CN107262100B

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

Info

Publication number: CN107262100B
Application number: CN201710472480.5A
Authority: CN
Inventors: 蒋惠亮; 赵焕利; 潘保凯
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2017-06-21
Filing date: 2017-06-21
Publication date: 2020-02-07
Anticipated expiration: 2037-06-21
Also published as: CN107262100A

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 takes nano calcium carbonate as a carrier, and makes an alkaline precipitator react with metal salt of a catalytic active component to load the catalytic active component on the carrier; in addition, the surfactant is added in the preparation process, and the adsorption behavior of the active metal is influenced by competitive adsorption of the surfactant and the active metal ions during the precipitation reaction; meanwhile, due to the wetting and spreading characteristics of the surfactant, the wetting and permeation of the active metal salt solution to the carrier are promoted, so that the dispersibility of the active component of the catalyst on the carrier is better, and the activity of the prepared catalyst is improved.

Description

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, belonging to the technical field of nano-catalysts.

Background

Natural oil and fat widely exist in nature, but due to the existence of unsaturated bonds in the natural oil and fat, the natural oil and fat are mostly in liquid state at normal temperature, have low melting point, are easily oxidized by oxygen in the air, change color and taste, and are difficult to store. The oil hydrogenation technology can improve the quality of natural oil and make the natural oil and fat widely applied to the industry and the food processing industry. The rapid development of the grease hydrogenation industry leads the research work of the catalyst to be paid attention.

The earliest grease hydrogenation catalysts were prepared from metallic nickel, and later, certain achievements were achieved by using carriers to load noble metals, and catalysts which change the metallic active components and load the metallic active components on different carriers have been continuously studied and discussed in recent years. The synergistic effect of several different metal active components can raise catalytic activity and selectivity. Different catalyst supports also have a greater influence on the selective hydrogenation of fats and oils. The proper carrier can reduce the cost of the catalyst, so that the catalyst has stronger market competitiveness.

At present, the industry mainly uses nickel-based catalysts, and the common nickel-based catalysts are as follows: the single-component nickel-based catalyst comprises Ni/silicon oxide, Ni/active carbon, Ni/alumina sol and the like, the two-component nickel-based catalyst comprises Ni-Fe/aluminum oxide, Ni-Cu/kieselguhr and the like, the multi-component nickel-based catalyst comprises Cu-Ni-Al/kieselguhr, Cu-Ni-Cr/kieselguhr, Ni-Fe-La/aluminum oxide and the like, and the non-metallic alloy catalyst comprises Ni-P, Ni-B and the like. Some reported catalyst carriers have the problems of complex preparation, difficult material obtaining, high price and the like, and some active components of the catalysts have also been reported in documents, but the catalyst carriers also have the problems of high price, high calcination temperature, harsh preparation conditions and the like.

In the previous research, the inventor develops a hydrogenation catalyst (CN104437582A) which has lower preparation cost, higher activity and good stability by using nano calcium carbonate as a catalyst carrier and changing the active components of the catalyst; the catalyst adopts nano calcium carbonate as a carrier, and a precipitation method is used for loading a catalytic active component on the carrier in the form of metal salt, wherein the catalytic active component is mainly nickel, and the catalytic active auxiliary agent is one or more of aluminum, cobalt, zinc, iron and the like; the method has simple operation steps, can greatly reduce the unsaturation degree, namely reduce the iodine value of the grease, and improve the melting point and the hardness. However, the catalytic activity thereof is yet to be further improved.

Disclosure of Invention

In order to solve the problems, the invention provides a nano-catalyst for oil hydrogenation with improved catalytic activity and a preparation method thereof, and solves the problems of high price, difficult material taking, to-be-improved catalytic activity and the like of the existing hydrogenation catalyst.

The invention relates to a preparation method of a grease hydrogenation nano catalyst in the early stage, which takes nano calcium carbonate as a carrier, and makes an alkaline precipitator react with metal salt of a catalytic active component to load the catalytic active component on the carrier; the improvement of the preparation method of the catalyst is that the surfactant is added in the preparation process, and the adsorption behavior of the active metal is influenced by the competitive adsorption of the surfactant and the active metal ions during the precipitation reaction; meanwhile, due to the wetting and spreading characteristics of the surfactant, the wetting and permeation of the active metal salt solution to the carrier are promoted, so that the dispersibility of the active component of the catalyst 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 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) and adjusting the pH value, continuously stirring and carrying out aging 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.

In one embodiment, the surfactant is a nonionic surfactant, a cationic surfactant or a mixture of the two ionic surfactants, and the surfactant is fatty alcohol polyoxyethylene ether with a carbon chain of C8-C20, fatty amine polyoxyethylene ether, fatty acid mono/diethanolamide and polyoxyethylene ether thereof, and alkyl quaternary ammonium salt with a carbon chain of C8-C20. Preferred are fatty acid mono/diethanolamides with a carbon chain of C8-C20.

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

In one embodiment, the alkaline precipitant maintains the solution at a pH of 7 to 10, preferably 8 to 9.

In one embodiment, the mass ratio of the alkaline precipitant to the metal salt is 1:1 to 1:10, preferably 1:4 to 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): 20-22.

In one embodiment, the reaction temperature is 30 to 70 ℃.

In one embodiment, the carrier is non-active nano calcium carbonate with a particle size distribution of 10-100 nm, such as 30-50 nm.

In one embodiment, the carrier is dispersed in deionized water at a temperature in the range of 5 to 80 deg.C, preferably 25 to 55 deg.C.

In one embodiment, the alkaline precipitant is readily decomposable Na₂CO₃，NaHCO₃，NaOH，(NH₄)₂CO₃，NH₄HCO₃，NH₃·H₂O, urea and the like, and one or more of the O, the urea and the like.

In one embodiment, the alkaline precipitant is formulated with deionized water into a concentrated aqueous solution.

In one embodiment, the catalytically active component comprises nickel as a main component and a catalytically active promoter, wherein the catalytically active promoter is one or more of aluminum, cobalt, zinc, iron, and the like.

In one embodiment, the atomic mole ratio of nickel to the co-promoter metal in the catalytically active component is: al is 3-1000% Ni and Co is 500-3000%.

In one embodiment, Al is 5-10; co is 500-600.

In one embodiment, the metal salt is formulated with deionized water as a concentrated aqueous solution.

In one embodiment, the metal salt is Ni (NO)₃)₂·6H₂O，NiSO₄·6H₂O，Al(NO₃)₃·9H₂O，Zn(NO₃)₂·6H₂O，NiCO₃·2Ni(OH)₂·4H₂O，Co(NO₃)₂·6H₂O, and the like.

In one embodiment, the preparation method is specifically as follows:

under the condition that the reaction temperature is 25-80 ℃, adding a certain amount of alkaline precipitator into the carrier nano calcium carbonate, uniformly stirring, and then dropwise and uniformly adding a metal salt solution containing a catalytic active component of a surfactant while stirring; adjusting the pH value to be within the range of 7-10 by using an alkaline precipitator and a metal salt solution, continuously stirring, carrying out aging reaction for a period of time, finally carrying out suction filtration on the deposit, washing the deposit to be neutral by using deionized water at the same temperature, then carrying out spray washing for three times by using ethanol, and drying the deposit at the temperature of 85-110 ℃ until the deposit is absolutely dry. Crushing, grinding, sieving, roasting at 350-450 ℃ for 2-3 h under the protection of nitrogen, reducing at 400-500 ℃ for 2-3 h in hydrogen atmosphere, cooling the reduced catalyst to be stable to below 100 ℃ under the protection of nitrogen or hydrogen, wrapping with hardened oil, passivating, and forming to obtain the required catalyst.

In one embodiment, the preparation method is specifically as follows:

under the condition that the reaction temperature is 25-80 ℃, adding a certain amount of surfactant into the aqueous dispersion of the carrier nano calcium carbonate, stirring and dissolving, adding a certain amount of alkaline precipitator, stirring uniformly, and then adding a metal salt solution of a catalytic active component dropwise and uniformly while stirring; adjusting the pH value to be within the range of 7-10 by using an alkaline precipitator and a metal salt solution, continuously stirring, carrying out aging reaction for a period of time, finally carrying out suction filtration on the deposit, washing the deposit to be neutral by using deionized water at the same temperature, then carrying out spray washing for three times by using ethanol, and drying the deposit at the temperature of 85-110 ℃ until the deposit is absolutely dry. Crushing, grinding, sieving, roasting for 2-3 h at 350-450 ℃ under the protection of nitrogen, and then reducing for 2-3 h at 400-500 ℃ in a hydrogen atmosphere. Under the protection of nitrogen or hydrogen, the reduced catalyst is cooled and stabilized, wrapped by hardened oil and formed into the required catalyst.

The second purpose of the invention is to provide the catalyst prepared by the method and the application of the catalyst in the field of grease hydrogenation.

The invention has the advantages and effects that:

according to the method, a certain amount of surfactant is added, and the competitive adsorption of the surfactant on the surface of the carrier is utilized, so that the adsorption behavior of active metal ions on the surface of the carrier is influenced, and the size and the dispersity of active metal ion clusters are limited. Meanwhile, the existence of the surfactant improves the wettability and permeability of the active metal solution on the carrier in the preparation process, and effectively improves the catalytic activity of the catalyst. Meanwhile, the method has the advantages of simple operation steps, stable performance, economy and practicability, and is suitable for hydrogenation conversion of unsaturated oil into saturated fatty acid ester. Can greatly reduce the unsaturation degree, namely reduce the iodine value of the grease, improve the melting point and the hardness and enhance the oxidation resistance.

Detailed description of the preferred embodiments

The present invention will be described in detail below.

Example 1

Adding 20g of nano calcium carbonate into a 250mL three-neck flask, adding 50mL of prepared 0.5mol/L aqueous solution of alkaline precipitator sodium carbonate, starting a stirrer to well disperse calcium carbonate powder, heating in a water bath to 50 ℃, stirring for 30min, taking 50mL of prepared 0.5mol/L aqueous solution of nickel nitrate and 10mL of prepared 0.5mol/L aqueous solution of aluminum nitrate (the atomic molar ratio of Ni to Al is 5:1), uniformly mixing, adding 0.35 g of surfactant lauryl polyoxyethylene ether-9, and stirring and dissolving to obtain a solution containing 0.01mol/L of surfactant. Adding the solution into a dropping funnel, adding the solution into a three-neck flask containing a carrier and a precipitator at the speed of 3s/d, measuring the pH value under the reaction environment by using a precise pH meter after the dropwise addition is finished, adjusting the pH value to about 7 by using a sodium carbonate aqueous solution, reacting for 6 hours, after the reaction is finished, carrying out vacuum filtration on the precipitate, washing the precipitate to be neutral by using deionized water, carrying out leaching for three times by using absolute ethyl alcohol, taking out a filter cake, and drying the filter cake in a 100 ℃ oven until the absolute drying is carried out to obtain a catalyst precursor. And crushing and grinding the obtained catalyst precursor, sieving, adding into a tubular muffle furnace, introducing 20mL/min nitrogen for protection, programming to 350 ℃, roasting for 2 hours, heating to 400 ℃, introducing 30mL/min hydrogen, reducing for 2 hours, cooling and stabilizing the reduced catalyst, and uniformly coating the obtained natural oil hydrogenation nickel-based nano catalyst with hardened oil.

Taking 40g of industrial-grade palm oil into a 100mL high-pressure reaction kettle, accurately weighing 0.1g of catalyst (the catalyst amount is 0.7 per mill of the palm oil), sealing the reaction kettle, introducing hydrogen to start reaction, and stirring at the rotating speed of 500 r/min. After the reaction, a sample was taken and the iodine value of the product was measured in accordance with 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 the example 1 is replaced by octadecyl amine polyoxyethylene ether-20 with the same molar concentration, and other steps or parameters are consistent with those in the example 1.

Example 3

The surfactant lauryl alcohol polyoxyethylene ether-9 in example 1 was replaced with the same molar concentration of coco fatty amine polyoxyethylene ether-9, and the other steps or parameters were in accordance with example 1.

Example 4

The surfactant lauryl polyoxyethylene ether-9 in example 1 was replaced with lauric monoethanolamide at the same molar concentration, and the other steps or parameters were the same as in example 1.

Example 5

The surfactant lauryl polyoxyethylene ether-9 in example 1 was replaced with dodecyl dimethyl benzyl ammonium bromide at a concentration of 0.001mol/L, and the other steps or parameters were in accordance with example 1.

Example 6

The surfactant lauryl polyoxyethylene ether-9 in example 1 was replaced with lauric diethanolamide, and the other steps or parameters were the same as in example 1.

Example 7

Adding 20g of nano calcium carbonate into a 250mL three-neck flask, adding 30mL of lauric acid diethanolamide aqueous solution with the concentration of 0.02mol/L, adding 50mL of prepared alkaline precipitator 0.5mol/L sodium carbonate aqueous solution, starting a stirrer to well disperse calcium carbonate powder, heating a water bath to 50 ℃, stirring for 30min, adding 50mL of prepared 0.5mol/L nickel nitrate aqueous solution and 10mL of prepared 0.5mol/L aluminum nitrate aqueous solution (the atomic molar ratio of Ni to Al is 5:1), stirring and mixing uniformly, adding the solution into a dropping funnel, adding the solution into the three-neck flask containing the carrier and the precipitator at the speed of 3s/d, after the dropping is finished, measuring the pH value under the reaction environment by using a precise pH meter, adjusting the pH value to about 7 by using the sodium carbonate aqueous solution, reacting for 6h, after the reaction is finished, carrying out vacuum filtration on the precipitate, and washed with deionized water to neutrality. The other steps were in accordance with example 1.

Example 8

The active ingredient distribution ratio in example 7 was changed to 800:1 as the atomic molar ratio Ni: Co, and the rest of the procedure was unchanged.

Example 9

The active ingredient distribution ratio in example 7 was changed to 400:1 in terms of atomic molar ratio of Ni to Fe, and the mixture was added to a dropping funnel after being mixed uniformly, and the rest of the procedure was unchanged. Finally, the iodine value of the product is measured according to GB/T5532-2008, the melting point of the product is measured by a micro melting point instrument capillary method, and the evaluation parameters of the product are shown in Table 1.

Comparative example 1

In contrast to example 7, no surfactant was added and the other steps or parameters were in accordance with example 1.

Comparative example 2

In contrast to example 8, no surfactant was added and the other steps or parameters were in accordance with example 8.

Comparative example 3

In contrast to example 9, no surfactant was added and the other steps or parameters were in accordance with example 9.

The inventors measured the evaluation parameters (iodine value and melting point) of the products after hydrogenation of fats and oils obtained by using the catalysts obtained in examples 1 to 9 and comparative examples 1 to 3: iodine value evaluation reaction time was 60 min. The results are shown in Table 1.

TABLE 1 catalytic Effect of catalysts prepared by different methods

	Reaction temperature of	Reaction pressure, MPa	Reaction time, hr	Iodine value, gI of the product₂/100g
					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 iodine value is determined according to the national standard GB/T5532-2008

From examples 7 to 9 and corresponding comparative examples 1 to 3, it is known that the catalytic efficiency of the catalyst can be effectively improved by adding the surfactant, and the iodine value of the product obtained by adding the catalyst prepared by adding the surfactant and used for oil hydrogenation is reduced by 27% to 67% compared with the catalytic effect of the catalyst prepared by not adding the surfactant and under the same conditions.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

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:

(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.