PYROLYSIS OF POLYURETHANE COMPOUND-CONTAINING MATERIAL IN ORDER TO RECOVER RAW MATERIALS

Abstract

The invention relates to a process according to claim 1 and pyrolysis devices used therein for the pyrolysis of pyrolysis stock comprising polyurethane-containing material, allowing carrying out pyrolysis on an industrial scale. According to the invention, even with higher amounts of pyrolysis stock an amount of pyrolysis product is obtained that contains cleavage products which can be reused for the synthesis of polyurethane-containing material.

Claims

1. A pyrolysis process, comprising: (a) introducing a pyrolysis feedstock comprising: i) a material comprising at least one polymeric compound having at least one polyurethane structural unit of the formula (I), ##STR00015## where Q is a hydrocarbon radical having 8 to 70 carbon atoms, and n is a number having a value of 2 to 10, and * denotes a covalent bond to the polymer backbone, and ii) at least one catalyst influencing thermal degradation of said polymeric compound, into a reactor; (b) degradation at least of the material of the pyrolysis feedstock introduced in step (a) in the reactor at a temperature of 250? C. to 700? C. to obtain a gas-phase product as pyrolysate and a non-gas-phase pyrolysis residue, wherein (i) during said degradation, the amount of oxygen gas in the reactor is not more than 2.0% by volume based on the total volume of the gases present in the reactor, and (ii) during said degradation, the pyrolysate is discharged from the reactor, and (iii) said pyrolysis residue is discharged from the reactor; (c) cooling the discharged pyrolysate to a temperature of less than 250? C. to obtain a pyrolysis product selected from pyrolysate condensate, pyrolysate sublimate or a mixture thereof; and (d) optionally working up the pyrolysis product.

2. The process as claimed in claim 1, wherein the temperature in step (b) is from 300? C. to 700? C.

3. The process as claimed in claim 1, wherein the absolute pressure in step (b) is not more than 1.2 bar.

4. The process as claimed in claim 1, wherein the introduced pyrolysis feedstock is temperature-controlled at a target temperature of 250? C. to 700? C. and that, on reaching the target temperature, the residence time of the temperature-controlled pyrolysis feedstock until the time of discharge of the pyrolysis residue resulting therefrom is from 1 second to 5 hours.

5. The process as claimed in claim 1, wherein the step of discharging the pyrolysate from the reactor comprises (i) passing a gas stream through the reactor or (ii) suction.

6. The process as claimed in claim 1, wherein the step of discharging the pyrolysate from the reactor comprises passing a gas stream through the reactor, the flow rate of which in the reactor, as the superficial velocity, is from 0.01 m/s to 20 m/s.

7. The process as claimed in claim 1, wherein at least steps (a) and (b) run concomitantly in the context of continuous process control.

8. The process as claimed in claim 1, wherein the amount of oxygen gas in the reactor in step (b) is not more than 0.5% by volume, based on the total volume of the gases present in the reactor.

9. The process as claimed in claim 1, wherein an inert gas is passed through the reactor packed with said material.

10. The process as claimed in claim 1, wherein the polymeric compound contains at least one polyurethane structural unit of the formula (Ia) ##STR00016## where n is a number having a value of 0 to 8, and * denotes a covalent bond to the polymer backbone.

11. The process as claimed in claim 1, wherein the polymeric compound is obtained by reaction at least of i1) at least one organic isocyanate compound containing two to ten isocyanate groups attached to a hydrocarbon unit having 8 to 70 carbon atoms; with i2) at least one organic compound having at least two hydroxy groups.

12. The process as claimed in claim 11, wherein the at least one organic isocyanate compound contains, as said hydrocarbon unit, a unit that is derived from aliphatic hydrocarbon units, cycloaliphatic hydrocarbon units, araliphatic hydrocarbon units, aromatic hydrocarbon units or heterocyclic hydrocarbon units.

13. The process as claimed in claim 11, wherein the at least one organic isocyanate component comprises at least one polyphenylpolymethylene polyisocyanate of the formula (III), ##STR00017## where n is a number having a value of 0 to 8.

14. The process as claimed in claim 1, wherein said material is introduced into the reactor in the form of solid particles.

15. The process as claimed in claim 1, wherein the catalyst comprises at least one compound from the group consisting of inorganic salts, minerals, metal oxides, mixed oxides, clays, and zeolites.

16. The process as claimed in claim 1, wherein the catalyst comprises a basic catalyst.

17. The process as claimed in claim 1, wherein the catalyst comprises a heterogeneous catalyst.

18. (canceled)

19. A composition comprising, in each case based on the total weight of the composition, (i) 0% and 40% by weight of at least one aromatic compound having at least two amino groups, (ii) 0% and 35% by weight of at least one aromatic compound having just one amino group, (iii) 0% to 40% by weight of at least one hydrocarbon compound containing at least one functional group having at least one oxygen atom and no functional group having a nitrogen atom, (iv) where the proportions by weight within the parts by weight ranges from (i), (ii) and (iii) are selected such that the sum total of the selected proportions by weight from (i), (ii) and (iii) together with the parts by weight of other ingredients add up to 100% by weight.

Description

EXAMPLES

a) Providing the Pyrolysis Feedstock:

[0195] A rigid polyurethane foam was produced by standard processes from the components shown in Table 1.

TABLE-US-00001 TABLE 1 Components of the rigid foam: % by wt. Constituents Polyol having an OH value of 450 30.10 Polyol with o-tolylenediamine as starter 8.60 having an OH value of 400 Polyol having an OH value of 112 2.58 Mixture of 0.86 Polycat? 5, Polycat? 8 and Polycat? 41 .sup.1 Silicone (stabilizer) 0.86 Isocyanate Desmodur? 44V20 (pMDI) 57.00 .sup.1 catalysts, sold by Evonik, Germany .sup.2 liquid, dark brown isocyanate from Covestro Deutschland AG, based on diphenylmethane 4,4-diisocyanate (MDI) with isomers and higher-functional homologs (pMDI)

[0196] To provide the various pyrolysis feedstocks P1 to P3, 1 g of the finely grated rigid polyurethane foam was intimately mixed with 4 g of one of the catalyst powders listed in Table 2. Pyrolysis feedstock P4 contained, as a comparison, no catalyst.

TABLE-US-00002 TABLE 2 Catalyst C1 to C3 and pyrolysis feedstock P1 to P3 Catalyst: C1 C2 C3 in pyrolysis P1 P2 P3 % by wt. MgO 5.0 70.0 0.0 % by wt. Al.sub.2O.sub.3 95.0 30.0 100.0 Structure Basic Al.sub.2O.sub.3 Hydrotalcite ?-Al.sub.2O.sub.3 precursor Particle size d.sub.50 40 40 40

b) Pyrolysis Procedure

[0197] The pyrolysis of the rigid polyurethane foam was carried out at 500? C. in a fixed-bed reactor having a volume of 25 ml with a through-flow of N.sub.2.

[0198] The flow rate of the nitrogen gas stream (superficial velocity) in the reactor was 0.07 m/s. A pyrolysis feedstock according to Table 1 was introduced into the reactor. The residence time of the introduced polyurethane material was 30 min. The reactor was heated to 500? C. and then held at this temperature for 30 min. Situated downstream of the reactor were three condensers for the separation of the liquid components from the resulting pyrolysis gas. The resulting content of carbonized material was determined by weighing the catalyst powder after the pyrolysis. The gas downstream of the three condensers was characterized by online IR. The components of the pyrolysis product obtained in the form of an oil were determined by GC-FID. This was done using an Agilent 7890A with a Supelco SPB 50 column. The pyrolysis oil was diluted 1:50 or 1:100 with acetone.

TABLE-US-00003 TABLE 3 Composition of the pyrolysate obtained [% by wt.]: Pyrolysis feedstock P1 P2 P3 P4 Catalyst C1 C2 C3 without Aniline* 19.0 11.0 10.0 Methylaniline* 8.3 3.0 5.0 mMDA* 2.3 20.0 4.1 Oil (not characterized) 40.0 29.0 35.0 53.2 containing pMDA* Gas phase after condensation H.sub.2O 0.5 20.0 CO.sub.2 10.0 13.0 10.0 CO 3.0 Carbonized material 10.0 10.0 30.0 17.3 Other gases 10.4 5.5 15.7 Total 100.0 100.0 100.0 100.0 *denotes constituents of the pyrolysis product

[0199] The pyrolysis product P2 containing the catalyst C2 was used to carry out a pyrolysis experiment at 500? C. and a pyrolysis experiment at 470? C. The distribution of the amines obtained was compared (see Table 4). This showed that at 470? C. more methylenedianiline (mMDA) is obtained in the pyrolysis product.

TABLE-US-00004 TABLE 4 Comparison of the distribution of the aromatic amines obtained [% by wt.]: P2 P2 Product 500? C. 470? C. Anilines 11 3 Methylaniline 3 3 mMDA 20 30