CS262366B1 - Process for the catalytic hydrogenating rafination of the mixture of hydrocarbons - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to the hydrotreating of liquid hydrocarbon mixtures resulting from the heat treatment and pressure gasification processes of coal having an aromatic character and an increased content of nitrogen, sulfur, oxygen and unsaturated hydrocarbons mixed with petroleum fractions.

Liquid fractions resulting from the coal heat treatment process, such as mainly gasoline fractions obtained by distillation of gas and generator tars or pressure gasification products Coal and isolated during scrubbing and gas purification, for example by the Rectisol process, are potential raw materials for gasoline production or in general motor fuels and also aromatic hydrocarbons. Although the amount of these raw materials is small compared to the petroleum raw materials processed in refineries, their processing and use for the above purposes is desirable and economical.

The gasoline or higher boiling fractions prepared by the distillation of tar raw materials are initially stripped of most of the phenolic compounds, and the phenolized product has a higher content of nitrogen compounds such as pyridine, quinoline and their homologues in addition to the moderate sulfur and unsaturated compounds. Due to the phenolization process, a slightly higher content of sodium phenolate, which results in a higher ash content, remains in the tar raw material. An example of the composition of the phenolized product is given in the table.

On the other hand, gasoline produced by pressure gasification and falling off during gas scrubbing by the Rectišol process contains, in addition to aromatics, an increased amount of sulfur and unsaturated compounds and low nitrogen substances.

Phenolized naphtha

Rectisol petrol

Density / 20 0,849 0.793 Distillation range who. boiling point ° C 88 51 end of boiling point ° C . 233 165 Bromine number g Br / 100 g 22.6 56.2 Sulfur% wt. 0.54 1.72 Organic principles mg / l 2 820 2.1 Aniline point ° C 39.5 38.1 Aroma content% by weight 33.5 48 20 ⁿ D 1,481 0 1,473 5 Nitrogen ppm 53 Dieny% wt. 6 8.5

In order to use tar raw materials as motor fuel components or for the production of aromatic hydrocarbons, or as raw materials for the pyrolysis and olefin production, their refining is necessary and thus the content of sulfur, nitrogen, oxygen and unsaturated substances is reduced. Since the total amount of these raw materials is relatively small, it is most advantageous to process them in a mixture, for example with medium-boiling petroleum fractions. Such a method of refining is the subject of MS. The invention according to AO 177 692 and AO 194 136. Processing in admixture with pyrolysis gasoline or cracked gasoline is the subject of U.S. Pat. AO 148 538 and AO 149 535.

The beneficial effect of dilution with eg oil fractions is also the reduction of the concentration of nitrogenous substances, which is much higher for coal distillates themselves. Active nitrogenous substances such as pyridines, picolines, lutidines and others exhibit relatively strong chemisorption at the active centers and the surface of the catalyst, and their hydrogenation products are difficult to desorb. They can therefore be considered catalytic poisons from this point of view. In addition, the high content of aromatic hydrocarbons and their nature, the higher content of unsaturated hydrocarbons and dienes, including the composition of sulfur compounds and higher concentrations of oxygen species, have led to the fact that hydrotreating of liquid coal products has so far required much more difficult hydrogenation conditions than petroleum. fractions.

Cobalt-molybdenum on alumina as a noice or molybdenum on alumina and combinations of these catalysts have hitherto been recommended and used as catalysts. Catalysts are used in a sulphide form and a very good degree of refining of a mixture of tar and petroleum distillates is only achieved at a pressure of 15 to 30 MPa. At lower pressures, refining deteriorates mainly for nitrogen compounds and the product does not meet quality requirements. It is typical of the catalysts used and, as a result of their character, that they are removed at high hydrogen pressure to remove sulfur, nitrogen, oxygen and unsaturated compounds with relatively low degradation of aromatic hydrocarbons, thereby maintaining the desirable aromatic character of the raffinate and hydrogen consumption not too high . The disadvantage is the need to operate at high pressure, to use expensive high pressure equipment and high pressure hydrogen. Moreover, since the mixture is mixed with petroleum fractions, which can normally be refined by low pressure processes alone, the total cost of upgrading the tar raw materials is high.

It has now been found that liquid hydrocarbons from the heat treatment and pressure gasification of coal mixed with a petroleum fraction can be hydrotreated at lower pressure by the process of the invention on a catalyst comprising metal oxides VIb and VIII. % of the periodic system on an active support containing SiO ₂ and promoted by fluorine compounds, in particular 5 to 15 wt. NiO and 24 to 40% touch. WO6 on alumina activated by the addition of silica gel in an amount corresponding to 5 to 15 wt. SiO ₂ and promoted by the addition of aluminum fluoride in an amount corresponding to 0.5 to 5% by weight of fluorine in the ignited catalyst in the presence of hydrogen or hydrogen-containing gas at 280 to 420 ° C, characterized in that the mixture containing distillates from heat treatment and pressurized gasification of coal boiling in the range of 30 to 300 ° C, such as phenolized gasoline from generator and gas tars and / or rectisol gasoline and at least 40% of the petroleum fraction having a boiling point not exceeding 550 ° C, at a pressure of 2,5 up to 20 MPa is contacted with hydrogen or a hydrogen-containing gas in a ratio of 3 3 -1

100 to 2000 m _n / m mixture and at a space velocity of 0.5 to 4 h comes in contact with the catalyst promotovaným addition of aluminum fluoride in the form * of 0.5 to trihydrate. A hollow-cylindrical catalyst having an outer diameter of 4 to 10 mm and an inner diameter of 2 to 6 mm can be accommodated in the inlet catalytic layer. A wide petroleum fraction boiling up to a maximum of 400 ° C may include gasoline, kerosene, gas oil or only some of these fractions. A vacuum distillate having a boiling point of not more than 550 ° C in a ratio of not more than 2 parts of vacuum distillate to 1 part of petroleum and tar distillate may also be added to the feedstock mixture.

Nickel-tungsten catalysts generally have better refining activity for nitrogen and oxygen compounds than Co-Mo or Ni-Mo catalysts. The catalyst used according to the invention is characterized by an acidic carrier and its promotion by aluminum fluoride in hydrate form results in a higher selective effect in hydrotreating.

Since both the tar distillates and the gasification gasoline of coal have a high content of unsaturated hydrocarbons and are susceptible to the formation of resins and deposits, it is preferable to process them as far as possible fresh and distilled and to store them so that they do not come into contact with oxygen , i.e., in an atmosphere of nitrogen or a mixture of hydrogen and hydrocarbon gases or another gas or gas mixture not containing free oxygen.

The tar feedstocks also contain diene hydrocarbons, and upon heating to reaction temperatures they polymerize and form deposits that settle in the apparatus or catalyst, especially when most of the lighter fractions evaporate. The addition of medium-boiling fractions, which remain partially liquid under the reducing conditions, allows the dissolution and leaching of these polymerization products, and hence, further equipment and catalyst cycles. Similarly, the added vacuum distillates having a boiling point of not more than 550 ° C are added at a rate of not more than 2 parts vacuum distillate to 1 part petroleum / tar distillate and remain largely liquid in reaction conditions. A certain disadvantage of vacuum distillates is the presence of asphaltenes. On the other hand, higher levels of asphaltenes can cause their dropping and formation of deposits due to the addition of tar petrol.

One of the components to be processed is also phenolized gasoline containing residues of phenolates manifested as increased ash content. When decomposed under the reaction conditions, the sulphides formed block the top layer of the catalyst in the reactor and gradually increase the hydraulic resistance of the layer.

Once the permissible value has been reached, the equipment must be shut down and usually the catalyst will be poured or replaced in or at the top of the reactor. In addition to the ash collection device, it is preferable to use a hollow-cylindrical catalyst having an outer diameter of 4 to 10 mm and an inner diameter of 2 to 6 mm at the top of the reactor.

Example 1

Petroleum atmospheric gas oil with a boiling end of 370 ° C was mixed with a mixture of phenolized and rectizole gasoline in a ratio of 60:40 (feedstock A) and 90:10 (feedstock B). The ratio of phenol to rectizole gasoline was 4: 1. The prepared feedstocks A and B were hydrotreated in a flow reactor and a catalyst volume of 100 cm under a hydrogen pressure of 3 to 5.

MPa in the temperature range of 340 to 360 ° C, volumetric velocities of 1 to 2 h ^-1 at a gas to su3 ratio of 1 000: 1 m ^ / m on the following catalysts:

I cobalt-molybdenum on an alumina support Al ₂ O ₃ containing 12.5 4 wt. % molybdenum oxide MoO ₃ and 4 wt. cobalt oxide CoO

II nickel-tungsten on an alumina support A1 ₂ O ₃ containing 7.5 4 wt. NiO and 28.2 4 wt. of tungsten oxide WO ₃

III nickel-tungsten on an alumosilicate carrier containing 10.2 4 wt. nickel oxide NIO,

30.1 4 wt. tungsten oxide WO ₃ and 10.5 4 wt. SiO ₂ and the rest was alumina

The nickel-tungsten IV according to the invention on an alumina support activated by the addition of silica gel and alumina fluoride of 11.5 4 wt.%, Nickel oxide NiO, 32.5 4 wt. tungsten oxide W ₃ , 10.1 4 wt. SiO ₂ and 1.8 wt. The residue was aluminum oxide Al ₂ 0 _3>

The results of the tests with feedstock A are shown in Table 1 and with feedstock B in Table 2. Nickel-tungsten catalysts are better in terms of nitrogen base refining than cobalt-molybdenum catalyst. The process of the invention with Catalyst IV gave better results. At lower pressures (5 and 3 MPa), the other nickel-tungsten catalysts exhibited a significantly lower desulfurization activity. Under the conditions of the invention, Catalyst IV gives the best results.

Table 1 - Activity of catalysts with raw material A

Attempts 1 2 3 4 5 . 6 7 8 Pressure MPa 10 5 Volumetric velocity ^h_1 1, 5 1, 0 -Catalyst AND II III IV AND II III IV Temperature ° C 360 350 350 350 360 360 360 350 Extraction Raw material Organic principles mg / l »30 65 35 30 1 110 40 30 10 Sulfur 4 wt. 0.61 0, 02 0 , 01 0.016 0.005 O, 06 0, , 05 0, 06 0,04 Aromatic hydrocarbons 4 wt. 36.5 26 21 19 20 28 25 23 24

Table 2 - Activity of catalysts with raw material B

Attempts 11 12 13 14 Pressure MPa 3 Volumetric velocity h ^-1 2 Catalyst AND II III IV Temperatures ° C 350 Extraction Raw material B Organic principles 91 55 45 35 Sulfur% wt. 1.16 0.104 0,115 0.120 0,038 Aromatic hydrocarbons % wt. 32.5 24.8 24.2 23.5 23.3

OBJECT OF THE INVENTION

Claims (3)

CLAIMS 1. Catalytic hydrotreating process for hydrocarbon mixtures derived from coal and oil processing on a metal oxide catalyst VI.b. and VIII. % of a periodic group on an active support containing SiO 2 and promoted by fluorine compounds, in particular 5 to 15 wt. % NiO and 24 to 40 wt. WO6 on alumina activated by the addition of silica gel in an amount corresponding to 5 to 15 wt. SiO ₂ and promoted by the addition of aluminum fluoride in an amount corresponding to 0.5 to 5 wt. fluorine in the ignited catalyst in the presence of hydrogen or hydrogen-containing gas at a temperature of 280 to 420 ° C, characterized in that the mixture containing distillates from the heat treatment and pressure gasification of coal boiling in the range 30 to 300 ° C such as % tar and / or rectisulphine gasoline and at least 40 wt. petroleum fractions having a boiling point up to 550 ° C and brought to a hydrogen or hydrogen-containing gas at a ratio of 100 to 20 MPa 2. The process of claim 1, wherein a vacuum distillate having a boiling point of not more than 550 ° C is added to the mixture of feedstocks entering the catalyst in a ratio of not more than 2 parts vacuum distillate to 1 part petroleum and tar distillate. 2,000 m ³ / m ^{3 of the} mixture and at a volumetric rate of 0.5 to 4 h ^-1 are contacted with a catalyst promoted by the addition of aluminum fluoride in the form of 0.5 to trihydrate. 3. A process according to claim 1, characterized in that a catalyst in the form of hollow cylinders having an outer diameter of 4 to 10 mm and an inner diameter of 2 to 6 mm is contained in the inlet catalytic layer.