Use of a catalyst composition for the catalytic depolymerization of plastics waste

Abstract

Use of a catalyst composition comprising A) a first component containing oxidic compounds comprising aluminum and silicon with a molar ratio of silicon to aluminum of more than 1) B) a second component containing an oxidic compound of silicon wherein the ratio of the number of acidic sites of component A, determined by temperature programmed desorption with ammonia as a base, to the number of acidic sites of component B, determined under the same conditions, is at least 3: in a process for the catalytic depolymerization of plastics waste.

Claims

1. A process comprising catalytic depolymerization of plastics waste using a catalyst composition comprising A) a first component containing oxidic compounds comprising aluminum and silicon with a molar ratio of silicon to aluminum of more than 1, and B) a second component containing an oxidic compound of silicon; wherein the ratio of the number of acidic sites of component A, determined by temperature programmed desorption with ammonia as a base, to the number of acidic sites of component B, determined under the same conditions, is at least 3:1; and wherein the catalyst composition contains at least 50 wt %, based on the combined weight of components A and B, of component B.

2. The process of claim 1 wherein component A comprises supported or unsupported zeolites.

3. The process of claim 1 wherein component A) is a fresh fluid catalytic cracking catalyst, an equilibrium fluid catalytic cracking catalyst or a mixture thereof.

4. The process of claim 1 wherein the plastics waste is selected from the group consisting of post consumer waste plastics, off-spec plastics, and industrial scrap plastic.

5. The process of claim 1 wherein the plastics waste comprises at least 50 wt % of polyolefins, styrene polymers or mixtures thereof.

6. The process of claim 1 wherein the plastics waste is essentially free of thermosetting polymers.

7. The process according to claim 1, wherein the catalyst composition contains at least 55 wt %, based on the combined weight of components A and B, of component B.

8. The process according to claim 7, wherein the catalyst composition contains at greater than 60 wt %, based on the combined weight of components A and B, of component B.

9. A catalytic composition, comprising A) a first component containing oxidic compounds comprising aluminum and silicon with a molar ratio of silicon to aluminum of more than 1 and B) a second component containing an oxidic compound of silicon, wherein the ratio of the number of acidic sites of component A, determined by temperature programmed desorption with ammonia as a base, to the number of acidic sites of component B, determined under the same conditions, is at least 3:1, and wherein the catalyst composition contains at least 50 wt %, based on the combined weight of components A and B, of component B.

10. The catalytic composition in accordance with claim 9 wherein component A) comprises supported or unsupported zeolites.

11. The catalytic composition in accordance with claim 9 wherein component A) is a fresh fluid catalytic cracking catalyst, an equilibrium fluid catalytic cracking catalyst or a mixture thereof.

12. The catalytic composition in accordance with claim 9 wherein the ratio of the number of acidic sites of component A to the number of acidic sites of component B, determined under the same conditions, is at least 5:1.

13. A process for the catalytic depolymerization of plastic waste, the process comprising a) in a first step, introducing plastics waste into a reactor, melting the plastics waste, and thereafter increasing the temperature to a temperature in the range of from 350 to 600 C., b) thereafter adding, to the molten plastics, a catalytic composition comprising as component A) a fluid catalytic cracking (FCC) catalyst and as component B) a compound based on oxidic compounds of silicon, wherein the ratio of the number of acidic sites of component A to the number of acidic sites of component B is at least 3:1, and wherein the catalyst composition contains at least 50 wt %, based on the combined weight of components A and B, of component B, c) carrying out the catalytic depolymerization at a temperature of from 350 to 600 C., and d) recovering the product fractions formed.

14. The process in accordance with claim 13 wherein component A) is a fresh fluid catalytic cracking catalyst, an equilibrium fluid catalytic cracking catalyst or a mixture thereof.

15. The process of claim 13 wherein the plastic waste comprises at least 50 wt % of polyolefins, styrene polymers or mixtures thereof.

16. The process of claim 13 wherein the plastics waste is selected from the group consisting of post consumer waste plastics, off-spec plastics, and industrial scrap plastic.

Description

EXAMPLES

(1) General Description of the Procedure

(2) 30 g of plastic (20% Polypropylene, 80% Polyethylene) were loaded inside the reactor and a defined amount of catalyst (approximately 20 g) was stored in a catalyst storage tank. The reactor was closed and heated from room temperature to 200 C. during 20 minutes, while simultaneously purging with a 150 mL/min nitrogen flow. When the internal temperature reached the melting point of the plastic, stirring was started and was slowly increased to 690 rpm. The temperature was held at 200 C. for 25-30 minutes. During this heating process, nitrogen coming out from the reactor was disposed of. Meanwhile, the catalyst storage tank containing the catalyst was purged with nitrogen several times.

(3) After this first pretreatment step, temperature was increased to the reaction temperature of 425 C. at a heating rate of 10 C./min, and the collection of gases and nitrogen in the corresponding gas sampling bag was started. When the internal temperature reached the reaction temperature, the catalyst was introduced into the reactor, and the circulation of the gaseous products was commuted to another pair of glass traps and corresponding gas sampling bag. This was considered as the zero reaction time.

(4) During selected time periods, liquid and gaseous products were collected in a pair of glass traps and their associated gas sampling bag, respectively. At the end of the experiment the reactor was cooled to room temperature. During this cooling step, liquids and gases were also collected.

(5) The reaction products were classified into 3 groups: i) gases, ii) liquid hydrocarbons and iii) residue (waxy compounds, ashes and coke accumulated on the catalyst). Quantification of the gases was done by gas chromatography (GC) using nitrogen as the internal standard, while quantification of liquids and residue was done by weight. Glass traps (along with their corresponding caps) were weighed before and after the collection of liquids, while the reactor vessel was weighed before and after each run.

(6) The simulated distillation (SIM-DIS) GC method was used to determine the different fractions in the liquid samples (according to the selected cuts), the detailed hydrocarbon analysis (DHA) gas chromatography method was used to determine the PIONAU components (P=paraffin, I=isoparaffin, O=Olefins, N=Naphthenes, A=Aromatics) in the gasoline fraction of the last withdrawn sample (C.sub.5-C.sub.11: Boiling point <216.1 C.; what includes C.sub.5-C.sub.6 in the gas sample and C.sub.5-C.sub.11 in the liquid samples), and two dimensional gas chromatography allowed the determination of saturates, mono-, di- and tri-aromatics in the diesel fraction of the last withdrawn liquid samples (C.sub.12-C.sub.21; 216.1<BP<359 C.).

(7) Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

Example 1

(8) 20 g of a mixture containing 75 wt % ECAT-DC (an equilibrated FCC catalyst obtained from Equilibrium Catalyst Inc.) and 25 wt % SiO.sub.2 was used. The ratio of the acidic groups of ECAT to the acidic groups in the SiO.sub.2 exceeded 5:1. Experiments were carried out using a plastic mixture comprising 80 wt % HDPE (High Density Poly-ethylene) and 20 wt % PP as raw materials. Reaction temperature was set to 425 C. Catalyst to plastic weight ratio was equal to 20/30 by wt.

Example 2

(9) Example 1 was repeated except that the mixture ratio of ECAT:SiO.sub.2 was 50:50 (% by wt.)

Example 3

(10) Example 1 was repeated except that the mixture ratio of ECAT:SiO.sub.2 was 25:75 (% by wt.)

Comparative Example 4

(11) Example 1 was repeated except that only SiO.sub.2 was used as catalyst.

Comparative Example 5

(12) Example 1 was repeated except that only ECAT-DC was used as catalyst.

(13) The results of the analysis of the yield is given in Table 2

(14) TABLE-US-00002 TABLE 2 Conversion and yield of certain fraction in % as function of reaction time. Yield of given fraction in % Conver- t Gaso- Kero- sion (min) Gas line sene Diesel HCO* in % Comparitive 0 0.04 0.18 0.09 0.04 0.02 0.36 Example 5 1.25 1.51 19.83 13.81 7.49 3.07 45.71 3.25 2.72 31.05 22.23 12.63 5.55 74.18 5 3.30 35.31 25.16 14.04 5.96 83.77 8 4.12 38.27 27.01 14.80 6.13 90.32 Comparitive 0 0.04 0.05 0.02 0.01 0.00 0.11 Example 4 25 1.37 4.24 2.75 1.17 0.27 9.80 40 2.22 6.75 5.25 3.04 0.38 17.64 60 3.17 9.58 8.52 6.58 0.59 28.44 90 4.66 13.62 14.20 14.36 1.51 48.35 Example 3 0 0.04 0.13 0.03 0.01 0.00 0.21 5 1.09 7.16 5.00 2.52 1.04 16.82 10 2.09 15.68 12.42 7.64 3.49 41.31 17 3.34 23.64 18.78 11.73 4.41 61.90 26 4.39 28.23 22.81 14.61 4.83 74.87 Example 2 0 0.05 0.09 0.01 0.01 0.00 0.16 2 0.98 9.27 5.74 2.83 0.76 19.59 5 1.84 18.76 12.88 7.78 2.97 44.23 8 2.71 25.92 18.53 11.60 4.88 63.63 17 4.79 35.61 26.05 16.31 6.98 89.74 Example 1 0 0.05 0.14 0.05 0.02 0.00 0.25 2 1.44 13.18 9.65 5.05 1.57 30.88 4 1.95 20.51 15.77 9.09 3.23 50.55 6.5 2.81 27.12 20.96 12.48 4.54 67.92 14 4.77 35.78 26.87 16.07 5.76 89.25 *Heavy cycle oil

(15) TABLE-US-00003 TABLE 3 Additional information on quality of the fractions obtained and listed in Table 2. Comp. Comp. Fraction Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Gasoline RON 77 77 77 71 77 MON 74 74 74 68 75 Diesel Saturated (wt %) 70.1 78.9 84.8 95.7 63.0 MonocyclicAromatic (wt %) 18.1 13.3 9.9 3.2 21.4 Dicyclic Aromatic (wt %) 11.2 7.4 5.1 1.0 14.9 Tricyclic Aromatic (wt %) 0.6 0.4 0.2 0.1 0.8 Polycyclic Aromatic (wt %) 11.8 7.8 5.3 1.1 15.6

(16) The data in Table 2 show that Comparative Example 4 (SiO.sub.2) yields high amounts of diesel but only low amounts of gasoline. ECAT when used without second component yields a high amount of gasoline but only lower yield of diesel.

(17) Furthermore, the diesel fraction obtained in Comparative Example 5 contained polycyclic aromatics in an amount exceeding the upper limit of 8% set forth in EN 590 for diesel (Table 3), i.e. the diesel fraction could not be directly used without further purification. The diesel fraction obtained in Comparative Examples 4 fulfilled the EN 590 specification, but, as can be seen from Table 2, the cumulative conversion as function of reaction time was entirely unsatisfactory.

(18) It is apparent from Table 2 that ECAT used alone has good conversion over time but that adding up to 50% of SiO.sub.2 does not deteriorate the performance too much. In Comparative Example 4, however, the conversion achieved over time is not feasible for an economical commercial operation.

(19) Furthermore RON (research octane number) and MON (motor octane number) for the gasoline fraction in Comparative Example 4 (71 and 68 respectively) was appr. 10% lower than for Examples 2 to 3 (77 and 74 in each case).

(20) These results show that only the composition comprising components A and B as described in the present invention lead to good conversion, gasoline fraction with high octane number and diesel fraction with polyaromatics content below the limit set forth in EN 590.

Comparative Example 6

(21) Example 1 was repeated except that a bottoms cracking additive BCA-105 purchased from Johnson Matthey was used as catalyst. This product, according to the datasheet had an attrition resistance in accordance with ASTM 757 D of 1.3, a surface area of 130 m.sup.2/g, an apparent bulk density of 0.80, and an aluminum oxide content of 68 wt %. The weight ratio Si/Al was 0.452. The average particle size was 90 m, with 12 wt % of the particles having an average diameter of less than 40 m and 2 wt % of the particles having a size of less than 20 m.

(22) TABLE-US-00004 TABLE 4 Selectivity towards given fractions obtained. Selectivity* towards certain fractions in % Gas Gasoline Kerosene Diesel HCO Example 1 5.3 40.1 30.1 18.0 6.5 Example 2 5.3 39.7 29.0 18.2 7.8 Example 3 5.9 37.7 30.5 19.5 6.5 Comparative Example 4 9.6 28.2 29.4 29.7 3.1 Comparative Example 5 4.6 42.4 29.9 16.4 6.8 Comparative Example 6 9.3 32.5 23.5 20.7 14.1 *selectivity is yield/conversion

(23) From the results compiled in table 4, one can see that another benefit of using a mixture of ECAT:SiO.sub.2 was a lower production of gas fraction, which is a product of no added value in terms of combustion energy. At the same time, high amounts of higher value gasoline, kerosene and diesel were produced. The comparative example 5 was also characterized by a low production of gas fraction; however, as previously observed from the results reported in table 3, the diesel fraction obtained in this comparative example contained polycyclic aromatics in an amount exceeding the upper limit of 8% set forth in EN 590 for diesel.

(24) Only the examples according to the invention gave simultaneously a low gas production and a diesel fraction with polyaromatics content below the limit set forth in EN 590 whilst the conversion as function of reaction time was kept satisfactory.