LU501713B1 - Biomass-based Carbon-silicon Material Supported Heteropoly Acid Catalyst and Preparation Method and Application Thereof - Google Patents

Biomass-based Carbon-silicon Material Supported Heteropoly Acid Catalyst and Preparation Method and Application Thereof Download PDF

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LU501713B1
LU501713B1 LU501713A LU501713A LU501713B1 LU 501713 B1 LU501713 B1 LU 501713B1 LU 501713 A LU501713 A LU 501713A LU 501713 A LU501713 A LU 501713A LU 501713 B1 LU501713 B1 LU 501713B1
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silicon material
acid
carbon
catalyst
reaction
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Xiaoxiang Han
Xiujuan Tang
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Univ Zhejiang Gongshang
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/08—Silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/18—Carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/14—Phosphorus; Compounds thereof
    • B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J27/188—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with chromium, molybdenum, tungsten or polonium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/14—Phosphorus; Compounds thereof
    • B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J27/188—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with chromium, molybdenum, tungsten or polonium
    • B01J27/19—Molybdenum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0027—Powdering
    • B01J37/0036—Grinding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/06—Washing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/082—Decomposition and pyrolysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/36—Biochemical methods
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds

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Abstract

The application provides a biomass-based carbon-silicon material supported heteropoly acid catalyst and preparation method and application thereof. The preparation method is as follows: (1) crushing rice straw, putting it in inorganic acid aqueous solution for oil bath reflux reaction, and calcining in inert gas atmosphere to obtain initial biomass carbon-silicon material; (2) mixing the obtained initial biomass carbon-silicon material with coupling agent and organic solvent, heating and reacting in oil bath, and extracting by Soxhlet to obtain carbon-silicon material carrier; (3) dispersing the obtained carbon-silicon material carrier in the heteropoly acid aqueous solution, heating and reacting in an oil bath, and after the reaction, sequentially removing water, washing and drying to obtain the biomass carbon-silicon material supported heteropoly acid catalyst. The supported catalyst may basically reach the catalytic performance of free catalyst, and is used in the selective preparation of lauric acid monoglyceride with high catalytic efficiency.

Description

DESCRIPTION LU501713 Biomass-based Carbon-silicon Material Supported Heteropoly Acid Catalyst and Preparation Method and Application Thereof
TECHNICAL FIELD The application relates to that technical field of esters preparation, and in particular to a preparation method of a biomass-based carbon-silicon material supported heteropoly acid catalyst and the application of the catalyst in the esterification reaction of lauric acid and glycerol.
BACKGROUND Glycerol laurate (GML) is not only an excellent emulsifier, but also a safe, efficient and broad-spectrum antibacterial agent. As a safe food additive, GML has been widely used in food, pharmaceutical, cosmetics and other industries. GML is usually prepared by direct esterification of lauric acid and glycerol in the presence of protic acid catalyst. Traditional catalytic methods have some problems such as complicated post-treatment, heavy environmental pollution, poor selectivity and low catalytic efficiency.
SUMMARY The application provides a preparation method of a biomass-based carbon-silicon material supported heteropoly acid catalyst and the application thereof. The supported catalyst can basically reach the catalytic performance of free catalyst, and it has high catalytic efficiency, good selectivity, little environmental pollution and good repeatability when used in the selective preparation of lauric acid monoglyceride.
A preparation method of biomass-based carbon-silicon material supported heteropoly acid catalyst comprises: (1) crushing rice straw, putting it in inorganic acid aqueous solution for oil bath reflux reaction, and calcining in inert gas atmosphere to obtain initial biomass carbon-silicon material; (2) mixing the obtained initial biomass carbon-silicon material with coupling agent and organic solvent, heating and reacting in oil bath, and extracting by Soxhlet to obtain carbon-silicon material carrier; (3) dispersing the obtained carbon-silicon material carrier in the heteropoly acid aqueous solution, heating and reacting in an oil bath, and after the reaction, sequentially removing water,
washing and drying to obtain the biomass carbon-silicon material supported heteropoly actdJ501713 catalyst.
Straw is a kind of agricultural waste, with abundant sources and high content of silicon dioxide and carbon. Carbon-silicon material derived from rice straw is a kind of porous carrier material with rich hierarchical porous structure and high specific surface area. Using carbon-silicon materials derived from rice straw as catalyst components can provide a new development space for a large number of waste materials, which is conducive to increasing the value of rice straw and improving the utilization of biomass resources.
Heteropoly acid is a kind of designable solid acid with strong acidity and strong oxidation, and it is a new kind of environment-friendly catalytic material. The adjustable catalytic characteristics and "pseudo-liquid phase" reaction field of heteropoly acid-catalyzed reaction often make it show better catalytic performance. However, the specific surface area of heteropoly acid itself is small, and it is easy to dissolve in polar solvent and difficult to separate during use, which limits its industrial application. Aiming at a series of reaction conditions and post-treatment problems in the process of selective esterification, a heteropoly acid catalyst supported on biomass carbon-silicon materials was developed.
The application found that the above problems can be effectively solved by immobilizing heteropoly acid on carbon-silicon materials. The heteropoly acid catalyst supported on biomass carbon-silicon material can effectively improve the thermal stability of heteropoly acid, which is linked by amino group and has excellent hydrothermal stability. At the same time, the carbon-silicon material has rich hierarchical porous structure, which can minimize the mass transfer resistance through nanopores. The high specific surface area of carbon material can expose more active sites to enhance its catalytic activity and reduce the amount of catalyst. After the reaction, the catalyst and the reaction mixture can be separated by simple filtration. In addition, the carrier carbon-silicon material is derived from straw, which is an agricultural waste with abundant sources and extremely low cost. Taking the carbon-silicon material derived from it as a catalyst component can help to increase the value of straw and reduce the cost of catalyst, and make full use of biomass resources, which is economical and environmentally friendly. Therefore, it is of great theoretical and practical significance to study the preparation and catalytic performance of carbon-silicon supported heteropoly acid catalyst.
Therefore, in this application, straw is used as the raw material to prepare the biomaks/501713 carbon-silicon material, which is combined with the coupling agent to obtain a biomass carbon-silicon material with amino groups on the surface, and then an ionic liquid exchange method and heteropoly acid aqueous solution are used to prepare the biomass carbon-silicon material supported heteropoly acid catalyst. And the heteropoly acid is bound with amino heteropoly acid through chemical bonds, so that the heteropoly acid is immobilized on the carbon-silicon material, the rich hierarchical porous structure of the carbon-silicon material can reduce mass transfer resistance, and the characteristic of high specific surface area can expose more active sites to enhance its catalytic activity, so that the catalytic activity and stability of the catalyst prepared by the application are remarkably improved, and the catalyst has good activity for selectively catalyzing and preparing monoglyceride laurate. After only 2 hours of reaction, the conversion of lauric acid was over 90%, the selectivity of lauric acid monoglyceride was over 80%, and all the catalysts could be recycled.
Several alternative ways are provided below, but they are not additional restrictions on the above general scheme, but only further supplements or preferences. On the premise that there is no technical or logical contradiction, each alternative way can be combined separately for the above general scheme, or among several alternative ways.
Optionally, the inorganic acid solution in step (1) is any one of hydrochloric acid, nitric acid, sulfuric acid, citric acid and oxalic acid; and the concentration of the inorganic acid aqueous solution is 1-3 mol/L.
Optionally, the mass ratio of the rice straw to the inorganic acid aqueous solution in step (1) is 1:5-15.
Further preferably, the inorganic acid aqueous solution is hydrochloric acid; the concentration of that inorganic acid aqueous solution is 1-1.5 mol/L; the mass ratio of rice straw to inorganic acid aqueous solution in step (1) is 1: 8-12.
Optionally, the oil bath reflux reaction in step (1) is carried out at 100-140°C for 2-12 hours.
Optionally, the calcination temperature in step (1) is 400-800°C for 2-12 hours.
Further, the calcination temperature is 600-700 °C; more preferably 700°C, and the calcination time is 3 to 6 hours.
Optionally, the coupling agent in step (2) 1s (3-aminopropyl) triethoxysilane. LU501713 Optionally, the organic solvent in step (2) is one of toluene, absolute ethanol and ethyl acetate.
Optionally, in step (2), the initial biomass carbon-silicon material, the coupling agent and the organic solvent are in a mass-volume ratio of 1 g:1-5 ml:25-35 ml.
Furthermore, in step (2), the mass volume ratio of the initial biomass carbon-silicon material, the coupling agent and the organic solvent is 1 g:1-2 ml: 28-32 ml.
Optionally, the solvent for Soxhlet extraction in step (2) is one of methanol, ethanol, acetone and ethyl acetate, which is different from the aforementioned organic solvent. It can also be understood that the organic solvent of the reaction system and the solvent for Soxhlet extraction do not choose the same solvent.
Optionally, the organic solvent is toluene, and the Soxhlet extraction solvent is methanol.
Optionally, the Soxhlet extraction temperature in step (2) is 65-120°C; Furthermore, the Soxhlet extraction temperature is 80-100°C.
Optionally, the temperature of the heating reaction in the oil bath in step (2) is 110-150°C and the time is 18-30 h.
Furthermore, in step (1), the calcination temperature in inert gas (such as nitrogen) atmosphere is 700°C for 4 hours; The Soxhlet extraction temperature in step (2) is 100°C.
Optionally, the heteropoly acid in the heteropoly acid aqueous solution in step (3) is any one of silicotungstic acid, phosphotungstic acid and phosphomolybdic acid.
Optionally, the temperature of the heating reaction in the oil bath in step (3) is 50-100°C and the time is 12-24 h.
Optionally, in step (3), when the carbon-silicon material carrier is dispersed in the heteropoly acid aqueous solution, the mass ratio of the heteropoly acid in the heteropoly acid aqueous solution to the carbon-silicon material carrier is 1-8 mmol/g.
It can also be understood that the amount of heteropoly acid in the heteropoly acid aqueous solution is 1-8 mmol/g based on the mass of the biomass carbon-silicon material.
Furthermore, the amount of heteropoly acid in the heteropoly acid aqueous solution is 1-4 mmol/g based on the mass of the biomass carbon-silicon material; Further, it is 1-2 mmol/g; Most preferably 1 mmol/g.
Optionally, in step (1), the temperature of oil bath reflux reaction is 120°C and the time isl2501713 h; the temperature of oil bath reaction in step (2) is 110°C and the time is 24h; in step (3), the temperature of oil bath reaction is 90°C and the stirring time is 12 hours.
The application also provides a biomass carbon-silicon material supported heteropoly acid catalyst prepared by the preparation method.
The application also provides the application of the biomass carbon-silicon material supported heteropoly acid catalyst in catalytic preparation of higher fatty acid esters.
The application also provides a method for preparing higher fatty acid esters by catalysis, which comprises the following steps: (1) taking alcohol and carboxylic acid as raw materials and the biomass carbon-silicon material supported heteropoly acid catalyst of as a catalyst, reacting in an oil bath at 80-170°C for 0.5-5 h; (2) cooling after the reaction, layering the catalyst and the reaction system, recovering the solid catalyst by filtration, and directly reusing the solid catalyst for the next reaction after washing and drying; the reaction system was separated and purified to obtain higher fatty acid esters.
The higher fatty acid ester is obtained by conventional separation and purification of the reaction system: excess alcohol is distilled off, and lauric acid monoglyceride is obtained by vacuum distillation.
Optionally, the carboxylic acid is one of C8-C20 saturated or unsaturated fatty acids; the alcohol is one of methanol, ethanol, propanol, ethylene glycol and glycerol. Further, the carboxylic acid is lauric acid and the alcohol is glycerol.
Optionally, the molar ratio of carboxylic acid to alcohol is 1: 2-9; optionally, the molar ratio of the carboxylic acid to the alcohol is 1:5-7. Under this optimum ratio, lauric acid conversion/%is above 94%, and monoester yield is above 80%.
Optionally, the amount of the catalyst is 1%-8% of the weight of the carboxylic acid, optionally, the amount of the catalyst is 5%-7% of the weight of the carboxylic acid. Under this optimum ratio, lauric acid conversion/%is above 94%, and monoester yield is above 80%.
More optionally, the molar ratio of the carboxylic acid to the alcohol is 1:5, and the amount of the catalyst is 5%-7% of the carboxylic acid mass.
Optionally, in step (1), the reaction takes place in an oil bath at 120-170°C for 1.5-2.5 hU501713 Furthermore, the range temperature in step (1) is 150-160°C.
More alternatively, the preparation of monoglyceride laurate is most preferably reacted in an oil bath at 150°C for 2 hours.
The yield and purity of lauric acid monoglyceride prepared by catalysis under the above optimum conditions can reach a high value.
Compared with the prior art, the application has at least one of the following beneficial effects: (1) In this application, straw is used as the raw material to prepare the biomass carbon-silicon material, so that heteropoly acid is immobilized on the carbon-silicon material, and the hydrothermal stability of the obtained catalyst is obviously improved, which has good activity for selectively catalyzing the preparation of lauric acid monoglyceride, high product selectivity and convenient recovery, and reduces the catalyst cost, makes full use of biomass, and is economical and environment-friendly.
(2) The outstanding advantage of this application is that the carbon-silicon material has rich hierarchical porous structure, which can minimize the mass transfer resistance through nanopores; carbon silicon material has the characteristics of high specific surface area, which can expose more active sites to enhance its catalytic activity and reduce the amount of heteropoly acid. After the reaction, the catalyst and the reaction mixture can be separated by simple filtration.
(3) More importantly, in this application, the carrier carbon-silicon material is taken from rice straw, which makes full use of biomass resources, is beneficial to the value-added of rice straw and the reduction of catalyst cost, and is economical and environmentally friendly.
DESCRIPTION OF THE INVENTION Next, the technical scheme of this application will be clearly and completely described with embodiments. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of this application.
Unless otherwise defined, all technical and scientific terms used herein have the santé/501713 meaning as commonly understood by those who belong to the technical field of this application. The terms used in the specification of this application are only for the purpose of describing specific embodiments, and are not intended to limit this application 2.
The raw materials used in the following embodiments are all commercial products.
Embodiment 1 Taking 1 mmol silicotungstic acid loaded on 1 g biomass carbon-silicon material as an embodiment, the preparation method of the catalyst is as follows: (1) Preparation of initial biomass carbon-silicon material: washing agricultural waste straw, putting into an oven at 80°C for overnight drying, and then crushing the dried straw to 80 meshes for later use; putting a certain amount of rice straw particles in dilute hydrochloric acid (deionized water: 35% HCI=9:1), the mass ratio of rice straw to dilute hydrochloric acid is 1: 10, and refluxing the mixture in oil bath to remove possible metal impurities in the rice straw; after washing with distilled water, vacuum filtering and drying overnight; calcining the obtained straw in a nitrogen atmosphere tube furnace, and obtaining the initial biomass carbon-silicon material after cooling; diluting hydrochloric acid concentration is deionized water: 35% HCl =9:1; the reaction temperature of oil reflux in bath is 120°C, and the reaction time is 2 h. The tube furnace calcination temperature is 700°C and the calcination time is 4 h.
(2) Preparation of carbon-silicon material carrier: putting the carbon-silicon material in toluene, then adding (3-aminopropyl) triethoxysilane into it, putting the reaction system in an oil bath, after the stirring reaction, washing the product with ethanol, suction filtering and vacuum drying to obtain carbon-silicon particles with amino groups on the surface; then, carrying out Soxhlet extraction with methanol as solvent, the fat possibly contained in the straw and related reagents remaining in the above operation are removed, and the carrier carbon-silicon material is obtained after drying; according to the mass of carbon-silicon particles, the amount of toluene is about 30 mL/g, the amount of (3-aminopropyl) triethoxysilane is 2 mL/g, the reaction temperature in oil bath is 110°C, and the reaction time is 24 hours. Soxhlet extraction temperature is 95°C and extraction time is 6 h.
(3) Putting an appropriate amount of carbon-silicon material carrier and an appropriate amount of silicotungstic acid solution in a three-necked flask, and stirring in an oil bath overnight. The amount of silicotungstic acid in silicotungstic acid solution is 1 mmol/g based à#/501713 the mass of carbon-silicon material carrier. The oil bath reaction temperature is 90°C and the reaction time is 24 h.
(4) After the reaction, distilling off the water, and washing the obtained solid compound several times with ether and then drying in vacuum at 75°C for 8 hours, thus obtaining the heteropoly acid catalyst supported by biomass carbon-silicon material, which is designated as 700-C-Si-NH>-H4S1W12040-1.
Respectively changing the calcination temperature of the tube furnace in the above step (1) to 400°C, 500°C, 600°C and 800°C, and then processing under the same conditions to obtain biomass carbon-silicon materials with different calcination temperatures, and then loading heteropoly acid to obtain biomass carbon-silicon materials with different calcination temperatures supported heteropoly acid catalysts: = 400-C-S1-NH»-HyS1W12040-1, 500-C-S1i-NH>-H4S1W12040-1, 600-C-Si-NH>- H4SiW12040-1 and 800-C-Si-NHz-H4S1W12040-1.
The biomass carbon-silicon material supported heteropoly acid catalysts with different calcination temperatures prepared above are used to catalyze the synthesis of lauric acid monoglyceride in the following embodiments.
Selecting the best calcination temperature of biomass carbon-silicon material, and then replacing the amount of silicotungstic acid in silicotungstic acid solution with 2 mmol/g based on the mass of carbon-silicon material carrier, and then processing under the same conditions to obtain biomass carbon-silicon material loaded with different amounts of heteropoly acid catalyst C-Si-NH;-H4SiW12040-2.
The biomass carbon-silicon material supported heteropoly acid catalysts with different loading amounts prepared above were used to catalyze the synthesis of lauric acid monoglyceride in the following embodiments.
Embodiments 2-6 Sequentially adding 10.0 g lauric acid, 23.0 g glycerol and 0.50 g supported catalyst (prepared in Embodiment 1) into a 100 mL three-necked flask equipped with reflux condenser tube, heating and reacting in an oil bath at 150°C for 2.0 hours; after the reaction, cooling, layering the catalyst and the reaction system, and taking the upper liquid for quantitative and directional analysis by gas chromatography; separating the solid catalyst by filtration, washing with ether and drying, directly using in the next reaction; distilling excess glycerol and distillit&501713 under reduced pressure to obtain monoglyceride laurate.
The esterification reaction results obtained by supporting heteropoly acid catalysts on carbon-silicon materials at different calcination temperatures are shown in Table 1. Table 1 Esterification reaction results of carbon-silicon materials supported catalysts at different calcination temperatures Catalvst Lauric acid Monoester Monoester atalys conversion rate/% selectivity % ield/% 400-C-Si-NH>-H:SiW12040-1 500-C-Si-NH,-HiSiW 1504-1 600-C-Si-NH,-HiSiW 1504-1 700-C-Si-NH2-H,SiW12040-1 800-C-Si-NHz-H;SiW120:-1 | ___ 909 | 835 | 759 | From the results in Table 1, it can be seen that different calcination temperatures have influence on the catalytic activity of the catalyst, among which the calcination temperature of carbon-silicon materials is in the range of 400°C-800°C, and lauric acid conversion rate, monoester selectivity and monoester yield can all achieve good results; from 600°C to 700°C, the conversion rate of lauric acid is over 90%, the monoester selectivity is over 85%, and the monoester yield is about 80%. When the calcination temperature of carbon material is 700°C, the prepared catalyst has the best catalytic activity.
Embodiments 7-8 The esterification reaction results obtained by loading different amounts of catalysts are shown in Table 2. Table 2 Esterification reaction results of catalysts with different loadings Catalvst Lauric acid Monoester Monoester AS conversion rate/% selectivity% yield/% The results in Table 2 show that: (1) the supported catalyst can basically achieve the catalytic performance of free catalyst, (2) the biomass carbon-silicon material supports silicotungstic acid, which can effectively improve the selectivity of silicotungstic acid t&J501713 monoglyceride laurate and the yield of monoester; (3) when the loading amount is 1 or 2 mmol/g, it has good catalytic activity, which indicates that when the loading amount is 1 mmol/g, the adsorption of heteropoly acid by carbon-silicon materials may have basically reached saturation. In addition, when the loading is 1 mmol/g, the relative content of carrier in C-Si-NH>-H4S1W12040-1 catalyst is higher, and the overall cost of the catalyst is lower when the catalytic effect is similar.
Embodiments 9-13 Sequentially adding 10.0 g lauric acid, 23.0 g glycerol and 0.50 g supported catalyst (prepared in Embodiment 1) into a 100 mL three-necked flask equipped with reflux condenser tube heating and reacting in an oil bath at 150°C for 2.0 hours; after the reaction, cooling, layering the catalyst and the reaction system, and separating the solid catalyst by filtration; after being washed and dried by ether, it can be directly used in the next reaction; taking the upper liquid for quantitative directional analysis of lauric acid conversion rate and lauric acid monoglyceride yield by gas chromatography. The esterification reaction results obtained by changing the molar ratio of glycerol to lauric acid are shown in Table 3.
Table 3 ews us From the results in Table 2, it can be seen that when the molar ratio of alkyd is in the range of 3-7, both lauric acid conversion rate and monoester yield can achieve good results. When the molar ratio of alcohol to acid is 5-7, the lauric acid conversion rate is above 94%, and the monoester yield is above 80%.
Embodiments 14-18 Sequentially adding 10.0 g lauric acid, 23 g glycerol and 0.5 g catalyst into a 100 mL three-necked flask equipped with reflux condenser, heating in an oil bath for 2.0 h, and then cooling after the reaction.
The catalyst is layered with the reaction system, and the solid catalylst/501713 is filtered and separated.
After being washed and dried by ether, it can be directly used for the next reaction.
The reaction conversion rate and the yield of monoglyceride laurate are analyzed by gas chromatography.
The esterification results obtained by changing the amount of catalyst are shown in Table 4. Table 4 Amount of catalyst /wt% Lauric acid co version Monoester yield/% rate/% ees we we | mi | From the results in Table 4, it can be seen that within the range of 3-7wt% of catalyst, both lauric acid conversion and monoester yield can achieve good results.
When the amount of catalyst is 5-7wt%, the conversion of lauric acid is above 94% and the yield of monoester is above 80%. Embodiments 19-24 Sequentially adding 10.0 g lauric acid, 23 g glycerol and 0.5 g catalyst into a 100 mL three-necked bottle equipped with reflux condenser, heating in an oil bath for 2.0 hours.
The catalyst is layered with the reaction system, and the solid catalyst is filtered and separated.
After being washed and dried by ether, it can be directly used for the next reaction.
The reaction conversion rate and the yield of monoglyceride laurate are analyzed by gas chromatography.
The esterification results obtained by changing the reaction temperature are shown in Table 5. Table 5 Reaction temperature/C Lauric acid co version Monoester yield/% rate/%
From the results in Table 5, it can be seen that both lauric acid conversion and monoestet)501713 yield can achieve good results in the reaction temperature range of 120-170°C. The conversion of lauric acid is above 94% and the yield of monoester is around 80% at the reaction temperature of 150-160°C.
Embodiments 25-30 In the above embodiment, after the reaction, the catalyst is cooled. The 700-C-S1-NH>-H4S1W12040-1 catalyst is separated from the reaction system by filtration, washed with ether and dried to obtain the recovered catalyst.
Sequentially adding 10 g lauric acid, 23 g glycerol and 0.5 g of the recovered 700-C-S1i-NH>-H4SiW12040-1 catalyst into a 100mL three-necked flask equipped with reflux condenser tube, and heating the mixture in an oil bath at 150°C for reaction; at the end of 2.0 h, analysing the conversion and yield of the reaction products by gas chromatography. The reusability of 700-C-S1i-NHz-H4SiW12040-1 catalyst in lauric acid monoglyceride reaction is shown in Table 6.
Table 6 LU 6 wa | tes | It can be seen from the results in Table 6 that the catalyst prepared by the method of this application can still maintain high lauric acid conversion rate and monoester yield after repeated use for 6 years.
The above embodiments show that the catalyst prepared by this method shows good catalytic activity and high monoglyceride selectivity at a low amount of heteropoly acid, and it is a green chemical technology with simple post-treatment and less pollution.

Claims (10)

CLAIMS LU501713
1. A preparation method of biomass-based carbon-silicon material supported heteropoly acid catalyst, characterized by comprising: (1) crushing rice straw, putting in inorganic acid aqueous solution for oil bath reflux reaction, and calcining in inert gas atmosphere to obtain initial biomass carbon-silicon material; (2) mixing the obtained initial biomass carbon-silicon material with coupling agent and organic solvent, heating and reacting in oil bath, and extracting by Soxhlet to obtain carbon-silicon material carrier; and (3) dispersing the obtained carbon-silicon material carrier in the heteropoly acid aqueous solution, heating and reacting in an oil bath, and after the reaction, sequentially removing water, washing and drying to obtain the biomass-based carbon-silicon material supported heteropoly acid catalyst.
2. The preparation method according to claim 1, characterized in that in step (1): the inorganic acid solution is any one of hydrochloric acid, nitric acid, sulfuric acid, citric acid and oxalic acid; the concentration of the inorganic acid aqueous solution is 1-3 mol/L; the mass ratio of the rice straw to the inorganic acid aqueous solution is 1-5:15; the temperature of the oil bath reflux reaction is 100-140°C and the time is 2-12 hours; and the calcination temperature is 400-800°C and the time is 2-12 hours.
3. The preparation method according to claim 1, characterized in that in step (2): the coupling agent is (3-aminopropyl) triethoxysilane; the organic solvent is one of toluene, absolute ethanol and ethyl acetate; the initial biomass carbon-silicon material, the coupling agent and the organic solvent are calculated according to the mass-volume ratio of 1g:1-5 ml:25-35 ml; the Soxhlet extraction solvent is one of methanol, ethanol, acetone and ethyl acetate and is different from the organic solvent; the Soxhlet extraction temperature is 65-120°C; and the temperature of the heating reaction in the oil bath is 110-150°C and the time is 18-30 hours.
4. The preparation method according to claim 1, characterized in that in step (3): the heteropoly acid in the heteropoly acid aqueous solution is any one of silicotungstic acid, phosphotungstic acid and phosphomolybdic acid,
and the temperature of the heating reaction in the oil bath is 50-100°C, and the time is 12-24J501713 h.
5. The preparation method according to claim 1, characterized in that in step (3), when the carbon-silicon material carrier is dispersed in the heteropoly acid aqueous solution, the mass ratio of the heteropoly acid in the heteropoly acid aqueous solution to the carbon-silicon material carrier is 1-8 mmol/g.
6. A biomass-based carbon-silicon material supported heteropoly acid catalyst prepared by the preparation method according to any one of claims 1 to 5.
7. An application of the heteropoly acid catalyst supported on biomass carbon-silicon material according to claim 6 in catalytic preparation of higher fatty acid esters.
8. A method for preparing higher fatty acid esters by catalysis, characterized by comprising: (1) taking alcohol and carboxylic acid as raw materials and the biomass-based carbon-silicon material supported heteropoly acid catalyst of claim 6 as a catalyst, reacting in oil bath at 80-170°C for 0.5-5 h; and (2) cooling after the reaction, layering the catalyst and the reaction system, recovering the solid catalyst by filtration, and directly reusing the solid catalyst for the next reaction after washing and drying; the reaction system is separated and purified to obtain higher fatty acid esters.
9. The method according to claim 8, characterized in that the carboxylic acid is one of saturated or unsaturated fatty acids of C8-C20; the alcohol is one of methanol, ethanol, propanol, ethylene glycol and glycerol.
10. The method according to claim 8, characterized in that the molar ratio of carboxylic acid to alcohol is 1:2-9; the amount of the catalyst is 1%-8% of the weight of the carboxylic acid; in the step (1), the reaction takes place in oil bath at 120-170°C for 1.5-2.5 h.
LU501713A 2022-03-24 2022-03-24 Biomass-based Carbon-silicon Material Supported Heteropoly Acid Catalyst and Preparation Method and Application Thereof LU501713B1 (en)

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