesel by means of the conventional process. A mixture 10 of reaction

residues and the first catalyst 16 entering the bottom of the vaporizer 13

is driven into a separator 8 via a spiral conveyor 2. A blower 3 is

employed to push the high-temperature flue gas into the separator 8 via

an entrance 6. Solid mixture 25 containing the first catalyst are flown up

to enter a cyclone 24 because they are lighter. Other heavy residues enter

the bottom of the separator 8 and are discharged from a hole 7. Thus, the

solid mixture 25 in the cyclone 24 drops into a storage tank 26, and then

is charged into the combustion chamber 21 by the spiral conveyor 27. In

the combustion chamber 21, organic substances in the mixture 25 are

burnt out and inorganic dusts are extracted together with high-

temperature flue gas. The first catalyst 16 is hereby recovered and falls

into the storage tank 17, subsequently. The heated first catalyst is then

charged into the reactor 14 by the spiral conveyor 29. The invention is further described by the following examples.

Example 1

Water glass (1,600kg, modulus>3) and powder A1₂0₃ (400kg) were

completely mixed to obtain a slurry. The slurry was mixed with catalyst

HZSM-5 (800kg). The resultant mixture was dried, formed, granulated,

and heated at 800°C for 4 hours to obtain the first catalyst with a Mohs'

scale of hardness of 8.5 and a diameter of 0.4 mm.

2,000 kg of the first catalyst prepared as indicated above was charged

into the combustion chamber 21, and simultaneously sprays 0^# diesel (or

recuperated pyrolysis gas) and air were led into the combustion chamber

21 to burn. The first catalyst was heated up to 600-700°C and then led

into the pyrolysis reactor 14. The screw (or reciprocating) extruder 4 was

used to push 1 ,400kg of waste plastics (PP25%, PS25%, and PE50%) into

the reactor 14 to perform the reaction. The temperature at the stock inlet

of the reactor 14 was controlled at 600-700°C, whereas the temperature at

the residue outlet thereof was controlled at 500-600°C. The catalyst DL-1

was arranged in the fixed bed 12, and the second catalytic reaction was

conducted therein. The reaction pressure was kept at 0.05-0.1 MPa.

Gasoline and diesel were obtained from the fractional column 9. The

mixture of the first catalyst and residues was charged into the combustion chamber 21 and was heated up to 600-700°C therein to separate the first

catalyst. The recovered first catalyst was introduced into the reactor 14

for heat supply.

Products generated from this Example are listed below:

1. Gasoline, 630kg, RON=93.5, components (by wt%): paraffin 19.9%,

cyclanes 12%, olefin 48%, arenes 9.9%, others 10.2%;

2. Diesel, 420kg, cetane value=52, components (by wt%): paraffin

15%, cyclanes 8%, olefm 55%, arenes 10%, others 12%;

3. Inorganic residues 140kg;

4. Flammable gas 210kg.

Claims

What I claim is:

1. A process for producing gasoline and diesel from waste plastic and/or

heavy oil comprises the steps of:

(a) mixing waste plastic and/or heavy oil with a first catalyst in a

pyrolysis reactor at high temperature to carry out a pyrolytic reaction and

a first catalytic cracking ; and

(b) introducing the products in step (a) into a fixed bed to perform a

second catalytic cracking with a second catalyst.

2. A process as claimed in Claim 1, wherein said first catalyst is made as

follows: powder A1₂0₃ is mixed with water glass to obtain a slurry, and

the resultant slurry is then mixed with catalyst HZSM-5; and resultant

mixture is dried, formed, granulized, and heated at 550-800°C.

3. A process as claimed in Claim 2, wherein the ratio between powder

A1₂0₃ and water glass is 1 :3-5 by weight and that between the slurry and

HZSM-5 is 1 :0.2-0.5 by weight.

4. A process as claimed in Claim 3, wherein said first catalyst is of a

Mohs' scale of hardness of 7-9, and a diameter of 0.2-0.5mm.

5. A process as claimed in Claim 1, wherein the process further comprises

the step of:

c) recycling the first catalyst in the reaction.

6. A process as claimed in Claim 1, wherein said catalyst in the fixed bed comprises 8% of CHO-1, 24% of REY, 25% of flokite and 43% of

catalyst ZSM-5, by weight.

7. A process as claimed in Claim 1, wherein the process is performed

under the standard atmosphere or higher.

8. A process as claimed in Claim 1, wherein the temperature of the first

catalyst is controlled at 500-l,000°C before entering the pyrolysis reactor,

and is controlled at 400-800°C while leaving the pyrolysis reactor.

9. A process as claimed in Claim 1, wherein the first catalyst advances in

the same flow direction as that of the waste plastics and/or heavy oil.