CN107262100B - Preparation method of oil hydrogenation nano catalyst with improved catalytic activity - Google Patents

Abstract

The invention discloses a preparation method of a nano-catalyst for oil hydrogenation with improved catalytic activity, and belongs to the technical field of nano-catalysts. The preparation method of the nano-catalyst for oil hydrogenation of the present invention takes nano-calcium carbonate as the carrier, makes the alkaline precipitant react with the metal salt of the catalytically active component, and loads the catalytically active component on the carrier; and, in the preparation process The addition of surfactants in the precipitation reaction affects the adsorption behavior of active metals through the competitive adsorption of surfactants and active metal ions during the precipitation reaction. The wetting and penetration of the carrier make the dispersibility of the catalyst active components on the carrier better, so that the activity of the prepared catalyst is improved.

Description

A kind of preparation method of oil hydrogenation nano-catalyst with improved catalytic activity

technical field

The invention relates to a preparation method of a nano-catalyst for oil hydrogenation with improved catalytic activity, and belongs to the technical field of nano-catalysts.

Background technique

Natural oils exist widely in nature, but due to the existence of unsaturated bonds in natural oils, they are mostly liquid at room temperature, with a low melting point. They are easily oxidized by oxygen in the air, change color and taste, and are difficult to store. Oil hydrogenation technology can improve the quality of natural oil and make it widely used in industry and food processing industry. With the rapid development of the oil hydrogenation industry, the research work of catalysts has also been paid attention to.

The earliest oil hydrogenation catalysts were prepared from metallic nickel. Later, some achievements have been made by using carriers to support precious metals. In recent years, catalysts that change the active components of metals and load them on different carriers have been continuously studied and discussed. The synergistic effect between a variety of different metal active components can improve the catalytic activity and selectivity. Different catalyst supports also have a great influence on the selective hydrogenation of oils and fats. A suitable carrier can reduce the cost of the catalyst and make it more competitive in the market.

At present, nickel-based catalysts are mainly used in the industry. Common nickel-based catalysts: single-component nickel-based catalysts include Ni/silica, Ni/activated carbon, Ni/alumina sol, etc., and two-component nickel-based catalysts include Ni- Fe/alumina, Ni-Cu/diatomite, etc. Multi-component nickel-based catalysts include Cu-Ni-Al/diatomite, Cu-Ni-Cr/diatomite, Ni-Fe-La/alumina, etc. Catalysts, and some non-metallic alloy catalysts such as Ni-P, Ni-B, etc. Some of the reported catalyst supports have problems such as complicated preparation, difficult to obtain materials or high price, and some active components of catalysts are reported in the literature, but there are also problems such as high price, high calcination temperature or harsh preparation conditions.

In the previous research, the inventor developed a kind of hydrogenation catalyst with low preparation cost, high activity and good stability (CN104437582A). The catalyst adopts nano calcium carbonate as the carrier, and the catalytic active components are supported on the carrier in the form of metal salts by precipitation method. The catalytic active components are mainly nickel, and the catalytic active assistants are aluminum, cobalt, zinc, iron, etc. One or more of them; the method has simple operation steps, and can greatly reduce the degree of unsaturation, that is, the iodine value of the grease, and increase the melting point and hardness. However, its catalytic activity needs to be further improved.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention provides a grease hydrogenation nanocatalyst with improved catalytic activity and a preparation method thereof, which overcomes the problems of the existing hydrogenation catalysts, such as relatively expensive price, difficult to obtain materials, and the catalytic activity needs to be improved.

The inventor's earlier preparation method of a nano-catalyst for oil hydrogenation uses nano-calcium carbonate as a carrier, makes an alkaline precipitant react with the metal salt of the catalytically active component, and loads the catalytically active component on the carrier; the catalyst of the present invention The improvement of the preparation method on this basis is that the surfactant is added in the preparation process, and the adsorption behavior of the active metal is affected by the competitive adsorption of the surfactant and the active metal ion during the precipitation reaction; The wetting and spreading characteristics promote the wetting and penetration of the active metal salt solution to the carrier, so that the dispersibility of the catalyst active components on the carrier is better, and the activity of the prepared catalyst is improved.

The preparation method comprises the following steps:

(a) adding a certain amount of alkaline precipitating agent to the carrier at a reaction temperature of 25 to 100° C., after stirring uniformly, dropwise adding the metal salt solution containing the catalytically active component of the surfactant dropwise while stirring; Or first add a certain amount of surfactant to the aqueous dispersion of the carrier nano-calcium carbonate, after stirring and dissolving, add a certain amount of alkaline precipitating agent, and then evenly add the metal salt solution of the catalytically active component dropwise while stirring;

(b) adjusting the pH, continuing to stir the aging reaction for a period of time, and finally filtering the sediment, washing, drying, grinding, sieving, and calcining under nitrogen protection, then reducing the reducing agent, wrapping, and molding, to prepare the oil and grease Hydrogen Nanocatalysts.

In one embodiment, the surfactant is a non-ionic surfactant, a cationic surfactant or a mixture of the above two ionic surfactants, and the surfactant is a fat with a carbon chain of C8-C20 Alcohol polyoxyethylene ether, fatty amine polyoxyethylene ether, fatty acid mono/diethanolamide and its polyoxyethylene ether, C8-C20 alkyl quaternary ammonium salt. Preferably, the carbon chain is C8-C20 fatty acid mono/diethanolamide.

In one embodiment, the mass ratio of the carrier to the alkaline precipitant is 10:1-30:1, preferably 20-25:1.

In one embodiment, the alkaline precipitant maintains the pH of the solution between 7 and 10, preferably between 8 and 9.

In one embodiment, the mass ratio of the alkaline precipitant to the metal salt is 1:1-1:10, preferably: 1:4-1:6.

In one embodiment, the mass ratio of the surfactant, the metal salt, and the carrier is (0.1-0.5):(7-10):(20-30), preferably 0.2:(7-8): 20 to 22.

In one embodiment, the reaction temperature is 30-70°C.

In one embodiment, the carrier is inactive nano-calcium carbonate, and the particle size distribution is between 10-100 nm, such as 30-50 nm.

In one embodiment, the carrier is dispersed in deionized water at a certain temperature, and the temperature is in the range of 5-80°C, preferably 25-55°C.

In one embodiment, the alkaline precipitant is easily decomposable Na ₂ CO ₃ , NaHCO ₃ , NaOH, (NH ₄ ) ₂ CO ₃ , NH ₄ HCO ₃ , NH ₃ ·H ₂ O, urea, etc., one or more of them.

In one embodiment, the alkaline precipitant is formulated into an aqueous solution of a certain concentration with deionized water.

In one embodiment, the catalytically active component is composed of nickel and a catalytically active assistant, where nickel is the main component, and the catalytically active assistant is one or more of aluminum, cobalt, zinc, iron, and the like.

In one embodiment, in the catalytically active component, the atomic molar ratio of nickel to co-agent metal is: Ni:Al=3-1000, Ni:Co=500-3000.

In one embodiment, Ni:Al=5-10; Ni:Co=500-600.

In one embodiment, the metal salt is formulated into an aqueous solution of a certain concentration with deionized water.

In one embodiment, the metal salt is Ni(NO ₃ ) ₂ .6H ₂ O, NiSO ₄ .6H ₂ O, Al(NO ₃ ) ₃ .9H ₂ O, Zn(NO ₃ ) ₂ .6H ₂ One or more of O, NiCO ₃ ·2Ni(OH) ₂ ·4H ₂ O, Co(NO ₃ ) ₂ ·6H ₂ O, etc.

In one embodiment, the preparation method is as follows:

Under the condition that the reaction temperature is 25-80 ℃, add a certain amount of alkaline precipitant to the carrier nano-calcium carbonate, and after stirring evenly, add the metal salt of the catalytically active component containing the surfactant dropwise while stirring. Solution; adjust the pH value in the range of 7-10 by alkaline precipitant and metal salt solution, continue stirring and aging reaction for a period of time, finally filter the sediment with suction, and wash with deionized water at the same temperature until neutral, and then use ethanol Rinse three times and dry at 85-110°C until absolutely dry. Pulverize and grind, sieve, then calcinate at 350-450°C for 2-3h under nitrogen protection, then reduce at 400-500°C for 2-3h in a hydrogen atmosphere, and then cool down the reduced catalyst to stabilize under nitrogen or hydrogen protection Below 100 ℃, it is the catalyst required to be wrapped with hardened oil, passivated, and shaped.

In one embodiment, the preparation method is as follows:

Under the condition that the reaction temperature is 25～80℃, a certain amount of surfactant is added to the aqueous dispersion of the carrier nano-calcium carbonate, after stirring and dissolving, a certain amount of alkaline precipitating agent is added, and after stirring evenly, one by one while stirring The metal salt solution of the catalytically active component is added dropwise evenly; the pH value is adjusted within the range of 7-10 by the alkaline precipitant and the metal salt solution, and the aging reaction is continued to be stirred for a period of time. Wash with ionized water until neutral, then rinse with ethanol three times, and dry at 85-110°C until absolutely dry. Pulverized and ground, sieved, then calcined at 350-450°C for 2-3h under nitrogen protection, and then reduced at 400-500°C for 2-3h in a hydrogen atmosphere. Under the protection of nitrogen or hydrogen, the reduced catalyst is cooled and stabilized, wrapped with hardened oil, and formed into the desired catalyst.

The second object of the present invention is to provide the catalyst prepared according to the above method, and the application of the catalyst in the field of oil and fat hydrogenation.

Advantages and effects of the present invention:

The method of the invention, by adding a certain amount of surfactant, utilizes the competitive adsorption of the surfactant on the carrier surface, affects the adsorption behavior of active metal ions on the carrier surface, and limits the size and dispersibility of active metal ion clusters. At the same time, the presence of the surfactant improves the wettability and permeability of the active metal solution on the carrier during the preparation process, and effectively improves the catalytic activity of the catalyst. At the same time, the method of the invention has simple operation steps, stable performance, economical and practicality, and is suitable for the hydrogenation of unsaturated fats and oils into saturated fatty acid esters. It can greatly reduce the degree of unsaturation, that is, reduce the iodine value of the oil, improve the melting point and hardness, and enhance the oxidation resistance.

specific implementation

The following is a detailed description of the present invention.

Example 1

Take 20g of nano calcium carbonate in a 250mL three-necked flask, add 50mL of prepared alkaline precipitant 0.5mol/L sodium carbonate aqueous solution, start the stirrer to make the calcium carbonate powder well dispersed, heat the water bath to 50°C, stir for 30min, take 50mL prepared 0.5mol/L nickel nitrate aqueous solution and 10mL prepared 0.5mol/L aluminum nitrate aqueous solution (atomic molar ratio Ni:Al=5:1), after mixing evenly, add 0.35g of surfactant ten Glycol polyoxyethylene ether-9 was stirred and dissolved into a solution containing a surfactant concentration of 0.01 mol/L. The above solution was added to the dropping funnel, added to the three-necked flask containing the carrier and the precipitant at a speed of 3s/d, and the dropwise addition was completed. With a precision pH meter, the pH value under the reaction environment was measured and adjusted to 7 or so, the reaction is carried out for 6 hours. After the reaction is completed, the precipitate is vacuum filtered, washed with deionized water until neutral, rinsed with absolute ethanol three times, and the filter cake is taken out and dried in a 100 °C oven to absolute dryness. , to obtain the catalyst precursor. The obtained catalyst precursor was pulverized and ground, sieved, put into a tubular muffle furnace, protected by nitrogen at 20 mL/min, programmed to heat up to 350 °C, calcined for 2 hours, then heated to 400 °C, passed through 30 ml/min of hydrogen, and reduced for 2 hours , the catalyst to be reduced is cooled and stabilized, and the obtained natural oil hydrogenation nickel-based nano-catalyst is uniformly wrapped with hardened oil.

Take 40g of industrial grade palm oil in a 100mL high pressure reactor, accurately weigh 0.1g of catalyst (the amount of catalyst is 0.7‰ of palm oil), seal the reactor, introduce hydrogen to start the reaction, and stir at 500r/min. Take samples after the reaction, and measure the iodine value of the product according to GB/T5532-2008. The reaction temperature, pressure, time parameters and results are shown in Table 1.

Example 2

The surfactant lauryl polyoxyethylene ether-9 in Example 1 was replaced with octadecylamine polyoxyethylene ether-20 with the same molar concentration, and other steps or parameters were the same as those in Example 1.

Example 3

The surfactant lauryl polyoxyethylene ether-9 in Example 1 was replaced with coconut oil-based fatty amine polyoxyethylene ether-9 with the same molar concentration, and other steps or parameters were consistent with those in Example 1.

Example 4

The surfactant dodeceth-9 in Example 1 was replaced with lauric acid monoethanolamide of the same molar concentration, and other steps or parameters were the same as those in Example 1.

Example 5

The surfactant dodecyl polyoxyethylene ether-9 in Example 1 was replaced with a concentration of 0.001 mol/L dodecyldimethylbenzyl ammonium bromide, and other steps or parameters were the same as those in Example 1.

Example 6

The surfactant dodeceth-9 in Example 1 was replaced with lauric acid diethanolamide, and other steps or parameters were the same as those in Example 1.

Example 7

Take 20g of nano calcium carbonate in a 250mL three-necked flask, add 30mL of lauric acid diethanolamide aqueous solution with a concentration of 0.02mol/L, add 50mL of prepared alkaline precipitant 0.5mol/L sodium carbonate aqueous solution, start the stirrer to make carbonic acid The calcium powder was well dispersed, the water bath was heated to 50°C, stirred for 30min, and 50mL of the prepared 0.5mol/L nickel nitrate aqueous solution and 10mL of the prepared 0.5mol/L aluminum nitrate aqueous solution (atomic molar ratio Ni:Al= 5:1), after stirring and mixing evenly, the above solution was added to the dropping funnel, added to the three-necked flask containing the carrier and the precipitant at a speed of 3s/d, the dropwise addition was completed, and a precise pH meter was used to measure the reaction environment. The pH value was adjusted to about 7 with an aqueous sodium carbonate solution, and the reaction was carried out for 6 h. After the reaction was completed, the precipitate was vacuum filtered and washed with deionized water until neutral. Other steps are the same as in Example 1.

Example 8

The active component distribution ratio in Example 7 was changed to atomic molar ratio Ni:Co=800:1, and the rest of the steps remained unchanged.

Example 9

The active component distribution ratio in Example 7 was changed to atomic molar ratio Ni:Fe=400:1, and the mixture was uniformly added into the dropping funnel, and the rest of the steps remained unchanged. Finally, the iodine value of the product was measured according to GB/T5532-2008, and the melting point of the product was measured by the capillary method of a micro melting point apparatus. The parameters of the evaluation product are shown in Table 1.

Comparative Example 1

Compared with Example 7, no surfactant was added, and other steps or parameters were the same as those of Example 1.

Comparative Example 2

Compared with Example 8, no surfactant was added, and other steps or parameters were the same as those of Example 8.

Comparative Example 3

Compared with Example 9, no surfactant was added, and other steps or parameters were the same as those of Example 9.

The inventors measured the product evaluation parameters (iodine value and melting point) of the catalysts obtained according to Examples 1-9 and Comparative Examples 1-3 for the hydrogenation of oils and fats. The results are shown in Table 1.

Table 1 Catalytic effect of catalysts prepared by different methods

Reaction temperature, °C Reaction pressure, MPa reaction time, hr Product iodine value, gI₂/100g Example 1 200 2.0 60 2.243 Example 2 200 2.0 60 1.570 Example 3 200 2.0 60 1.386 Example 4 200 2.0 60 1.119 Example 5 200 2.0 60 1.573 Example 6 200 2.0 60 0.923 Example 7 200 2.0 60 0.887 Example 8 200 2.0 120 0.278 Example 9 200 2.0 120 0.417 Comparative Example 1 200 2.0 60 2.711 Comparative Example 2 200 2.0 120 0.489 Comparative Example 3 200 2.0 120 0.571

Note: The determination of iodine value is carried out in accordance with the national standard GB/T5532-2008

It can be seen from Examples 7-9 and corresponding Comparative Examples 1-3 that the catalytic efficiency of the catalyst can be effectively improved by adding a surfactant, compared with the catalytic effect of the catalyst prepared without adding a surfactant under the same conditions. , the iodine value of the product obtained by adding the catalyst prepared by adding surfactant for the hydrogenation of oil decreased by 27% to 67%.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention should be defined by the claims.

Claims (6)

1. A preparation method of a grease hydrogenation nanometer catalyst with improved activity is characterized in that nanometer calcium carbonate is used as a carrier, and a surfactant is added to enable a catalytic active component to be more uniformly loaded on the carrier in the process of preparing the catalyst by adopting a precipitation method; the catalytic active component consists of nickel and a catalytic active auxiliary agent, wherein the nickel is used as a main component, and the catalytic active auxiliary agent is one or more of aluminum, cobalt, zinc and iron;

the method comprises the following steps:

(a) adding a certain amount of alkaline precipitator into a carrier at a reaction temperature of 25-100 ℃, uniformly stirring, and dropwise adding a metal salt solution containing a catalytic active component of a surfactant at a constant speed while stirring; or firstly adding a certain amount of surfactant into the aqueous dispersion of the carrier nano calcium carbonate, stirring and dissolving, then adding a certain amount of alkaline precipitator, and then stirring and uniformly adding the metal salt solution of the catalytic active component drop by drop;

(b) adjusting pH, continuously stirring and aging for reaction for a period of time, finally carrying out suction filtration, washing, drying, grinding and sieving on the deposit, roasting under the protection of nitrogen, reducing by using a reducing agent, and then wrapping and forming to obtain the oil hydrogenation nano-catalyst;

the surfactant is lauric acid diethanolamide;

the mass ratio of the surfactant, the metal salt and the carrier is (0.1-0.5): 7-10): 20-30.

2. The method of claim 1, wherein the catalytically active component has an atomic mole ratio of nickel to co-promoter metal of: al is 3-1000 Ni and Co is 500-3000.

3. The method according to claim 1, wherein the alkaline precipitant is readily decomposable Na₂CO₃、NaHCO₃、NaOH、(NH₄)₂CO₃、NH₄HCO₃、NH₃•H₂O or urea.

4. The method of claim 1, wherein the nickel salt of the metal salt is selected from the group consisting of Ni (NO)₃)₂•6H₂O、NiSO₄•6H₂O、NiCO₃•2Ni(OH)₂•4H₂One or more of O; the catalytic Co-agent metal salt of the metal salt is selected from Co (NO)₃)₂•6H₂O、Al(NO₃)₃•9H₂O、Zn(NO₃)₂•6H₂One or more of O.

5. A catalyst prepared by the method according to any one of claims 1 to 4.

6. Use of the catalyst according to claim 5 in the field of hydrogenation of fats and oils.