RU2626958C2 - Method for selective hydrogenation of unsaturated aldehydes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for producing saturated aldehydes by contacting a liquid organic feed containing unsaturated aldehydes with hydrogen or hydrogen-containing gas in presence of crustal catalyst comprising palladium particles of not more than 6 nm in size, applied in form of a layer not thicker than 150 microns on exterior surface of porous alumina carrier granules. Herewith the carrier has not less than 60% of pores with a diameter of 5 to 50 nm, and the hydrogenation is carried out at a liquid feed rate of 1-4 h^-1.

EFFECT: producing target products with high selectivity at high process efficiency and feedstock conversion.

25 cl, 8 dwg, 6 tbl, 6 ex

Description

The invention relates to a method for the selective hydrogenation of unsaturated aldehydes to saturated aldehydes in the presence of a catalyst consisting of palladium particles deposited on the outer surface of granules of a porous alumina carrier.

A method is known from the technical field for producing saturated aldehydes by hydrogenation of the corresponding unsaturated aldehydes in the presence of a heterogeneous catalyst at a temperature of 70-140 ° C, at atmospheric pressure (GB 1065628, publ. 04/19/1967). Used catalyst is a 0.05-0.5% wt. Platinum or palladium on a carrier (pumice) with the addition of copper, nickel or cobalt.

The disadvantages of this method are the low volumetric feed rate (in specific examples of the invention - 125 cm ³ / l⋅h (0.125 h ^-1 )), low yield of the target product (the content of saturated aldehyde in the product is 92-96%), while the greatest process efficiency is achieved using a catalyst with a high content of active component. According to the embodiments presented in GB 1065628, the palladium content in the catalyst is approximately 0.5% wt.

A known method of producing 2-ethylhexanal by hydrogenation of 2-ethylhexenal at a temperature of 60-150 ° C, a pressure of 100-300 atm and a feed rate of 0.4-0.6 kg of 2-ethylhexenal / l catalyst катализатора h (0.47-0, 71 h ^-1 ) in a reactor with a stationary catalyst bed (GB 1310143, publ. 14.03.1973). As a catalyst, 0.01-1% wt. platinum, palladium or ruthenium on an Al ₂ O ₃ or SiO ₂ support with a specific surface area of 40-150 m ² / g. The method allows to increase the yield of 2-ethylhexanal up to 96%.

The disadvantages of this method are the necessity of carrying out the process at high pressure (100-300 atm), low feed rate (0.4-0.6 kg of 2-ethylhexenal / l of catalyst ⋅ h), as well as low selectivity for the target product (content 2 ethylhexanal in the final product is 96% of the mass).

A known method of producing saturated aliphatic, cycloaliphatic and aromatic aldehydes by selective hydrogenation of the corresponding unsaturated aldehydes in the liquid phase in the presence of a palladium-containing catalyst (US 4273945, publ. 06.16.1981). The catalytic system contains 2-90% wt. palladium and 10-98% wt. oxides or salts of rare earth metals, or mixtures of various oxides or salts of rare earth metals on an Al ₂ O ₃ or silica gel support. The method is carried out at a temperature of 20-250 ° C and a pressure of 1-50 bar. The yield of the target product is 95-98%.

The disadvantages of this method are the need to use high pressure (up to 50 bar) to achieve relatively high conversion and selectivity, low yield of the target product (2-ethylhexanal content 95-98%), and the use of a catalytic system with a high palladium content (2-90 %).

A known method of producing n-butyraldehyde by selective hydrogenation of crotonic aldehyde (butene-2-al) in the liquid phase at a temperature of 30-50 ° C, a pressure of 5-16 atm and a feed space velocity of 0.65 h ^-1 in the presence of a catalyst based on palladium supported Al ₂ O ₃ , (US 4450300, publ. 05.22.84). The palladium content in the catalyst is 0.1-0.6% wt. This method allows to obtain the target product with a yield of 98.1-98.6%.

The disadvantages of this method are high pressure, low volumetric feed rate (0.65 h ^-1 ) and low yield of the target product - n-butyraldehyde.

A known method of producing 2-ethylhexanal by hydrogenation of 2-ethylhexenal at 80-160 ° C, 10-250 atm and a linear feed rate of 10-50 m / h in the irrigation zone, in a reactor with a stationary catalyst bed containing, preferably, 0.01 -1% wt. platinum, palladium or ruthenium on carriers of Al ₂ O ₃ or SiO ₂ (US 3903171, publ. 02.09.1975). The method avoids temperature jumps and, thus, reduces damage to the catalyst and prevents a subsequent decrease in product quality.

The disadvantages of this method are high pressure, low yield of the target product. In specific embodiments of the invention, the process is carried out at 40 and 200 atm, while the content of 2-ethylhexanal reaches 95.9%.

A known method of producing 2-ethylhexanal by hydrogenation of 2-ethylhexenal in two or more series-connected nodes, with each node involves the use of a single reactor, in which the catalyst is located, which represents 0.5% wt. palladium supported Al ₂ O ₃ . - commercial catalyst company Engelhard (US 5756856, publ. 05.26.1998). Hydrogenation is carried out at a temperature of 116-124 ° C and a pressure of 15 bar to obtain a hydrogenated product. A portion of the hydrogenated product is also recycled. The method allows to achieve high values of the conversion of 2-ethylhexenal - 99.9% and selectivity for 2-ethylhexanal - 99%.

The disadvantages of this method are the process at elevated pressure (15 bar), as well as the need to use two or more series-connected hydrogenation reactors.

A known method of producing 2-ethylhexanal by hydrogenation of 2-ethylhexenal at a temperature at the inlet of the reactor 50-80 ° C and a hot spot temperature of 80-110 ° C, a pressure of 1.5-2.5 MPa and a volumetric feed rate of liquid raw materials of 0.4- 1.2 h ^-1 in two successive reactors with a stationary catalyst bed, which is 0.1-0.5% wt. palladium supported γ-Al ₂ O ₃ (CN 1599789, publ. 26.01.2005). Part of the target product is recycled. The method allows to carry out the process at lower temperatures - 50-80 ° C, and also to achieve high values of conversion and selectivity - 99.9% and 99.5% or more, respectively.

The disadvantages of this method are high pressure (1.5-2.5 MPa), high metal consumption (carrying out the process in two reactors).

A known method of producing 2-ethylhexanal by hydrogenation of 2-ethylhexenal at a temperature of 130-150 ° C, a pressure of 1.5-2.0 MPa and a volumetric feed rate of liquid raw materials of 0.4-0.8 h ^-1 in an isothermal reactor with a stationary catalyst layer QSH-1, representing 0.2% wt. palladium supported on an Al ₂ O ₃ carrier. (CN 101759533, publ. 06/30/2010). The method allows to achieve high values of the conversion of 2-ethylhexenal - 99% or more, as well as high selectivity for the target product - 98% or more.

The disadvantages of this method are high pressure (1.5-2.0 MPa), low volumetric feed rate of liquid raw materials (0.4-0.8 h ^-1 ).

The closest analogue to the method of the present invention is the stage of hydrogenation of 2-ethylhexenal with a hydrogen-containing gas, which is part of the method for producing 2-ethylhexanoic acid described in patent RU 1697381 (publ. 02.27.1997). According to this method, the process is carried out in an oxygen-containing organic solvent at a temperature of 80-130 ° C, and a pressure of 0.1-5 MPa in a hydrogenation reactor with a stationary catalyst bed, which is 0.1-2.0% wt. palladium supported on Al ₂ O ₃ . Butyl isobutyrate or isobutyl butyrate is used as an oxygen-containing organic solvent in a mass ratio of 2-ethylhexenal: solvent - 1: 0.4-0.9. The flow of the reaction mixture after the reactor is directed to separation in a distillation column. The method allows to increase the stability of the catalyst (from 25-30 days to 2-3 months) while maintaining a high conversion of 2-ethylhexenal (99.1-99.8%) and to improve the quality of the target product after the rectification stage - the content of the main substance is up to 99 , 6%.

The main disadvantage of this method is the low volumetric feed rate of liquid raw materials, which negatively affects the overall performance of the process. In specific embodiments of the invention, the volumetric feed rate of the liquid feed is 0.4 h ^-1 . Also in the description of the method there is no data on the selectivity and yield of the target product after the reactor before the rectification stage, there is only data on the content of the target product in the rectification. However, such data may be overestimated due to the fact that the concentration of the target substance increases after the rectification process of the reaction mass leaving the reactor. In this case, the reaction mass directed to the rectification stage contains the target 2-ethylhexanal, the solvent contains alkyl butyrate, a certain amount of 2-ethylhexenal, etc. .

The present invention is to develop a method for the selective hydrogenation of unsaturated aldehydes to saturated aldehydes, characterized by high performance, conversion and selectivity for the target product.

The present invention discloses a method for producing saturated aldehydes by selectively hydrogenating unsaturated aldehydes with hydrogen or a hydrogen-containing gas in the presence of a crust catalyst, which is palladium particles deposited as a thin layer on the outer surface of the granules of a porous alumina support.

The technical result consists in increasing the volumetric feed rate of the raw material to 1-4 h ^-1 while maintaining high conversion (99% or more) and selectivity (99% or more) for the target product.

Also, the technical result is to increase the life of the catalyst.

The task and technical result are achieved through the use of a crusty catalyst, which is a palladium particles deposited in the form of a thin layer on the outer surface of a porous alumina carrier.

Brief Description of the Drawings

FIG. 1. Laboratory installation for the study of the hydrogenation process.

FIG. 2. Micrograph of the palladium layer on the carrier.

FIG. 3. Pore size distribution of the catalyst (desorption isotherm)

FIG. 4. The dependence of the activity of the catalysts on temperature (volumetric feed rate of liquid raw materials 2 h ^-1 ).

FIG. 5. The dependence of the selectivity of the catalysts on temperature (volumetric feed rate of liquid raw materials 2 h ^-1 ).

FIG. 6. The dependence of the selectivity of the catalysts on travel time (volumetric feed rate of liquid raw materials 4 h ^-1 )

FIG. 7. The dependence of the activity of the catalysts on the travel time (volumetric feed rate of liquid raw materials 4 h ^-1 )

FIG. 8. The dependence of the outputs of the target product depending on the travel time of the catalysts (volumetric feed rate of liquid raw materials 4 h ^-1 )

SUMMARY OF THE INVENTION

A method of producing saturated aldehydes by contacting a liquid organic feed containing unsaturated aldehydes with hydrogen or a hydrogen-containing gas in the presence of a crust catalyst, which is palladium particles no larger than 6 nm in size, deposited as a layer with a thickness of not more than 150 microns on the outer surface of the granules of a porous alumina carrier where the carrier has at least 60% pores with a diameter of 5 to 50 nm (according to the BJH method (Barett-Joyner-Halenda)), and where the hydrogenation is carried out at a volumetric feed rate of liquid feed 1-4 h ^-1 .

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, hydrogenation is carried out by contacting a liquid organic feed containing unsaturated aldehydes with hydrogen or a hydrogen-containing gas.

Unsaturated aldehydes that can be hydrogenated by the process of the invention include linear or branched unsaturated aldehydes, preferably containing from 3 to 10 carbon atoms, for example, 2-butenal, propenal, 3-phenylpropenal, etc., including the aldehydes obtained in the processes of aldol condensation of aldehydes, in particular, 2-ethylhexenal

In addition to unsaturated aldehydes, liquid organic raw materials may additionally contain various esters, aldehydes, ketones, alcohols, acids and other organic compounds of both normal and isostructure, mainly containing from 4 to 12 carbon atoms, for example, such as: 2-methylpropanal ( isobutyric aldehyde), butanal (butyric aldehyde), butyl isobutyl ether, diisobutyl ether, dibutyl ether, diisopropyl ketone, propyl isopropyl ketone, dipropyl ketone, butyl formate, isobutanol, isobutyl isobutyrate, butanol, butyl isobutyl at, 3-heptanone, isobutyl butyrate, butyl butyrate, butyl-2-ethylhexyl ether, 3-heptanol, 2-ethylhexanol, acetic acid, 2-ethylhexanoic acid, etc.

According to the present invention, the content of unsaturated aldehydes in a liquid organic medium should not exceed 20% of the mass, since the hydrogenation process is exothermic, and with a higher content of unsaturated aldehydes, it will be difficult to remove the released heat. The preferred content of unsaturated aldehydes in a liquid organic medium should not exceed 10% wt. more preferred content, especially when implementing the process on an industrial scale, should not exceed 7% wt.

Before being fed to the hydrogenation reactor, liquid organic raw materials containing unsaturated aldehydes can be preheated to a temperature of 50-100 ° C. The feed to the reactor is carried out with a space velocity of 1-4 hours ^-1 , preferably with a speed of 1-3 hours ^-1 , more preferably 1.3-1.8 hours ^-1 , and a space velocity of gaseous hydrogen 20-60 hours ^-1 preferably 20-50 hour ^-1 , more preferably 28-42 hour ^-1 .

Hydrogenation of unsaturated aldehydes is carried out with hydrogen, using either hydrogen or hydrogen-containing gases with a hydrogen content of 75 to 90% (vol.), For example, methane-hydrogen gas mixture.

The hydrogenation process is carried out at a temperature of 50-180 ° C, preferably at a temperature of 60-160 ° C, and at a pressure of 0.1-7 MPa, preferably at 0.1-5 MPa.

Hydrogenation is carried out in the presence of a crusty catalyst, which is palladium particles with a size of not more than 6 nm, deposited in the form of a layer with a thickness of not more than 150 microns (0.15 mm), on the outer surface of the granules of a porous alumina carrier;

The preferred particle size of palladium is not more than 5 nm, more preferred from 2 to 3 nm; the preferred thickness of the layer of palladium particles deposited on the outer surface of the granules of the porous alumina carrier is from 10 to 100 μm (0.01-0.10 mm), the more preferred thickness is from 30 to 85 μm (0.03-0.085 mm).

Alumina, preferably γ-Al ₂ O _{3, is} used as the porous alumina carrier.

Moreover, the alumina carrier should have at least 60% pores with a diameter of 5-50 nm (according to the BJH method), preferably at least 70%, more preferably at least 75%.

The use of a carrier with a high pore content of a smaller size, as shown in examples 4 and 6, leads to a decrease in conversion and selectivity, which may be due to the slow diffusion of molecules in the pore space, namely, to the difficulty in transporting the feedstock to the active component of the catalyst palladium (the reason for the drop in conversion), and the removal of the hydrogenated aldehyde molecules from the reaction zone, i.e. their delay in the zone of the active component of the catalyst (palladium), which can lead to hydrogenation of the -C = O bond (the reason for the selectivity loss).

The use of a carrier with a large number of pores with a diameter of more than 50 nm will also not allow achieving the claimed technical result, since such a carrier is macroporous and has a very small specific surface on which it is impossible to apply the active component - palladium in the form of particles of the required size, i.e. the catalyst will be low dispersed. This in turn will lead to a decrease in catalyst activity and a decrease in the conversion and selectivity of the hydrogenation process.

Accordingly, the catalyst used in the present invention is characterized by the following parameters:

palladium applied in an amount of from 0.1 to 0.35% of the mass, preferably 0.15-0.22% of the mass

specific surface (according to the BJH method) 100-200 m ² / g, preferably 127-172 m ² / g;

the pore volume (according to the BJH method) of 0.4-0.6 cm ³ / g, preferably 0.48-0.50 cm ³ / g;

the average pore diameter (according to the BJH method) of 7-15 nm, preferably 8.5-10.8 nm;

pore distribution (by BJH method, by desorption isotherm):

- 15-40% in the range of diameters 0-5 nm,

- 0-1% in the range of diameters of more than 50 nm,

- preferably 19-32% in the range of diameters 0-5 nm,

- 0.08-0.23% in the region of diameters greater than 50 nm.

The used catalyst is granules of various shapes (extrudate, balls, rings, etc.) and is loaded into the reactor in the form of one or more fixed layers.

The catalyst used can be obtained by the method described in RU 2183504, which includes the impregnation of a porous alumina carrier characterized by the above structural parameters with an aqueous solution of palladium and sodium salts, and drying, in which the impregnation is carried out with an aqueous solution of palladium and sodium acetates, and impregnated with a solution of palladium acetates and sodium porous alumina carrier before drying is maintained at atmospheric pressure or below atmospheric pressure and a temperature of 1-80 ° C for 0.5-24 hours

As an example of an apparatus for carrying out the invention, namely, a method for producing saturated aldehydes by hydrogenating a feed containing the corresponding unsaturated aldehydes, the apparatus shown in FIG. one.

The installation shown in FIG. 1, consists of a tubular reactor (6) with a fixed catalyst bed placed on a porous fluoroplastic plate. The flow inside the reactor is upward, whereby the preheated reaction mixture is fed into the lower part of the reactor and, passing through the catalyst bed, the reaction products leave the upper part.

During operation of the installation, the raw material coming from the tank (2) is pumped by the metering pump (3) and through the check valve (4) it enters the tee (5), where it is mixed with hydrogen coming from the cylinder (1) through the gearbox. From the tee, the gas-liquid mixture enters the lower part of the reactor (6), which is immersed in a thermostatically controlled liquid, heated to the reaction temperature, supported by the thermostat (7). Due to the fact that the supply of reagents is carried out from below, for even distribution of the reaction stream, the lower part of the reactor is filled with quartz (fraction with a diameter of 0.2-0.6 mm). After the quartz layer, the initial mixture enters the catalyst-filled layer.

After passing through the reactor, the reaction mass enters the separator (8), cooled by water, where the liquid reaction products are separated from hydrogen. The separator is equipped with a manometer for recording working pressure (11). Unreacted hydrogen leaves the upper part of the separator and through a fine adjustment valve (12), which maintains the pressure in the system, enters the flow fixation device (flow meter (13)), which measures the hydrogen flow rate. After that, hydrogen is removed from the system by blowing gas (14).

Liquid reaction products accumulate in the separator (8). Periodically (depending on the feed rate), a liquid sample is taken through a sampler (9) to a receiver (10) to determine the degree of hydrogenation of unsaturated aldehydes and verify that the process is stationary.

The size of the palladium particles on the support is determined by pulsed titration by CO chemisorption according to the procedure described in “Investigation of the formation of Pt / C catalysts on various carbon supports”, Journal of Inorganic Chemistry, 2009, V. 54, No. 10, p. 1-6.

The elemental composition of the catalysts was determined by X-ray fluorescence analysis (RFLA) on a Shimadzu XRF 1800 X-ray fluorescence spectrometer (Shimadzu, Japan).

The thickness of the palladium layer on the carrier is determined by optical microscopy using an optical microscope of a Nanovea scratch tester.

The structural characteristics of the catalyst samples were measured using a Tristar 3100 specific surface area catalyst (Micromeretics, USA).

The specific surface area of catalyst samples was calculated using the single and multipoint BET method, the STSA (Statistical Thickness Surface Area (STSA) method, ASTM D6556).

Pore volume and size are determined using the BJH model (Barett-Joyner-Halenda) from adsorption and desorption isotherms at a relative pressure P / Po = 0.99, and the specific surface and micropore volume were calculated using the t-plot method. The error in determining the specific surface was 5 rel. %

The invention is illustrated, but not limited to, by the following examples.

Example 1. Obtaining a hydrogenation catalyst (catalyst according to the invention).

999 g of alumina carrier with a total pore volume of 0.48 cm ³ / g, specific surface area of 127 m ² / g, average pore diameter of 10.8 nm, pore distribution of 19.5% in the range of diameters 0-5 nm, 80.27% in the range of diameters of 5-50 nm, 0.23% in the range of diameters of more than 50 nm, they are impregnated with an aqueous solution of 500 cm ³ containing 4.3 g of sodium acetate and 2.11 g of palladium acetate, after which the impregnated carrier is maintained at atmospheric pressure and a temperature of 20 ° C for 10 hours, and then dried at 150 ° C.

The particle size of the palladium on the carrier is determined by the method of chemisorption of CO.

The results are presented in Table 1.

The thickness of the palladium layer on the support was determined by optical microscopy. The results are presented in FIG. 2.

As can be seen from FIG. 2, the palladium layer thickness is not the same, and varies from site to site. The thickness of the palladium layer is from 10 μm to 100 μm, preferably from 30 μm to 85 μm. The average palladium layer thickness is 44 μm.

Table 2 presents the elemental composition of the catalyst obtained in example 1.

The structural characteristics of the catalyst obtained in example 1 are presented in Table 3.

The pore size distribution of the catalyst obtained in Example 1 is shown in FIG. 3.

Example 2. Obtaining a hydrogenation catalyst (catalyst comparison).

999 g of alumina carrier with a total pore volume of 0.48 cm ³ / g, specific surface area of 227 m ² / g, average pore diameter of 6.3 nm, pore distribution of 44.3% in the range of diameters 0-5 nm, 55.67% in the range of diameters of 5-50 nm, 0.03% in the range of diameters of more than 50 nm, is impregnated with an aqueous solution of 500 cm ³ containing 4.3 g of sodium acetate and 2.11 g of palladium acetate, after which the impregnated carrier is maintained at atmospheric pressure and a temperature of 20 ° C for 10 hours, and then dried at 150 ° C.

The elemental composition of the reference catalyst obtained in Example 2 is shown in Table 4.

The structural characteristics of the comparison catalyst obtained in example 2 are shown in Table 5.

Example 3. Hydrogenation of liquid raw materials using the catalyst obtained in example 1.

In a tubular reactor with a volume of 34.2 cm ³ load 10 cm ^{3 of the} catalyst obtained by the method described in example 1, which is 0.22% wt. palladium deposited on alumina and having a grain size of 1-2 mm. The catalyst before the process is not crushed, loaded in layers. The first layer is filled with a layer of quartz with a fraction of 0.2-0.6 mm to uniformly split the flow of the reaction mass. Then, the catalyst is loaded into the reactor, while a monolayer of catalyst granules is alternated with a layer of the same volume of fine quartz chips. Further, the catalyst layer is covered with a layer of quartz to the top of the reactor.

Liquid raw materials with a volumetric feed rate of 2 h ^-1 are supplied by a continuous metering pump of the brand Gilson 307 to the mixer. The composition of the liquid feed is shown in Table 6. Hydrogen in the volume ratio of feed: H ₂ = 1:22 (in terms of atmospheric pressure) is supplied to the mixer from a cylinder using a gas flow regulator under a pressure of 10 atm. Next, the reaction mixture after the mixer is fed to the heater, and then to the lower part of the reactor. The reactor is heated in an oil bath at a rate of 2 ° C / min from room temperature to 120 ° C of the experimental temperature.

After passing through the reactor, the reaction mass is sent to a gas-liquid separator, cooled by water, in which liquid products are separated from hydrogen. The separator is equipped with a pressure gauge for recording operating pressure. Unreacted hydrogen leaves the upper part of the separator and is fed through a fine adjustment valve to a gas flow meter. Liquid reaction products accumulate in the separator. To determine the dependence of the activity and selectivity of the catalyst on temperature, experiments were carried out in the range of 80-160 ° C. The results obtained are presented in FIG. 4-5.

Example 4 (comparative). Hydrogenation of liquid feed using a catalyst obtained in example 2.

The process is carried out according to the procedure described in example 3. The difference is that they use the catalyst obtained according to the procedure described in example 2. The results obtained are presented in FIG. 4-5.

From the results of experiments on the effect of temperature on conversion and selectivity (Examples 3-4 and the corresponding Figs 4-5), it can be seen that for the catalyst obtained in Example 2, the conversion value is observed, at temperatures up to 140 ° C, lower than that for the catalyst obtained in example 1. For the catalyst obtained in example 2, with increasing temperature, the conversion increases, but the selectivity begins to decrease at 120 ° C. Thus, the catalyst obtained in example 1 is superior to the catalyst in example 2 in the sum of the conversion and selectivity over the entire temperature range.

Example 5. Hydrogenation of liquid raw materials using the catalyst obtained in example 1 (life tests (catalyst life) with a travel time of 400 hours).

The process is carried out according to the method described in example 3. The difference is that the life tests are carried out at a constant temperature of 140 ° C, a volumetric feed rate of liquid feed 4 h ^-1 and a travel time of 400 hours. The results are presented in Fig. 6-8.

Example 6 (comparative). Hydrogenation of liquid raw materials using the catalyst obtained in example 2 (resource tests (catalyst life) with a travel time of 400 hours).

The process is carried out according to the method described in example 3. The difference is that the life tests are carried out using a narrow pore catalyst obtained according to the method described in example 2, at a constant temperature of 140 ° C and at a volumetric flow rate of liquid feed 4 hours ^-1 at a travel time within 400 hours. The results are presented in FIG. 6-8.

From the results of the life test experiments of Examples 5 and 6 and the corresponding FIG. 7 and 8 shows that for the catalyst obtained in example 2, there is a decrease in activity and selectivity during the hydrogenation process, which may be due to the closure of the pores of the catalyst due to the formation of oligomers on its surface (for example, as a result of the polycondensation of aldehydes, etc. . In this case, the catalyst obtained in example 1 is characterized by stability over the entire travel time, showing high activity and selectivity.

Claims (25)

1. A method of producing saturated aldehydes by contacting a liquid organic feed containing unsaturated aldehydes with hydrogen or a hydrogen-containing gas in the presence of a crust catalyst, which is palladium particles no larger than 6 nm in size, deposited as a layer with a thickness of not more than 150 microns on the outer surface of the porous granules alumina carrier, where the carrier has at least 60% pores with a diameter of 5 to 50 nm and where the hydrogenation is carried out at a volumetric feed rate of liquid raw materials of 1-4 h ^-1 . 2. The method according to claim 1, where the unsaturated aldehydes are linear or branched unsaturated aldehydes containing from 3 to 10 carbon atoms. 3. The method of claim 1, wherein the liquid feed further comprises 2-methylpropanal (isobutyric aldehyde), butanal (butyric aldehyde), 2-ethylhexenal, butyl isobutyl ether, diisobutyl ether, dibutyl ether, diisopropyl ketone, propyl isopropyl ketone, butyl butyl propyl ketone, dipropyl ketone, butyl propyl ketone isobutyl isobutyrate, butanol, butyl isobutyrate, 3-heptanone, isobutyl butyrate, butyl butyrate, butyl-2-ethylhexyl ether, 3-heptanol, 2-ethylhexanol, acetic acid, 2-ethylhexanoic acid. 4. The method according to p. 1, where the content of unsaturated aldehydes in a liquid organic medium should not exceed 20% wt. 5. The method according to p. 4, where the content of unsaturated aldehydes in a liquid organic medium should not exceed 10% wt. 6. The method according to p. 5, where the content of unsaturated aldehydes in a liquid organic medium should not exceed 7% wt. 7. The method according to p. 1, where the hydrogenation is carried out at a volumetric feed rate of liquid raw materials 1-3 h ^-1 . 8. The method according to p. 7, where the hydrogenation is carried out at a volumetric feed rate of liquid raw materials of 1.3 -1.8 h ^-1 . 9. The method according to p. 1, where the hydrogenation is carried out at a volumetric rate of hydrogen supply of 20-60 h ^-1 . 10. The method according to p. 9, where the hydrogenation is carried out at a volumetric rate of hydrogen supply of 20-50 h ^-1 . 11. The method according to p. 10, where the hydrogenation is carried out at a volumetric flow rate of hydrogen 28-42 h ^-1 . 12. The method according to p. 1, where the hydrogenation is carried out at a temperature of 50-180 ° C. 13. The method according to p. 12, where the hydrogenation is carried out at a temperature of 60-160 ° C. 14. The method according to p. 1, where the hydrogenation is carried out at a pressure of 0.1-7 MPa. 15. The method according to p. 14, where the hydrogenation is carried out at a pressure of 0.1-5 MPa. 16. The method according to p. 1, where the particle size of palladium is not more than 5 nm. 17. The method according to p. 16, where the particle size of palladium is from 2 to 3 nm. 18. The method of claim 1, wherein γ-Al ₂ O _{3 is} used as the porous alumina carrier. 19. The method according to p. 1, where the alumina carrier has at least 70% pores with a diameter of from 5 to 50 nm. 20. The method according to p. 19, where the alumina carrier has at least 75% of the pores with a diameter of from 5 to 50 nm. 21. The method according to p. 1, where palladium is deposited on the surface of the granules of an alumina carrier in an amount of 0.1-0.35% wt. 22. The method according to p. 21, where palladium is deposited on the surface of the granules of an alumina carrier in an amount of 0.15-0.22% by weight. 23. The method of claim 1, wherein the palladium particle layer thickness is 10 μm to 100 μm. 24. The method according to p. 23, where the thickness of the layer of palladium particles is from 30 microns to 85 microns. 25. The method according to p. 24. where the average thickness of the palladium particles is 44 microns.

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