KR910004885B1 - Process for the production of edible oils - Google Patents

Abstract

No content.

Description

How to prepare cooking oil

1 is a schematic view showing a conventional batch hydrogenation reactor.

2 is a plot showing the catalysis of reaction time in a conventional hydrogenation reactor using reformer hydrogen and liquid hydrogen.

3 is a plot showing the conversion of product as temperature function for irreversible reaction.

The present invention relates to a method for producing hydrogenated cooking oil.

Various processes are known in the art for the hydrogenation of unsaturated oils to produce edible oils of suitable and high selectivity, and the literature relating to them is as follows.

U.S. Patent No. 4,584,139 describes an improved single hydrogenation catalyst and process using the same for hydrogenating animal and vegetable oils, the catalyst comprising Raney) metal alloy surface layer, which is mainly derived outside the crystalline precursor of the tacky beta structure. The catalyst can be applied to both continuous and batch hydrogenation, showing improved activity, improved triene to diene selectivity and low isomerization rate.

Hydrotreated oils exhibited lower linolenic and stearic acid content, lower trans-isomer percentages and lower melting points compared to commercial products with equivalent iodine values.

U.S. Patent 4,666,635 describes a catalytic isoaddition process of unsaturated compounds using nickel-silica catalysts. The catalyst comprises agglomerates having an average particle size of 2 to 100 μm, the agglomerates having an outer surface free of at least 60% carrier particles.

US Pat. No. 4,307,026 describes a hydrogenation process of unsaturated fatty acid derivatives containing fatty acids having two or more double bonds in addition to fatty acids having two double bonds, the unsaturated fatty acid derivatives being ethylenediamine or homologues and / or Or a palladium, platinum or rhodium catalyst treated with the derivative and hydrogenated at a temperature of -20 ° C to 100 ° C. The hydrogenation process is very selective and little isomerization to trans-fatty acids occurs.

For example, in the process of hydrogenating soybean oil to 2% linolenic acid content, the linolenic acid content is reduced to only 45-52%. Under the same conditions, the untreated catalyst reduces the content of linolenic acid to about 35%.

U.S. Patent No. 4,385,001 discloses that cooking oil can be selectively hydrogenated using a cobalt catalyst of zero supported catalytic activity. If cobalt is supported on alumina, the selectivity of hydrogenation is substantially independent of the nature of the alumina. The process is sufficiently selective that the continuous hydrogenation process can be carried out with the same selectivity obtained in a batch process using a conventional catalyst.

U.S. Patent No. 4,424,163 describes that it is possible to selectively reduce fatty substances by using a catalyst composed mainly of zero valent nickel dispersed on a strong metal, a carrier exhibiting carrier interaction. A particularly preferred catalyst is nickel, which is dispersed in titania and then activated in hydrogen at temperatures above about 325 ° C. The catalyst is sufficiently selective that a fixed bed catalyst can be used to continuously reduce fatty matter.

U.S. Patent No. 4,424,162 describes the hydrogenation of fatty materials using a zero-valent platinum group metal supported on an alpha (α) -alumina that is selective over a metal supported on a porous alumina. Particular preference is given to alpha-alumina having a surface area of about 5 m 2 / g or less, a micropore volume of about 0.05 ml / g or less and a large pore volume of about 0.25 ml / g or less. Using these methods, continuous hydrogenation based on a fixed bed process is sufficiently selective and can be performed commercially.

US Pat. No. 4,479,902 describes a method for selectively reducing fatty matter using a catalyst comprising zero value platinum or palladium dispersed on a carrier exhibiting strong metal-carrier interactions. Particularly preferred catalysts are platinum or palladium catalysts, which are dispersed in titania and then activated in hydrogen at temperatures above about 325 ° C. The catalyst is sufficiently selective that it is possible to continuously reduce the fatty matter using the catalyst in the fixed bed.

U.S. Patent No. 4,510,092 describes a method for continuously hydrogenating fatty materials on a fixed catalyst bed using noble nickel on alpha-alumina. Partial hydrogenation until the iodine value (IV) is about 110 can be successfully performed using alpha-alumina having a surface area of about 5 m 2 / g or less and SFI can be used for the purpose product. To provide the product.

US Pat. No. 4,510,091 allows selective continuous hydrogenation of fatty substances to be carried out on a fixed bed of zero nickel on an alpha-alumina carrier. The selectivity of this continuous hydrogenation can be improved by performing hydrogenation in an upflow fashion. When soybean oil is used, hydrogenation continues until the iodine number (IV) is about 110, where the partially hydrogenated soybean oil can be compared to the solids content obtained from batch hydrogenation using a conventional commercial catalyst at a solids content. have.

U. S. Patent No. 4,547, 319, supported, phosphoric acid-modified zero valent nickel catalysts show improved selectivity in hydrogenation of fatty materials. The increased catalyst of this catalyst continuously reduces the fatty matter with selectivity comparable to the selectivity observed in batch reduction using conventional nickel catalysts.

Hydrogenation to high selectivity cooking oil products is carried out by utilizing catalyst loading, temperature control, liquid hydrogen and hydrogen flow control. According to the invention, the maximum product conversion is achieved by raising the reactor temperature to the maximum working temperature as soon as possible, followed by evaporation while maintaining the reactor isothermally at zero maximum temperature until the desired iodine value (IV) is obtained. Obtained by injecting liquid hydrogen into the reactor.

In order to understand the present invention, it is important to understand the current situation of hydrogenation processes and the problems encountered in the implementation of these processes. Hydrogenation is the process of adding hydrogen to the ethylene bond present in the fatty acid having an unsaturated double bond in the presence of a metal catalyst (eg nickel).

Most commercial hydrogenation processes are carried out as a batch operation. 1 is a typical batch hydrogenation reactor. Batch reactors also consist of a large cylindrical pressure vessel equipped with a stirrer, heating and cooling coils. The parameters that need to be adjusted to produce a specific target product are catalyst type as well as temperature, agitation, pressure and catalyst concentration.

Hydrophobic water is fed to the vessel through a sparge ring at the lower position of the reaction vessel. Hydroxides react with hydrogen fed into the liquid phase and a double bond unsaturated oil. The hydrogen consumption rate depends on the working conditions of the phone. Hydrogen that does not react as a liquid phase passes into the headspace of the reactor, where hydrogen is remixed with oil for further reaction.

The pressure in the reactor is regulated and maintained by an outlet valve in the gas headspace, which is typically opened by hand to relieve high pressure. In practice, in order to prevent an increase in inert fraction in the headspace, the reactor discharges the inert fraction throughout the reaction, where some gaseous hydrogen is lost. This loss of hydrogen typically represents a total consumption of about 20-30%.

Most hydrogenated natural gas reforms produce their own hydrogen. Conventional reformer systems built before 1980 typically have MEA and methanation cleaning systems. More recent reformer systems use pressure swing adsorption (PSA) to remove impurities.

The purity of the reformer hydrogen is normally very high, from 97 to 99%.

However, small amounts of impurities, such as CO, O, sulfur compounds, etc., are still present in the gas. These contaminants react with nickel and cause the catalyst to lose activity. Carbon monoxide and oxygen react with nickel (Ni) to form NiCO and NiO, respectively. However, this extends the induction period. NiCO is reversible at reaction temperatures above 420 ° F, but this temperature is outside the temperature limits of most cooking oil hydrogenation processes. Sulfur compounds (eg H ₂ S, SO ₂ ) react irreversibly with Ni. Hydrogen obtained from a liquid hydrogen source (LHS) does not lose the activity of the catalyst because it is virtually free of these contaminants. A comparison of the reformer and the liquid hydrogen raw material is shown in the table below.

When the hydrogenation apparatus is run from reformer hydrogen to produce hydrogen from the LHY source, the rate of inactivation of the catalyst is greatly reduced due to purity. Unfortunately, since the hydrogenation reaction is exothermic, high catalysis (activity) increases the temperature of the reactor which is detrimental to the product specification. If the catalyst load is arbitrarily reduced and / or other working variables are not adjusted accordingly, the initial reactivity is too low, and the product breakdown will be difficult.

The present invention provides the necessary interrelationships to maximize and control the conversion from reformer hydrogen to LHY source hydrogen.

In addition, the present invention provides the necessary technology to maximize the use of LHY during hydrogenation by correlating the effects of catalyst loading, starting temperature, maximum allowable temperature, and hydrogen consumption rate.

The hydrogenation reaction of the cooking oil can be represented by the following reactor.

As shown in FIG. 2, when reformer H ₂ is used (line AD), catalysis decreases rapidly. It has been demonstrated that the use of LHY source hydrogen with few pollutants does not significantly reduce the activity of the catalyst. In order to obtain the same catalytic activity (action) at point C with reformer H ₂ , a large amount of catalyst must be used (line BC).

Besides the catalyst concentration, the reaction is also temperature controlled. The total conversion rate increases with increasing catalyst concentration or temperature. However, at high temperatures, the equilibrium concentration of the final product may change and the product may not meet the specification. For example, at high temperatures, the formation of linolenic acid and isolinolic acid is advantageous over the formation of oleic acid.

Figure 3 also describes the relationship of the conversion of compounds as a function of temperature, where the reaction is irreversible (ie A → B → C), where A is the starting material, B is the desired product, and C is the desired product. It is not a byproduct. In the irreversible step reaction, the maximum content of inverted intermediate product B is represented by the thermal equilibrium curve.

The point where the energy and material balance curves meet is the maximum point (To). Under this condition, the maximum content of the simulated conversion rate is obtained. The conversion rate of B at higher temperatures can actually be reduced.

In summary, the present invention is to improve the hydrogenation process of unsaturated cooking oil to produce a suitable and high selectivity product. The basic process involves contacting hydrogen with unsaturated oils in the presence of a metal catalyst at elevated temperatures and pressures. An improved process is a method of operation where liquid hydrogen raw material (LHS) hydrogen is used; The catalyst concentration and starting temperature and maximum working temperature are determined by the selectivity of the product and the temperature ramping used to raise the working temperature from the starting temperature to the maximum temperature is done as quickly as possible in the reactor.

In the process of the present invention, the catalyst concentration for the product with suitable selectivity is 50 to 60 ppm and the catalyst concentration for the product with high selectivity is 70 to 110 ppm.

The starting temperature of the product with moderate selectivity is 260-280 ° F, and the starting temperature for high selectivity products is 290-320 ° F. The starting temperature should be set as high as possible. However, the temperature suitable for thermal reactions should not be exceeded. The selectivity and final iodine of the product depend on (IV), but the maximum temperature to run the reactor is 300 to 500 ° F.

The temperature ramping (rise rate) should be 8 ° F or higher from the initial temperature of the reactor to the maximum working temperature. Once the catalytic reaction begins, it is important to add external heat (or steam) if necessary to increase the temperature of the reactor to the maximum allowable temperature as soon as possible.

It is important to maintain isothermal conditions at the maximum working temperature, but otherwise the product selectivity will be difficult.

Hydrogen inlet flow should be measured and compared with the expected hydrogen consumption for a given oil. The hydrogen consumption rate for a given oil can be obtained by plotting the rate of change in iodine value over time.

If the flow rate is lower than the expected value, the outlet valve must be opened to allow more hydrogen to enter the reactor. If the flow rate is much higher than expected, the outlet valve must be closed to indicate the flow rate of hydrogen into the reactor. Thus, mass transfer can be maximized while minimizing physical loss and total catalyst load of H ₂ .

The process is run by mixing oil and catalyst in a batch reactor. Once the oil and catalyst are well mixed, the mixture is heated to the starting temperature and hydrogen flow starts. After starting the hydrogen flow, the temperature should be raised to the maximum temperature as soon as possible. The reaction is run until the iodine value of the product reaches the desired value for the product of the selected feature in the process.

The use of this process significantly reduced the amount of catalyst used and the reaction time needed to produce the desired (good) product. Moreover, the present invention produced more details.

The following examples are presented to demonstrate the efficiency of the process of the present invention.

Example 1

Hydrogenation was carried out to unsaturated cooking oils to produce oils of suitable selectivity having the specifications shown in Table 1. In order to compare the process of this invention with the process of the prior art, the hydrotreatment test was performed at least 3 times, and each test used the derivative prior art process or the process of this invention. In addition to the product oil specification (Table), Table I lists the appropriate operating conditions of the product analysis and process (the figures presented here are averages of the results of multiple tests). The process produced more breakdown (standard) products.

TABLE I

Example II

Hydrogenation was carried out to a saturated cooking oil to prepare a second oil having suitable selectivity with the details shown in Table II.

In order to compare the present invention as described in Example I, a hydrotreatment test was carried out at least three times, each of which used a conventional powder process or the process of the present invention.

In addition to the product oil breakdown in Table II, the product's analysis and the appropriate operating conditions of the process (the figures shown here are the average of the values carried out several times). As can be seen from Table II, the process of the present invention produced more breakdown products.

TABLE II

Product # 2 with Proper Selectivity

Example III

Finally, hydrogenation was performed to unsaturated cooking oils to produce oils of high selectivity with the specifications shown in Table III. As described in Examples I and III, to compare the present invention, at least three hydrotreatment tests were conducted, each test using a fine powder process or the process of the present invention.

In addition to the product oil specification, Table III shows the appropriate conditions for product analysis and process (the figures presented here are the averages of several runs). Prepared.

TABLE III

Product with high selectivity

To summarize the results of the three examples, Table IV provides a comparison between the process of the prior art and the process of the present invention. The data in Table IV clearly shows that the process of the present invention resulted in a significant reduction in reaction time and catalyst concentration in addition to more in-product products as shown in Tables I to III above.

TABLE IV

Working variables

The invention has been described with reference to various specific embodiments of the invention. These examples are not intended to limit the invention, and the scope of the invention should be determined by the following claims.

Claims (4)

A hydrogenation method of the above unsaturated oil in which an unsaturated oil is reacted with hydrogen in the presence of a metal catalyst to prepare an edible oil having a suitable or high selectivity, the liquid hydrogen evaporated using hydrogen recovered as a liquid from a suitable vessel. Injected into the reactor to react with an unsaturated oil; Maintaining the catalyst concentration in the range of 50 to 110 ppm; Selecting a starting temperature for the reactor at a temperature between 260 ° F and 320 ° F; Once the catalytic (contact) reaction has started, increase the reactor temperature by increasing the maximum working temperature between 300 ° F and 500 ° F at a rate of 8F / min or more; And maintaining the hydrogen flow rate at a concentration such that the total amount of hydrogen required for the reaction can be obtained by controlling the hydrogen discharged from the reaction. The method of claim 1, wherein the concentration of the catalyst is 50 to 60 ppm, the starting temperature range is 260 ° F to 280 ° F. The method of claim 1, wherein the catalyst has a concentration of 75 to 100 ppm and a starting temperature of 290 ° F. to 320 ° C. 6. The process according to claim 1, wherein the reaction proceeds until the iodine value (IV) of the product reaches a good iodine value for the unsaturated oil to be hydrogenated.

Images