CLIAMS:1. A process for preparing liquid hydrocarbon fuel from waste; said process comprising the following steps:

a) grinding the waste to obtain ground waste having a particle size ranging from 0.01 mm to 20 mm;
b) admixing at least one fluid medium with the ground waste to obtain a slurry;
c) heating the slurry at a predetermined temperature and at a first predetermined pressure for a predetermined time period in the presence of hydrogen having a second predetermined pressure and at least one catalyst to obtain a reaction mass comprising liquid hydrocarbon fuel, gaseous products and solid products;
d) cooling the reaction mass to obtain a cooled reaction mass; and
e) separating liquid hydrocarbon fuel from the cooled reaction mass,
wherein, said catalyst comprises an active component comprising at least two metal salts, at least one support and optionally at least one promoter in predetermined quantities.

2. The process as claimed in claim1, wherein said waste is selected from waste plastic, rejected plastic and combinations thereof.

3. The process as claimed in claim 1, wherein said fluid medium is water.

4. The process as claimed in claim 1, wherein the amount of said gaseous and solid products in the reaction mass is in the range of 10-30%.

5. The process as claimed in claim 1, wherein said first predetermined pressure is in the range of 50-300 bars and said second predetermined pressure is in the range of 10-50 bars.

6. The process as claimed in claim 1, wherein said predetermined temperature is in the range of 350-450 oC.
7. The process as claimed in claim 1, wherein the amount of said catalyst with respect to waste plastic ranges from 1 to 20 wt%. ,TagSPECI:FIELD :
The present disclosure relates to a process for preparing liquid hydrocarbon fuel from waste plastics.

BACKGROUND:
The increase in the use of plastic products caused by sudden growth in living standards has had a significant impact on the environment. Plastics have now become a necessary material and the demand is continually increasing due to their diverse and attractive applications in the household and in industries. Thermoplastic polymers make up a high proportion of waste and this amount is continuously increasing around the globe. Hence, waste plastics pose a very serious environmental challenge because of their huge quantity and disposal problem as thermoplastics do not degrade for very long time. Due to this reason, many wild mammals and marine mammals die every year eating discarded waste plastic bags mistaken for food.
The property of high durability makes the disposal of waste plastic an even more serious environmental problem as land filling is the most used disposal route. The disposal of waste plastic by landfill or incineration releases toxic gases such as COx, NOx, SOx etc., which are hazardous to the environment and have a negative impact. The environmental concerns related to climate change are coming more and more into focus.
Conventionally, pyrolysis and cracking catalysts are used for recycling plastics which produces significant amounts of C1 – C5 gases or low molecular weight hydrocarbon liquids that are not suitable for fuel oil. These processes produce lighters (gas), heaviers and carbon black along with liquid fuels. The production of carbon black and lighters are not economical or desirable. Therefore, there is felt the need for a process which produces a comparatively high yield of liquid hydrocarbon fuel from waste plastic or rejected plastic.
This disclosure suggests a simple and cost effective process for preparing liquid hydrocarbon fuel from waste plastics.

OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a process for preparing a hydrocarbon fuel from waste plastics.
Another object of the present disclosure is to provide a hydrothermal liquefaction process for producing hydrocarbon fuel from the waste plastics.
Still another object of the present disclosure is to provide a hydrothermal liquefaction process in the presence of a catalyst for converting the waste plastics into hydrocarbon fuel.
Yet another object of the present disclosure is to provide an environmentally friendly, simple, safe and cost effective process for producing hydrocarbon fuel from the waste plastics.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY:
The present disclosure provides a process for preparing hydrocarbon fuel from waste plastic by a hydrothermal liquefaction process in the presence of a catalyst and hydrogen. The process involves the step of degradation or de-polymerization of the polymer by heating the waste plastic in a reaction vessel in the temperature range of 350-450 oC, under a pressure ranging 50-300 bars in the presence of a catalyst and hydrogen having a pressure range 10-50 bar to obtain a reaction mass comprising 70-90 % liquid hydrocarbon fuel and 10-30 % gaseous and solid products. The carbon black formation is not observed in the reaction mass. The catalyst used in the process of the present disclosure is a bimetallic or a multi-metallic catalyst with or without the use of a promoter.

DETAILED DESCRIPTION
Waste plastics can be grouped as industrial and municipal plastic wastes according to their origin. These groups have different qualities and properties and are subjected to different management strategies. The hydrothermal liquefaction process has attracted significant attention over recent decades for the production of liquid hydrocarbon fuel from waste plastics.
The process of the present disclosure envisages a simple process for producing liquid hydrocarbon fuel from waste plastics which does not require the step of up-gradation of the hydrocarbon fuel. The process of the present disclosure produces a minimal amount of gaseous and solid products along with the liquid hydrocarbon fuel. The process is carried out by hydrothermal liquefaction process (HTL) in the presence of a catalyst and hydrogen.
In accordance with the present disclosure, the process is described below.
To carry out the process, the waste plastic is obtained and crushed in a grinder to obtain crushed/ground waste plastic. The waste plastic includes, but is not limited to, muncipal waste platsics, industrial waste plastics, plastic manufacturing reject and post consumer waste rejects such as the plastic that is fully value extracted or not fit for recycling into either crude or fuel grade. The waste plastic is selected from the groups consisting of Low-density polyethylene (LDPE), High-density polyethylene (HDPE), Polypropylene (PP), Polystyrene (PS), Polyvinyl chloride (PVC), Polyethylene terephthalate (PET) and Poly-lactic acid (PLA).
The HTL process of the present disclosure can run for individual polymeric/plastic waste and mixed plastic wastes.
The crushed waste plastic having a particle size ranging from 0.01 mm to 20 mm is taken further for treatment. The crushed/ground plastic is admixed with at least one fluid medium to make a slurry. The mixing of the fluid medium and the crushed waste plastic is carried out by stirring the mixture at a speed ranging from 450 rpm to 500 rpm for a time period ranging from 5 minutes to 60 minutes. The fluid medium is typically water.
In the present disclosure, the hydrothermal liquefaction of waste plastic is carried out in a batch reactor (reaction vessel). The slurry obtained in the above step is heated at a predetermined temperature and a first predetermined pressure for a predetermined time in the presence of hydrogen having second predetermined pressure and a catalyst, in the reaction vessel to obtain a reaction mass. The reaction mass comprises liquid hydrocarbon fuel, gaseous products and solid products.
The catalyst used in the process of the present disclosure is a heterogeneous catalyst comprising two or more transition metals and/or noble metals on an oxide support or zeolite support with or without a promoter. The amount of catalyst used with respect to waste plastic in the process of the present disclosure ranges from 1 wt% to 20 wt% depending on the reaction mass.
In an embodiment, the catalyst composition of the present disclosure comprises optionally at least one promoter component, an active component comprising at least two metal salts, at least one support in predetermined quantities.
The catalysts used in this process have dual functionality. The catalysts degrade polymers into oil components and reform the products into liquid hydrocarbon oil which is free from heteroatoms such as oxygen, nitrogen, sulphur and the like. In an exemplary embodiment, the catalysts have the ability to degrade polymers, co-polymers and mixed polymers. The catalysts also have the functionality of hydrodeoxygenation, hydrodenitrogenation and hydrodesulphurization. The catalysts used in the process of the present disclosure can be easily recovered and reused by simple filtration, washing and drying.
The promoters used in the catalyst composition of the present disclosure are selected from the group consisting of Group IIA metals, Group IIIA metals, Group VA metals, Group VB metals and Group VIIIB metals of the periodic table. The promoter is first impregnated on a carrier by an equilibrium method (promoter (metal) dissolved in water or organic solvent to obtain 100% clear solution) using a rotation process in the temperature range of 30 to 60°C. The concentration of the promoter on the support/carrier varies from 0.01 to 2 wt%. The active metals in the catalyst are from group VIII, VIb and group VIIb metal salts and mixtures thereof. The concentration of metal salts and mixtures of metal salts used in the process of the present disclosure is in the range of 0.1 to 5 wt% and 0.1 to 12 wt% with respect to the solid support. The solid support of the catalyst composition is selected from the group, including but is not limited to, oxides of alumina, silica, zirconia, alumina-silica, mesoporous silica, mesoporous zeolites, zeolite and the like. A stabilizing agent may be used in the process of making the catalyst composition. The stabilizing agent, which can be used as a solubilizing agent, may be at least one selected from the group consisting of hexamethyleneimine (HMI), ammonia solution, piperidine, pyrrolidine, morpholine, piperazine hydrate, 2-methyl cyclohexyl amine and cyclohexylamine.
The predetermined temperature is the temperature in the reaction vessel, which is in the range of 350-450 oC and the first predetermined pressure is the pressure in the reaction vessel, which is in the range of 50-300 bars. The predetermined time is the time used for heating the slurry along with the catalyst and hydrogen in the reaction vessel, which is in the range of 15-20 minutes. In an exemplary embodiment, the temperature of the reaction vessel is 400 oC and the pressure is 250 bars.
The second predetermined pressure is the pressure of hydrogen. The hydrogen used in the process of the present disclosure is passed in the reactor along with the slurry. The pressure of the hydrogen is in the range of 10-50 bars while passing in the reaction vessel.
The reaction mass obtained after the hydrothermal liquefaction process is cooled. Liquid hydrocarbon fuel is a major component of the cooled reaction mass along with a minimal amount of gaseous and solid products. The separation of liquid hydrocarbon fuel is carried out simply by decanting the liquid hydrocarbon fuel from the cooled reaction mass.
The amount of liquid hydrocarbon fuel obtained from the process of the present disclosure from waste plastic is in the range of 70-90% and the amount of gaseous and solid products is in the range of 10 to 30%. The formation of carbon black has not been observed in the reaction mass.
The present disclosure is further illustrated herein below with the help of the following experiments. The experiments used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of embodiments herein. The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. These laboratory scale experiments can be scaled up to industrial/commercial scale.
Experimental details:
Example 1: Production of hydrocarbon fuel:
20 gm of waste plastic was taken for the experiment. The waste plastic was crushed/ground to obtain the crushed/ground waste plastic. 20 ml water was added into the crushed waste plastic and stirred for 15 minutes to obtain a slurry.
The slurry (40 gm), catalyst (0.2 mg) and hydrogen gas with the pressure of 35 bars were loaded in a reaction vessel. The reaction vessel was heated at a temperature 415 oC and pressure of reaction vessel was increased to 250 bars for carrying out the process. The waste plastic got de-polymerized at this stage and the obtained reaction mass comprise a liquid hydrocarbon fuel, gaseous products and solid product.
The reaction mass was cooled to ambient temperature and liquid hydrocarbon fuel was separated by decantation from the reaction mass.
The yield of liquid hydrocarbon fuel was 83%, that of gaseous product was 10 % and solid product was 7 %. The result is shown in entry 9 of Table 1.
Similarly, the experiments 3-8 were carried out by changing the raw waste plastic type and the composition of the catalyst by maintaining the reaction condition same as explained in example 1. The experiements were also carried out without use of catalyst (entry 1 and 2).
The results are given in table 1 below;

Table 1: Catalytic Hydrothermal Liquefaction (HTL) of waste plastics
Entry No. Types of waste plastics Catalyst Oil yield (%)
1 PP-HP No catalyst 55
2 PP-CP No catalyst 53
3 PP-HP CoMo/Al2O3 82
4 PP-CP CoMo/Al2O3 68
5 PP-CP PtSn/ZSM-5 59
6 ICP-PP CoMo/Al2O3 75
7 ICP-PP PtSn/ZSM-5 58
8 ICP-PP + PP-CP CoMo/Al2O3 72
9 ICP-PP + PP-CP CoMo/Nb/Al2O3 83

Polypropylene (PP) is a thermoplastic material. PP is available as a homopolymer (PP-HP) and copolymer (PP-CP) of ethylene-propylene comonomers. The copolymer may further be a random copolymer in which ethylene is randomly distributed in the polymer matrix or as a block copolymer in which blocks of ethylene and propylene are attached to the main chain. Block copolymers are also known as impact copolymers. Impact copolymer polypropylene (ICP-PP) is a complicated copolymer and is widely used.

From the table 1, it is observed that the introduction of the heterogeneous catalysts in the process for converting waste polymer/plastic to hydrocarbon fuel improves the yield of the desired product. In case of HTL of PP-HP in the presence of CoMo/Al2O3 catalyst, yield was increased from 55% (No catalyst) to 82%. Similarly, in case of PP-CP the oil yield was increased to 68%. HTL with mixed waste polymers were also conducted in presence of CoMo/Al2O3 and niobium promoted CoMo/Nb/Al2O3 (Entry no 8 and 9) and it was found that the Nb promoted CoMo catalysts has superior activity.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The process of the present disclosure described herein above has several technical advantages including but not limited to the realization of:
1. A process for producing liquid hydrocarbon fuel from waste plastic does not need the step of up-gradation.
2. A process for producing liquid hydrocarbon fuel from waste plastic which does not need the use of an organic solvent.
3. A process for producing liquid hydrocarbon fuel from waste plastic with comparatively high yield.
4. The catalyst used in the process of the present disclosure can be regenerated, recycled and reused.

The exemplary embodiments herein quantifies the benefits arising out of this disclosure and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein has been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.