A process of conversion of waste polymeric materials into hydrocarbon fractions

FIELD OF THE INVENTION

The present invention relates to a method of conversion of waste polymeric materials into hydrocarbon fractions, gasoline and diesel oil.

BACKGROUND OF THE INVENTION

With the rapid development of plastic industry, plastic products became important in our daily life and in the industrial production. Hence, more wastes from plastics are generated in accompanying with the abundant applications of plastics. Since the waste plastic materials practically cannot be decomposed under the natural condition, unnecessary plastic had polluted our survival environment.

In this connection, there is a steadily increasing demand for technology of converting waste plastic materials into useful products.

A method of converting waste organic solvents to obtain hydrocarbon fractions in the presence of a catalytically effective amount of an active oxide of hexavalent group 6b metal, such as chromium, is described in patent US4748289. However this method is effective only for converting of light hydrocarbons.

In the patent US5700751 a catalyst used for converting waste plastics, comprising a carrier and active components with the following formula: A ₃ B _b Al ₀ M _d Na _e Ca _f Fe ₉ O _x is described, wherein A is selected from the group consisting of potassium, barium, phosphorus, vanadium, chromium, rare earth elements and their mixture; B selected from the group consisting of molybdenum, tungsten, nickel, germanium and platinum series; and M selected from WO or (NH ₄ J ₂ WO ₄ , wherein a is from 25 to 26,35 percent by weight; b from 36 to 37,05 percent; c from 7,2 to 9 percent; d from 1 ,14 to 1 ,55 percent; e from 1 ,75 to 2,15 percent; f from 2,40 to 2,80 percent; and g from 2,42 to 3,2 percent; and x is a sum of oxygen needed for chemical bonding valences of said components in the catalyst.

Yield of liquid and gas product of conversion of waste plastics does not exceed 84.3 %. The reaction time is from 8 to 11 hours. A specific productivity of the catalyst is 4.5 - 11 kg polymer/(kg catalyst*h).

In this process the amount of the catalyst is small and the temperature of conversion is low. However, the conversion of waste polymeric materials proceeds the long period of time and the yield of liquid and gas products is small.

DETAILED DESCRIPTION OF THE INVENTION

An object of the present invention is a method of conversion of waste polymeric materials into hydrocarbon fractions, gasoline and diesel oil.

According to the present invention the conversion of waste polymeric materials can be carried out at the presence of the catalyst which includes one or more of the elements of transition metals, where in, at least, one of elements of the same metals has a various degree of oxidation.

Preferably, the catalyst includes elements of metals selected from the group consisting of iron, zinc, chromium, copper, platinum, rare earth elements and their mixture. Preferably, elements of metals are in the form of oxides.

In addition, the catalyst can includes alumina, silica, oxides of magnesium and boron and their mixture.

The catalyst of this invention is in the form of powder or granules depending upon the engineering of the particular process employed. Thus a fixed bed will have larger particles than fluidized bed. Therefore catalyst particle sizes can range from about 0,001 microns up to about 5 mm. The process of the present invention is most conveniently carried out at the presence of moving catalyst in a continuous manner, although semi-continuous operations and fixed bed catalyst may also be employed.

Preferably, a film evaporator or a rotating drum-type reactor are used as reactor.

Preferably, process of conversion of waste polymeric materials is combined with a process of removing products of decomposition.

EXAMPLE 1

4,6 g of the catalyst consisting of (% wt): CrO ₃ - 1 ; Cr ₂ O ₃ - 14; CuO - 0,4; SiO ₂ - 84,6 in the form of a powder, consisting of 60-140 μm grains, and 96 g polyethylene according to GOST 273-83 is added to a 0,25-liter reactor with a stirrer. The mixture obtained is heated at 415±10 ⁰ C and 10 MPa within 1 ,5 hour.

9,5 g of gas product and 73,5 g of liquid product are obtained. The yield of liquid and gas products are 86,5%. The composition of the obtained liquid product is shown in table.

EXAMPLE 2

According to this example a process of conversion of waste polymeric materials is combined with a process of removal products of decomposition.

As reactor the rotor-film evaporator is used and the process is carry out at 405+10 ⁰ C, atmosphere pressure. As the catalyst the mixture of (%wt): Fe ₂ O ₃ - 6; FeO - 0,6; Cr ₂ O ₃ - 4; MoO ₂ - 0,2; B ₂ O ₃ - 0,9; AI ₂ O ₃ - 88,3 is used.

Within the first 30 minutes 100 g/h of the melt of polypropylene (GOST 3521-99) is , fed to the top of a reactor, containing 5,3%wt. of the catalyst with a particles size 40-100 μm. The residence time is equal 20 min.

The gas stream (a mixture of hydrocarbons Ci - C ₂₀ ) is removed from the top of the reactor, cooled to 25 ⁰ C and passed through a gas-liquid separator.

In 30 minutes after the beginning of the process a fluid flow (20 g/h), containing unreacted polypropylene and the catalyst is removed from the bottom of the reactor. This fluid flow is mixed with the melt of polypropylene (80 g/h) and fed to the top of reactor.

The experiment is carried out within 240 hours. 1 ,9 kg of gas products and 17,1 kg of liquid products are obtained. The total yield of gas and liquid products is 99,9%. The yield of liquid products is 90,0%.

The liquid products consist of hydrocarbon C4-C12 (71% wt), C13-C18 (23%wt.) and >Cig (6% wt.) and includes alkanes (40% wt), alkenes (54% wt.), cycloalkanes (5% wt.) and others (1 % wt.). The gas products consist of hydrogen, methane, ethane, ethylene, propane, propene, butanes and butenes.

EXAMPLE 3

The vertical tubular jacketed reactor (inner diameter of 16 mm and of 500 mm in length) was charged with two layers of the catalyst. The first layer of the catalyst, %wt: Cr ₂ O ₃ - 11 ; ZnO - 0,1; MgO - 5%, Pt - 0,1 , SiO ₂ - carrier. The second layer of the catalyst: CrO ₃ - 1 ,5, NiO - 4, Pd - 1 ,5; AI ₂ O ₃ - carrier.

15 g/h melt mixture of polypropylene (43% wt.), polyethylene (34% wt.) and polystyrene (23% wt.) and 100 ml/h hydrogen was supplied into the top of catalytic layer.

The temperature of the first catalytic layer was maintained at 395+15 ⁰ C and the second catalytic layer - 420+15 ⁰ C. The pressure of reactor was maintained at 2,5 MPa.

The gas stream (a mixture of hydrocarbons C ₁ - C ₂ o and hydrogen) is removed from bottom of the reactor, cooled to 25 ⁰ C and passed through a gas-liquid separator.

The experiment is carried out within 32 hours. 57 g of gas products and 422 g of liquid products are obtained. The total yield of gas and liquid products is 99,8%. The yield of liquid products is 87,9%.

The liquid products consist of hydrocarbons C ₄ -C ₁₂ (73% wt), Ci ₃ -C ₁₈ (16% wt.) and >C ₁₉ (11% wt.) and includes alkanes (71 % wt.), alkenes (2% wt.), cycloalkanes (9% wt.), aromatic (18% wt.) and others (1 % wt.). The gas products consist of hydrogen, methane, ethane, ethylene, propane, propene, butanes and butenes.

EXAMPLE 4

A rotating drum-type reactor is used as reactor and a process of conversion of waste polymeric materials is integrated with a process of removal products of decomposition.

The heating and conversion of waste polymeric materials carry out in drum-type reactor half-filled with ceramic heated beaters (balls of diameter 3 mm).

The mixture of (%wt): MnO ₂ - 1 ; MnO - 0,2; CuO - 0,2; Cr ₂ O ₃ - 8; MoO ₂ - 0,2; B ₂ O ₃ - 0,5; Pt - 0,2, AI ₂ O ₃ - 89,7 is used as the catalyst.

The mixture of 3,9 g of the catalyst in the form of a powder consisting of 60-140 μm grains and 97,9 g of crushed agricultural plastic films and beaters are heated until 700 ⁰ C feed to reactor by two screw feeders. The mix catalyst and plastic films is instantly heated by the beaters, resulting in instant destruction of plastic material and generation of hydrocarbon. The residence time is equal 27 min.

The gas stream (a mixture of hydrocarbons C ₁ - C ₂ o) is removed from the top of the reactor, cooled to 25 °C and passed through a gas-liquid separator.

Cooled beaters and the catalyst are removed from the bottom of reactor and then heated up in the furnace and return into the reactor.

The experiment is carried out within 48 hours. The total amount of the polymer fed into a reactor is 500 g.

91 g of gas products and 401 g of liquid products are obtained. The total yield of gas and liquid products is 99,9%. The yield of liquid products is 80,2%.

The liquid products consist of hydrocarbons C ₄ -C ₁₂ (51 % wt.), C- ₁₃ -C- ₁₈ (26% wt.) and >C ₁₉ (23% wt.) and includes alkanes (36% wt.), alkenes (52% wt.), cycloalkanes (9% wt.), aromatics (1 % wt.) and others (2% wt.). The gas products consist of hydrogen, methane, ethane, ethylene, propane, propene, butanes and butenes.