Application of activated aluminum oxide in degradation of fusel oil of Baijiu

Abstract

The invention discloses application of activated aluminum oxide in degradation of fusel oil in white spirit in the technical field of fusel oil degradation. The activated aluminum oxide is acidic aluminum oxide or neutral aluminum oxide. According to the method, activated aluminum oxide is used as a catalyst, and green degradation of fusel oil in Baijiu is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of fusel oil degradation, and particularly relates to application of activated alumina in the degradation of fusel oil in liquor. Background Art

[0002] Fusel oils, also known as higher alcohols, are a mixture of monohydric alcohols with three or more carbon atoms. Among them, n-propanol, n-butanol, isopentanol, isobutanol, octanol, active amyl alcohol, n-pentanol, tyrosol, and tryptophan are the main fusel oils in baijiu. Fusel oils are important flavor compounds in baijiu, contributing to the unique flavor profiles and contributing significantly to the body and mouthfeel of the liquor. Fusel oils are a double-edged sword in baijiu. In appropriate amounts, they enhance the liquor's quality through esterification and flavor enhancement. However, excessive amounts can disrupt the liquor's balance, imparting a pungent and bitter taste, and pose health risks. When consumed in excess, baijiu beverages with an inappropriate fusel oil content require liver metabolism due to their large molecular weight. However, their oxidation rate is significantly lower than that of ethanol, resulting in a prolonged residence time in the body and a continuous accumulation of toxicity, often leading to a hangover. This hangover is often manifested as headaches, dizziness, nausea, and difficulty sobering up. Severe intake of fusel oil can lead to chronic alcohol poisoning and cardiovascular disease, damage to the nervous system, chronic liver disease and cirrhosis. Therefore, during the production process of liquor, it is generally necessary to degrade some of the fusel oil in the liquor.

[0003] At present, the degradation of fusel oil in liquor is generally carried out using adsorption materials, and the mainstream adsorption materials are macroporous adsorption resins and activated carbon materials for adsorption and removal. Macroporous adsorption resins are a type of polymer material with a highly cross-linked network structure and permanent voids. Their multi-level pore structure and surface chemical modification characteristics can dynamically adsorb and selectively retain fusel oil molecules through intermolecular van der Waals forces, π-π conjugation effects, and hydrogen bonding. However, they cannot precisely control the adsorption of certain fusel oil components, which may cause the loss of some beneficial substances and affect the taste and quality of the wine. Therefore, different types of resins can be selected to adsorb different components of fusel oil. Moreover, its adsorption capacity is relatively stable and has a large capacity, but it needs to be replaced regularly, and the replacement cost is relatively high. Activated carbon is a hydrophobic porous carbon adsorbent with a large specific surface area (600-1600m 2 / g), well-developed pores, and a large adsorption capacity. Its adsorption mechanisms utilize physical adsorption (van der Waals forces), chemical adsorption, and ion exchange. It selectively adsorbs easily adsorbed macromolecules, substances that cause turbidity, and highly polar molecules in wine. However, its selectivity is poor, and it adsorbs other flavor compounds along with fusel oils. An appropriate amount of charcoal can effectively remove fusel oils. Excessive use not only increases wine loss but can also impart an unpleasant odor to the wine.

[0004] Activated carbon adsorption is inexpensive and has good physical stability, but its adsorption selectivity is unreasonable and its adsorption capacity is small. It not only adsorbs fusel oil, but also other beneficial flavor substances (such as esters and acids), changing the flavor and taste of the liquor and potentially affecting the quality of the liquor.

[0005] Therefore, developing efficient, low-cost, green and environmentally friendly fusel oil degradation technology will provide theoretical and technical solutions for improving the quality and greening of liquor, which is of great significance to promoting the greening and standard development of the industry. Summary of the Invention

[0006] The present invention aims to provide an application of activated alumina in the degradation of fusel oil in liquor, so as to achieve green degradation of fusel oil in liquor.

[0007] Furthermore, the application of activated alumina in the degradation of white wine fusel oil.

[0008] Furthermore, activated alumina is used as a catalyst in the degradation of fusel oil in liquor. Being non-toxic, insoluble, and reusable, activated alumina can reduce the activation energy of fusel oil esterification, accelerate the reaction rate, and shorten the degradation time required, achieving green degradation. Furthermore, the catalyst maintains its chemical properties and quality before and after the reaction and is recyclable, reducing production costs and meeting the economic and efficient requirements of industrial production.

[0009] Furthermore, the activated alumina is acidic alumina or neutral alumina.

[0010] Furthermore, the fusel oil is at least one of isoamyl alcohol and n-butanol. Isoamyl alcohol and n-butanol are the main fusel oil components in baijiu that cause adverse effects such as a "headiness" and a bitter taste. Using activated alumina to degrade these components can effectively reduce the content of fusel oil in baijiu, thereby reducing the risk of discomfort symptoms such as headaches and dizziness after drinking baijiu.

[0011] Furthermore, the application is a method for degrading fusel oil in liquor using activated alumina.

[0012] Furthermore, the activated alumina is neutral. To degrade fusel oil in liquor, the neutral alumina is added to the Maotai-flavor liquor and allowed to fully react at a temperature of 70°C to 150°C. This temperature range ensures that the neutral alumina exhibits optimal catalytic activity, accelerating the esterification reaction of fusel oil, while also preventing excessive loss of other volatile flavor compounds in the liquor due to excessive temperatures, thereby preserving the unique flavor and aroma of Maotai-flavor liquor.

[0013] Furthermore, the reaction time is 3 to 5 hours.

[0014] Furthermore, the activated alumina is acidic. To degrade fusel oil in liquor, the acidic alumina is added to the Maotai-flavor liquor and allowed to fully react at a temperature of 70°C to 130°C. This temperature range is suitable for liquor distillation and is conducive to the subsequent promotion and application of activated alumina. Furthermore, this temperature maximizes the catalytic degradation of fusel oil by the active sites on the acidic alumina surface, improving degradation efficiency.

[0015] Furthermore, the reaction time is 3 to 5 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Gas chromatograms of mixed standards of different samples.

[0017] Figure 2 These are the regression curves of isoamyl acetate and n-butyl acetate at different sample concentrations.

[0018] Figure 3 The regression curves are shown at different sample concentrations.

[0019] Figure 4 This is a curve chart showing the effect of neutral alumina dosage on the esterification rate of synthesized isoamyl acetate.

[0020] Figure 5 This is a curve diagram showing the effect of reaction time on the esterification rate of isoamyl acetate.

[0021] Figure 6 This is a curve diagram showing the effect of reaction temperature on the esterification rate of isoamyl acetate.

[0022] Figure 7 This is a curve diagram showing the effect of the molar ratio of acetic acid to isoamyl alcohol on the esterification rate of isoamyl acetate.

[0023] Figure 8 This is a curve chart showing the effect of the amount of acidic alumina on the esterification rate of synthesized isoamyl acetate.

[0024] Figure 9 This is a curve diagram showing the effect of reaction time on the esterification rate of isoamyl acetate.

[0025] Figure 10 This is a curve diagram showing the effect of reaction temperature on the esterification rate of isoamyl acetate.

[0026] Figure 11 This is a curve diagram showing the effect of the molar ratio of acetic acid to isoamyl alcohol on the esterification rate of isoamyl acetate.

[0027] Figure 12 The effect of the amount of neutral alumina on the esterification rate of synthesized n-butyl acetate.

[0028] Figure 13 This is a curve chart showing the effect of reaction time on the esterification rate of n-butyl acetate.

[0029] Figure 14 This is a curve diagram showing the effect of reaction temperature on the esterification rate of n-butyl acetate.

[0030] Figure 15 This is a curve diagram showing the effect of the molar ratio of acetic acid to n-butanol on the esterification rate of n-butyl acetate.

[0031] Figure 16 This is a curve chart showing the effect of the amount of acidic alumina on the esterification rate of synthesized n-butyl acetate.

[0032] Figure 17 This is a curve chart showing the effect of reaction time on the esterification rate of n-butyl acetate.

[0033] Figure 18 This is a curve diagram showing the effect of reaction temperature on the esterification rate of n-butyl acetate.

[0034] Figure 19 This is a curve diagram showing the effect of the molar ratio of acetic acid to n-butanol on the esterification rate of n-butyl acetate.

[0035] Figure 20 This is the gas chromatogram of the flavor compounds of Maotai-flavor liquor.

[0036] Figure 21 Chromatogram of Maotai-flavor liquor after reaction. DETAILED DESCRIPTION

[0037] The following is further described in detail through specific implementation methods:

[0038] 1. Materials and Methods

[0039] 1.1 Materials and Methods

[0040] 1.1.1 Materials

[0041] 1.1.1.1 Sample

[0042] Maotai-flavor liquor

[0043] 1.1.1.2 Main Reagents

[0044] The reagents used in this experiment are shown in Table 1

[0045] Table 1 Main experimental reagents

[0046]

[0047] 1.1.1.3 Main instruments and equipment

[0048] The main instruments used in the experiment are shown in Table 2

[0049] Table 2 Main experimental instruments

[0050]

[0051] 1.1.2 Test methods

[0052] 1.1.2.1 Synthesis of Isoamyl Acetate

[0053] In a 100mL beaker, add a certain amount of acetic acid, isoamyl alcohol, catalyst, add stirrer and zeolite, load condensing tube, start heating reflux, in the beaker, have liquid reflux and can start timing, reaction finishes, and adopts the method for naturally cooling to room temperature to cool down.The reaction solution that has cooled down is filtered and processed, filters and reclaims catalyst, adds appropriate amount of anhydrous magnesium sulfate drying, collects dried reaction solution.The crude product obtained will be by gas chromatography detection acetic acid, isoamyl alcohol, the relative content of isoamyl acetate, calculates esterification yield, and formula is as follows:

[0054]

[0055] 1.1.2.2 Synthesis of n-butyl acetate

[0056] Add a certain amount of acetic acid, n-butanol, and a certain amount of catalyst to a 100 mL beaker in sequence. Install a condenser reflux apparatus and heat to reflux. Start timing when distillate begins to flow. After the reaction is complete, stop heating, cool naturally to room temperature, and filter to recover the catalyst. Add an appropriate amount of anhydrous magnesium sulfate to the reaction mixture for dehydration and drying. Collect the dried mixture and determine the peak areas of acetic acid, n-butanol, and n-butyl acetate by gas chromatography. Quantify the target ester by comparison with the standard curve, and calculate the esterification rate based on the initial molar amount of the reaction using the following formula:

[0057]

[0058] 1.1.2.3 Degradation of fusel oil in sauce-flavored liquor

[0059] Add a certain amount of Maotai-flavor liquor and a certain amount of catalyst to a 100mL beaker, install a condenser, heat and reflux, start timing when distillate begins to appear, stop heating after the reaction is completed, cool naturally to room temperature, and filter the catalyst.

[0060] The content of fusel oil in Maotai-flavor liquor was detected by gas chromatography, and the degradation of target compounds in fusel oil was calculated using the standard curve method.

[0061] 1.1.2.4 Gas chromatography conditions

[0062] The fusel oils measured in this experiment were isoamyl alcohol and n-butanol, two common alcohols in the fermentation of Maotai-flavor liquor. Based on the type and content of organic acids in the liquor and the feasibility of the esterification reaction, acetic acid was selected as the acid involved in the esterification. Gas chromatography was used for quantitative analysis of the reaction system. The standard samples used were isoamyl ester, acetic acid, n-butanol, isoamyl acetate, n-butyl acetate, and ethyl acetate, all of analytical grade.

[0063] The chromatographic column used in this experiment was LZP-930 (30m×0.32mm×0.5μm), and the stationary phase was methyl polysiloxane; the injection port temperature was 210℃; the column temperature conditions were: the initial temperature of the chromatographic column was 45℃, maintained for 2 minutes, and then increased to 150℃ at 8℃ / min, and continued to maintain the temperature for 3 minutes; the injection volume was 1μL; and the split ratio was 40:1.

[0064] Carrier gas: high-purity nitrogen, column head pressure: 20 psi, column flow rate: 1 mL / min; air: 40 mL / min; hydrogen: 30 mL / min.

[0065] The catalyst in this application is the corresponding neutral alumina or acidic alumina.

[0066] 1.2 Fusel oil degradation analysis method

[0067] 1.2.1 Quantitative analysis of ester compounds

[0068] The quantitative analysis of ester compounds in this experiment was carried out using the corrected area normalization method and the external standard method to quantitatively analyze the generated esters and calculate the esterification rate.

[0069] 1.2.1.1 Correction Area Normalization Method

[0070] Normalization is a commonly used chromatographic quantitative analysis method in gas chromatography. By measuring the peak area (or peak height) of all components in the sample and their corresponding correction factors, the relative content of each component is calculated. The formula is as follows:

[0071]

[0072] Where: Fi: correction factor, Ai: peak area (or peak height) of component i.

[0073] 1.2.1.2 External Standard Curve Method

[0074] The calibration curve is a commonly used quantitative analysis method in gas chromatography. It performs quantitative analysis by comparing the peak area or peak height of the test sample with that of a standard of known concentration. A standard solution of a specific concentration is prepared in dichloromethane and then graded. The analysis conditions are the same as those used for the reaction solutions (isoamyl alcohol, n-butanol, isoamyl acetate, n-butyl acetate) and alcohol samples. A calibration curve is constructed using the compound's peak area as the horizontal axis and its concentration as the vertical axis.

[0075] 2. Results and Discussion

[0076] 2.1 Gas chromatography detection of fusel oil and related esters

[0077] 2.1.1 Gas chromatography detection of alcohols and esters

[0078] By performing chromatographic measurements on single and mixed standards of ethanol, isoamyl alcohol, n-butanol, ethyl acetate, n-butyl acetate, and isoamyl acetate, the standard chromatographic peak order and retention time were determined, such as Figure 1 The results show that the elution time of ethanol is 1.353 min, the elution time of ethyl acetate is 2.369 min, the elution time of n-butanol is 4.152 min, the elution time of isoamyl alcohol is 5.557 min, the elution time of n-butyl acetate is 6.265 min, and the elution time of isoamyl acetate is 7.598 min.

[0079] 2.1.2 Gas chromatography correlation measurement

[0080] The correlation between the sample concentration and the actual detection concentration was analyzed by regression line analysis, and the concentration gradient was 1.0, 2.0, 4.0, 6.0, 8.0, and 10 mg / mL. Figure 2 As shown, the regression equation for isoamyl acetate is: y = 1509.52897 x-187.29519, where R 2 =0.99997; the correlation equation for n-butyl acetate is: y=1261.88913·x+111.57703, and its R 2 =0.99993; Their correlation coefficients are all above 0.9999, so the correlation is good.

[0081] To measure the content of fusel oil in wine samples, a series of small concentration standard sample gradients were designed, the concentration gradient of isoamyl alcohol was 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1 mg / mL; the concentration gradient of n-butanol was 0.01, 0.05, 0.1, 0.5, 1 mg / mL; the concentration gradient of isoamyl acetate was 0.1, 0.2, 0.5, 1.0, 2.0 mg / mL; the concentration gradient of n-butyl acetate was 0.1, 0.2, 0.5, 1.0, 2.0 mg / mL; the concentration gradient of ethyl acetate was 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 2.0 mg / mL. Figure 3 As shown, the relevant regression equation of isoamyl alcohol is: y = 2972.78636x + 3.17875, and its R 2 =0.99992, the relevant regression equation for n-butanol is: y = 3958.61918x - 11.28572, and its R 2 =0.99994; the relevant regression equation for ethyl acetate is: y=1198.82411x-21.56712, and its R 2 =0.99909, the relevant regression equation for isoamyl acetate is y=1695.07017x-34.72158, and its R 2 =0.99951; the relevant regression equation for n-butyl acetate is y=1333.7163x+3.79405, and its R 2 =0.99981. Correlation coefficient R 2 All of them reached above 0.999, and the correlation was good.

[0082] 2.2 Isoamyl alcohol degradation analysis

[0083] 2.2.1 Analysis of the catalytic degradation of isoamyl alcohol by neutral alumina

[0084] 2.2.1.1 Neutral Alumina Catalyst Dosage

[0085] Under the conditions of 0.087 mol of acetic acid, 1.9:1 molar ratio of acetic acid to isoamyl alcohol, 110°C reaction temperature and 1.0 h reaction time, the effect of catalyst dosage on esterification rate was investigated. The results are as follows: Figure 4 As shown, Figure 4 The results show that as the amount of catalyst increases, the esterification rate increases; when the catalyst dosage is 1.5g (0.0147mol), the esterification rate reaches the maximum, the esterification rate by external standard method is 23.33%, and the esterification rate by area normalization method is 24.63%, and the difference between the two is not much; with the continued increase in catalyst dosage, the esterification rate decreases slightly, and the optimal catalyst dosage is 1.5g.

[0086] 2.2.1.2 Reaction time

[0087] The effect of reaction time on the esterification rate was investigated under the conditions of 0.087 mol of acetic acid, a molar ratio of acetic acid to isoamyl alcohol of 1.9:1, a reaction temperature of 110°C, and a catalyst amount of 1.5 g (0.0147 mol). The results are as follows: Figure 5 As shown. Figure 5 It can be seen that the esterification rate increases with increasing reaction time. At a reaction time of 3.5 hours, the area normalization method reaches its maximum esterification rate of 46.2%. At a reaction time of 4.0 hours, the esterification rate by the external standard method is 44%. Further extension of the reaction time decreases the esterification rate. This is because excessive reaction time causes premature distillation of isoamyl acetate, reducing the esterification rate. The optimal reaction time is 3.5 hours. Therefore, the optimal reaction time is 3.5 hours.

[0088] 2.2.1.3 Reaction temperature

[0089] The effect of temperature on the esterification rate was investigated under the conditions of 0.087 mol of acetic acid, a molar ratio of acetic acid to isoamyl alcohol of 1.9:1, a reaction time of 1.5 h, and a catalyst dosage of 1.5 g (0.0147 mol). The results are as follows: Figure 6 As shown. Figure 6 It can be seen that as the reaction temperature increases, the esterification rate increases. When the reaction temperature is 130°C, the maximum esterification rate is reached, and the esterification rate can reach 35.32%. As the reaction temperature continues to rise, the esterification rate begins to decrease, and the optimal reaction temperature is 130°C.

[0090] 2.2.1.4 Molar ratio of acid and alcohol

[0091] The amount of acetic acid was fixed at 0.1 mol, the amount of catalyst was 1.5 g (0.0147 mol), the reaction temperature was 100 ° C, and the reaction time was 1 h. The amount of isopentanol was changed to investigate the effect of the acid-alcohol molar ratio on the esterification rate. The results are as follows: Figure 7 As shown. Figure 7 It can be seen that as the amount of isoamyl ester increases, the esterification rate decreases. Excess acid helps to improve the esterification rate. Excess acetic acid can provide more protons (H + ), enhancing the catalytic efficiency of the acidic sites on the alumina surface, promoting proton transfer and intermediate formation, thereby improving reaction efficiency. When this catalyst is used to catalyze the degradation of fusel oil in liquor, this phenomenon indirectly reduces the impact of the high acid content in Maotai-flavor liquor.

[0092] 2.2.1.5 Orthogonal experiment

[0093] In order to more accurately investigate the effects of catalyst dosage, reaction time, and reaction temperature on the esterification rate of isoamyl acetate under a fixed dosage of acetic acid and isoamyl alcohol (1.9:1), an orthogonal experiment with three factors (A, B, C) and three levels (1, 2, 3) was adopted based on the single factor experiment. The results are shown in Table 3 below.

[0094] Table 3 Orthogonal test L9(3 3 ) results and analysis

[0095]

[0096]

[0097] As shown in Table 3, of the three factors, reaction temperature has the most significant impact on the reaction, followed by reaction time, and finally catalyst dosage. It can be seen that the optimal reaction conditions are a reaction temperature of 130°C, a reaction time of 3.5 hours, and an optimal catalyst dosage of 1.5 g (0.0147 mol). Based on the above experimental results, the optimal reaction conditions were determined. Three experiments were repeated under the optimal reaction conditions, and the esterification rates were 56.39%, 60.58%, and 65.58%, respectively, for an average esterification rate of 60.85%.

[0098] 2.2.2 Analysis of Isoamyl Alcohol Degradation Catalyzed by Acidic Alumina

[0099] 2.2.2.1 Acidic Alumina Catalyst Dosage

[0100] Using acidic alumina as catalyst, the amount of acetic acid was fixed at 0.087 mol, the molar ratio of acetic acid to isoamyl alcohol was 1.9:1, the reaction temperature was 110℃ and the reaction time was 1.5h, the effect of catalyst amount on the esterification rate was investigated. The results are as follows Figure 8 As shown. Figure 8 As can be seen from the figure, when the catalyst dosage is 0.5g (0.0049mol), the esterification rate reaches the maximum, which can reach 17.75%. As the catalyst dosage increases, the esterification rate decreases. Therefore, it can be concluded that the optimal catalyst dosage is 0.5g (0.0049mol).

[0101] 2.2.2.2 Reaction time

[0102] The effect of reaction time on the esterification rate was investigated by fixing the amount of acetic acid at 0.087 mol, the molar ratio of acetic acid to isoamyl alcohol at 1.9:1, the amount of catalyst at 0.5 g (0.0049 mol), and the reaction temperature at 110°C. The results are as follows: Figure 9 As shown. Figure 9It can be seen that with the increase of reaction time, the esterification rate increases. The esterification rate reaches the maximum at the time point of 3.5h, which is 35.60%. Then the esterification rate decreases, so the optimal reaction time is 3.5h.

[0103] 2.2.2.3 Reaction temperature

[0104] The effect of reaction time on the esterification rate was investigated by fixing the amount of acetic acid to 0.087 mol, the molar ratio of acetic acid to isoamyl alcohol to 1.9:1, the amount of catalyst to 0.5 g (0.0049 mol), and the reaction time to 1.5 h. The results are as follows: Figure 10 As shown. Figure 10 As can be seen from the figure, the esterification rate significantly increases with increasing reaction temperature. The esterification rate reaches its maximum at 130°C, reaching 32.33%. After that, the esterification rate decreases and increases, but remains relatively unchanged from the esterification rate at 130°C. Therefore, the optimal reaction time is 130°C.

[0105] 2.2.2.4 Acid-alcohol ratio

[0106] The reaction time, reaction temperature and catalyst dosage were explored. In order to further explore the esterification rate, the reaction was carried out at a fixed acetic acid content of 0.1 mol, a reaction temperature of 110°C, a reaction time of 1.5 h, a catalyst dosage of 0.5 g (0.0049 mol), and different acid-alcohol ratios. The results are as follows Figure 11 As shown. Figure 11 As can be seen from the figure, the esterification rate of isoamyl alcohol decreases with the increase of the amount of isoamyl alcohol. However, at a ratio of 1:1.2, the esterification rate increases, but then decreases again after 1:1.2. The results show that excess acid can promote the esterification reaction.

[0107] 2.2.2.5 Orthogonal experiment

[0108] In order to more accurately investigate the effects of catalyst dosage, reaction time, and reaction temperature on the esterification rate of isoamyl acetate under a fixed dosage of acetic acid and isoamyl alcohol (1.9:1), an orthogonal experiment with three factors (A, B, C) and three levels (1, 2, 3) was conducted on the basis of a single factor experiment. The results are shown in Table 4 below.

[0109] Table 4 Orthogonal test L9(3 3 ) results and analysis

[0110]

[0111] As can be seen from Table 4, among the three factors, reaction temperature has the most significant effect on the reaction, followed by reaction time, and finally the amount of catalyst. It can be seen that the suitable reaction conditions are a reaction temperature of 130°C, a reaction time of 3.5h, and the most suitable catalyst amount is 0.5g (0.0049mol). Based on the above experimental results, the optimal reaction conditions were determined. The experiment was repeated three times under the optimal reaction conditions, and the esterification rates were: 57.34%, 55.07%, and 62.30%, respectively, with an average esterification rate of 58.24%.

[0112] 2.3 n-Butanol degradation analysis

[0113] 2.3.1 Analysis of n-butanol degradation catalyzed by neutral alumina

[0114] 2.3.1.1 Neutral Alumina Catalyst Dosage

[0115] Under the conditions of fixed acetic acid dosage of 0.087 mol, molar ratio of acetic acid to n-butanol of 1.6:1, reaction time of 1.0 h and reaction temperature of 100 ° C, the effect of catalytic rate on the esterification rate of n-butanol and acetic acid was investigated. The results are as follows Figure 12 As shown. Figure 12 As can be seen from the figure, the esterification rate of n-butyl acetate from acetic acid and n-butanol increases with increasing catalyst dosage. The esterification rate reaches a maximum of 13.25% at a catalyst dosage of 1.5 g (0.0147 mol). The esterification rate decreases after 1.5 g (0.0147 mol), indicating that the optimal catalyst dosage is 1.5 g.

[0116] 2.3.1.2 Reaction time

[0117] In order to better explore the effect of reaction time on the esterification rate, an experiment was conducted under the conditions of fixed acetic acid 0.87 mol, acetic acid and n-butanol molar ratio of 1.6:1, catalyst dosage of 1.5 g (0.0147 mol) and reaction time of 100 ° C. The experimental results are as follows Figure 13 As shown. Figure 13 As can be seen from the figure, the esterification rate of n-butyl acetate increases with time, reaching its highest point at 29.10% at 3.5 hours. After reaching its peak, the esterification rate decreases with time. Therefore, the optimal reaction time is 3.5 hours.

[0118] 2.3.1.3 Reaction temperature

[0119] The effects of catalyst dosage and reaction time on the esterification rate were investigated, and the effect of reaction temperature on the esterification rate was also investigated. Therefore, the effect of reaction temperature on the esterification rate was investigated under the conditions of 0.087 mol of acetic acid, a molar ratio of acetic acid to n-butanol of 1.60:1, a catalyst dosage of 1.5 g (0.0147 mol) and a reaction time of 1.0 h. The results are as follows: Figure 14 As shown. Figure 14 As can be seen from the figure, the esterification rate of n-butyl acetate increases with increasing reaction temperature, reaching its highest esterification rate of 31.46% at 140°C. After reaching the highest esterification rate, the esterification rate decreases with increasing reaction time. Therefore, the optimal reaction time is 140°C.

[0120] 2.3.1.4 Molar ratio

[0121] The reaction time, reaction temperature and catalyst dosage were explored. In order to further explore the esterification rate, the reaction was designed to be carried out at a fixed acetic acid content of 0.1 mol, a reaction temperature of 110°C, a reaction time of 1.5 h, a catalyst dosage of 1.5 g (0.0147 mol), and a ratio of different substances. The results are as follows Figure 15 As shown. Figure 15 As can be seen from the figure, the esterification rate of n-butyl acetate decreases with the increase of the amount of isoamyl alcohol, but at 1:0.8 and 1:1.0, the esterification rate does not change significantly. The results show that peracid can promote the esterification reaction and increase the esterification rate.

[0122] 2.3.1.5 Orthogonal Experimental Analysis

[0123] The acetic acid dosage was fixed at 0.087 mol, and the molar ratio of acetic acid to n-butanol was 1.6:1. The main factors influencing n-butyl acetate formation included catalyst dosage, reaction time, and reaction temperature. To more comprehensively explore the impact of these factors on the esterification yield, an orthogonal experiment was conducted based on the single-factor experiments. The results are shown in Table 5.

[0124] Table 5 Orthogonal test L9(3 3 ) results and analysis

[0125]

[0126] Table 5 shows that reaction time has the most significant impact among the three factors, with the order of reaction time > reaction temperature > catalyst dosage. Analysis shows that the optimal reaction conditions are a fixed acetic acid dosage of 0.087 mol, a fixed acetic acid:n-butanol molar ratio of 1.6:1, a reaction temperature of 130°C, a reaction time of 3.5 h, and a catalyst dosage of 1.0 g. Based on these experimental results, the optimal reaction conditions were determined. Three experiments were repeated under these optimal conditions, resulting in esterification yields of 58.70%, 55.56%, and 63.83%, respectively, for an average esterification yield of 59.36%.

[0127] 2.3.2 Analysis of n-butanol degradation catalyzed by acidic alumina

[0128] 2.3.2.1 Acidic Alumina Catalyst Dosage

[0129] In order to investigate the effect of acidic alumina on the esterification rate of n-butyl acetate from acetic acid and n-butanol, the effect of catalyst dosage on the esterification rate was investigated under the following conditions: 0.087 mol of acetic acid, the ratio of acetic acid to n-butanol was 1.6:1, the reaction time was 1.0 h, and the reaction temperature was 100 °C. Figure 16 As shown. Figure 16 As can be seen from the figure, the esterification rate increases with the increase in catalyst dosage. When the catalyst dosage is 1.5g (0.0147mol), the esterification rate reaches its maximum, 12.82%. After that, the esterification rate decreases with the increase in catalyst dosage. Therefore, it can be seen that the optimal catalyst dosage is 1.5g (0.0147mol).

[0130] 2.3.2.2 Reaction time

[0131] The effect of reaction time on the esterification rate of n-butyl acetate from acetic acid and n-butanol was investigated under the following conditions: 0.087 mol of acetic acid, a molar ratio of acetic acid to n-butanol of 1.6:1, a catalyst dosage of 1.5 g (0.0147 mol), and a reaction temperature of 100°C. Figure 17 As shown. Figure 17 As can be seen from the figure, the esterification rate increases significantly with the extension of reaction time. When the reaction time is 3.5h, the esterification rate is the highest, at 30.88%. As the reaction time is further extended, the esterification rate decreases. Therefore, it can be seen that the optimal reaction time is 3.5h.

[0132] 2.3.2.3 Reaction temperature

[0133] Under the conditions of fixed acetic acid at 0.087 mol, acetic acid and n-butanol molar ratio at 1.6:1, reaction time at 1.0 h, and catalyst dosage at 1.5 g (0.0147 mol), the effect of reaction temperature on esterification rate was investigated by changing the reaction temperature. The results are as follows Figure 18 As shown. Figure 18 It can be seen that the esterification rate increases with the increase of reaction temperature. When the reaction temperature is 130℃, the esterification rate reaches the highest, 29.62%. As the reaction temperature continues to increase, the esterification rate decreases. Therefore, it can be seen that the optimal reaction temperature is 130℃.

[0134] 2.3.2.4 Molar ratio

[0135] The reaction time, reaction temperature and catalyst dosage were explored. In order to further explore the esterification rate, the reaction was designed to be carried out at a fixed acetic acid content of 0.1 mol, a reaction temperature of 110°C, a reaction time of 1.5 h, a catalyst dosage of 1.5 g (0.0147 mol), and a ratio of different substances. The results are as follows Figure 19 As shown. Figure 19 As can be seen from the figure, the esterification rate of n-butyl acetate decreases with the increase of the amount of isoamyl alcohol, but at 1:0.8 and 1:1.0, the esterification rate does not change significantly. The results show that excess acid can promote the esterification reaction and increase the esterification rate.

[0136] 2.3.2.5 Orthogonal Experimental Analysis

[0137] The effects of reaction temperature, reaction time, and catalyst dosage on the esterification yield were investigated. To further explore their influence on the esterification yield, a single-factor experiment was designed with a fixed molar ratio of acetic acid (0.087 mol) and acetic acid to n-butanol (1.6:1) to further investigate the effects of these factors on the esterification yield. The results are shown in Table 6 below.

[0138] Table 6 Orthogonal test L9(3 3 ) results and analysis

[0139]

[0140] Table 6 shows that of the three factors, reaction time has the most significant impact on the reaction, followed by reaction temperature, and finally catalyst dosage. The order of influence is reaction time > reaction temperature > catalyst dosage. Analysis shows that, with a fixed acetic acid content of 0.087 mol and a molar ratio of acetic acid to n-butanol of 1.6:1, the optimized conditions are a reaction temperature of 130°C, a reaction time of 3.5 h, and a catalyst dosage of 1.5 g (0.0147 mol). Using these optimized conditions, the esterification yields of n-butyl acetate were 61.14%, 54.34%, and 59.55%, respectively, with an average esterification yield of 58.34%.

[0141] 2.4 Study on the esterification effect of neutral alumina on ethanol, isopentanol and n-butanol

[0142] 2.4.1 Catalytic Ethanol Analysis

[0143] To investigate the catalytic effect of the catalyst on ethanol, the effects of reaction time, reaction temperature, and catalyst on the esterification yield of ethanol and acetic acid were investigated under the optimized conditions determined by orthogonal experiments. With a fixed acetic acid content of 0.087 mol, a 1:1 molar ratio of acetic acid to ethanol, a reaction temperature of 130°C, a reaction time of 3.5 h, and a catalyst dosage of 1.5 g (0.0147 mol), the esterification yield was 10.80%. This yield was lower than that of isopentyl and n-butyl esters under the same conditions.

[0144] 2.4.2 Analysis of the catalytic effect of catalysts on ethanol, n-butanol and isoamyl alcohol

[0145] Based on an orthogonal experiment, a mixed reaction of ethanol and isoamyl alcohol was conducted to investigate the effect of the catalyst on their esterification yields. The reaction conditions were a fixed acetic acid content of 0.087 mol, a 1:1:1 molar ratio of acetic acid, ethanol, and isoamyl alcohol, and a temperature of 130°C, a reaction time of 3.5 hours, and a catalyst dosage of 1.5 g (0.0147 mol). The esterification yield of ethanol to ethyl acetate was 5.45%, while the esterification yield of isoamyl alcohol to isoamyl acetate was 10.22%. Under the same molar ratios, the catalyst showed a better catalytic effect on isoamyl alcohol than on ethanol.

[0146] To simulate the ethanol content in Maotai-flavor liquor, a 52.5% ethanol solution was prepared using 53.0 mL of anhydrous ethanol and 47.0 mL of ultrapure water in a 100 mL volumetric flask. The acetic acid content was fixed at 0.087 mol, and the molar ratio of acetic acid, ethanol, and isoamyl alcohol was 1:1.22:0.53. The reaction time was 3.5 h, the reaction temperature was 130°C, and the catalyst dosage was 1.5 g (0.0147 mol). The results are shown in Table 7.

[0147] Table 7 Esterification rate of ethanol, isoamyl alcohol, water and acetic acid system

[0148]

[0149] Table 7 shows that the esterification yield of ethanol to ethyl acetate was 2.48%, while the esterification yield of isoamyl alcohol to isoamyl acetate was 4.82%. The low esterification yield is primarily due to the high ethanol content in the simulated Maotai-flavor liquor, which results in a high water content in the reaction, causing the esterification reaction to proceed in reverse, ultimately leading to a low esterification yield. These results indicate that neutral alumina has a better catalytic effect on isoamyl alcohol than on ethanol.

[0150] To simulate the ethanol content in sauce-flask liquor, a 52.5% ethanol solution was prepared in a 100.0 mL volumetric flask for the reaction. The acetic acid content was fixed at 0.087 mol, and the molar ratio of acetic acid, ethanol, and n-butanol was 1:1.22:0.62. The reaction conditions were a reaction temperature of 130°C, a reaction time of 3.5 h, and a catalyst dosage of 1.0 g (0.0098 mol). The results are shown in Table 8.

[0151] Table 8 Esterification rate of ethanol, n-butanol, water and acetic acid system

[0152]

[0153] As shown in Table 8, the esterification rate of ethanol to ethyl acetate is 2.42%, while the esterification rate of n-butanol to n-butyl acetate is 3.62%. The results show that the esterification rate of n-butanol is better than that of ethanol.

[0154] To further investigate the catalytic effect of neutral alumina on the reaction of ethanol with n-butanol and isoamyl alcohol, this experiment was conducted at a lower temperature, considering the boiling point of ethanol is 78.3°C. The reaction ratio of acetic acid, ethanol, and isoamyl alcohol was 1:1:1. The results are shown in Table 9 below:

[0155] Table 9 Results and analysis of ethanol and isoamyl alcohol mixture

[0156]

[0157] As can be seen from Table 9, under the same conditions, the esterification rates of isoamyl alcohol and n-butyl ester catalyzed by the catalyst were higher than those of ethanol. This further demonstrates that alumina has a better catalytic effect on isoamyl alcohol than on ethanol, and in a mixed system of ethanol and isoamyl alcohol, the catalyst has a preferential selectivity for isoamyl alcohol.

[0158] 2.5 Research on the recycling of activated alumina

[0159] The above results demonstrate that the catalyst exhibits excellent catalytic activity for the synthesis of isoamyl acetate. To investigate the catalyst's service life, four recycling experiments were conducted using a fixed acetic acid dosage of 0.087 mol, a molar ratio of acetic acid to isoamyl alcohol of 1.9:1, a reaction temperature of 130°C, a reaction time of 3.5 hours, and 1.5 g (0.0147 mol) of neutral alumina as the catalyst. The results are shown in Table 10. The data in Table 10 demonstrate the catalyst's reusability and its potential for industrial application.

[0160] Table 10 Effect of catalyst reuse on isoamyl acetate

[0161]

[0162] 2.5.1 Gas Chromatography of Sauce Liquor Samples

[0163] The gas chromatogram of 52.5° sauce-flavor liquor is as follows Figure 20 As shown, according to Figure 1 , it can be seen that the peak times of the standard samples of isoamyl alcohol and n-butanol in the wine sample are 5.5min and 4.1min respectively. Calculated from the standard curve equation, the isoamyl alcohol content in 52.5° sauce-flavor liquor is 0.13307mg / mL, or 144.02mg / kg, and the n-butanol content is 0.03408mg / mL, or 36.88mg / kg. The test results are consistent with the concentration range of 100-300mg / kg for isoamyl alcohol and 20-50mg / kg for n-butanol in sauce-flavor liquor.

[0164] 2.5.2 Application of Activated Alumina in Degrading Fusel Oil in Maotai Liquor

[0165] 2.5.2.1 Neutral Alumina Catalyzed Fusel Oil in Maotai Liquor

[0166] (1) The optimal reaction conditions obtained from the orthogonal experimental table above are 130°C, 3.5h, and 1.5g (0.0147mol) of neutral alumina. The optimal reaction conditions were applied to the actual Maotai-flavor liquor sample for reaction. The results were calculated to show that the content of isopentanol was 0.05568mg / mL, or 60.25mg / kg; the content of n-butanol was 0.02016mg / mL, or 21.82mg / kg. The content of isopentanol and n-butanol in the liquor sample after the reaction was lower than that in the original liquor sample. The results show that the neutral alumina catalyst has a catalytic esterification effect on fusel oil in Maotai-flavor liquor.

[0167] (2) Considering the boiling point of the substances in the sauce-flavor liquor, the reaction was carried out at a temperature of 100°C and a reaction time of 3.5 h. 1.5 g (0.0147 mol) of neutral alumina was added to the sauce-flavor liquor for reaction. After the reaction was completed, the liquor was cooled naturally. The sample was subjected to two gas chromatography tests to obtain its gas chromatogram. Figure 21 As shown by Figure 21The contents of isopentanol and n-butanol can be calculated by looking at their peak time and peak area. The contents of isopentanol are 0.09136 mg / mL and 0.12403 mg / mL, with an average content of 0.107695 mg / mL, or 116.55 mg / kg. The contents of n-butanol are 0.0253 mg / mL and 0.0308 mg / mL, with an average content of 0.02805 mg / mL, which is converted to mg / kg, or 29.526 mg / kg. The contents of isopentanol and n-butanol are lower than those of the original liquor sample. The results show that neutral alumina has a catalytic effect on fusel oil in sauce-flavored liquor.

[0168] (3) Considering the volatilization of flavor substances in sauce-flavored liquor and the boiling point of ethanol, this experiment was set to carry out the catalytic reaction at a lower temperature, that is, the reaction temperature was 70℃, the reaction time was 3.5h and the catalyst dosage was 1.5g (0.0147mol). The results were calculated and the content of isopentanol was 0.0975mg / mL, i.e. 105.52mg / kg; the content of n-butanol was 0.02576mg / mL, i.e. 26.64mg / kg. The content of isopentanol and n-butanol in the liquor sample after the reaction was lower than that in the original liquor sample. The results show that neutral alumina has a catalytic esterification effect on fusel oil in sauce-flavored liquor.

[0169] 2.5.2.2 Catalytic Removal of Fusel Oil in Maotai Liquor Using Acidic Alumina

[0170] (1) Considering the effect of high temperature on the volatility of substances in sauce wine, an improvement was made on the basis of orthogonal experiment. The reaction temperature was 100℃, the reaction time was 3.5h, and the amount of acidic alumina catalyst was 0.5g to study the degradation of fusel oil. The experimental results were calculated. The isopentanol content in sauce wine was 0.11666mg / mL and 0.08726mg / mL, with an average of 0.10196mg / mL, i.e. 110.35mg / kg. The n-butanol content was 0.0172mg / mL and 0.0215mg / mL, with an average of 0.01935mg / mL, i.e. 20.94mg / kg. The results showed that the contents of isopentanol and n-butanol were lower than those in the original wine sample, but both isopentanol and n-butanol were lower than those in the original wine sample after drying. The results show that acidic alumina can degrade fusel oil in sauce wine.

[0171] (2) Further study the degradation of fusel oil in sauce-flavor liquor by the catalyst, and considering that the boiling point of ethanol is 78.3℃, the reaction temperature is 70℃, the reaction time is 3.5h and the amount of acidic alumina catalyst is 0.5g (0.0049mol). Results After calculation, the content of isopentanol in the liquor is 0.10722mg / mL, i.e. 116.03mg / kg; the content of n-butanol is 0.023476mg / mL, i.e. 25.40mg / kg. The results show that the content of isopentanol and n-butanol in the sauce-flavor liquor decreased after heating and catalytic reflux.

[0172] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. Application of activated alumina in the degradation of fusel oil in liquor.

2. The use of the activated alumina according to claim 1 in the degradation of white wine fusel oil, characterized in that: Application of activated alumina as catalyst in the degradation of fusel oil in liquor.

3. The use of the activated alumina according to claim 1 or 2 in the degradation of white wine fusel oil, characterized in that: The activated alumina is acidic alumina or neutral alumina.

4. The use of the activated alumina according to claim 3 in the degradation of white wine fusel oil, characterized in that: The fusel oil is at least one of isoamyl alcohol and n-butanol.

5. The use of the activated alumina according to claim 4 in the degradation of white wine fusel oil, characterized in that: The application is a method for degrading fusel oil in liquor with activated alumina.

6. The use of the activated alumina according to claim 5 in the degradation of white wine fusel oil, characterized in that: Furthermore, the activated alumina is neutral alumina. When degrading fusel oil in liquor, the neutral alumina is put into the sauce-flavor liquor and fully reacted at a temperature of 70°C to 150°C.

7. The use of the activated alumina according to claim 6 in the degradation of white wine fusel oil, characterized in that: The reaction time is 3 to 5 hours.

8. The use of the activated alumina according to claim 5 in the degradation of white wine fusel oil, characterized in that: The activated alumina is acidic alumina. When degrading fusel oil in liquor, the acidic alumina is put into the sauce-flavor liquor and fully reacted at a temperature of 70° C. to 130° C.

9. The use of the activated alumina according to claim 8 in the degradation of white wine fusel oil, characterized in that: The reaction time is 3 to 5 hours.

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