Production process of fatty secondary alcohols based on biodiesel

Abstract

The invention discloses a production process of fatty secondary alcohols based on biodiesel, belonging to the technical field of secondary alcohol preparation, and comprising the following steps: adding a first catalyst to biodiesel, and carrying out a heat preservation reaction to obtain a first product; liquid-phase oxidation of the first product in the presence of a second catalyst, a third catalyst and an oxygen atmosphere to obtain a second product; adding a secondary alcohol to the second product and carrying out an esterification reaction to obtain a third product; recovering crude secondary alcohol borate in the third product, and hydrolyzing the crude secondary alcohol to obtain the secondary alcohol. The invention provides an oxidation process for preparing fatty secondary alcohols using biodiesel as a raw material, avoiding the use of petroleum-based raw material liquid paraffin, and not forming polluting gases such as sulfur dioxide that are harmful to organisms in tail gas emissions, thereby greatly improving economic benefits while reducing environmental pollution.

Description

Technical Field

[0001] The invention relates to the technical field of secondary alcohol preparation, and in particular to a production process of fatty secondary alcohol based on biodiesel. Background Art

[0002] Secondary alcohol nonionic surfactants (Secondary Alcohol Ethoxylates) are products of a two-step addition reaction between a secondary alcohol obtained by catalytic oxidation of normal liquid paraffin with a certain carbon number and ethylene oxide (or propylene oxide and / or butylene oxide). The first step involves the addition of ethylene oxide in the presence of an acidic catalyst to produce an alkoxylation product with an average addition molarity of 1-2.5 moles. After catalyst removal and distillation, an intermediate alkoxylation product with an average addition molarity of 2-3.5 moles is obtained, free of free alcohol. The second step involves the addition of ethylene oxide to this intermediate in the presence of a conventional alkaline catalyst to produce a nonionic surfactant with a high molar addition molarity. Compared with nonionic surfactants starting with primary alcohols of similar molecular weight, secondary alcohol nonionic surfactants have the advantages of low pour point, low odor, strong penetrating wetting power, strong emulsifying power, fast bubble breaking, narrow gel range, and good biodegradability. Their various performances are close to those of the TX series and better than those of the straight-chain AEO series. They can be used in combination with other types of anionic, nonionic, and cationic surfactants, and have outstanding synergistic effects, which can greatly reduce the use and consumption of auxiliary agents, and can also improve the effectiveness of thickeners for paints and improve the flushing properties of solvent-based systems. They are widely used in textile printing and dyeing, refining and bleaching, paint emulsifiers, papermaking deinking agents, pesticide and fertilizer wettable powder emulsifiers, dry cleaning agents, textile processing and oil field extraction.

[0003] The current preparation process for secondary fatty alcohols is to catalyze the oxidation of normal liquid paraffin with boron oxide compounds (including boric acid, metaboric acid, boron oxide, etc.), with an oxidation conversion rate of 10-30%. The oxidation product is subjected to a flash or distillation process to separate the unreacted normal liquid paraffin and a small amount of ketone impurities with a lower boiling point. The obtained heavy component (secondary alcohol borate) is purified by hydrolysis, alkali washing, water washing, etc., and then passed through a light removal distillation tower to remove a small amount of residual liquid paraffin and small molecular impurities to obtain pure secondary fatty alcohols.

[0004] The above-mentioned preparation process uses a single raw material and a narrow scope, resulting in significant limitations. Furthermore, oil prices fluctuate significantly due to international fluctuations. Biodiesel is a renewable energy source with a wide range of raw materials, allowing for the recycling of waste oil. To further expand raw material access, the present invention proposes a process for producing secondary fatty alcohols using biodiesel as a raw material. Summary of the Invention

[0005] To address the above problems, the present invention uses biodiesel as the main raw material instead of the currently widely used petroleum-based liquid paraffin, and provides a biodiesel-based fatty secondary alcohol production process, so that the fatty secondary alcohol produced by biodiesel can achieve the same structure and performance as the commercially available fatty secondary alcohol produced by petroleum-based liquid paraffin.

[0006] The purpose of the present invention is achieved by adopting the following technical solutions:

[0007] A biodiesel-based fatty secondary alcohol production process comprises the following steps:

[0008] (1) adding a first catalyst to biodiesel, and reacting at 170-200° C. for 5-8 hours to obtain a first product;

[0009] (2) liquid-phase oxidation of the first product in the presence of a second catalyst, a third catalyst, and an oxygen atmosphere to obtain a second product;

[0010] (3) adding a secondary alcohol to the second product and performing an esterification reaction to obtain a third product;

[0011] (4) recovering the crude secondary alcohol borate in the third product, and the remaining material is sequentially washed with alkali and water and then returned to step (2) to be combined with the first product to participate in the liquid phase oxidation;

[0012] (5) hydrolyzing the recovered crude secondary alcohol borate to obtain a secondary alcohol;

[0013] The preparation method of the first catalyst comprises the following steps:

[0014] S1. Weigh calcium nitrate and dissolve it in deionized water, and adjust the pH to alkaline with ammonia water to obtain a calcium nitrate solution; weigh ammonium dihydrogen phosphate and dissolve it in deionized water to obtain an ammonium dihydrogen phosphate solution, and slowly add the calcium nitrate solution and the calcium dihydrogen phosphate solution to a hot ethanol solution in which calcium phosphate is dispersed. After the addition is completed, adjust the pH to not less than 10 with ammonia water, continue to keep warm and stir for 0.5-1 hour, transfer the mixed solution to a hydrothermal reactor, heat it to 100-130° C. under autogenous pressure, and keep it warm for reaction for 20-24 hours. After the reaction is completed, cool it, separate the precipitate, wash it with deionized water and ethanol solvent in sequence, dry it, and then calcine it at 500-600° C. for 1-2 hours to obtain product A;

[0015] S2. Dispersing the product A in an ethanol solvent to obtain a dispersion; slowly adding a mixed solution of copper nitrate and nickel nitrate and a mixed solution of sodium carbonate and sodium hydroxide to the dispersion at the same time, stirring and mixing for 1-2 hours, standing overnight, separating the precipitate, washing with deionized water and ethanol solvent in sequence, drying, calcining at 500-600° C. for 1-2 hours, then heat-treating at 280-400° C. in a reducing atmosphere for 2-3 hours, and cooling to obtain the product.

[0016] In some preferred embodiments, the biodiesel is saturated fatty acid methyl ester with a carbon number of 8-30.

[0017] In some preferred embodiments, the amount of the first catalyst added is 1%-10% by weight of the biodiesel.

[0018] In different embodiments, the added amount of the first catalyst can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% by weight of the biodiesel, etc.

[0019] In some preferred embodiments, the second catalyst is dehydrated boric acid, and the third catalyst is an amino base substance.

[0020] In some preferred embodiments, the added amount of the dehydrated boric acid is 0.5%-10% by weight of the biodiesel; and the added amount of the amino base substance is 0.001%-0.1% by weight of the biodiesel.

[0021] In different embodiments, the added amount of the dehydrated boric acid can be 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% and the like based on the weight of the biodiesel; similarly, in different embodiments, the added amount of the amino base substance is 0.001%, 0.005%, 0.008%, 0.01%, 0.05%, 0.09%, 0.1% and the like based on the weight of the biodiesel.

[0022] In some preferred embodiments, the oxygen content in the oxygen atmosphere is 2 vol%-10 vol%.

[0023] In different embodiments, the oxygen content may be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and so on.

[0024] In some preferred embodiments, the reaction temperature of the liquid phase oxidation is 140-200° C., and the reaction pressure is 0-3.0 MPaG.

[0025] In different embodiments, the reaction temperature can be 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, etc.; similarly, in different embodiments, the reaction pressure can be 0.0 MPaG, 0.5 MPaG, 0.8 MPaG, 1.0 MPaG, 1.5 MPaG, 1.8 MPaG, 2.0 MPaG, 2.5 MPaG, 2.8 MPaG, 3.0 MPaG, etc.

[0026] In some preferred embodiments, the esterification reaction is carried out under nitrogen flow or reduced pressure and at a temperature of 100-200°C.

[0027] In different embodiments, the esterification temperature can be 100° C., 120° C., 130° C., 150° C., 170° C., 200° C., etc.

[0028] In some preferred embodiments, the concentration of the calcium nitrate solution in step S1 is 0.1-1 mol / L, the concentration of the ammonium dihydrogen phosphate solution is 0.1-1 mol / L, and the molar ratio of the calcium nitrate to the ammonium dihydrogen phosphate and the calcium phosphate is 1:(1-1.2):(2-2.2); the molar ratio of the copper nitrate to the nickel nitrate, the sodium carbonate and the sodium hydroxide in step S2 is 1:(0.8-1.1):(1.2-1.3):(0.38-0.4).

[0029] In some preferred embodiments, aromatic hydrocarbons are added to the biodiesel, and the amount of the aromatic hydrocarbons added is 0.001%-2% by weight of the biodiesel.

[0030] In different embodiments, the aromatic content may be 0.5%-2%, 0.3%-0.5%, 0.05%-0.3%, less than 0.05%, etc. To achieve optimal conversion and selectivity, the preferred range of aromatic addition is 0.05%-0.3%, more preferably 0.1%-0.25%, and most preferably 0.15%-0.23%.

[0031] In some preferred embodiments, the aromatic hydrocarbon is one or more of benzene, alkylbenzene, naphthalene, alkylnaphthalene, and anthracene.

[0032] The beneficial effects of the present invention are:

[0033] The invention provides an oxidation process for preparing fatty secondary alcohols using green and renewable biodiesel as a raw material. Specifically, the biodiesel is first pre-treated under the action of a first catalyst, and undergoes a decarboxylation reaction, a hydrolysis reaction, and a hydrogenation reaction using methanol as a hydrogen source. The first catalyst is separated to obtain a first product. The first product is then subjected to liquid-phase oxidation and esterification to obtain a third product containing a secondary alcohol borate. The secondary alcohol borate is recovered and hydrolyzed to obtain a fatty secondary alcohol. The remaining material is removed from impurities and returned to continue liquid-phase oxidation. The invention uses pre-treatment, ion-exchanges copper and nickel metal ions with alkaline calcium phosphate / calcium phosphate complexes, and then reduces to obtain the first catalyst. The first catalyst is used to promote conversion rate, thereby improving process production rate. The production process of the invention uses biodiesel as a raw material, avoids the use of petroleum-based raw material liquid paraffin, and does not generate polluting gases such as sulfur dioxide that are harmful to organisms in tail gas emissions, thereby greatly improving economic benefits while reducing environmental pollution. As a further technical solution of the invention, the invention also significantly promotes the oxidation conversion rate and selectivity of biodiesel by adding a small amount of aromatic hydrocarbons, further improving economic benefits. DETAILED DESCRIPTION

[0034] The present invention is further described with reference to the following examples.

[0035] Example 1

[0036] A biodiesel-based fatty secondary alcohol production process comprises the following steps:

[0037] (1) adding a first catalyst to biodiesel and reacting at 180° C. for 6 hours to obtain a first product;

[0038] The amount of the first catalyst added is 1.8% by weight of the biodiesel. The preparation method of the first catalyst comprises the following steps:

[0039] S1. Weigh calcium nitrate and dissolve it in deionized water, adjust the pH to alkaline with ammonia water to obtain a 0.5 mol / L calcium nitrate solution; weigh ammonium dihydrogen phosphate and dissolve it in deionized water to obtain a 0.4 mol / L ammonium dihydrogen phosphate solution, slowly add the calcium nitrate solution and the calcium dihydrogen phosphate solution to the hot ethanol solution in which calcium phosphate is dispersed, adjust the pH to not less than 10 with ammonia water after the addition is completed, continue to keep warm and stir for 0.5-1 hour, transfer the mixed solution to a hydrothermal reactor, heat to 100-130° C. under autogenous pressure and keep warm for reaction for 20-24 hours, cool after the reaction is completed, separate the precipitate, wash with deionized water and ethanol solvent in sequence, dry, and then calcine at 500-600° C. for 1-2 hours to obtain product A;

[0040] Wherein, the molar ratio of the calcium nitrate to the diammonium phosphate and the calcium phosphate is 1:1.1:2.1;

[0041] S2. Dispersing the product A in an ethanol solvent to obtain a dispersion; slowly adding a mixed solution of copper nitrate (0.5 mol / L) and nickel nitrate (0.5 mol / L) and a mixed solution of sodium carbonate (0.8 mol / L) and sodium hydroxide (0.25 mol / L) to the dispersion simultaneously, stirring and mixing for 1 hour, standing overnight, separating the precipitate, washing with deionized water and ethanol solvent in sequence, drying, calcining at 550° C. for 1 hour, cooling to 300° C. and replacing with a hydrogen atmosphere, continuing heat treatment for 2 hours, and cooling to obtain;

[0042] Wherein, the molar ratio of the copper nitrate to the nickel nitrate, the sodium carbonate, and the sodium hydroxide is 1:0.9:1.2:0.38;

[0043] (2) liquid-phase oxidation of the first product in the presence of a second catalyst, a third catalyst, and an oxygen atmosphere to obtain a second product;

[0044] (3) adding a portion of the secondary alcohol (5 wt %) obtained in the alcohol recovery tower to the second product and performing an esterification reaction to obtain a third product;

[0045] (4) recovering the crude secondary alcohol borate in the third product, and the remaining material is sequentially washed with alkali and water and then returned to step (2) to be combined with the first product to participate in the liquid phase oxidation;

[0046] (5) The recovered crude secondary alcohol borate is subjected to hydrolysis treatment to obtain a secondary alcohol. The hydrolysis, alkali washing, water washing, and distillation of the crude secondary alcohol borate are conventional processes and will not be described in detail here.

[0047] The biodiesel is a saturated fatty acid methyl ester with a carbon number of 8-30;

[0048] The second catalyst is dehydrated boric acid, and the third catalyst is an amino base substance;

[0049] The amount of the dehydrated boric acid added is 1.5% of the weight of the biodiesel; the amount of the amino base substance added is 0.05% of the weight of the biodiesel;

[0050] The oxygen content in the oxygen atmosphere is 8 vol%;

[0051] The reaction temperature of the liquid phase oxidation is 170°C and the reaction pressure is 0.1 MPaG;

[0052] The esterification reaction is carried out under nitrogen flow at a temperature of 200°C.

[0053] Example 2

[0054] A biodiesel-based fatty secondary alcohol production process comprises the following steps:

[0055] (1) adding aromatic hydrocarbons and a first catalyst to biodiesel, and reacting at 180° C. for 6 hours to obtain a first product;

[0056] The aromatic hydrocarbon is a mixture of benzene and naphthalene in an equal molar ratio, and the amount of the aromatic hydrocarbon added is 1.2% by weight of the biodiesel; the amount of the first catalyst added is 1.8% by weight of the biodiesel, and the preparation method of the first catalyst is the same as that of Example 1;

[0057] (2) liquid-phase oxidation of the first product in the presence of a second catalyst, a third catalyst, and an oxygen atmosphere to obtain a second product;

[0058] (3) adding a portion of the secondary alcohol (5 wt %) obtained in the alcohol recovery tower to the second product and performing an esterification reaction to obtain a third product;

[0059] (4) recovering the crude secondary alcohol borate in the third product, and the remaining material is sequentially washed with alkali and water and then returned to step (2) to be combined with the first product to participate in the liquid phase oxidation;

[0060] (5) hydrolyzing the recovered crude secondary alcohol borate to obtain a secondary alcohol;

[0061] The biodiesel is a saturated fatty acid methyl ester with a carbon number of 8-30;

[0062] The second catalyst is dehydrated boric acid, and the third catalyst is an amino base substance;

[0063] The amount of the dehydrated boric acid added is 1.5% of the weight of the biodiesel; the amount of the amino base substance added is 0.05% of the weight of the biodiesel;

[0064] The oxygen content in the oxygen atmosphere is 5 vol%;

[0065] The reaction temperature of the liquid phase oxidation is 180°C and the reaction pressure is 0.1 MPaG;

[0066] The esterification reaction is carried out under nitrogen flow or reduced pressure, and the esterification reaction temperature is 150°C.

[0067] Example 3

[0068] A process for producing fatty secondary alcohols based on biodiesel is the same as that of Example 2, except that the amount of aromatic hydrocarbon added is 0.5% by weight of the biodiesel.

[0069] Example 4

[0070] A process for producing fatty secondary alcohols based on biodiesel is the same as that of Example 2, except that the amount of aromatic hydrocarbon added is 0.05% by weight of the biodiesel.

[0071] Example 5

[0072] A process for producing fatty secondary alcohols based on biodiesel is the same as that of Example 2, except that the amount of aromatic hydrocarbon added is 0.01% by weight of the biodiesel.

[0073] Comparative Example 1

[0074] A process for producing fatty secondary alcohols based on biodiesel is the same as that of Example 1, except that in step (1), the first catalyst is replaced by Pricat Cu 60 / 8 catalyst and HTC Ni 500 catalyst in an equal weight ratio.

[0075] Comparative Example 2

[0076] A process for producing fatty secondary alcohols based on biodiesel is the same as that of Example 1, except that the first catalyst is not added in step (1).

[0077] To further verify the effects of the present invention, the oxidation conversion rate and apparent selectivity of the production processes described in Examples 1-5 and Comparative Examples 1-2 were calculated, wherein oxidation conversion rate (%) = (mass of raw biodiesel - mass of unreacted biodiesel) * 100 / mass of raw biodiesel; apparent selectivity (%) = mass of biodiesel converted from monohydric secondary alcohol * 100 / mass of reacted biodiesel. The calculation results are shown in the following table:

[0078]

[0079] As can be seen from the table, when the aromatic content is 1.2%, the oxidation conversion rate is 18.2% and the selectivity is about 78.6%; when the aromatic content is 0.5%, the oxidation conversion rate is 23.3% and the selectivity is about 83.5%; when the aromatic content is 0.05%, the oxidation conversion rate is 27.1% and the selectivity is about 89.4%; when the aromatic content is 0.01%, the oxidation conversion rate is 23.8% and the selectivity is about 82.1%; the corresponding distillation kettle residues are (50kg / t→30kg / t→20kg / t→30kg / t), and the aromatic content is controlled between 0.05% and 0.3%. The oxidation reaction has a high conversion rate and selectivity, indicating that adding a small amount of aromatics to the raw materials can increase the yield of biodiesel in the oxidation reaction and reduce consumption.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A process for producing fatty secondary alcohols based on biodiesel, characterized in that: The following steps are involved: (1) adding a first catalyst to biodiesel, and reacting at 170-200° C. for 5-8 hours to obtain a first product; (2) liquid-phase oxidation of the first product in the presence of a second catalyst, a third catalyst, and an oxygen atmosphere to obtain a second product; (3) adding a secondary alcohol to the second product and performing an esterification reaction to obtain a third product; (4) recovering the crude secondary alcohol borate in the third product, and the remaining material is sequentially washed with alkali and water and then returned to step (2) to be combined with the first product to participate in the liquid phase oxidation; (5) hydrolyzing the recovered crude secondary alcohol borate to obtain a secondary alcohol; The preparation method of the first catalyst comprises the following steps: S1. Weigh calcium nitrate and dissolve it in deionized water, and adjust the pH to alkaline with ammonia water to obtain a calcium nitrate solution; weigh ammonium dihydrogen phosphate and dissolve it in deionized water to obtain an ammonium dihydrogen phosphate solution, and slowly add the calcium nitrate solution and the ammonium dihydrogen phosphate solution to a hot ethanol solution in which calcium phosphate is dispersed. After the addition is completed, adjust the pH to not less than 10 with ammonia water, continue to keep warm and stir for 0.5-1 hour, transfer the mixed solution to a hydrothermal reactor, heat it to 100-130° C. under autogenous pressure, and keep it warm for reaction for 20-24 hours. After the reaction is completed, cool it, separate the precipitate, wash it with deionized water and ethanol solvent in sequence, dry it, and then calcine it at 500-600° C. for 1-2 hours to obtain product A; S2. Dispersing the product A in an ethanol solvent to obtain a dispersion; slowly adding a mixed solution of copper nitrate and nickel nitrate and a mixed solution of sodium carbonate and sodium hydroxide to the dispersion simultaneously, stirring and mixing for 1-2 hours, standing overnight, separating the precipitate, washing with deionized water and ethanol solvent in sequence, drying, calcining at 500-600° C. for 1-2 hours, and then heat-treating at 280-400° C. in a reducing atmosphere for 2-3 hours, and cooling to obtain the product; The second catalyst is dehydrated boric acid, and the third catalyst is an amino base substance.

2. A biodiesel-based fatty secondary alcohol production process according to claim 1, characterized in that: The biodiesel is a saturated fatty acid methyl ester with a carbon number of 8-30.

3. A biodiesel-based fatty secondary alcohol production process according to claim 1, characterized in that: The added amount of the dehydrated boric acid is 0.5%-10% of the weight of the biodiesel; and the added amount of the amino base substance is 0.001%-0.1% of the weight of the biodiesel.

4. A biodiesel-based fatty secondary alcohol production process according to claim 1, characterized in that: The oxygen content in the oxygen atmosphere is 2 vol%-10 vol%.

5. A biodiesel-based fatty secondary alcohol production process according to claim 1, characterized in that: The reaction temperature of the liquid phase oxidation is 140-200° C., and the reaction pressure is 0-3.0 MPaG.

6. A biodiesel-based fatty secondary alcohol production process according to claim 1, characterized in that: The esterification reaction is carried out under nitrogen flow or reduced pressure and at a temperature of 100-200°C.

7. A biodiesel-based fatty secondary alcohol production process according to claim 1, characterized in that: The concentration of the calcium nitrate solution in step S1 is 0.1-1 mol / L, the concentration of the ammonium dihydrogen phosphate solution is 0.1-1 mol / L, and the molar ratio of the calcium nitrate to the ammonium dihydrogen phosphate and the calcium phosphate is 1:(1-1.2):(2-2.2); the molar ratio of the copper nitrate to the nickel nitrate, the sodium carbonate and the sodium hydroxide in step S2 is 1:(0.8-1.1):(1.2-1.3):(0.38-0.4).

8. A biodiesel-based fatty secondary alcohol production process according to claim 1, characterized in that: Aromatic hydrocarbons are added to the biodiesel, and the amount of the aromatic hydrocarbons added is 0.001%-2% of the weight of the biodiesel.

9. A biodiesel-based fatty secondary alcohol production process according to claim 8, characterized in that: The aromatic hydrocarbon is one or more of benzene, alkylbenzene, naphthalene, alkylnaphthalene and anthracene.

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