DD269161A1 - METHOD FOR PRODUCING HARDENED FATS - Google Patents

Abstract

The invention relates to a process for the fatty hardening of improved Ni / SiO 2 catalysts. The catalyst precursor is reduced at lower temperatures and shorter reduction times by passing the reducing hydrogen over hydrogenation-active molding before entering the catalyst bed to be reduced. The catalyst precursor has a pore volume of at least 1 cm 3 / g and a certain composition.

Description

The invention relates to a process for the preparation of hydrogenated fats from unsaturated natural oil with Vc using a specially suitable Ni / SiOj catalyst. The hydrogenated fats are especially suitable as high quality food products for food.

Characterization of the known technical solutions

The fat hardening is world-wide operated. The fat hardening is achieved by hydrogenation of the olefinic double bonds contained in the fatty acid molecule and / or rearrangement of remaining olefinic double bonds in the trans form. Predominantly, work is carried out in discontinuously operating plants at hydrogen pressures of 0.1 to 1.0 MPa and temperatures of 410 to 490K. As curing catalysts almost exclusively in the reaction medium suspendieite nickel catalysts are used.

The cure process is influenced by a variety of factors. It is generally true that with low catalyst inserts and thus slower curing, fatty acids having several double bonds in the molecule are hydrogenated (selective hydrogenation), while an increase in the catalyst concentration, the hydrogenation temperature and the hydrogen pressure bring about an unselective hydrogenation. Increasing the temperature also causes an increase in trans formation during curing. The catalyst used in addition to the catalyst activity in particular by catalyst handles, üie in the natural oils are always present in different amounts, influenced.

In comparison of the curing properties of different catalysts therefore consistently oils of uniform nature are required. Despite a large number of proposals for optimum process management using improved catalysts, the catalyst costs still represent a very high proportion of hydrogenation costs. The main advantage of improving the fat hardening processes is, therefore, the development of more active and more toxic catalysts uniform oil charge, both factors are inseparable and manifest in an overall higher activity.

These catalysts are prepared by nickel salts are precipitated together with the carrier from aqueous solution or the carrier is wholly or partially suspended before the precipitation in the precipitation solution. Optionally, further activating metal components are precipitated with the nickel salts. The precipitate is then separated off, washed, dried and partially or thermally treated so he ^r jestellte catalyst precursor is usually reduced with hydrogen, and then entered to the air stabilization of suitable protective materials or freed and for a precise be observed program of dissolved hydrogen partially oxidized , As a hydrogenation-active component of Ni / SiO ₂ catalysts, the surface of the metallic nickel acts. Crucial for the catalytic activity of Ni / SiGyKatalysatoren is therefore the formation of a large metallic nickel surface in the catalyst production. The formation of a large metallic nickel surface is influenced by a number of factors in the production process of the catalysts, such as precipitation conditions, composition and the like. An important step in the production of nickel / SiGy hydrogenation catalysts is the conversion of the nickel from the oxide form into the metallic form. In the Redutoion of oxidic catalyst. Pre-stage, the catalytic activity of Ni / SiO ₂ catalysts is significantly influenced and finally adjusted.

Unfavorable reduction conditions lead to less active catalysts also from catalyst precursors, which actually have all the prerequisites for a high catalytic activity. The main reason for the insufficient activity is then usually an insufficient degree of Recluktionsgrad (proportion of metallic nickel in the total nickel content of the catalyst) or damage caused by excessive temperatures. The reduced catalysts in these cases have too low a proportion of metallic nickel and catalytically active metallic nickel surface.

Technically, the reduction is usually carried out with a reducing gas at temperatures up to 900K. By known methods, a recirculating reducing gas (usually hydrogen) is passed through a bed of unreduced catalyst.

üio results of the reduction are boi this '' experienced however not satisfiyond. It must hohh high reduction temperatures and long reduction zooms have been complied with in order to achieve sufficient levels of reduction. In order to obtain a sufficient concentration of hydrogen in the Kroislaufgas constantly Toil dos Gasos from ^ okreist and must be replaced by roeinen hydrogen. However, the costs for the reduction according to this method are very high, so that the catalysts thus reduced have only an average activity. In order to improve the effectiveness of the reduction of Ni / SiOj catalysts, it has been proposed to introduce reduction-promoting promoters, such as platinum, palladium or silver, into the catalyst precursor (SU-PS 1142162). Although these additives allow the reduction temperature to be lowered and the reduction times to be shortened, there is a simultaneous increase in the cost of the catalyst and a decrease in the catalytic activity, and to lower the reduction temperature and the reduction time, the catalysts have been proposed in part at low temperatures and subsequently mix components (for example olefins or aromatic hydrocarbons) which react with the hydrogen with the evolution of heat, by means of this Exothermic heating of the Katalysatorbottes and thereby a substantial reduction of the nickel is achieved (GB-PS 1 574 389, In order to start the exothermic reaction of the added reactants, a layer of already reduced catalyst can be applied to the catalyst bed to be reduced (German Offenlegungsschrift 3,415,509).

All these methods have in common that it is possible to reduce the temperature of the recycle gas at the entrance of the Reduktionsbottes with high equipment cost (metering and evaporation of liquid additives, separation of the reaction products from the cycle gas), the reduction temperature and thus jine possible thermal damage to the catalyst but unabated high is. The reduction of the catalyst in the bed is also not uniform, since in the bed strong temperature gradients are inevitable and the control of the exothermic reaction causes great problems.

Object of the invention

The aim of the invention is to develop a process for fat curing, which makes it possible to achieve the same degree of cure with reduced catalyst use as with previously known methods.

Explanation of the essence of the invention

This object is achieved by carrying out the fat-hardening at temperatures of 410-490 K and hydrogen pressures of 0.1-1 MPa with inventively improved suspended Ni / SiO ₂ catalysts. The reaction is carried out batchwise in the stirred autoclave or continuously in stirred tank cascades. The catalyst used according to the invention is characterized in that it contains at least 40% by weight of nickel and at least 10% by weight of SiO ₂ in the unreduced state, and a mass ratio of nickel to carbon chemically bound in nickel salts of carbonaceous acids having a maximum of 2 carbon atoms in the molecule. It has a pore volume of at least 1.0cm ³ / rj and a grain size of 3-10mm in its unreduced state.

It is important for the activity and selectivity of the catalyst used according to the invention that the hydrogen stream used for the reduction of the catalyst precursors is introduced through a bed of moldings before entering the catalyst precursor, and the outer surface is treated with catalytically hydrogenation-active metals of the 8th subgroup of the catalyst Periodic table of elements is occupied. The ratio of the volume of this hydrogenation-active shaped bed to the volume of the catalyst precursor bed to be reduced must be 1 to 4 to 8. It is of crucial importance for the activity of the catalyst used according to the invention that the shaped bed has a high catalytic hydrogenation activity. This activity is achieved in particular by applying to the moldings platinum or palladium in concentrations of from 0.01% by weight to about 0.5% by weight, subsequently reducing and / or nickel in reduced and free-flowing form in quantities from 1 to 30 Ma .-% added. The hydrogenation-active components must be arranged on the outer surface of the molded body. It is advantageous if the shaped-body packing is arranged as close as possible to the bed to be reduced. Essential for the catalyst used in the invention is that in the catalyst precursor, a sufficiently high proportion of the nickel contained in carbonaceous acids such. As formic acid or oxalic acid is bound. The reduction temperatures must be above 500K. By maintaining the conditions described, a substantial reduction of the c < required reduction temperature and reduction time is achieved. In addition, since deposits of impurities from the additives or coking of the catalyst surface are excluded, catalysts are obtained with very high catalytic activity.

The additional costs for the shaped bed in front of the reduction bed are low because the bed of shaped bed can be used for a large number of reduction cycles.

embodiments

The determination of the boundary conditions for the preparation of the catalyst used according to the invention was carried out in extensive series of experiments by means of the methods of statistical experimental design and evaluation. The following examples show some characteristic results. For all examples a uniform oil charge was used.

example 1

Rape oil with an iodine value of 104 is hardened in a stirred autoclave on a Ni / SiOj catalyst. The Ni / SiO 2 catalyst is characterized by having a nickel content of 36.2 mass% and an SiO 2 content of 9.1 mass% in the unreduced state, and a 121: 1 mass ratio of nickel to carbon, a pore volume of 0.38 cmVg and a grain size over 10 mm bositzt. It is reduced in the water stream, then the hydrogen is completely desorbed with a stream of nitrogen from the catalyst and the catalyst after cooling to 353K in a nitrogen stream with an oxygen content of 1 vol .-% stabilized. After milling to a particle size <32 pm, the catalyst is used in an autoclave for hydrogenation.

Table 1 summarizes the catalyst reductant and fat hardening conditions, as well as the residual iodine counts of the hydrogenated fat.

Table 1 test no. Catalyst reduction temperature reduction time (K) (h) 1 643 5 2 643 5 3 603 10 4 603 10 Hydrogenation temperature Hydrogen pressure Catalyst concentration Curing time (K) (MPa) (%) (h) 453 0.15 0.05 1 423 0.15 0.05 1 453 0.15 0.08 1 423 0.15 0.08 1 residual iodine 63 70 65 73

Example 2 (comparative example)

Rape oil with an iodine value of 104 is hardened in a stirred autoclave on a Ni / SiGy catalyst. The catalyst is characterized by having a nickel content of 43.6% by mass and an SiO ₂ content of 10.7% by mass and a weight ratio of nickel to carbon of 28: 1, a pore volume of 1 in the unreduced state. 19cm ³ / gundineKorngiöße from 3 to 5 mm has. It is reduced in the hydrogen stream, then the hydrogen completely desorbed in a nitrogen stream in nitrogen from the catalyst and the catalyst after cooling to 353 K in a nitrogen stream with an oxygen content of 1 vol .-% stabilisieit. After milling to a grain size <32μπι the catalyst is used for hydrogenation.

Table 2 summarizes the catalyst regeneration and the fat hardening conditions as well as the residual iodine numbers achieved.

Table 2 Experiment No. (K) (h) 5 6 Catalyst reduction temperature reduction time (K) (MPa) (%) (h) 643 5 603 10 Cure temperature Hydrogen pressure Catalyst concentration Curing time 453 0.15 0.05 1 453 0.15 0.05 1

Residual iodine number 61 62

The comparison with Table 1 shows that the catalyst with the higher nickel, and SiO ₂ content of. Example 2, although a slightly higher activity than that used in Example 1, but not yet achieved a significant reduction in the residual iodine numbers compared to Example 1.

Example 3 (comparative example)

Rape oil with an iodine value of 104 is hardened in a stirred autoclave on a Ni / SiGy catalyst. The catalyst is characterized by having a nickel content of 36.2 mass% and an SiO ₂ content of 9.1 mass% and a weight ratio of nickel to carbon of 121: 1, a pore volume of, in the unreduced state 0,38cnv7g and has a grain size over 10mm. It is reduced in the effluent stream, which is passed through a packed bed having a platinum content of 0.02% at the reduction temperature immediately before catalyst reduction. The ratio of the shaped bed to the volume of the catalyst bed is 1: 4.

Table 3 summarizes the catalyst reduction and the cure conditions as well as the residual iodine numbers achieved.

Table) Experiment no. (K) (h) 7 8th 9 Catalyst reduction temperature reduction time (K) (MPa) (%) (h) 643 5 643 603 10 Fat hardening temperature Hydrogen pressure Catalyst concentration Hardening time 453 0.15 0.05 1 423 0.15 0.08 1 453 0.15 0.05 1

Residual iodine number 63 71 66

The above values show that the degree of hydrogenation of the resulting fat is not substantially different from that in Examples 1 and 2.

Example 4 (Inventive Example)

Rape oil with an iodine value of 104 is cured in a stirred autoclave on a Ni / Si0 ₂ catalyst. The catalyst is characterized by having in the unreduced state a nickel content of <13.6Ma .-% and a SiO ₂ -GeInIt of 10.7 M a .-% and a mass ratio of nickel to carbon of 38: 1, a Pore volume of 1.19cm ³ / g and a grain size of 3 to imin busitzt. It is reduced in the hydrogen stream, which is passed at the llecluktionstemperatur immediately before the catalyst reduction through a shaped bed with a palladium content of 0.01 Ma. ·%. The volume of the molded body bulk to the volume of the catalyst bed is 1: 4. After ReJuktion the hydrogen is completely desorbed with a stream of nitrogen from the catalyst and the catalyst after cooling to 353K in a nitrogen stream with an oxygen content of 1 vol .-% stabilized. After milling to a particle size < 32 pm, the catalyst is used for hydrogenation.

Table 2 summarizes the catalyst reduction and the fat hardening conditions as well as the outstanding residual iodine numbers.

Table 4 Experiment no. (K) (h) 10 11 12 13 Catalyst reduction temperature reduction time (K) (MPa) (%) (h) 603 5 603 5 603 5 553 10 Fat hardening temperature Hydrogen pressure Catalyst concentrate curing time 453 0.15 0.05 1 453 0.15 0.02 1 423 0.15 0.03 1 453 0.15 0.05 1

Residual iodine number 42 66 62 50

In comparison of Table 4 with Tables 1-3 shows that with the catalyst used in the invention significantly higher degrees of hydrogenation or with significantly reduced catalyst use same hydrogenation levels are achieved as with higher amounts of known catalysts.

Example 5 Example According to the Invention

Rübö! with an iodine number of 104 is cured in a stirred autoclave on a Ni / SiO ₂ -Kata! ysator. The catalyst is characterized by having a nickel content of 40.7 mass% and a SiO 2 content of 16.6 mass% in the unreduced state and a mass ratio of nickel to carbon of 96: 1, a pore volume of 1.03 cm ³ / g and a grain size of 3 to 5mm has. It is reduced in the hydrogen stream, which is passed at the reduction temperature immediately before the catalyst reduction through a shaped bed with a nickel content of 15Ma .-%. The volume of the shaped bed to the volume of the catalyst bed is 1: 8. After the reduction, the hydrogen is completely desorbed from the catalyst with a nitrogen stream and the catalyst, after cooling to 353K, is stabilized in a stream of nitrogen with an oxygen content of 1% by volume. After milling to a particle size <32 pm, the catalyst is used for hydrogenation.

In Table 5, the catalyst reduction and the cure conditions are set forth.

Table 5 Experiment No. (K) (h) 14 15 Catalyst reduction temperature reduction time (K) (MPa) (%) (l ·) 603 5 603 5 Cure temperature Hydrogen pressure Catalyst concentration Curing time. 453 0.15 0.05 1 453 0.15 0.03 1

Residual iodine number 47 67

Comparison of Table 5 with Tables 1-3 shows that with the catalyst employed according to the invention, significantly higher degrees of hydrogenation or, with a significantly reduced amount of catalyst, the same degree of hydrogenation as with higher amounts of known catalysts are achieved ,

Example 6 (example according to the invention)

Rape oil with an iodine value of 104 is hardened in a stirred autoclave anoi.iom Ni / SiO ₂ catalyst. The catalyst is characterized in that in or unreduzi "i th state has a nickel content of 48,9Ma .-% and a SiO, content of 10,2Ma ^_1-0 AsOWJeOiP Massoverhältnis of nickel to Kohlenstolf of 6: 1, a pore volume of 1.38 cm ³ / gundoinu grain size from u to 10 mm It is passed in the hydrogen stream, in the reduction stream immediately before catalyst reduction through a molded article, with a platinum content of 0.01 mass% and a nickel content of 2 mass% The volume of the shaped bed to the volume of the catalyst bed is 1: 7 After dor reduction, the Wasi erstoff with a nitrogen flow completely dosorbiort from the catalyst and the catalyst after cooling to 353KiDr ^- IUMi nitrogen flow with an oxygen content of 1 vol. % stabilized After grinding to a grain size <32 .mu.m, the catalyst is used for the hydrogenation.

In Table 6, s'-id summarizes the catalyst reduction and the fat curing conditions as well as the achieved R cstjodzahicn.

Table 6 Experiment no. (K) (h) 16 17 Catalyst reduction temperature reduction time (K) (MPa) (% »(h) 603 5 603 5 Fat hardening temporary hydrogen pressure Kaialysatorkonzentration cure time 453 0.15 0.05 1 543 0.15 0.03 1

Residual iodine number 44 62

Comparison of Table 1 with Tables 1-3 shows that with the catalyst used according to the invention substantially higher degrees of hydrogenation or with significantly reduced catalyst charge / hydrogen ratios are achieved, as with higher amounts of known catalysts.

Claims (1)

Process for the curing of natural oils on nickel / silicon dioxide catalysts at temperatures of 393K to 493K, hydrogen pressures of 0.1 to 1 MPa and hydrogenation times of 1 to 5 hours, characterized in that the catalyst used before the reduction of a nickel content of at least 40Ma % and an SiO ₂ content of at least 10 mass% and a mass ratio of nickel to carbon of at most 100: 1, wherein the carbon is chemically bound in nickel salts of carbonic acids having a maximum of 2 carbon atoms in the molecule, the unreduced catalyst Pore volume of at least 1.0cm ³ / g and a grain size of 3 to 10mm, the unreduced catalyst is reduced with a Wasserst '^ fstrom at 550 to 610K, the immediately before entering the Katalysatorschüttuna at the reduction temperature by a bed of moldings, which has a platinum or palladium content of 0.01 to 0.5% by mass and / or a pitch lgehait from 1 to 30Ma .-%, is conducted, the ratio of the shaped body bed to the catalyst bed 1.4 to 8 and the catalyst for the curing in amounts of 0.012 to 0.08 wt .-% is used. Field of application of the invention