RU2452563C1 - METHOD OF HYDRATING VEGETABLE OIL ON Pd-CONTAINING CATALYSTS - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to hydration of vegetable oils. Proposed method differs from known processes in that hydration id carries out on catalyst made up of crystallites of catalytically active palladium applied on carbon carrier surface with granule size of 1.0-5.0 nm, specific surface of 100-450 m²/g, mean pore size of at least 4 nm and ratio of basal-to-lateral faces of carbon lattice packs varying from 0.7 to 1.4.

EFFECT: reduced content of trans-isomers.

2 cl, 3 tbl, 10 ex

Description

The invention relates to the oil industry, in particular to a method for the hydrogenation of vegetable oils and fats, and can be used in food, perfumery, petrochemical and oil refining industries.

Known methods for the hydrogenation of oils and fats, as well as free fatty acids in the presence of catalysts based on transition metals Mo, W, Rh, Ir, Ru, Os, Ti, Re, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au , Zn, Ga, et al. (JI Gray and LF Russel, J. Am. Oil Chemists Soc. 56 (1979) 36-44). In this series, hydrogenation processes involving Ni-containing catalysts are most widely used. However, nickel systems are inferior in activity to catalysts based on noble metals (palladium, platinum, ruthenium), in the presence of which the necessary degree of hydrogenation of vegetable oils is achieved under milder conditions (at relatively low temperature and H ₂ pressure) and with less catalyst loading. Features and prospects of using noble metal catalysts in the hydrogenation of vegetable oils are described in reviews by PN Rylander, J. Am. Oil Chemists' Soc., 47 (1970) 482-486) and ES Jang, MY Jung, DB Min, Comprehensive reviews in food science and food safety, 1 (2005) 22-30. They noted, in particular, that in terms of activity in the hydrogenation of multiple C — C bonds of fatty acids, these metals are arranged in a series: Pd>Rh> Pt >>Ir> Ru >> Os, and in the formation of trans isomers in partially hydrogenated products: Pt <Ir <Ru ~ Rh <Pd. From the above data it follows that the use of active Pd catalysts leads to an increased content of trans isomers in the products of hydrogenation of oils, which are undesirable for food use.

The hydrogenation process involving such catalysts is carried out mainly in a batch mode using a suspended catalyst. The synthesis of salomas is carried out in the temperature range of 80-250 ° C at atmospheric or elevated pressures by supplying hydrogen to a suspension of the catalyst in oil. The content of trans isomers in the products obtained in this way exceeds 40 wt.% [RU 2105050, C11C 3/12, 02.20.1998].

The activity and selectivity of the platinum group metals deposited on an inorganic substrate in the hydrogenation of vegetable oils, fats and fatty acids depend on such factors as the composition of the catalyst, the type of carrier, the dispersion of the active component and its distribution over the catalyst grain, and also on the modes of the catalytic hydrogenation process.

The known method [US 4479902, C11C 3/11, 10.30.1984], in which the continuous hydrogenation of vegetable oils is carried out on Pd or Pt catalysts deposited on titanium dioxide, with a metal content of 0.1 wt.% At a temperature of 150-250 ° C, pressure hydrogen from atmospheric to 14 atm. The carrier is spherical granules or extrudates about 1.6 mm in size. A feature of the proposed method is the use of TiO ₂ as a carrier prepared by the deposition method, which ensures a sufficiently high specific surface area (130 m ² / g). The disadvantages of the method include a low reaction rate and a low degree of hydrogenation of double bonds. So, under optimal conditions, hydrogenation of soybean oil in a flow mode in the presence of 0.1% Pd / TiO ₂ leads to a product with an iodine number of 97.9.

In the patent [US 5234883, B01J 21/06, 08/10/1993] the curing of unsaturated fatty acids is carried out on a catalyst with a high palladium content (0.5-10 wt.%; Metal particle size 5-50 nm). The method is characterized by the use of a catalyst — TiO ₂ — as a carrier, obtained by molding primary particles of 20 nm in size with the following granule size distribution: <0.5 mm - 29%, 0.5-1.0 mm - 32%,> 1 mm - 39%. A feature of the method is the preparation of primary particles of the TiO ₂ support by the pyrogenic method, which leads to a lower specific surface (50 m ² / g). The low catalytic activity, apparently, is a consequence of the low specific surface area of the carrier.

The authors of the patent [FR 2175223, С07С 53/00, B01J 23/00, 10/19/1973] for a continuous method for the hydrogenation of unsaturated fatty acids offer a Pd / Al ₂ O ₃ catalyst with a palladium content of from 0.5 to 5.0 wt.%. The carrier is molded in the form of tablets (3.2 × 3.2 mm) or extrudates (1.6 × 3.2 mm). Hydrogenation conditions: temperature 93-232 ° С, hydrogen pressure from 6.9 to 69 atm, hydrogen / fatty acid ratio 1: 1-20: 1, supply of fatty acids 0.1-2 l / h per 1 liter of catalyst.

In the present patent, instead of γ-Al ₂ O ₃ , which can interact with fatty acids to give aluminum compounds that block the active sites of the metal, as well as polluting the catalyst and product, the authors propose using a more inert α-Al ₂ O ₃ as a carrier. To maintain satisfactory activity, hydrogenation involving Pd / α-Al ₂ O _{3 is} carried out at high hydrogen pressures (> 21 atm). Under such “harsh” conditions, due to the blocking of the active sites on the hydrophilic surface of alumina by the impurities of sodium soap and polar phosphatides contained in the oil, the catalyst is rapidly deactivated.

The closest technical solution to the claimed invention, which is taken as a prototype, is the method [RU 2260037, C11C 3/12, 09/10/2005] for producing food-grade salomas by liquid-phase hydrogenation of vegetable oils with hydrogen in the presence of a palladium catalyst supported on a carbon carrier. In this case, palladium nanocluster is used as a palladium catalyst, and nanocarbon cluster material is used as a carbon carrier. The process is carried out in the temperature range of 60-90 ° C. The invention allows the reuse of the catalyst, as well as to reduce the content of trans isomers in the hydrogenation products.

The disadvantage of this method is the low productivity of the reactor equipment, since in order to reduce the content of trans isomers in the products, the reaction temperature is reduced to 60-90 ° C; this reduces the rate of hydrogenation of vegetable oils. In particular, in example 1 of the description of the invention, it is noted that the process is carried out for 6 hours. Traditionally, the hydrogenation of oils is carried out at higher temperatures in less time: see patent RU 2105050, С11С 3/12, 02.20.1998 (examples 1 and 2) where the hydrogenation time at 170 ° C is 60 and 90 min, respectively. Thus, the implementation of the hydrogenation process of the prototype at low temperatures of 60-90 ° C and a significant duration of the process (see table, page 4), which is 4-6 hours, provides a reduced content of trans isomers in the hydrogenation products (31.1-32.4 %), however, the reactor productivity under these conditions is low.

The present invention solves the problem of efficient hydrogenation of vegetable oils in a flow mode, providing salomas with a trans-isomer content of less than 30 wt.%.

The present invention provides a method for hydrogenating vegetable oils in a flow mode on a stationary layer of a Pd-containing catalyst, which, while maintaining the iodine number (including), reduces the content of trans isomers in the resulting salomas to less than 30 wt.%.

The problem is solved by carrying out the hydrogenation process in a continuous mode on a stationary catalyst bed at a temperature of 140-190 ° C, a hydrogen pressure of 2-8 bar and a feed rate of 3-10 kg / (kg _ct · h). In this case, in the lower part of the reactor, hydrogen and oil are mixed, and the resulting mixture is passed through the catalyst bed from the bottom up.

Hydrogenations are carried out on a catalyst, which is a crystallite of catalytically active palladium deposited on the surface of a carbon carrier having a ratio of the areas of the basal and side faces of the carbon mesh packets from 0.7 to 1.4.

Carriers are carbon materials having a granule size of 1.0-5.0 mm, a specific surface area of 100-450 m ² / g and an average pore size of at least 4 nm.

Distinctive features of the present invention in comparison with the prototype are:

1) hydrogenation of vegetable oils in a continuous flow mode on a stationary catalyst bed;

2) the use as a catalyst of crystallites of catalytically active palladium deposited on the surface of a carbon material, which is used as a carbon material, characterized by a substructural parameter R (the ratio of the areas of the basal and side faces of the carbon mesh packets) from 0.7 to 1.4, having a grain size of 1.0-5.0 mm, specific surface area 100-450 m ² / g and average pore size not less than 4 nm.

3) conducting the process of hydrogenation of vegetable oils at a temperature of 140-190 ° C, a hydrogen pressure of 2-8 bar and a feed rate of 3-10 kg / (kg _ct · h).

The following are examples 1-10, illustrating the hydrogenation process according to the proposed method.

Example 9 is given for comparison, and example 10 is given as a prototype.

The main characteristics of the porous carbon materials used for the preparation of Pd / C catalysts are shown in Table 1. Table 2 shows the characteristics of the catalysts and hydrogenation modes of sunflower oil, corresponding to the examples below. In all examples, sunflower oil with y.h. 131.7 g I _2/100 g and the fatty acid composition specified in Table 3.

Example 1

2.0 g of catalyst 0.5 wt.% Pd / C2 (fr. 2.0-3.0 mm), pre-mixed with a quartz sample of 15-17.5 cm ^3, are loaded into a stainless steel tubular reactor (internal diameter - 20 mm). The reactor is hermetically connected to the system. The system is purged with nitrogen, then with hydrogen, and the hydrogen pressure is increased to 3 bar. On the control panel, the required reaction temperature is set (140 ° C) and the reactor is heated. Sunflower oil is loaded into a container for raw materials. Before dosing into the reactor, the oil is heated to 60 ° C. The hydrogenation process is carried out at a hydrogen feed of 200 cm ³ / min, a sample for analysis of product quality are taken every 2-3 hours. During the experiment on feed flow rate is controlled so that the iodine value of the product obtained corresponded to 70-75 g I _2/100 g To ensure such a regime for 142 hours of the experiment, the feedstock consumption was reduced from 10 to 7 g / h.

The fatty acid composition of the resulting salomas is determined in accordance with GOST R5148399, the content of trans isomers is determined in accordance with GOST R55100-2003, the iodine number is determined according to the standard procedure (Guide to Research Methods, Technological Control and Accounting for Production in the Oil and Fat Industry, Leningrad, 1982, vol. 1, s .908).

The characteristics of the averaged samples of the product obtained in this way for 142 hours are shown in table 3.

Examples 2-8.

The methodology for the process of hydrogenation of sunflower oil corresponds to example 1; 4 types of Pd / C catalyst are used, which differ in the content of the active component, fractional composition and texture characteristics of the support; the conditions of the hydrogenation process vary. The properties of the catalysts and the parameters of the hydrogenation process in examples 2-8 are shown in table 2, and the characteristics of the resulting products are shown in table 3.

Example 9

The tests of the catalyst are carried out in a thermostatically controlled autoclave (Parr reactor) with a volume of 300 ml equipped with a magnetic stirrer. For this, 50 mg of catalyst 1.0 wt.% Pd / C4 (FR 100-200 microns) and 50 g of sunflower oil are introduced into the reactor. The system is purged with nitrogen, then the nitrogen is displaced with hydrogen. The process is carried out at a pressure of 3 bar and a temperature of 140 ° C, the stirring speed of the reaction mass is 1000 rpm. The duration of the control by volume of hydrogen so that the iodine value of the resulting product is in the range 70-75 g I _2/100 g catalyst was then separated on a filter and analyzed physico-chemical parameters of hydrogenated fat.

Characteristics of the obtained product with y.ch. 71.3 g I _2/100 g are shown in Table 3.

Example 10

Testing of the catalyst is carried out as in example 9. In this case, 10 mg of catalyst 0.4 wt.% Pd / C3 (FR <5 μm) is added to the reactor.

Characteristics of the obtained product with y.ch. 72.4 g I _2/100 g are shown in Table 3.

As follows from the above examples and tables, the present invention allows to solve the problem of efficient hydrogenation of vegetable oils in a flow mode and to ensure the production of salomas with the content of trans isomers below 30 wt.%.

Table 1 Fractional composition, texture and substructural characteristics of porous carbon materials Sample Texture properties ¹⁾ Substructural characteristics ²⁾ Fraction S _beats V _∑ V _mi L L _a L _c R No. m ² / g with ³ / g cm ³ / g nm nm nm - mm C1 449 0.86 0.00 7.7 4.5 3.8 1.4 1.0-2.0 C2 402 0.68 0.00 6.8 4.0 3.5 1.3 2.0-3.0 Sz 384 0.74 0.00 7.7 3.5 3.6 1.0 <0.005 C4 359 0.53 0.00 5.9 3.5 4.0 0.8 0.10-0.20 C5 303 0.32 0.00 4.2 3.4 3.8 0.8 3.0-5.0 C6 112 0.50 0.00 17.9 3.4 4.0 0.7 2.0-3.0

^{1) The} texture characteristics of carbon carriers were determined from data on nitrogen adsorption at 77K using an ASAP 2400 automatic volumetric setup (Micrometritics).

S _beats (m ² / g) - specific surface area by BET. The surface area was calculated on the site of the isotherm, where P / P ₀ = 0.05-0.20; the area of the nitrogen molecule in the filled monomolecular layer was taken equal to ω = 0.162 nm ² ;

V _∑ (cm ³ / g) - total pore volume (pore volume less than 5000 Å). Calculated from nitrogen adsorption at P / P ₀ = 0.98.

V _mi (cm ³ / g) is the volume of micropores. They calculated using the comparative method on the isotherm sections corresponding to the region between micropore filling and the onset of capillary condensation; the value of V _mi corresponds to the total volume of ultramicro- and supermicropores, that is, the volume of micropores smaller than 20 Å;

L (nm) is the average mesopore size calculated by the BET model as L = 4V _∑ / S _BET .

. ^{2) The} substructural characteristics of the coals were determined by X-ray diffraction (URD-6 diffractometer, Cu K _α radiation, graphite monochromator). The thickness of the carbon mesh packet in the direction perpendicular to the mesh (L _c ) was determined by the broadening of the line 002, and in the direction along these grids (L _a ) by the broadening of line 10. The dimensionless substructural parameter R reflects the ratio of the areas of the basal and lateral faces of the carbon mesh packets in UN calculated as

.

table 2 The composition of the catalysts and hydrogenation conditions of sunflower oil Example No. Catalyst Hydrogenation Process Parameters Catalyst mass PH ₂ , bar T, ° C Consumption H ₂ cm ³ / min Feed rate, kg / (kg _ct · h) Duration
h Flow hydrogenation on a stationary catalyst bed one 0.5% Pd / C2 2.0 g 3 140 200 5.0-3.5 142 2 1.0% Pd / C2 1.5 g 5 140 200 8.0-6.7 29th 3 0.5% Pd / C2 2.0 g 7 140 200 6.5-6.0 12 four 0.5% Pd / C6 2.0 g 3 180 200 6.2-6.0 8 5 0.5% Pd / C2 3.0 g 3 140 200 4.3-3.3 82 6 0.5% Pd / C1 2.0 g 3 140 200 8.5-7.5 thirty 7 0.5% Pd / C2 2.0 g 8 190 200 10.0-9.0 fourteen 8 0.3% Pd / C5 5.0 g 3 140 200 2.2-2.0 eleven Hydrogenation in static mode (reactor "Parr") 9 ¹⁾ 1.0% Pd / C4 50 mg 3 140 w ³⁾ = 1000 rpm 10 ²⁾ 0.4% Pd / C3 10 mg 3 140 w = 1000 rpm ^{1) a} comparative example; ²⁾ prototype; ³⁾ w is the intensity of mixing.

Table 3 Properties of salomas obtained by hydrogenation of sunflower oil on palladium catalysts Example No. Oil / catalyst Iodine number Fatty acid composition, wt.% Trans isomers, wt.% S12: 0 S14: 0 S16: 0 C18: 0 C18: l S18: 2 - Sunflower seed oil 131.7 0.08 0.13 7.21 4.69 21.43 65.11 0.4 one 0.5% Pd / C2 71.3 0.10 0.16 7.81 21.72 55.98 13.16 28.5 2 1.0% Pd / C2 71.7 0.46 0.33 8.49 25.43 45.09 18.32 20.5 3 0.5% Pd / C2 71.2 0.09 0.12 7.79 28.83 42.21 19.83 18.4 four 0.5% Pd / C6 71.2 0.08 0.15 7.79 27.47 44.82 18.62 23.0 5 0.5% Pd / C2 73.1 0.02 0.09 7.04 27.59 40.94 07/23 14.8 6 0.5% Pd / C1 70.7 0.08 0.76 9.64 20.18 50.59 13.74 25.3 7 0.5% Pd / C2 74.1 0.09 0.11 7.18 03/17 63.11 11.23 22.1 8 0.3% Pd / C5 72.8 0.10 0.13 7.80 24.35 48.99 17.47 28.3 9 1.0% Pd / C4 71.3 0.01 0.08 6.45 12.65 76.80 2.89 46.5 10 0.4% Pd / C3 72.4 0.05 0.06 6.53 12.30 74.90 4.83 43.1

Claims (2)

1. The method of hydrogenation of vegetable oils on stationary palladium-containing catalysts, characterized in that the hydrogenation is carried out on a catalyst comprising crystallites of catalytically active palladium deposited on the surface of a carbon carrier having a granule size of 1.0-5.0 mm, a specific surface of 100-450 m ² / g, and the average pore size of not less than 4 nm, and the ratio of the areas of the basal and lateral faces of the packages of carbon networks from 0.7 to 1.4. 2. The method according to claim 1, characterized in that the hydrogenation is carried out on a stationary catalyst bed at a temperature of 140-190 ° C, a hydrogen pressure of 2-8 bar and a feed rate of 3-10 kg / (kg _ct · h).