CZ302708B6 - Process for preparing mixture of ethylene and propylene from renewable resources - Google Patents

Abstract

The present invention makes it possible to prepare a mixture of ethylene and propylene by catalytic transformation of renewable raw materials onto a mixture of n-alkanes that are further subjected to pyrolysis in the presence of steam to a mixture containing at least 47 percent by weight of ethylene and at least 16 percent by weight of propylene. The renewable resources are represented by vegetable oils and vegetable fats even used oils and fats. The preparation process of the present invention is characterized in that at least one renewable raw material is transformed by catalysis in the presence of hydrogen to a mixture of gaseous and liquid hydrocarbons, water, CO and COi2. Subsequently, pyrolysis thereof takes place in the presence of steam to a mixture containing at least 47 percent by weight of ethylene and at least 16 percent by weight of propylene. Preferred is the preparation process if 1 to 99 percent by weight of crude oil materials, characterized by hydrocarbon composition and boiling point within the range of 100 to 580 degC are added to the gaseous and liquid hydrocarbons, and further a process in which hydrogen formed during pyrolysis is used for catalytic transformation of the renewable raw materials.

Description

Process for producing a mixture of ethylene and propylene from renewable sources

Technical field

The invention relates to a process for the production of a mixture of ethylene and propylene from renewable sources, in particular biomass.

BACKGROUND OF THE INVENTION

Currently, there is growing pressure on the use of renewable energy sources. While the production of motor fuels from renewable raw materials is carried out in practice and is widely described in both scientific and patent literature, the production of olefins, especially ethylene and propylene, has not yet been described from these sources.

Biomass is an important source of alternative raw materials for the production of fuels and chemicals. By converting it, it is possible to obtain either suitable chemical intermediates or at least suitable chemical raw materials. Plant oils and animal fats are important raw materials of plant and animal origin, which are to some extent similar to petroleum fractions from a chemical point of view. They are essentially mixtures of triglycerides, i.e. fatty acid triglycerides, which are characterized by long chains with a hydrocarbon structure with a high atomic H / C ratio.

Until now, ethylene has been produced exclusively by pyrolysis of petroleum hydrocarbon reactions in the presence of water vapor. The main raw materials used were liquefied gases, primary gasoline, atmospheric gas oil and vacuum residue from the hydrocracking of the vacuum distillate, the so-called hydrocrackate. The hydrocarbon fractions with a high atomic H / C ratio are considered to be the optimum feedstock for the production of ethylene. Liquefied gases and naphtha best meet this requirement. The use of atmospheric gas oil or hydrocracking vacuum residue is forced by the lack of more advantageous lighter raw materials.

The most preferred pyrolysis feedstock is n-alkanes, since they best meet the above requirement for a high atomic H / C ratio and provide a product with a relatively higher olefin content and a lower aromatic hydrocarbon content. Isoalkanes also behave similarly to n-alkanes, which in addition provide relatively high yields of propylene. Less preferred feedstocks are olefins which are prone to the formation of condensation products and high molecular weight pyrolysis products.

The least suitable raw materials are aromatic hydrocarbons whose aromatic rings are highly stabilized and therefore do not cleave into light olefins during pyrolysis. Aromatic hydrocarbons primarily provide condensed products and / or coke. An exception is the long-chain aliphatic aromatic hydrocarbons, where the olefin source is precisely this chain. The second major product of industrial pyrolysis in pyrolysis units with an annual production capacity of up to several hundred thousand tons of ethylene is propylene. The average yield of ethylene without recycling is 25 to 27% by weight, the average yield of propylene is approximately 15% by weight.

The above mentioned raw materials of biological origin can also be used for the production of motor fuels. US 2004/0230085 A1 describes a process for producing hydrocarbons from raw materials of biological origin. The hydrocarbons produced are identified as suitable components for the production of diesel. The process consists of two basic steps: first, hydrodeoxygenation is performed to remove the oxygen present in the raw materials of biological origin, and hydrocarbons are obtained which are isomerized in the second step on the isomerization catalyst. The product is a mixture of branched hydrocarbons - isoalkanes. The disadvantage of this process is that n-alkanes are isomerized to isoalkanes and that the reaction products need to be separated.

US 2004/0055209 A1 and WO 2004/022674 A1 define fuel compositions for compression ignition engines. The fuel blending components are obtained from raw materials of biological origin, in particular vegetable oils, animal and fish fats and mixtures thereof. The proportion of these components in the resulting diesel fuel is in the range of 0.1 to 80% by weight.

The hydrocarbons can be obtained according to GB 1524781 A1 by thermal cleavage of vegetable oils. This cleavage takes place at temperatures of 300 to 700 ° C in the presence of a catalyst which is silica-alumina mixed with a transition metal oxide. The process is carried out at atmospheric pressure and involves separation and purification of the products. Its disadvantage is the necessity of separation and cleaning of products and undefined handling of by-products.

Catalytic cleavage of fatty acid triglyceride using a catalyst which is zeolite Y in admixture with AUCfi, CoMo on AfiCT or NiMo on AfCfi is described in DE 3340711 A1. The product is paraffinic hydrocarbons. The reaction temperatures and pressures are in the range of 300 to 600 ° C, respectively. 1 to 20 MPa. The disadvantage of this process is the relatively low yield of liquid nalkanes (<60%) and the high consumption of hydrogen, which comes exclusively from an external source.

EP 14891 57 A1 describes a process for converting oil and fat based raw materials and waste materials into high hydrocarbon mixtures. These products are obtained by exposure to a fixed bed of activated carbon at high temperatures ranging from 150 to 850 ° C. The unsaturated products may be further hydrogenated. The hydrocarbon-containing mixture obtained by the process described in the patent is usable as a fuel or fuel or for the production of chemicals. The disadvantage of this process is that it requires an external source of hydrogen and that the product is a complex mixture of products which must be further purified and separated from which ethylene and propylene cannot be obtained in high yield.

Pyrolysis (cleavage of hydrocarbons in the presence of water vapor) of hydrotreated and hydrotreated petroleum hydrocarbon fractions that do not contain simes and nitrogen compounds is described in U.S. Pat. No. 6,210,561. Hydrogenation by refining is reduced to S contents below 100 ppm (parts per million) and N below 15 ppm. The aromatic hydrocarbons in the feedstock are hydrogenated on a catalyst containing Pt or Pd. Saturated and refined products are subsequently pyrolytically cleaved in the presence of water vapor. The yield of ethylene, propylene and butadiene from the refined feedstock will increase by about 2.5 wt. compared to the use of the original, unrefined raw material. A disadvantage of this process is that the feedstock used to produce olefins comes from a fossil non-renewable carbon source and that ethylene yields are low, typically <30%.

Pyrolysis) kan to produce ethylene disclosed in U.S. Patent 6,407,301th raw material hydrocarbons are C ₅ to C _it, one of which is the adsorption of the isolated fraction with a high content of n-alkanes. Adsorption separation is reported as a preferred method for isolating n-alkanes from mixtures with other hydrocarbons. In this case too, the disadvantage is that ethylene is obtained by cleaving the raw material of fossil origin and the need to separate n-alkanes from complex mixtures.

Said drawbacks are at least partially overcome by the process for producing the ethylene / propylene mixture from the renewable sources of the invention.

SUMMARY OF THE INVENTION

A process for producing a mixture of ethylene and propylene from renewable sources, characterized in that at least one renewable raw material selected from the group consisting of vegetable oils and vegetable fats, even spent, is treated by a catalyst comprising at least one substance selected from Ni, Mo, Co and W is catalytically converted in the presence of hydrogen to a mixture of gaseous and liquid hydrocarbons, water, CO and CO ₂ and then pyrolyzed in the presence of water vapor to a mixture containing at least 47 wt. % of ethylene and at least 16 wt. propylene.

A preferred process for the production of a mixture of ethylene and propylene from renewable sources, characterized in that from 1 to 99% by weight of a mixture of gaseous and liquid hydrocarbons is added. petroleum feedstocks boiling in the range of 100 to 580 ° C and having a hydrocarbon composition

Component Concentration (% w / w) n-Alkanes + iso-Alkanes 50 to 75 Olefins 0 to 5 Naphthenes 15 to 35 Aromatics 5 to 20

Note: BTX is a fraction consisting of C ₆ to C 8 aromatics.

Another preferred method for producing a mixture of ethylene and propylene from renewable sources, characterized in that the hydrogen produced by pyrolysis is used for catalytic conversion.

The invention solves the production of a mixture of ethylene and propylene from biomass. The production of the present invention comprises catalytic conversion (ie, transformation in the presence of a catalyst comprising at least one selected from the group consisting of Ni, Mo, Co and W) of renewable raw materials containing tri acyl glycerides, most preferably vegetable oils and fats including vegetable t5 and animal waste (preferably animal fats, rendered fats and spent vegetable oils and fats) in the presence of hydrogen to a hydrocarbon product with a very high content of aliphatic hydrocarbons - n-alkanes (> 95% by weight) and propane.

The starting standard refined feedstock is fed from the reservoir together with the hydrogen to a heated fixed bed tubular reactor. If the raw material is vegetable oil, there is no need to heat the tank. If the raw material is animal fat, the tank and the feed path should be heated to a temperature of at least 80 ° C. The feedstock can also be injected only after it has been mixed with a suitable petroleum fraction. The reactor is heated to a temperature in the range of 150 to 450 ° C and the reaction pressure is maintained in the range of 1 to 20 MPa. The catalyst used is one of the transition metals, preferably Ni, Mo, Co and W, and their combinations. These active ingredients are deposited on a carrier to achieve good dispersion. Alumina (AbO2) or aluminosilicates, either amorphous or zeolites or mesoporous molecular sieves, are used as the carrier. The catalyst load is characterized by a weight hourly space velocity (WHSV) indicating the amount of raw material in kg processed per kg of catalyst per hour. The WHSV is usually in the range of 0.2 to 5 h ^-1 .

After cooling, the products are readily separated into a liquid phase containing n-alkanes and water and a gas phase, the main components of which are propane, CO, CO ₂ , CH ₄ and hydrogen. The liquid product is pyrolyzed in the presence of water vapor to produce a high yield of a mixture of ethylene and propylene (ethylene > 40 wt%, propylene > 15 wt%). Either the entire liquid fraction (n-alkanes + water) can be pyrolyzed without the need to dry the hydrocarbon fraction, or only the hydrocarbon fraction (n-alkanes). Each of these fractions can also be pyrolyzed in admixture with petroleum hydrocarbon fractions. The gaseous product is subjected to fractional distillation together with conventional pyrolysis products. In this separation, hydrogen is obtained for hydrogenation, which is an advantage of the process according to the invention, and propane, which is used as feed to the pyrolysis reactor. This means that propane, which is produced as a by-product of the hydrotreating of raw materials from renewable sources of biological origin, is also recovered to ethylene and propylene. The separated hydrogen can advantageously be used in the catalytic hydrogenation treatment of the above-mentioned renewable raw materials into hydrocarbons.

The treatment of mixtures of hydrocarbon fractions, recovered refinery feedstocks, together with petroleum fractions, in particular atmospheric gas oil and hydrocrackate, not only increases the yield of the ethylene / propylene mixture, but also facilitates the processing of these fractions.

The reason is to reduce the aromatics content of the oil fractions by mixing them

with the n-alkanes of the volcanic hydrocarbon fraction from renewable sources, which is another advantage of the process according to the invention. There are two ways to reduce aromatics. 1. increasing the yield of ethylene and propylene mixtures while maintaining energy performance; or 2. reducing the energy performance of the process while maintaining the yield of the ethylene and propylene mixture, eg by reducing the ratio of water vapor to hydrocarbon feedstock.

DETAILED DESCRIPTION OF THE INVENTION 10

Example 1

Treatment of the renewable raw material - rapeseed oil - at a temperature of 320 ° C and a pressure of 7 MPa in the presence of a NiMo / NH 4 catalyst and hydrogen produced a mixture containing CO. WHAT _? water, methane, propane and a mixture of n-alkanes predominantly having from 15 to 18 carbon atoms in the molecule. No other waste products are produced in this process. The approximate composition of the mixture is summarized in Table 1.

1 - Composition of the mixture resulting from the catalytic processing of rapeseed oil (% by weight)

Composition of the mixture Content n-alkanes 85 propane 5 WHAT. CO2, methane 7 water 6

By reducing the pressure in the outlet tank of the mixture from 7 MPa to atmospheric pressure, 25 gaseous and liquid phase separations were achieved. Pyrolysis of a mixture containing liquid fractions, especially n-alkanes

C | _? -Cis and water were obtained in high yield by olefins, especially ethylene and propylene. The yields of pyrolysis products of this mixture are shown in Table 2. Pyrolysis was performed at 810 ° C. In particular, the yield of ethylene significantly exceeds the yields obtained by the cleavage of conventional petroleum feedstocks. By way of comparison, the yield of ethylene in the pyrolysis of the most typical of the liquid feedstock, the primary gasoline, is in the range of 25 to 27% by weight.

2 - Yields of pyrolysis products of the mixture obtained by catalytic treatment of rapeseed oil, resp. naphtha (% by weight)

Product Mixture Primary gasoline Ethylene 48.3 26.1 Propylene 17.4 15.0 Butadiene 5.6 6.8 BTX 1.3 10.6 Other 21.9 35.7 Oils 5.5 5.8

Note: BTX is a fraction consisting of C ₆ to C ₆ aromatics.

As can be seen in Table 2, the yields of ethylene and propylene obtained by pyrolysis of the blend are significantly higher than those of the normal gasoline pyrolysis. At the same time, the formation of undesirable waste products, especially pyrolysis oils, was reduced. Hydrogen, which during the pyrolysis of hydrocarbons

The amount of about 1% by weight is used as a raw material in the catalytic treatment of rapeseed oil.

Example 2

Mixture produced by processing a renewable raw material, containing mainly C1-alkanes C _{5 to 8,} and water, whose preparation is described in Example 1 was poured into děliěky where it separated into two layers. The lower layer contained water and the upper, hydrocarbon layer contained n-alkanes and C 10 ₅ -Cig. After separation of the water, the hydrocarbon layer was pyrolyzed at 810 ° C.

The yields of the pyrolysis products were identical to those shown in Table 2.

Example 3

The catalytic treatment of the rapeseed oil described in Example 1 also yielded propane in a yield of 5% by weight. (see Table 1). This by-product was pyrolyzed at 810 ° C. The yields of the products obtained are shown in Table 3. It is apparent from the results that propane also provides high yields of olefins, in particular ethylene and propylene, during pyrolysis.

Table 3 - Yields of pyrolysis products of propane obtained by catalytic treatment of rapeseed oil (% by weight)

Product Yield Ethylene 43.7 Propylene 21.2 Butadiene 4.1 BTX 4.8 Other 26.1 Oils 0.1

Example 4

The hydrocarbon fraction containing n-alkanes prepared as described in Example 1 was mixed with one of the standard pyrolysis feedstocks - a vacuum residue from the vacuum distillate hydrocracking process (hydrocrackate, HCVD) in a 1: 9 by volume ratio. shows the composition of the vacuum residue used from the vacuum distillate hydrocracking process.

Table 4 - Composition of the vacuum residue from the vacuum distillate hydrocracking process

Component Concentration (% w / w) n-Alkanes + iso-Alkanes 71.7 Naphthenes 19.3 Aromatics 9.0

The mixture thus prepared was pyrolyzed at 810 ° C. The yields of the individual products obtained are shown in the following table together with the yields of the products obtained by pyrolysis of HCVD alone carried out under the same conditions. This table shows that by adding the hydrocarbon fraction produced according to Example 1 to the vacuum residue from the hydrocracking of the vacuum distillate, the yield of ethylene and propylene is greatly increased. The addition of the hydrocarbon fraction produced according to Example 1 to IICVD also has the advantage of reducing the aroma content of the resulting mixture and thereby reducing the formation of coke during pyrolysis.

l abulka - Yields of hydrocrackate pyrolysis products (IICVD) and IICVD mixtures with a liquid hydrocarbon fraction (9: 1 vol.) obtained by catalytic treatment of rapeseed oil (% by mass.)

Product HCVD HCVD with n-alkanes Ethylene 28.2 35.2 Propylene 14.5 15.8 Butadiene 7.3 6.6 BTX 8.3 6.4 Other 28.1 26.1 Oils 13.6 9.9

INDUSTRIAL APPLICABILITY The invention is industrially applicable in the production of alkantic fractions from renewable sources and their subsequent pyrolysis to olefins, in particular ethylene and propylene.

Claims (3)

PATENT CLAIMS CLAIMS 1. A process for the production of a mixture of ethylene and propylene from renewable sources, characterized in that at least one renewable raw material is selected from the group consisting of vegetable oils and vegetable fats, even spent, by the action of a catalyst comprising at least one substance selected from Ni. Mo, Co and W are catalytically converted in the presence of hydrogen to a mixture of gaseous and liquid hydrocarbons, water, CO and CH 2 and then pyrolyzed in the presence of water vapor to a mixture containing at least 47 wt. % of ethylene and at least 16 wt. propylene. 2. A process according to claim 1, wherein from 1 to 99% by weight of a mixture of gaseous and liquid hydrocarbons is added. petroleum feedstocks boiling in the range of 100 to 580 ° C and having a hydrocarbon composition Component Concentration (% w / w) n-Alkanes + iso-Alkanes 50 to 75 Olefins 0 to 5 Naphthenes 15 to 35 Aromatics 5 to 20 Process according to claim 1 or 2, characterized in that the hydrogen produced by pyrolysis is used for catalytic conversion.