RU2769187C1 - Catalyst for processing stable gas condensate into aromatic hydrocarbons, method for production thereof and method for production of aromatic hydrocarbons using same - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to petrochemical industry and specifically to a method of producing a catalyst for processing stable gas condensate into aromatic hydrocarbons, as well as a catalyst obtained using said method, and a method of producing aromatic hydrocarbons. Proposed method of producing catalyst consists in preparing mixture, consisting of tetraethylorthosilicate, water, tetrapropylammonium hydroxide and aluminium isopropoxide, taken in molar ratio tetraethylorthosilicate:water:tetrapropylammonium hydroxide:aluminium isopropoxide, equal to 1:34–36:0.1–0.12:0.04–0.06, obtained mixture is crystallized by hydrothermal-microwave treatment at microwave radiation power of 60 W, radiation frequency of 2.45 GHz, pressure of 3.7 MPa, temperature of 180–200 °C, for 1.4–1.6 hours, followed by temperature reduction to 150–170 °C and repeated hydrothermal-microwave treatment under the above conditions, the formed precipitate is subjected to filtration, washing with distilled water, drying for 1.5–2 hours at temperature of 180–200 °C, then the formed powder is calcined at temperature of 540–560 °C to obtain a zeolite of MFI structure in hydrogen form, after which the said zeolite is impregnated with an aqueous solution simultaneously containing zinc and chromium nitrates, the impregnated zeolite is dried for 1.5–2 hours at temperature of 70–80 °C and calcination at temperature of 540–560 °C for 3–4 hours to decompose nitrates with formation of zinc and chromium oxides. Obtained catalyst contains high-silica zeolite of structure MFI in hydrogen form, zinc oxide, chromium oxide, with the following ratio of components, wt. %: zinc oxide 1.0–1.5, chromium oxide 1.2–1.8, said zeolite is the rest, up to 100.

EFFECT: disclosed group of inventions increases efficiency of the catalyst for processing stable gas condensate into aromatic hydrocarbons, a method for production thereof and a method of producing aromatic hydrocarbons using said catalyst.

3 cl, 4 tbl, 1 ex

Description

SUBSTANCE: group of inventions relates to the petrochemical industry, namely, to a catalyst for producing aromatic hydrocarbons in the processing of stable gas condensate, a method for producing said catalyst and a method for producing aromatic hydrocarbons using it.

The prior art catalysts for the processing of stable gas condensate into aromatic hydrocarbons, methods for producing these catalysts, as well as methods for producing aromatic hydrocarbons using the latter , 2007, RU 2672665, 2018). The disadvantages of these technical solutions include such as the multicomponent composition of catalysts, the use of rare and harmful elements in the latter, reduced selectivity of catalysts in relation to the formation of aromatic hydrocarbons, the duration of the catalyst synthesis procedure, and the multi-stage methods for obtaining catalysts.

Closer analogues of the proposed group of inventions are a catalyst for processing stable gas condensate into aromatic hydrocarbons, a method for producing it and a method for producing aromatic hydrocarbons using it, described in the source of information - A.A. Karavaev. Obtaining intermediate products of petrochemistry from alternative raw materials on zeolite-containing catalysts. Thesis. Moscow, 2018, p. 30-32, 94-95, 97.

Thus, a method for obtaining a catalyst for processing stable gas condensate into aromatic hydrocarbons is described, which is as follows. Spend hydrothermal-microwave synthesis of zeolite MFI in hydrogen form. To do this, in a flat-bottomed flask with a magnetic stirrer, the calculated amounts of reagents - tetraethylorthosilicate, tetra-n-propylammonium hydroxide and aluminum isopropoxide are dissolved in distilled water. Stirring is carried out until complete homogenization of the mixture. The resulting mixture is placed in a 100 ml Teflon autoclave and loaded into a Speed Wave Berghof - 4 microwave unit (maximum microwave power is 1450 W, radiation frequency is 2.45 GHz). The synthesis is carried out at 190-215°C for 180 minutes. The resulting suspension is centrifuged, washed with distilled water and dried at 190°C for 1.5 hours. To remove the template (an organic structure-forming substance), the powder is calcined at 550°C for 5 hours to obtain MFI zeolite in hydrogen form.

Then the MFI zeolite is promoted by impregnation with aqueous solutions of zinc (II) nitrate hexahydrate (Zn(NO ₃ ) ₂ ⋅6H ₂ O) and chromium (III) nitrate nanohydrate Cr(NO ₃ ) ₃ ⋅9H ₂ O. For this, the calculated amount of the indicated salts are dissolved in distilled water, after which they are slowly poured into a porcelain cup with zeolite with constant stirring with a glass rod. The impregnated zeolite is left to dry in air for a day, after which it is dried at 100°C and 300°C for an hour. Then calcination is carried out at 500°C for 4-5 hours to decompose nitrates with the formation of zinc and chromium oxides, respectively. The mass fraction of zinc and chromium in the catalyst is 1.0% of the mass. each metal, there is also oxygen associated with zinc and chromium in the catalyst, since they are contained in the catalyst in the form of oxides. The resulting catalyst contains high-silica zeolite MFI synthesized in hydrogen form, zinc oxide, chromium oxide, in the following ratio, wt %: zinc oxide 1.21; chromium oxide 1.5; the specified zeolite - up to 100.

The disadvantage of this method lies in its duration and obtaining the target catalyst with reduced stability.

The disadvantage of the catalyst is its reduced stability. Thus, the specified catalyst after 4 hours of operation reduces the selectivity and activity and requires regeneration by heating in a stream of air to 700°C.

The described method for obtaining aromatic hydrocarbons from a stable gas condensate is as follows.

The feedstock is contacted with the catalyst obtained as described above and containing high silica zeolite MFI in hydrogen form, zinc oxide, chromium oxide, in the following ratio, wt %: zinc oxide 1.21; chromium oxide 1.5; the specified zeolite - the rest, up to 100% at a temperature of 360-550°C, atmospheric pressure, space velocity of supply of a stable gas condensate of 0.68-1.37 h ^-1 .

The disadvantage of this method lies in the fact that the use of the latter catalyst with reduced stability leads to a decrease in the regeneration period of the catalyst.

A common drawback of the known technical solutions is the lack of stability of the described catalyst obtained in the manner described above and used in the production of aromatic hydrocarbons. Thus, the above technical solutions are not effective enough.

The technical problem to be solved by this group of inventions is to increase the efficiency of the catalyst for processing stable gas condensate into aromatic hydrocarbons, the method for its production and the method for producing aromatic hydrocarbons using it.

This technical problem is solved by creating a method for producing a catalyst for processing stable gas condensate into aromatic hydrocarbons, which consists in preparing a mixture consisting of tetraethylorthosilicate, water, tetrapropylammonium hydroxide and aluminum isopropoxide, taken in a molar ratio of tetraethylorthosilicate: water: tetrapropylammonium hydroxide: aluminum isopropoxide , equal to 1:34-36:0.1-0.12:0.04-0.06, the resulting mixture is crystallized by hydrothermal microwave treatment at a microwave power of 60 W, a radiation frequency of 2.45 GHz, a pressure of 3, 7 MPa, temperature 180-200°C, for 1.4-1.6 hours, followed by lowering the temperature to 150-170°C and repeated hydrothermal-microwave treatment under the above conditions, the resulting precipitate is filtered, washed with distilled water, drying for 1.5-2 hours at a temperature of 180-200°C, then the resulting powder is calcined at a temperature of 540-560°C to obtain zeol ite of the MFI structure in hydrogen form, after which the specified zeolite is impregnated with an aqueous solution simultaneously containing zinc and chromium nitrates, the impregnated zeolite is dried for 1.5-2 hours at a temperature of 70-80°C and calcined at a temperature of 540-560°C within 3-4 hours for the decomposition of nitrates with the formation of oxides of zinc and chromium, with the production of a catalyst containing high-silica zeolite of the MFI structure in hydrogen form, zinc oxide, chromium oxide in the following ratio of components, % wt.:

zinc oxide 1.0-1.5 chromium oxide 1.2-1.8 said zeolite the rest, up to 100

This technical problem is also solved by creating a catalyst for processing stable gas condensate into aromatic hydrocarbons containing high-silica zeolite of the MFI structure in the hydrogen form, zinc oxide, chromium oxide, in the following ratio of components, % wt.:

zinc oxide 1.0-1.5 chromium oxide 1.2-1.8 said zeolite the rest, up to 100,

obtained in the manner described above.

This technical problem is also solved by creating a method for obtaining aromatic hydrocarbons from a stable gas condensate, including contacting a stable gas condensate at a temperature of 360-600°C, atmospheric pressure, a volumetric feed rate of a stable gas condensate of 0.7-1.4 h ^-1 with the above described a catalyst containing a high-silica zeolite of the MFI structure in the hydrogen form, zinc oxide, chromium oxide, in the following ratio of components, % wt.:

zinc oxide 1.0-1.5 chromium oxide 1.2-1.8 said zeolite the rest, up to 100,

obtained in the manner described above.

The obtained technical result consists in providing an increase in the stability of the catalyst by optimizing the crystallization conditions for the process of obtaining the zeolite used in the specified catalyst and optimizing the conditions for the introduction of promoters. Thus, the described catalyst, obtained by the method described above and used in the method for producing aromatic hydrocarbons, is able to work for at least 7-8 cycles (14-16 hours) before regeneration.

The essence of the described group of inventions is as follows.

The catalyst for processing stable gas condensate into aromatic hydrocarbons is prepared as follows.

Get high silica zeolite MFI in hydrogen form. To do this, prepare a mixture consisting of tetraethyl orthosilicate, water, tetrapropylammonium hydroxide and aluminum isopropoxide, taken in a molar ratio of tetraethylorthosilicate: water: tetrapropylammonium hydroxide: aluminum isopropoxide, equal to 1:34-36:0.1-0.12:0.04- 0.06.

Upon receipt of the catalyst, the following reagents are used: tetraethylorthosilicate OSCH CAS 78-10-4; tetra-n-propylammonium hydroxide OSCh CAS: 4499-86-9; aluminum isopropoxide chemically pure C AS: 555-31-7.

The resulting mixture is stirred with a heated magnetic stirrer at a speed of 700 rpm until complete homogenization. The resulting gel is subjected to crystallization. To do this, the specified gel is poured into 100 ml Teflon autoclaves with temperature and pressure sensors, which are placed in a microwave unit with built-in non-contact temperature and pressure sensors. The unit operates at a frequency of 2450 MHz and has a maximum power of 2000 watts. The treatment is carried out at a microwave power of 60 W, a radiation frequency of 2.45 GHz, and a pressure of 3.7 MPa. The stage of crystallization is carried out at a given operating temperature in an autoclave 180-200°C. Heating to the operating temperature occurs within 0.4-0.6 hours. The crystallization time is 1.4-1.6 hours. After that, the temperature in the autoclave is reduced to 150-170°C and the hydrothermal-microwave treatment is repeated under the above conditions - at a microwave radiation power of 60 W, a radiation frequency of 2.45 GHz, a pressure of 3.7 MPa, at an operating temperature in an autoclave of 180-200 ° C, a crystallization time of 1.4-1.6 hours. Heating to the operating temperature after lowering the temperature occurs within 0.17-0.33 hours. After cooling the autoclaves, the precipitate formed is filtered off and washed with distilled water, then dried at 180-200 ° C for 1.4-1.5 hours. The resulting powder is calcined at 540-560 ° C until a white color of the powder is reached, which indicates the complete decomposition of the organic template, with the formation of a zeolite of the MFI structure in the hydrogen form.

Then the resulting zeolite is promoted and the target catalyst is molded. Zeolite promotion is carried out by the method of complete moisture absorption of the calculated amount of an aqueous solution of chromium and zinc nitrates with dried zeolite powder.

The promotion process is carried out as follows. The specified zeolite in a porcelain Cup with stirring impregnated with an aqueous solution, simultaneously containing zinc and chromium nitrates. The impregnated zeolite is dried in a muffle furnace for 1.5-2 hours at 70-80°C and calcined in a muffle furnace to decompose nitrates to form zinc and chromium oxides, respectively. The calcination is carried out by raising the temperature within 0.9-1.1 h to 540-560°C and maintaining at this temperature for 3-4 hours. After calcination, the promoted catalyst is tableted.

As a result, a catalyst for the processing of stable gas condensate is obtained, containing high-silica zeolite MFI in hydrogen form, zinc oxide, chromium oxide, in the following ratio of components, % wt.:

zinc oxide 1.0-1.5 chromium oxide 1.2-1.8 said zeolite the rest, up to 100

Then, to obtain aromatic hydrocarbons, a stable gas condensate is contacted at a temperature of 360-550°C, atmospheric pressure, a space velocity of a stable gas condensate of 0.7-1.4 h ^-1 with the catalyst obtained as described above - a catalyst containing high-silica zeolite MFI in hydrogen form, zinc oxide, chromium oxide, in the following ratio of components:

zinc oxide 1.0-1.5 chromium oxide 1.2-1.8 said zeolite the rest, up to 100

The example below illustrates the described group of inventions, but does not limit its application.

Example.

As a feedstock, stable gas condensate of the Kovytkinskoye gas condensate field is used, which has the characteristics shown in table 1.

The following reagents are used to prepare the catalyst:

tetraethylorthosilicate OSCh CAS 78-10-4; tetra-n-propylammonium hydroxide OSCh CAS: 4499-86-9; aluminum isopropoxide chemically pure CAS: 555-31-7; distilled water, GOST 6709-72.

To carry out the synthesis of MFI zeolite with a silica module, SiO ₂ /Al ₂ O ₃ , equal to 40, in a glass conical flask, dissolve in 12 ml of distilled water 4.2 ml of tetraethylorthosilicate, 2.2 ml of a 20% aqueous solution of tetrapropylammonium hydroxide and 0.2 g of aluminum isopropoxide, which corresponds to a molar ratio of 1:35:0.11:0.05, and stirred with a heated magnetic stirrer for 1.5 h at a speed of 700 rpm. The resulting mixture (in the form of a gel) is transferred to a 100 ml Teflon autoclave with temperature and pressure sensors, and the contents of the Teflon autoclave are subjected to microwave treatment. For microwave processing, a Speed Wave-4 microwave unit from Berghof Products + Instruments GmbH with built-in non-contact temperature and pressure sensors is used. The unit operates at a frequency of 2450 MHz and has a maximum power of 2000 watts. The treatment is carried out at a microwave power of 60 W, a radiation frequency of 2.45 GHz, a pressure of 3.7 MPa, and an autoclave temperature of 190°C. The crystallization time is 1.5 h (heating to operating temperature is carried out for 0.5 h). Then the temperature in the autoclave is reduced to 150°C, after which the contents of the autoclave are subjected to repeated hydrothermal-microwave treatment under the above conditions - at a microwave power of 60 W, a radiation frequency of 2.45 GHz, a pressure of 3.7 MPa, at a temperature in the autoclave of 190° C (heating after lowering the temperature to the specified operating temperature is carried out for 0.2 h). After cooling the autoclave, the precipitate formed is filtered off and washed with distilled water, then dried in a muffle furnace for 1.5 hours at a temperature of 190°C. The resulting powder is calcined at a temperature of 550°C until complete decomposition of the organic template (achievement of a white color of the powder). The result is a high silica MFI zeolite in hydrogen form with a silica module of 40. This zeolite is then promoted. Obtaining a promoted catalyst is carried out by the method of complete moisture absorption of the calculated amount of an aqueous solution of chromium and zinc nitrates with dried powder of the obtained zeolite. The following reagents are used for promotion: chromium (III) nitrate 9-water (Ch), GOST 4471-78; zinc nitrate 6-water (H), GOST 5106-77; distilled water, GOST 6709-72.

The promotion process is carried out as follows. The specified zeolite in a porcelain Cup with stirring impregnated with an aqueous solution, simultaneously containing zinc and chromium nitrates. The impregnated zeolite is dried in a muffle furnace for 2 hours at 80°C and calcined in a muffle furnace to decompose nitrates to form zinc and chromium oxides, respectively. The calcination is carried out by raising the temperature for 1 hour to a temperature of 550°C and keeping at this temperature for 3 hours. The amount of components is selected so that the content of zinc oxide is 1.21 wt. The calcined promoted catalyst is tableted using a hydraulic press, and then crushed and a fraction of 0.5-2 mm is taken.

The process of obtaining aromatic hydrocarbons is carried out by contacting the catalyst described above with a stable gas condensate at a temperature of 550°C, atmospheric pressure, a volumetric feed rate of a stable gas condensate of 1.16 h ^-1 , a contact time of 0.86 h.

Within two hours of operation, the catalyst shows an aromatic hydrocarbon yield of 44 wt%, including BTX 35 wt%. After that, 7 two-hour cycles of catalyst operation are repeated at a temperature of 550°C, atmospheric pressure, a volumetric feed rate of a stable gas condensate of 1.16 h ^-1 , a contact time of 0.86 h. In all cycles, the yield of aromatic hydrocarbons is 43-45% of the mass ., including BTK (benzene-toluene-xylene fraction) - 34-36% of the mass. The resulting catalyst does not reduce activity and selectivity for 16 hours (8 two-hour cycles), that is, the catalyst is stable and does not require regeneration.

Table 2 shows the group composition, % wt. the resulting liquid product.

Table 3 shows the fractional composition of the obtained liquid product, % wt.

Table 4 shows the composition of the resulting BTX-fraction.

As follows from the above data, the described catalyst for the processing of stable gas condensate to produce aromatic hydrocarbons has increased stability, namely, it retains its original activity and selectivity for at least 8 cycles, i.e. 16 hours (known catalyst for 2 cycles).

Thus, the catalyst for processing stable gas condensate into aromatic hydrocarbons, the method for producing said catalyst, and the method for producing aromatic hydrocarbons using it are characterized by increased efficiency due to the said increased stability of the described catalyst, while maintaining a high yield of aromatic hydrocarbons and the selectivity of the catalyst with respect to the indicated hydrocarbons.

The above described technical result is achieved in the scope of the set of the declared features of the group of inventions and is not achieved if the specified scope is violated.

Claims (4)

1. A method for producing a catalyst for processing stable gas condensate into aromatic hydrocarbons, which consists in preparing a mixture consisting of tetraethylorthosilicate, water, tetrapropylammonium hydroxide and aluminum isopropoxide, taken in a molar ratio of tetraethylorthosilicate : water : tetrapropylammonium hydroxide : aluminum isopropoxide, equal to 1 : 34-36: 0.1-0.12: 0.04-0.06, the resulting mixture is crystallized by hydrothermal-microwave treatment at a microwave power of 60 W, a radiation frequency of 2.45 GHz, a pressure of 3.7 MPa, temperature of 180-200°C for 1.4-1.6 hours, followed by a decrease in temperature to 150-170°C and repeated hydrothermal-microwave treatment under the above conditions, the resulting precipitate is filtered, washed with distilled water, dried for 1.5-2 hours at a temperature of 180-200°C, then the resulting powder is calcined at a temperature of 540-560°C to obtain a zeolite of the MFI structure in the hydrogen form, after which is carried out by impregnating the specified zeolite with an aqueous solution simultaneously containing zinc and chromium nitrates, drying the impregnated zeolite for 1.5-2 hours at a temperature of 70-80°C and calcining at a temperature of 540-560°C for 3-4 hours for decomposition nitrates with the formation of oxides of zinc and chromium to obtain a catalyst containing high-silica zeolite of the MFI structure in hydrogen form, zinc oxide, chromium oxide in the following ratio of components, % wt.: zinc oxide 1.0-1.5 chromium oxide 1.2-1.8 said zeolite the rest, up to 100 2. Catalyst for the processing of stable gas condensate with the production of aromatic hydrocarbons, obtained according to claim 1. 3. A method for producing aromatic hydrocarbons from a stable gas condensate, including contacting a stable gas condensate at a temperature of 360-550 ° C, atmospheric pressure, a volumetric feed rate of a stable gas condensate of 0.7-1.4 h ^-1 with a catalyst according to claim 2 or received under item 1.