CS219595B1 - Process for preparing linear alkenes and alkanes - Google Patents

Abstract

The invention relates to a method for preparing linear alkenes from collected and waste raw materials. The essence of the invention lies in the fact that thermal decomposition is subjected exclusively or partially, or alternatively in a continuous process; waste and collected polyethylene, pigmented with titanium dioxide, at a temperature of 400 to 460 °C under a pressure equal to or close to atmospheric, in a stream of inert gas, while the gas stream and steam are cooled before the charge only above the freezing point of the product hydrocarbons and the steam is passed through a layer of liquid product. The significance of the invention lies in the preparation of nalkene from collected and waste raw materials for the production of biodegradable surfactants and detergents.

Description

The invention relates to a process for the preparation of linear alkenes and alkanes from collection and waste materials.

In order to produce biodegradable surfactants and detergents, n-alkenes are needed, with the advantage that their double bond is at the end (alpha-olefins) or near the end of the chain molecule. Numerous processes by which such n-alkenes can be prepared, e.g. polymerization of ethylene using Ziegler-Natta catalysts, catalytic dehydrogenization, or non-catalytic cracking of n-alkenes. The destructive methods are based on defined, unbranched alkanes obtained e.g. by adsorption on molecular sieves or by urea catalysis. These technologies significantly increase the cost of paraffinic raw material and ultimately detergents for use e.g. in household.

It is further known that a mixture of n-alkenes and nparaffins is also produced by thermal destruction of polyethylene. E.g. podfa Japan Kokai Tokkyo Koňo 80 71, 789 of 30 May 1980/22. 11. 1978 Waste polyolefins are pyrolized to obtain oligomers a) or hydrocarbon oils. In the example, starting from polyethylene granules, pyrolyzed at 420 ° C in a polyolefin melt and at 300 ° C above its level for 5 hours to obtain 91.2% w / w. mixtures of C ₅ O C ₃₃ hydrocarbons.

According to Schmidt F., Hles Vendel: Pyrolysis of Ogranic Wastes in Magyar Asvanyolaj és Foldgazkiserl. Intézet Kol. 1980 20, 117-32, when pyrolyzed at 380-500 ° C waste from polyethylene, polypropylene, agglomerates, polystyrene or PVC. Polyolefins yielded 72 to 94% liquid products and 6 to 18% gaseous products. The liquid product consists of alcohols, alkenes and aromas.

The cited patents and publications do not disclose the suitability of the olefins thus obtained for use in the manufacture of surfactants, or their relative proportions relative to paraffins.

SUMMARY OF THE INVENTION The invention consists in subjecting to thermal decomposition exclusively or in part, alternately alternatively, waste and recovered titanium dioxide pigmented polyethylene, at a temperature of 400 to 460 ° C at a pressure equal to or near atmospheric, in a stream of inert gas, and the vapor prior to the charge is cooled to a temperature greater than or equal to 40 ° C of the hydrocarbons produced and the remaining vapors are passed through a bed of liquid product.

The process for preparing alkenes and alkanes from the collection and waste materials of the present invention is characterized by subjecting thermally decomposed waste polyethylene pigmented with titanium dioxide, e.g. the milk bags from the collection, or at least a portion of the batch, constitute this pigmented collection and waste material. Pyrolytic decomposition of this material in a weak stream of inert gas, e.g. nitrogen, it is in the range of 400 to 460 ° C. The decomposition begins at approximately atmospheric pressure at 400 to 410 ° C, proceeds very intensively from 435 ° and ends at 450 to 460 ° C. Slight catalytic effect pigment enables higher product yield and particularly olefins to C _1S, desirable for laundry detergents, which obtained olefins are branched, which arise from the catalytic cracking parafímov. This is probably because titanium dioxide can lyse the disintegration of macromolecules alone in the kata polyolefin melt, but since it is not in contact with the vapor phase above the melt, it does not affect fragment isomerization. An advantage of the invention is also that about 35% of olefins have a double bond at the end of the molecule and do not contain more terminal methyl groups than olefins prepared in known ways in the absence of titanium dioxide, indicating that they are not substantially branched.

The solid aerosol settlements formed, in particular at the onset of thermal decomposition, are prevented by the present invention in that the vapors are cooled to a temperature of greater than 40 ° C prior to the furnace and the furnace is adapted to pass the cooled vapor and inert gas stream. in direct contact (bubbling) through liquid condensate. Downstream of the charge, an inert gas, largely free of organic vapors, passes through a water or brine cooler where it is freed of the smallest proportions of condensable hydrocarbons and can be recirculated to the cracking reactor in a known manner.

Compared with the known processes, in the microdispersed titanium dioxide process, a product is obtained comprising 59.7% of the fraction up to _and including C _n , comprising olefins, paraffins and virtually no aromatics. Therefore, the paraffinic component after processing of olefins by its structure and composition is also suitable as a raw material for oxidation to fatty alcohols or for chlorination for the production of alkylbenzenes. The thermal decomposition of the polyolefin can be conducted almost to the end without changing the composition of the product and reducing off-gas losses. According to the invention, the decomposition proceeds faster than according to the known methods cited.

The effect of titanium dioxide can also be demonstrated in the pyrolysis of the waxy first portions of polyethylene production (high pressure example 3).

219 595). Without the use of titanium dioxide as a catalyst, the olefin yield to C ₁₃ including, significantly lower (29.3%), to C _{1 R} including 59.6%. With the addition of 1% titanium dioxide powder, which is only poured into the melt, but which does not dissipate perfectly in the melt, the catalytic effect is evident (40.7 and 65.7%, respectively) but with respect to the much smaller surface area of titanium dioxide compared to pigmented raw material the effect is weaker.

Example 1

Thermal decomposition of the titanium dioxide pigmented polyethylene foil collection (cleaned milk bags) in a weak nitrogen stream in a glass flask at 400 to 450 ° C, gas purging and vapor-liquid condensate from the previous batch was trapped

78.2 wt. the remainder in the bank after the decomposition was 14.2 wt. losses by degassing

7.6 wt.

Ingredients: Fraction up to C ₈ , boiling point up to 5172.67 kPa 9.5%.

The fraction of C _lo to C _13, including, the boiling point of the

12572.67 kPa 50.2%.

The fraction _of C ₆ to C including, the boiling point of the

19072.67 kPa 18.5%.

Example 2

Thermal decomposition of waste, unpigmented colorless and colored polyethylene films (86.1 g) together with the remainder of the pigmented oxygen-titrated foil (37.6 g) under conditions as in Example 1 yielded 89.2 g of liquid condensate, i. j. 72.1%, the decomposition flask residue was 24.5 g, m.p. j. 19.8% degassing loss 8.1%.

Ingredients:

Fraction up to C ₉ 12,0%

Fraction Ci _{0 —} C ₁₃ 33,6%

The fraction of C ₁₄ -C _i8 retention 37.2% and the remainder 10.2%

93.0% losses and gases 7.0% wt.

By the procedure of Example 1 and the same apparatus and under the same conditions, 515 g of a waxy waste product from the production of high pressure polyethylene was pyrolyzed. 384 g (74.6%) of liquid condensate were obtained, which upon cooling turned into a light-yellow thixotropic crystalline slurry. The residue which did not evaporate in the pyrolysis flask was 50 g (9.7%) of a waxy mass. Gas and aerosol stick losses of 81 g [15.7%].

The condensate was subjected to vacuum distillation:

Fraction up to C ₉ Fraction up to C _ln —C ₁₃ Fraction up to C _T4 —G, »Fraction above C _u

8.85% wt.

20.44% wt. 30.34% wt. 36.82% wt.

% (non-distillated residue) 96.45 wt. losses (easy shares) 3,55%

Example 4

By the procedure of the previous examples, but with the addition of 1 wt. of rutile titanium dioxide powder, 463 g of waxy polyethylene was pyrolyzed as in Example 3. After the practical decomposition (the development of condensable vapors), 359.3 g of liquid condensate were obtained, i. j. 77.6%.

The following fractions were distilled:

Fraction up to C ₉ Fraction up to C _{] n} —C _n Fraction up to C ₁₄ —Ci * Fraction above C _{] R}

13.4 wt. 27.3 wt. 25.0 wt. 29.6 wt.

(undistilled residue)

95.3 wt. losses (1 light shares)

4.7%

Claims (1)

219 395). Without the use of titanium dioxide as a catalyst, and the olefin yield to C13 is significantly lower (29.3%), it is 59.6% in C1R. With the addition of 1% titanium dioxide powder, which is only poured into the melt, but which does not disperse in the molten carbonate, it is catalytically evident (40.7 and 65.7%, respectively), but with a much smaller surface of titanium dioxide. the effect is weaker compared to the pigmented raw material. EXAMPLE 1 Thermal decomposition of polyethylene oxide film, pigmented with TiO2 (milk bags), in a weak nitrogen stream in a glass flask, 400-450 [deg.] C., in a gas vapor wash with a liquid condensate layer in a pre-dried feed. % of the original was captured at 78.2 wt. the remainder in the flask was 14.2% by weight. % degassing losses of 7.6% by weight. Ingredients: Fraction to Cq incl., Temperature to 5172.67 kPa 9.5%. Fraction Clo to C13 including, boiling point up to 12572.67 kPa 50.2%. Cu to C16 fraction including, boiling point up to 19072.67 kPa 18.5%. Example 2 89.2% by thermal decomposition of waste, unpigmented colorless and color polyethylene films (86.1 g) together with the residue after titanium dioxide pigmented decomposition film (37.6 g) under the conditions of Example 1 g of liquid condensate, ie 72.1%, the remainder of the decomposition flask was 24.5 g, ie 19.8% degassing loss of 8.1%. Composition: C9 fraction 12.0% C10-C13 fraction 33.6% C14-C18 fraction 37.2% containment and 10.2% residue 93.0% loss and gases 7.0% w / w EXAMPLE 3 515 g of a waxy waste product from the production of a high pressure polyethylene were subjected to the same procedure as in Example 1 and in the same apparatus and under the same conditions. This resulted in 384 g (74.6%) of a liquid condensate which, upon cooling, was changed to a pale yellow thixotropic crystalline crystal. The residue that was not evaporated in the pyrolysis flask was 50 g (9.7%) of the bulk material. Losses in the form of gases and aerosols 81 g (15.7%). The condensate was subjected to vacuum distillation: Fraction to C9Fraction of Cll-Cl3 Fraction to CT4-GI Fraction over Cu 8.85 wt. 20.44% by weight 30.34% by weight. % (non-distilled residue) 96.45 wt. Losses (Light Particles) 3.55% Example 4 By the procedure as in the previous examples, but with the addition of 1 wt. of rutile titanium dioxide powder, 463 g of waxy polyethylene of Example 3 were pyrolyzed. After practical completion of the condensation development, 359.3 g of liquid condensate, i.e. 77.6%, were formed. The fractions obtained were distilled by distillation: Fraction to C9 Fraction to C11-Cn Fraction to C14-Ci * Fraction above C13 R 13.4 wt.% 27.3 wt. (non-distillated residue) 95.3 wt. Losses (Light Particles) 4.7% SUBJECT OF THE INVENTION A process for the preparation of linear alkenes and alkanes characterized in that they undergo thermal decomposition exclusively or alternatively alternatively, waste and scrap polyethylene, pigmented with oxygen titanium dioxide, at a temperature of 400 DEG-460 DEG C. under a pressure of atmospheric or near atmospheric, in a stream of inert gas, thereby cooling the gas stream and vapor to a temperature greater than or equal to 40 DEG C. of the product hydrocarbons and steam are passed through a layer of liquid product. SOUP 1214-84