WO2012131485A1

WO2012131485A1 - Process for separation of pure constituents

Info

Publication number: WO2012131485A1
Application number: PCT/IB2012/000648
Authority: WO
Inventors: Anil Bakaya
Original assignee: Percy Kean Technologies Pty. Ltd
Priority date: 2011-03-31
Filing date: 2012-04-02
Publication date: 2012-10-04

Abstract

The present invention provides a method for extracting hydrocarbons from carbon containing waste material in an eco-friendly, commercially competent, efficient and safe technological environment.

Description

PROCESS FOR SEPARATION OF PURE CONSTITUENTS

FIELD OF THE INVENTION

The present invention relates a method for separation of pure constituents from carbon and non carbon containing substances. In an aspect the invention relates to a method for preparation of fuel from mixture of carbon containing material such as hydrocarbon waste and more particularly to a method for the preparation of fuel substantially free of sulfur from mixture of hydrocarbon waste including plastic waste and like.

BACKGROUND OF THE INVENTION

Plastic has been a part of our lives for over ages, and its requirement is never ending. From storing food, plastic carry bags, chairs, tables, packaging, disposable syringes, disposable cup and plates, to various toys and other articles; we use it almost every day in some or the other form.

Now-a-days there is an increased trend of using disposable items which are made up of plastic such as carry bags and some are essential for maintaining hygiene such as disposable syringes, utensils, other medical instruments, plastic disposable gloves, drinking bottles etc. Overall, it has led to extensive use of plastic. Government has taken certain major steps to cut down and restrict the use of plastic bags.

Inspite of that, the use of plastic is increasing every day. The formidable problem associated with plastic waste is that they are at present non-biodegradable, and their incineration is harmful due to production of noxious or toxic fumes. The conventional process for recycling plastic waste consumes large amount of energy and time. Nevertheless these recycled plastic wastes after a certain rounds of recycling lose the quality standards and are unable to get recycled or degraded further. Hence, there are large amount of plastic that cannot be recycled. This results in large amount of accumulation of plastic waste and hence leads to plastic pollution in the society and environment. Thus, there is a need to develop ways and means of efficient disposal of plastic waste.

One of the approaches for such disposal is conversion of plastic waste into fuel disclosed by Indian patent 1427/DEL/2005, which describes a process for the preparation of fuel from plastic and non plastic wastes. This process, however, is limited to the combination of non recyclable polyolefinic plastic waste and non- plastic combustible waste; at a predetermined ratio, both wastes can be processed and converted into solid fuel.

There are several patents such as US 4982027 which describes a process for reprocessing of carbon containing wastes; US 2003199718 which describes a process for converting plastic waste into lubricating oils; and US 5758025 which describes a method for processing recycled or scrap plastics.

The processes described in prior art for processing of plastic waste and obtaining crude oil are done generally by pyrolysis or by incineration or by de-polymerization at very high temperature, thus, it requires extreme processing conditions of temperature and pressure; and hence use of high energy. Such processes also produce obnoxious gases and residual ash remains contaminated by carbon. Saving the climate from hazardous gases and improving the yield of oil per ton remained prime issues of research for several years.

Hence, there is an imminent need for a novel method whereby non-recyclable and recyclable plastic can be converted efficiently into fuel. The present invention solves the problem in the prior art and also provides an environment friendly and an economic method for converting recyclable plastic into substantially sulphur free fuel.

OBJECT OF THE INVENTION

The object of the present invention is to provide a method for extracting hydrocarbon form plastic waste in an eco-friendly, commercially competent, efficient and safe technological environment and converting such plastic waste into fuel. SUMMARY OF THE INVENTION

The method of the present invention for producing hydrocarbons from a carbon containing material comprises the steps of: i) finely dividing a carbon-containing material; ii) adding a mixture of catalyst to the material of step (i) to obtain a hydrocarbon mixture; iii) heating the hydrocarbon mixture of step (ii) in an anaerobic environment for at least 15 minutes to l hour resulting in emission of a hydrocarbon gas; iv) condensing vapors of the hydrocarbon gas obtained at step (iii) to obtain a hydrocarbon oil in liquid state; v) recovering and recycling the uncondensed hydrocarbon gas of step (iv) into furnace; and vi) separating a residual char and an inorganic material from the hydrocarbon mixture of step (i ii).

In one aspect, where the starting material used contains sulphur, the hydrocarbon oil obtained is also likely to contain sulphur elements. In such a case, desulphurisation of the oil assumes importance, and the same is effected by a method comprising the steps of: i) mixing crude hydrocarbon oil with benzene, to form a mixture; ii) subjecting the mixture of step (i) to elevated temperature of 50- 1 10°C under total reflux of benzene;

Hi) heating a mixture of catalyst comprising finely divided zinc and finely divided iron separately for 1 hour; iv) adding a portion of the heated catalyst mixture to the mixture of crude hydrocarbon oil and benzene; v) heating the mixture at a temperature of preferably 50- 1 10 °C under total benzene reflux; vi) creating a catalyst bed using the catalyst mixture; vii) pouring the mixture of step (v) over the catalyst bed and subjecting to filtration under vacuum; viii) optionally subjecting the mixture of step (vii) to distillation to remove benzene under vacuum to obtain crude oil with sulphur content of not more than 0.1 %.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 : Is a diagrammatic representation of the method of producing hydrocarbons from a carbon containing material.

Figure 2: Depicts magnetic separation of finely divided iron from ash. DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for the production of hydrocarbon oil which can be used as fuel from carbon containing waste materials such as hydrocarbon wastes, oil shale, coals, biomass, wastes including plastic waste, electronic waste, agricultural waste, mine waste, old rags, old tires, waste paper, used batteries, animal waste, and/or human waste wherein the fuel produced is substantially sulphur free.

The method for producing hydrocarbons from a carbon containing material comprises the steps of: ii) adding a catalyst to the material of step (i) to obtain a hydrocarbon mixture; iii) heating the hydrocarbon mixture of step (ii) in an anaerobic environment for at least 15 minutes - 1 hour resulting in emission of hydrocarbon gas; iv) condensing vapours of hydrocarbon gas obtained at step (iii) to obtain hydrocarbon oil in liquid state; v) recovering and recycling uncondensed hydrocarbon gas of step (iv) into furnace; and vi) separating residual char and inorganic material from the hydrocarbon mixture of step (iii).

This hydrocarbon oil mixture can be separated into a diesel distillate, kerosene, naphta, or light or heavy fuel oil by controlling the temperatures of the condensor stages. By variations in the temperature of the reactor and vapor reflux it is also possible to make hydrocarbon wax in the range of 350°C to 550°C.

In one aspect, where the starting material used contains sulphur, the hydrocarbon oil obtained is also likely to contain sulphur elements. In such a case, desulphurisation of the oil assumes importance, and the same is effected by a method comprising the steps of: i) mixing crude hydrocarbon oil with benzene, to form a mixture; ii) subjecting the mixture of step (i) to elevated temperature of 50-1 10°C under total reflux of benzene; iii) heating a mixture of catalyst comprising finely divided zinc and finely divided iron separately for 1 hour; iv) adding a portion of the heated catalyst mixture to the mixture of crude hydrocarbon oil and benzene; v) heating the mixture at a temperature of preferably 50- 1 10 °C under total benzene reflux; vi) creating a catalyst bed using the catalyst mixture; vii) pouring the mixture of step (v) over the catalyst bed and subjecting to filtration under vacuum; viii) optionally subjecting the mixture of step (vii) to distillation to remove benzene under vacuum to obtain crude oil with sulphur content of not more than 0. 1 %.

In the method of the invention as described above, the crude hydrocarbon oil of step (a) is mixed with benzene preferably in the ratio of 1 : 1 . Further, in the said method, at step (iii), the hydrocarbon mixture is subjected to heating for 15-45 minutes. Anaerobic environment as referred in step (iii) may be an anaerobic reactor.

The catalyst used for de-sulphurisation is a mixture of finely divided iron and finely divide zinc in a ratio of 1 : 1.

The mixture of step (e) is distilled to remove the benzene under vacuum by setting initial temperature in the range of 70°C to 100°C. preferably 90°C and simultaneously it is increased to 90°C to 120°C for about 1 to 1 .5 hours until benzene is substantially recovered. The sulphur content of the crude hydrocarbon oil obtained at the end of desulphurization process contain not more than 0.1 % of sulphur or not less than 860ppm of sulphur.

The invention is further illustrated by the figures wherein in figure 1 depicts the treatment of plastic waste (201 ) to generate hydrocarbon oils (21 1 and 214) and hydrocarbon gas (217) from it. The mixed plastic waste (201 ) may include any type of plastic waste in shredded form, and it includes but is not limited to LDPE, PP, PS, HDPE, ABS, PVC and others. The mixture of plastic waste must be shredded. The quantity of this material is weighed before it is fed into a reactor for purposes of calculating the yield.

The plastic, which has been purged with nitrogen to remove oxygen, is fed into the stainless steel reactor at a rate of roughly 400kg per hour. In addition to shredded dry feed, the reactor feeder may accept a liquid feed (202) (for example, waste oil). The catalyst mixture (203) is continuously added. The catalyst mixture must contain electrolytic iron powder which represents 1 % of the total feedstock. It can also contain various amounts of the following depending on the type of plastic: silica gel ( 1 - 10%), fullers earth ( 1 -10%), calcium bicarbonate ( 1 - 10%) and/or sodium carbonate ( 1 - 10%).

In the anaerobic reactor (207) the plastic waste with the additives is slowly mixed. The reactor is heated initially from the combustion of natural gas (204) mixed with air (205) which indirectly heats the reactor to allow for a reaction temperature of 250°C to 425°C.

Within the anaerobic reactor long carbon chains of the molten plastic are broken down with the help of catalysts. The reaction time ranges from 1 5 minutes to 1 hour. When the broken down components of the molten plastic have reached their boiling point in the reaction chamber, their vapors evolve from the liquid mixture. A temperature controlled vapour chamber along the top of the reactor allows heavy oils to be refluxed back to the reactor chamber for further decomposition while al lowing lighter vapours to be passed through a pipe (208) to the condenser system. The desired boiling range of the passed through lighter vapours can be controlled by the temperature of the vapour chamber. The residual char and any inorganic materials (such as metal, dirt, and ash) continuously fall out through the ash removal chute (209).

The hot vapour (208) is carried out of the reactor chamber and drawn to a first condenser unit (210), where a temperature controlled quench spray (at 100°C to 250°C) condenses the hot vapours into liquid. The condensed liquid falls to the bottom of the column into a reservoir where the liquid then re-circulates through a heat exchanger (210) to be cooled (to the quench spray temperature) before it is introduced at the top of the condenser as the quench spray. The condensed oil product is constantly removed from the reservoir (21 1 ) to maintain a liquid level as new product is introduced. The temperature of the spray ( 100°C to 250°C) controls the boiling range of the condensate. Vapours that boil below the spray temperature remain in vapour phase (212) where they continue into second condenser (213), which is maintained at a lower temperature to fully condense the rest of the vapours. The remaining liquid is separately collected into another hydrocarbon storage vessel (214). Both fuels collected (21 1 and 214) can be sold in the market. However, the same may be subjected to desulphurization as discussed below. Depending on end use, the oil can be further treated with additives, centrifuge or blending according to end user requirements.

Any vapour product that has not condensed in the second condenser (21 5) is collected and sent through a gas scrubber (216). The gas contains a calorific value in the range of 18,000 to 22,000 Btu/Lb (similar to natural gas). This gas (217) is recycled to the burner (206) and should be sufficient to provide all the ongoing heating requirements for the process.

Catalyst Recovery

The catalyst like fuller's earth and silica gel used in the treatment of plastic waste may be recovered by conventional process. Finely divided iron and zinc that has been converted into sulphides of iron and zinc may be recovered by closed loop process. Further, the iron may also be separated from the residues by magnetic separation process as shown in Fig 2. In magnetic separation process, the residue containing ash and iron particle is passed through the magnetic roller. The magnetic conveyor belt divides the residue into ash and iron particles.

Moreover, the catalysts that are used in the method of desulphurization such as finely divided iron and zinc get converted into sulfides of iron and zinc. The iron and zinc sulfide is recycled and can be reused for a fresh batch of oil containing sulphur. EXAMPLE 1 : Conversion of plastic waste into hydrocarbon fuel

Plastic waste in the form of mixture of old plastic bags of about 100 gms was taken and shredded in a shredder. This was added to a stainless steel reaction vessel with the catalyst. The iron catalyst which is used here, is electrolytic metallic iron in finely divided form of preferably 200 mesh. The catalyst and mixture of waste were subjected to heat at about 250°C to 425°C in an anaerobic environment. At about 250°C vapor starts coming out and is led to a condenser which condenses about 70% to 80% of it into oil. About 10% to 20% comes out as hydrocarbon gas and about 5% will come out as sludge. The sludge contains ash, inert material, and catalyst. Oil and gas continue to come out until temperature reaches 425°C. The quantity of oil produced varies depending on the temperature at which it is produced. The reaction takes 15 minutes to 1 hour and is carried out at predetermined atmosphere pressure. In a further modification, additional catalysts can be used depending on feedstock: silica gel ( 1 -10%), fullers earth ( 1 - 10%), calcium bicarbonate ( 1 -10%) and/or sodium carbonate ( 1 -10%). Plastic vapour gets converted to small molecules of hydrocarbons in liquid form.

Similar to Example 1 , the same process was used for plastic portion of electronic waste, agricultural waste, hydrocarbon wastes, biomass, mine waste, old rags, old tires, waste paper, animal waste, and produced hydrocarbon oil.

Catalyst Recovery

The catalyst like fuller's earth and silica gel will be recovered by conventional process. Finely divided iron and zinc that has been converted to sulfide of iron and zinc during the process can be recovered. Also, the iron particle can be recovered from the residue by magnetic roller. The magnetic conveyor belt in the magnetic roller separates the iron from the residue. Magnetic separation of iron catalyst by magnetic roller is very efficient process. At commercial scale the percentage recovery of the catalyst is around 95% and at lab scale the recovery is around 55% to 75%. It has been observed that when 8.5g of residue contain ash and iron when processed through the magnetic separation process then around 0.55g to 0.75g of iron was recovered.

TABLE 1 : The process is summarized below.

Components of the catalyst can be recycled for reuse.

Feed Plastic Waste

Catalyst Mixture (primarily electrolytic iron powder, and 1 %

also others such as Fullers Earth, Silica Gel, calcium

bicarbonate and/or sodium carbonate)

Temperature 250 °C to 425 °C

Pressure Atmospheric

Reaction Time 15 minutes - 1 hour

The Product Yield Quantity (Wt %)

Liquid Hydrocarbon 60-80 %

Gas 10-20 %

Residue 5- 10 %

TABLE 2: different types plastics were developed using the process of the invention and the output i.e. the oil yield thereof is as below: (For 100 Kg plastic)

Raw material Suitability Catalytic De- Fuel Gas Carbon polymerization recovery recovery residue in Temperature°C in liters in Kg. Kg-

Polyethylene Very good 375 90 17 8 (PE)

Polypropylene Very good 375 90 15 5 (PP)

Polystyrene Very good 350 93 15 5 (PS)

ABS Plastic Very good 375 93 17 10

(ABS)

Polyurethane Fair 375 90 16 6

Fiber Fair, 350 45 1 5 5

Reinforced Fibers are to be

Plastic (FRP) removed

Polyamide Fair 375 70 15 7 (Nylon)

Polyethylene Fair 350 65 18 9 Terphthalate

(PET)

Polyvinyl Suitable in 340 35 1 5 5 chloride (PVC) presence of special catalyst

Rubber Fair 375 45 15 35

(Tyres or

automobile

parts)

Mixed Plastic Good 375 70 12 8

TABLE: 3 The oil that was generated from plastic waste (Example 1 ) was tested for product characteristics and same is as below:

S. No. PARAMETER UNIT

1 Appearance Liquid

2 Density, gm/cc 0.781 @ 15°C

Colour Brown

4 Viscosity. N-S/sq.m 1 .75 CSt @ 40^u C

5 . pH Not applicable

6 Boiling Range, ° C Initial Boiling Point : 59°C, Final Boiling Point : 372°C

7 C/H Ratio 6.00

8 Cloud point, ^υ C 16

9 Pour point, ⁰ C 6

10 Flash point ^U C 63 1 1 Smoke point, °C 67

12 Gross Calorific value, Kcal/Kg 1 1 1 1 5

1 3 Net Calorific value, Kcal/Kg 10395

14 Sulphur content, ppm 50

15 Residue at 370 °C 88 Grams

TABLE 4: Hydrocarbon fuel that was generated from plastic waste was tested for product characteristics and same is as below:

Hydrocarbon fuel

oil Hydrocarbon fuel oil

Heavy Fraction Light Fraction

Batch Batch

Density at 15 °c,

gm/cc 0.801 1 0.7334

Flash Point °c 63 <5

Sulphur 62ppm 58ppm

Pour Point, °C 27 <0

DIST IBP °C 164 48

5%v 193 78

10%v 209 90

20%v 232 106

30%v 255 121 40%v 275 1 30

50%v 298 1 36

60%v 321 140

70%v 341 145

80%v 358 1 55

90%v 365 1 89

95%v 232

FBP ,°C 237

Rec at370°C 93

Net Cal Value,

kcal Approx. 1 1043 Approx. 1 1261

K.V.at 40°C, est 4.56

Example 2: Desulphurisation of Oil

Sample- 200ml crude oil received with 2.87% sulphur.

Catalyst- 20 grams of finely divided zinc and 20 grams of finely divided iron divided into two portions.

Procedure- The crucibles containing the catalysts mentioned above are kept in in muffle furnace for 1 hour at 200°C.

200ml crude oil is combined with 200ml of benzene in a round bottom flask. The round bottom flask is slowly heated to a temperature of 80°C for 1 hour under total reflux of benzene. After 1 hour the stirring and heating is stopped. One crucible containing the catalyst is removed from furnace and added to the mixture of crude oil and benzene through a funnel. The neck is closed and the stirring and heating is continued for 2 hours at a temperature of 80°C under total reflux. The other crucible is removed from furnace and placed on filter paper to act as a catalyst bed in a Buckner Funnel Assembly. Once the stirring and heating has stopped in the round bottom flask, the mixture of crude oil, benzene and catalyst is poured over the catalyst and filtration is done under vacuum.

After filtration is complete, the filtrate obtained consists of crude oil and benzene. The filtrate is distilled to remove the benzene. Initially a temperature in the range of 70°C to 100°C, preferably 90 °C is maintained and step-by-step it is increased to 90°C to 120°C, preferably 1 10 °C. Distillation is carried out under vacuum and it is continued for roughly 1 - 1 .5 hours until the last drop of benzene is recovered, and only crude oil sample remains.

The input was crude oil residue of 2.87% sulphur and our process was able to reduce the sulphur content of this to 0.086% or 860 ppm

The sulphur content of the hydrocarbon oil converts the finely divided zinc to zinc sulphide. Likewise, finely divided iron will get converted to iron suphide. In a separate known process finely divided zinc is recovered from zinc sulphide and finely divided iron is recovered from iron sulphide. The recovered zinc and iron can be used as a catalyst for a fresh batch of oil containing sulphur.

TABLE 5: The characteristics of crude oil obtained by the above mentioned process:

Feed Crude Oil (2.87% sulphur content)

Catalyst A : Finely divided zinc (200 mesh) 10%

Catalyst B : Finely divided iron (200 mesh) 10%

Temperature 80 °C to 200 °C

Pressure Atmospheric

Reaction Time 5 - 6 hours

The Product Yield Recovery Liquid Crude Oil 0.086 % sulphur content

Benzene 80-90 % recovery

Catalyst A & B Recovered from zinc sulphide & iron sulphide

While the invention has been described in connection with specific and preferred embodiments thereof, it is capable of further modifications without departing from the spirit and scope of the invention. This application is intended to cover all variations, uses, or adaptations of the invention, following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice to which the invention pertains, or as are obvious to persons skilled in that art, at the time the departure is made. It should be appreciated that the scope of this invention is not limited to the detailed description of the invention herein above, which is intended merely to be illustrative, but rather comprehends the subject matter defined by the following claims.

Claims

We Claim:

1. A method of producing hydrocarbons from a carbon containing material, comprising the steps of : i) finely dividing a carbon-containing material; ii) adding a mixture of catalyst to the material of step (i) to obtain a hydrocarbon mixture; iii) heating the hydrocarbon mixture of step (ii) in an anaerobic environment for at least 15 minutes to l hour resulting in emission of a hydrocarbon gas; iv) condensing vapors of the hydrocarbon gas obtained at step (iii) to obtain a hydrocarbon oil in liquid state; v) recovering and recycling the uncondensed hydrocarbon gas of step (iv) into furnace; and vi) separating a residual char and an inorganic material from the hydrocarbon mixture of step (iii).

2. The method as claimed in claim 1 , wherein the carbon containing materials are selected from the group consisting of hydrocarbon wastes, biomass, waste including plastic waste, electronic waste, agricultural waste, mine waste, old rags, old tires, waste paper, used batteries, animal waste, human waste and mixture thereof.

3. The method as claimed in claim 1 , wherein the mixture of catalyst is selected from the group consisting of finely divided electrolytic metallic iron, silica gel, fullers earth, calcium bicarbonate, sodium carbonate and mixture thereof.

4. The method as claimed in claim 3, wherein the electrolytic metallic iron is in a finely divided form of approximately 150 to 250 mesh, preferably 200 mesh, representing 1 % of the plastic waste feedstock.

5. The method as claimed in claim 1 , wherein the heating of mixture of step (iii) is at temperature in the range of 250°C to 425°C.

6. The method as claimed in claim 1 , wherein the mixing of step (iii) is done for predetermined time, preferably in the range of 15 minutes to 1 hour.

7. The method as claimed in claim 1 , wherein the hydrocarbon gas mixture of step (v) is recycled for continuous heating and contains a calorific value in the range of 18,000 to 22,000 Btu/Lb.

8. The method as claimed in claim 1 , wherein the hydrocarbon oil mixture of step (iv) has a boiling point in the range of 50°C to 350°C and carbon numbers ranging from C5-C20 is separated into fractions.

9. The method as claimed in claim 1 . wherein the catalyst such as electrolytic metallic iron is separated through magnetic separation and recycled for reuse.

10. The method as claimed in claim 1 , wherein the hydrocarbon oil is subjected to de- sulphurization using a catalyst selected from group consisting of finely divided zinc, finely divided iron and mixture thereof.

1 1 . A method of de-sulphurization of crude hydrocarbon oil comprising the steps of: i) mixing crude hydrocarbon oil with benzene, to form a mixture; ii) subjecting the mixture of step (i) to elevated temperature of 50- 1 10°C under total reflux of benzene; iii) heating a mixture of catalyst comprising finely divided zinc and finely divided iron separately for 1 hour; iv) adding a portion of the heated catalyst mixture to the mixture of crude hydrocarbon oil and benzene; v) heating the mixture at a temperature of preferably 50-1 10 °C under total benzene reflux; vi) creating a catalyst bed using the catalyst mixture; vii) pouring the mixture of step (v) over the catalyst bed and subjecting to filtration under vacuum; viii) optionally subjecting the mixture of step (vii) to distillation to remove benzene under vacuum to obtain crude oil with sulphur content of not more than 0.1 %.

12. The method as claimed in claim 1 1 , wherein the de-sulphurization of hydrocarbon oil results to produce a liquid crude oil product with reduced sulphur content of not more than 0.1 % or 860 ppm.

13. The method as claimed in claim 1 , wherein the process for producing hydrocarbon yields about 70-80% of hydrocarbon oil, about 10-20% of hydrocarbon gas and about 1 - 10% of ash.