Chemistry of hydrocarbon compounds – Production of hydrocarbon mixture from refuse or vegetation – From synthetic resin or rubber
Patent
1994-01-12
1997-06-17
Caldarola, Glenn A.
Chemistry of hydrocarbon compounds
Production of hydrocarbon mixture from refuse or vegetation
From synthetic resin or rubber
208 72, C07C 100, C07C 404
Patent
active
056399375
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The instant invention relates to a process for the production of olefins from plastic waste.
DESCRIPTION OF THE PRIOR ART
Waste management of plastic waste, in particular of contaminated mixtures of plastic waste, which leads to the production of valuable materials is to a considerable extent still a technically unsolved problem.
The separate collection of plastic packaging material in households and trade (dual system), which has been recently introduced in the Federal Republic of Germany at several locations is expected to lead after introduction of the system in the total area of Germany to a quantity of packaging waste of approximately 1 million tons per year.
Since waste incineration, labeled as "thermal recycling" encounters strong opposition in the public and since pyrolysis, i.e. heating of plastic waste in the absence of oxygen, leads essentially to products of little value, at present only few processes are promising with regard to the production of useful, valuable materials from plastic waste, which can be used as substitutes for products made from crude oil.
In addition, these processes are in an experimental state at present. One of these more promising processes is the hydrogenative cleavage of mixtures of plastic waste at high hydrogen pressure and at high temperature, whereby depending on the feed material, up to 90 weight-% of saturated hydrocarbons may be obtained, boiling in the range of gasoline and gas oil.
This process has been disclosed in several patents, for example, in the German Patent P 34 42 506 and in the European Patent 0 236 701.
A further interesting process, which permits the separation of composite materials into the individual components, in particular composite paper/polyethylene/aluminum-foils, which serve as packaging material for beverages, has been disclosed in German Patent P 40 28 999.
By these processes, after having been developed into an industrial stage, at least part of the waste, consisting of plastic packaging material can be reused in a reasonable way.
A process, by which in a thermal and a catalytical stage, polyethylene, polypropylene and polystyrene, respectively mixtures of these components can be cleaved, forming unsaturated and saturated hydrocarbons, is described in Japan Chemical Week May 31, 1990, pages 6 and 7.
In a temperature range of up to 500.degree. C., approximately 60 weight-% of liquid hydrocarbons, 30 weight-% of gaseous hydrocarbons and 10 weight-% of a coke-like residue are obtained.
Approximately 50 weight-% of the liquid products are unsaturated hydrocarbons. Ethylene and propylene are obtained only in a quantity of 4.5 and 7.6 weight-% respectively.
SUMMARY OF THE INVENTION
By the instant invention applicant has now succeeded in further improving recycling of plastic waste, by a process, characterized in that plastic waste is transferred into a molten state by heating, the viscosity of the melt is adjusted to a desired value by thermal cracking, and the product thus obtained is heated to 700.degree. to 1100.degree. C., at a residence time of 0,02 to 10 seconds.
BRIEF DESCRIPTION OF THE DRAWINGS
The sole FIGURE of the Drawing is a simplified schematic or flow sheet illustrating an apparatus suitable for carrying out the process of this invention.
DETAILED DESCRIPTION
Although the thermal cleavage of so-called naphtha, which represents a crude oil fraction boiling in a range of approximately 100.degree. to 170.degree. C., is the most important process at present for the production of ethylene and propylene, and although it is known that gas oil and vacuum gas oil can also be cleaved to ethlene and propylene in satifactory yields, and although it is known that even crude oil can be thermally cleaved, whereby also ethylene and propylene are obtained to a certain extent, the person skilled in the art, has until now not been able to solve the problem of producing ethylene and propylene by direct thermal treatment of plastic waste after a thermal pretreatment, although such a process represents genuine
REFERENCES:
patent: 3956414 (1976-05-01), Oshima
patent: 3985820 (1976-10-01), Albright et al.
patent: 4851601 (1989-07-01), Fukuda et al.
patent: 4982027 (1991-01-01), Korff et al.
patent: 5232489 (1993-08-01), Mertens-Gottselig et al.
patent: 5364995 (1994-11-01), Kirkwood et al.
Fuji Recycle Industry KK, Japan Chemical Week, "Useful Oil Reclaimed from Waste Plastics (Polyolefin)", May 31, 1990, pp. 6 and 7.
Hammer Hartmut
Hover Hermann
Caldarola Glenn A.
RWE Entsorgung Aktiengesellschaft
Yildirim Bekir L.
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