RU2597269C1 - Method of heterogeneous catalyst producing for synthesis of hydrocarbons from methanol - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemical industry, namely to production of heterogeneous catalysts for converting methanol into hydrocarbons, and can be successfully used in chemical industry including for obtaining of fuels. Method of heterogeneous catalyst producing includes application of active component in the form of metal oxide on a support - modified zeolite of pentasil-type (ZSM-5). Application of active component in the form Fe₃O₄ is performed by processing of solution Fe(NO₃)₃·9H₂O in ethanol at ratio Si/Fe from 6 to 22 with subsequent recovery by ethylene glycol at the temperature of 248÷252 °C at heating rate of 1-3 °C per minute for 5÷7 hours in nitrogen atmosphere with further cooling to room temperature, after that hydrothermal treatment is carried out by adding to Fe₃O₄·SiO₂ a mixture of NaOH, tetrapropylammonium hydroxide (TPAOH, 50 wt%), NaAlO₂ and deionized water in weight ratio of (0.75÷0.85):(0.015÷0.025):(0.81÷0.83):(0.015÷0.025):(3.75÷3.85) while stirring for 2÷2.5 hours with subsequent heating to 178÷182°C and holding for 22÷24 hours. Then nickel is applied to the surface of obtained catalyst Fe₃O₄·ZSM-5: 0.45÷0.55 g Fe₃O₄·ZSM-5 is introduced into the beaker containing 0.2182÷0.2186 g of nickel ethylacetonate and 1.98÷2.02 ml of acetone, solution is stirred, dried under vacuum and catalyst is placed in tubular furnace, where it is heated to temperature of 298÷302°C in argon flow for 0.99÷1.01 hours at heating rate 4.99÷5.01 °C/min and held at temperature of 298÷302 °C for 1.99÷2.01 hours.

EFFECT: technical result is improvement of efficiency and stability of heterogeneous catalyst production process, while maintaining its high activity during multiple use in synthesis of hydrocarbons from methanol.

1 cl, 5 dwg, 1 tbl, 11 ex

Description

The invention relates to the chemical industry, and in particular to the field of production of heterogeneous catalysts for the conversion of methanol to hydrocarbons, and can be successfully implemented at enterprises of the chemical industry, including for the production of fuels.

A known method of producing a catalyst based on zeolite by treating zeolite with an aqueous solution of alkali at a temperature of about 100 ° C (Plahotnik V.A., Ermakov R.V. A decationized CVM type zeolite was treated with a hot 1M aqueous solution of N-tetrapropylammonium hydroxide, selectively removing only X-ray amorphous aluminosilicates of a tape layered (clay) nature. Organic alkali acts only on the surface of zeolite crystals, since the effective diameter of the base molecules significantly exceeds the size of the entrance windows into the channels of this zeolite. After processing, the authors obtained a refined (conditioned) sample of a zeolite CVM, free from impurities of extraneous aluminosilicates.

The disadvantage of this method is the difficulty in selecting the conditions for the synthesis of the optimal catalyst due to differences in the initial composition of zeolites, in addition, alkali treatment is an expensive and environmentally inappropriate operation.

There is also a method of producing a catalyst for the synthesis of hydrocarbons from methanol, described in application No. 2009147473, publ. 06/27/2011, including the modification of a zeolite catalyst with a value of R = 25-60 sodium hydroxide solution, after which the sodium cations are replaced by ion exchange with ammonium ions so that the content of sodium cations in the zeolite does not exceed 0.2 wt. % in terms of sodium oxide, then the zeolite is molded with a composite mixture of aluminum oxyhydroxide gel with aluminum nitrate or zirconyl nitrate, then mixed with silica sol and urea, after heat treatment, granules of a catalyst possessing the necessary porosity and resistance to water vapor are obtained.

The disadvantage of this method is the difficulty in selecting the conditions for the synthesis of the optimal catalyst, as well as the use of expensive components.

Closest to the claimed method for producing a catalyst is a method for producing heterogeneous catalysts for producing aromatic hydrocarbons of a series of benzene from methanol (RU 2477656, CL B01J 29/40, C10G 35/095, С07С 1/20, 02/07/2012), including modification with a pyrophosphate mixture zirconium, zinc oxide and zirconia decated pentasil type zeolite (e.g. ZSM-5, ZSM-8 or ZSM-11) with a molar ratio SiO ₂ / Al ₂ O ₃ = 120-200, containing sodium cations in an amount equivalent to 0.059- 0.010 wt. % sodium oxide, molded with a binder of gamma modification of alumina and zirconia, with the following components, wt. %: 65 (zeolite - 96.5-97.8 with a modifier content (59 wt.% ZrP ₂ O ₇ ; 31 wt.% ZnO and 10 wt.% ZrO ₂ ), comprising 3.5-2.2) and 35 - binder, from the sum of anhydrous oxides (aluminum oxide - 80% and zirconium dioxide - 20%).

The main disadvantages of the described method are the use of a large number of catalyst components, as well as weak binding of the catalyst components.

The objective of the invention is to develop a method for producing a heterogeneous catalyst for the synthesis of hydrocarbons from methanol, which provides increased structural stability and reduced losses of the active component of the catalyst during synthesis, storage and use due to its reliable fixation in the pores of the carrier.

The technical result of the invention is to increase the efficiency and stability of the process of obtaining a heterogeneous catalyst while maintaining its high activity during repeated use in the synthesis of hydrocarbons from methanol.

The problem and the technical result are achieved in that in the method for producing a heterogeneous catalyst for the synthesis of hydrocarbons from methanol, comprising applying the active component in the form of metal oxide on a carrier - a modified pentasil type zeolite (ZSM-5), according to the invention, applying the active component in the form of Fe ₃ O ₄ is carried out by treating the carrier with a solution of Fe (NO _{3) 3} · 9H ₂ O in ethanol at a Si / Fe ratio of from 6 to 22, followed by stirring at room temperature until complete evaporation of the ethanol, and dried I eat at a temperature of 38 ÷ 42 ° C for 22 ÷ 24 hours and restore ethylene glycol at a temperature of 248 ÷ 252 ° C with a heating rate of 1 to 3 ° C per minute for 5 ÷ 7 hours in a nitrogen atmosphere, followed by cooling to room temperature after which a hydrothermal treatment is carried out by introducing a mixture of NaOH, tetrapropylammonium hydroxide (TPAOH, 50% wt.), NaAlO ₂ and deionized water in a mass ratio (0.75 ÷ 0.85) in Fe ₃ O ₄ · SiO ₂ :( 0.015 ÷ 0.025) :( 0.81 ÷ 0.83) :( 0.015 ÷ 0.025) :( 3.75 ÷ 3.85) with stirring for 2 ÷ 2.5 hours, followed by heating 178 ÷ 182 ° С and keeping at current 22 ÷ 24 hours, after which nickel is applied to the surface of the obtained catalyst Fe ₃ O ₄ · ZSM-5: 0.45 ÷ 0.55 g of Fe ₃ O ₄ · ZSM-5 is introduced into a beaker containing 0.2182 ÷ 0 , 2186 g of nickel ethyl acetate and 1.98 ÷ 2.02 ml of acetone, the solution is stirred, dried under vacuum and the catalyst is placed in a tube furnace, where it is heated to a temperature of 298 ÷ 302 ° C in an argon stream for 0.99 ÷ 1.01 hours with a heating rate of 4.99 ÷ 5.01 ° C / min and maintained at a temperature of 298 ÷ 302 ° C for 1.99 ÷ 2.01 hours.

The use of decated pentasil zeolite (ZSM-5) as a carrier provides an increase in the bond strength of the carrier with the active component. The use of Fe ₃ O ₄ nanoparticles allows the use of ZSM-5 as a carrier with a pore size of less than 0.7 nm. In addition, the resulting particles exhibit magnetic properties. If you use the same silica gel without Fe ₃ O ₄ nanoparticles under the same conditions, the ZSM-5 phase can also be formed, however, at the same sizes (6–9 μm), spherical crystals are not observed. It is assumed that the presence of Fe ₃ O ₄ nanoparticles has a significant effect on the crystallization of ZSM-5, forming magnetic microspheres, which makes it possible to freely separate it from the reaction medium after the process.

At a Si / Fe ratio of 6 to 22, spherical morphology is observed in the catalysts, which allows for higher stability and reproducibility of their catalytic properties. An increase in this ratio above 22 leads to the formation of unstable particles of a non-spherical configuration, with a Si / Fe value of less than 6, according to the results of experiments, the activity of the synthesized heterogeneous catalyst significantly decreases.

Due to the reduction of ethylene glycol, Fe ₃ O ₄ nanoparticles are firmly fixed in the pores of silica gel. Subsequent hydrothermal treatment of the obtained powder in a slightly alkaline medium prevents the exit of Fe ₃ O ₄ nanoparticles from the pores of silica gel.

The high temperature of the hydrothermal treatment leads to the rapid formation of crystals (nanorods) ZSM-5. Thus, homogeneous Fe ₃ O ₄ nanoparticles are uniformly scattered in the voids between ZSM-5 crystals, while the accumulation of zeolite crystals can also be controlled. The hydrothermal treatment of the catalyst promotes the formation of spherical ZSM-5 particles with strongly bonded Fe ₃ O ₄ nanoparticles, which significantly increases its stability upon repeated use.

Treatment of the support with a solution of Fe (NO ₃ ) ₃ · 9H ₂ O in ethanol with further stirring and drying ensures uniform distribution of Fe ions in the pores of the support.

The presence of nickel on the surface of the catalyst ensures its high activity in the reaction of the synthesis of hydrocarbons from methanol.

The invention is illustrated by drawings, where in FIG. 1 shows an SEM image of a catalyst with a ratio of Si / Fe = 6, FIG. 2 is an SEM image of a catalyst with a ratio of Si / Fe = 11, in FIG. 3 is an SEM image of a catalyst with a ratio of Si / Fe = 22, in FIG. 4 - dependence of the conversion of methanol to hydrocarbons on the reaction time when using the optimal catalyst in 4 consecutive experiments.

Obtaining a heterogeneous catalyst for the synthesis of hydrocarbons was carried out as follows.

A portion of Fe (NO ₃ ) ₃ · 9H ₂ O (depending on the pore volumes of silica gel and the density of Fe (NO ₃ ) ₃ · 9H ₂ O) from 0.38 to 1.41 g was dissolved in 10 ml of ethanol, then was added to the solution 2.5 g of mesoporous SiO _2. The mixture was stirred at room temperature until ethanol was completely evaporated. The remaining powder was dried at 40 ° C for 24 hours. To this powder, a few drops of ethylene glycol were added as a reducing agent and placed in a tube furnace, where they were heated to 250 ° C at a heating rate of 2 ° C per minute for 6 hours under nitrogen atmosphere, after which the powder was cooled to room temperature. The resulting compound Fe ₃ O ₄ · SiO _{2 was} converted to Fe ₃ O ₄ · ZSM-5 during hydrothermal treatment. For this, 0.8 g of Fe ₃ O ₄ · SiO _{2 was} added to the mixture of 0.02 g of NaOH, 0.82 g of tetrapropylammonium hydroxide (TPAON, 50 wt%), 0.02 g of NaAlO ₂ and 3.8 g of deionized water , the resulting mixture was stirred for 2 hours, then the mixture was transferred to an autoclave heated to 180 ° C, and kept at this temperature for 24 hours. After cooling to room temperature, the powder was washed with deionized water and dried at 100 ° C for 12 hours. Next, nickel was applied to the surface of the catalyst. For this, 0.5 g of Fe ₃ O ₄ · ZSM-5 was added to a 50 ml beaker containing 0.2184 g of nickel ethyl acetate and 2 ml of acetone, the solution was stirred, dried under vacuum, and placed in a tube furnace, where it was heated to a temperature 300 ° C in a stream of argon for 1 hour with a heating rate of 5 ° C / min and kept at a temperature of 300 ° C for 2 hours.

Magnetic microspheres obtained catalyst have relatively uniform size (6-9 microns), high surface area (340 ^m2 / g), good magnetic properties (~ 8.6 emu / g) and good dispersibility.

The relative mass content of the active component and the carrier is selected based on the results of the experiments (examples 1-3). The catalyst was prepared according to the method described above, varying the weight of a sample of Fe (NO ₃ ) ₃ · 9H ₂ O.

Example 1

An example was carried out similarly to the above procedure, but 2.82 g of Fe (NO ₃ ) ₃ · 9H ₂ O was dissolved in 10 ml of ethanol, which corresponded to the ratio Si / Fe = 3.

As a result, particles of a generally non-spherical configuration were formed, practically not showing activity in the reaction of the conversion of methanol to hydrocarbons.

Example 2

An example was carried out similarly to the above procedure, but 1.41 g of Fe (NO ₃ ) ₃ · 9H ₂ O was dissolved in 10 ml of ethanol, which corresponded to the ratio Si / Fe = 6.

As a result, particles of a spherical configuration were formed, the image of which was obtained by scanning electron microscopy (Fig. 1).

Example 3

An example was carried out similarly to the above procedure, but 0.77 g of Fe (NO ₃ ) ₃ · 9H ₂ O (Si / Fe ratio = 11) was dissolved in 10 ml of ethanol.

As a result, particles of a spherical configuration were formed, the image of which was obtained by scanning electron microscopy (Fig. 2).

Example 4

An example was carried out similarly to the above procedure, but 0.38 g of Fe (NO ₃ ) ₃ · 9H ₂ O (Si / Fe ratio = 22) was dissolved in 10 ml of ethanol.

As a result, particles of a spherical configuration were formed, the image of which was obtained by scanning electron microscopy (Fig. 3).

Example 5

An example was carried out similarly to the above procedure, but 0.28 g of Fe (NO ₃ ) ₃ · 9H ₂ O (Si / Fe ratio = 30) was dissolved in 10 ml of ethanol.

As a result, unstable particles of a non-spherical configuration were formed, practically not showing activity in the reaction of the conversion of methanol to hydrocarbons.

Comparison of SEM images obtained in examples 2-4 showed that the most optimal (spherical and stable) particles were obtained in example 3 (Si / Fe ratio = 11). With a Si / Fe content of 6 to 22, the catalysts exhibit a spherical morphology of approximately the same size as the optimum Si / Fe ratio = 11. An increase in this ratio above 22 leads to the formation of unstable particles of a non-spherical configuration, with a decrease in the ratio of less than 6, according to the results of experiments, the activity of the catalyst significantly decreases.

Example 6

The example was carried out analogously to example 3, but the hydrothermal treatment was carried out for 3 hours.

Example 7

The example was carried out analogously to example 3, but the hydrothermal treatment was carried out for 6 hours.

Example 8

The example was carried out analogously to example 3, but the hydrothermal treatment was carried out for 12 hours.

In FIG. 4 presents the results of the analysis of the degree of crystallinity of the samples from examples 3, 6, 7, and 8 using a powder x-ray. As can be seen from the figure, the greatest degree of crystallinity is observed during hydrothermal treatment for 24 hours (~ 95%). Moreover, a further increase in processing time is impractical, since it does not lead to an increase in the degree of crystallinity.

Example 9

The example was carried out analogously to example 3, but the hydrothermal treatment was carried out at a temperature of 160 ° C. As a result, unstable particles of a non-spherical configuration were formed, practically not showing activity in the reaction of the conversion of methanol to hydrocarbons.

Example 10

The example was carried out analogously to example 3, but the hydrothermal treatment was carried out at a temperature of 200 ° C. As a result, unstable particles of a non-spherical configuration were formed, practically not showing activity in the reaction of the conversion of methanol to hydrocarbons.

In the example below, the catalytic properties of the obtained catalysts (with a Si / Fe ratio of 11) in the synthesis of hydrocarbons from methanol (Example 11) were investigated.

Example 11

7.3 g of catalyst fractions up to 0.125 mm were placed in a flow-through tubular reactor with external electric heating. Hydrocarbons were synthesized by purging a mixture of nitrogen and methanol vapor through a fixed catalyst bed. Reaction conditions: nitrogen feed rate - 10 ml / min, methanol feed rate - 0.1 ml / min, temperature - 350 ° C, pressure - 1.5 bar. As a result of the experiment, a 75% conversion of methanol to hydrocarbons was recorded. In addition, we studied the activity of the catalyst with repeated use (after regeneration with a mixture of oxygen and nitrogen (2% vol.) At a gas flow rate of 50 ml / min).

The experimental results are shown in table 1 and in FIG. 5.

Thus, experiments have shown that with repeated use of the regenerated catalyst, 80-85% of its initial activity is retained. The results obtained indicate that the use of a catalyst with an optimal Si / Fe ratio of 11 allows a high degree of conversion of methanol to hydrocarbons to be achieved. In addition, the possibility of reuse of the catalyst with the preservation of most of its initial activity has been proved.

This method of producing a heterogeneous catalyst for the synthesis of hydrocarbons from methanol can be successfully applied at chemical plants for the synthesis of effective catalysts for the production of hydrocarbons from methanol.

Claims (2)

1. A method of producing a heterogeneous catalyst for the synthesis of hydrocarbons from methanol, comprising applying the active component in the form of metal oxide on a carrier - a modified pentasil type zeolite (ZSM-5), characterized in that the application of the active component in the form of Fe ₃ O _{4 is} carried out by treating the carrier with a solution Fe (NO ₃ ) ₃ · 9H ₂ O in ethanol at a Si / Fe ratio of 6 to 22, followed by reduction with ethylene glycol at a temperature of 248 ÷ 252 ° C with a heating rate of 1 to 3 ° C per minute for 5-7 hours in nitrogen atmosphere, followed by cooling to room temperature, after which the hydrothermal treatment is carried out by introducing into Fe ₃ O ₄ · SiO _{2 a} mixture of NaOH, tetrapropylammonium hydroxide, NaAlO ₂ and deionized water in a mass ratio (0.75 ÷ 0.85) :( 0.015 ÷ 0.025) :( 0 , 81 ÷ 0.83) :( 0.015 ÷ 0.025) :( 3.75 ÷ 3.85) with stirring for 2 ÷ 2.5 hours, followed by heating 178 ÷ 182 ° С and keeping for 22 ÷ 24 hours, then nickel is applied to the surface of the obtained catalyst Fe ₃ O ₄ · ZSM-5: 0.45 ÷ 0.55 g of Fe ₃ O ₄ · ZSM-5 is introduced into a beaker containing 0.2182 ÷ 0.2186 g of nickel ethyl acetate and 1.98 ÷ 2.02 ml of acetone, the solution is mixed melt, dry under vacuum and the catalyst is placed in a tube furnace, where it is heated to a temperature of 298 ÷ 302 ° C in an argon stream for 0.99 ÷ 1.01 hours with a heating rate of 4.99 ÷ 5.01 ° C / min and incubated at a temperature of 298 ÷ 302 ° C for 1.99 ÷ 2.01 hours. 2. The method according to p. 1, characterized in that after processing the carrier with a solution of Fe (NO ₃ ) ₃ · 9H ₂ O in ethanol, the resulting mixture is stirred at room temperature until the ethanol is completely evaporated, and then dried at a temperature of 38 ÷ 42 ° C 22 ÷ 24 hours

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