Method for recovering illegal cooking oil by using overheated methanol

Abstract

The invention relates to the technical field of waste resource utilization, and provides a method for recycling illegal cooking oil by using overheated methanol. According to the method disclosed by the invention, the superheated steam-state methanol is reacted with the illegal cooking oil, so that the yield of the biological fuel oil can be improved, and the obtained biological fuel oil mainly comprises various hydrocarbon substances which are similar to those of petrochemical diesel oil, so that the quality of the biological fuel oil is higher; furthermore, sodium hydroxide is adopted as a catalyst and a reactant, on one hand, the transesterification can be catalyzed and strengthened, on the other hand, organic acid and sodium hydroxide react to generate organic acid sodium, and the organic acid sodium can be used as a surfactant. In conclusion, according to the method provided by the invention, two products with high added values can be obtained in one step, the yield of the biological fuel oil is high, the energy consumption is low, the process is simple, low-carbon and efficient recovery of the illegal cooking oil is realized, and a new technical path is provided for resource utilization of the illegal cooking oil.

Description

Technical Field

[0001] The present invention relates to the technical field of waste resource utilization, and in particular to a method for recycling waste cooking oil by utilizing superheated methanol. Background Art

[0002] At present, common waste oil conversion technology mainly contains thermal cracking, microemulsion and transesterification.Wherein, thermal cracking is that waste oil is cracked under hot conditions, makes macromolecular organic matter therein chemical bond fracture, is cracked into small-molecule gas, liquid and solid product, and this method needs high temperature and high pressure condition, and energy consumption is large and easily produces harmful gas.Microemulsion technology is that waste oil is mixed with solvent, emulsifying agent and water etc., makes waste oil be evenly dispersed in aqueous phase with the form of tiny droplet, forms microemulsion, and this method emulsifying agent consumption is large, and cost is high and poor stability.The principle of transesterification is to add alcohol in waste oil, and under the effect of catalyzer, the triglyceride in waste oil and alcohol generation transesterification reaction generate fatty acid ester (i.e. biodiesel) and glycerine.

[0003] Compared to other methods, transesterification offers significant advantages in terms of process maturity and environmental friendliness, making it the most commonly used technology for converting waste cooking oil. However, waste cooking oil and alcohol form a heterogeneous system, making them difficult to fully mix. This results in low mass transfer efficiency, resulting in low waste cooking oil conversion rates and poor quality biodiesel. Summary of the Invention

[0004] In view of this, the present invention provides a method for recovering waste cooking oil using superheated methanol. The method uses superheated steam methanol to react with waste cooking oil, resulting in a high yield and high quality biofuel oil, while also obtaining a high-value product, surfactant.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for recovering waste cooking oil using superheated methanol comprises the following steps:

[0007] Mixing waste cooking oil and methanol and reacting them to obtain a product liquid; in the reaction, the methanol is in a superheated vapor state;

[0008] The product liquid is distilled to obtain biofuel oil.

[0009] Preferably, the volume ratio of methanol to waste cooking oil during the mixing is 1:(0.5-5).

[0010] Preferably, the mixing further comprises adding sodium hydroxide; the mass of the sodium hydroxide is less than or equal to 30% of the mass of the waste cooking oil.

[0011] Preferably, when sodium hydroxide is further added to the mixture, after obtaining the product liquid, the process further comprises subjecting the obtained product liquid to solid-liquid separation to obtain a solid product and a liquid product; distilling the liquid product to obtain biofuel oil; and the solid product is organic acid sodium.

[0012] Preferably, the mass of the sodium hydroxide is 0 to 30% of the mass of the waste cooking oil.

[0013] Preferably, in the reaction, the superheat degree of the superheated steam methanol is 30-200°C.

[0014] Preferably, the reaction is carried out in a reactor, and the filling degree of the reactor is 1:(5-20).

[0015] Preferably, the reaction temperature is 180-320° C., and the insulation time is 0-1 h.

[0016] Preferably, the reaction pressure is 0-3 MPa and is not 0.

[0017] Preferably, the reaction is carried out under a protective atmosphere.

[0018] Preferably, the heating rate to the reaction temperature is 3 to 10° C. / min.

[0019] The present invention provides a method for recycling waste cooking oil using superheated methanol, comprising the following steps: mixing waste cooking oil and methanol and reacting them to obtain a product liquid; during the reaction, the methanol is in a superheated vapor state; and distilling the product liquid to obtain biofuel oil. The present invention uses superheated vapor-state methanol to react with waste cooking oil, thereby strengthening the reaction between oil and methanol to generate diglycerides and methyl esters, thereby increasing the rate of transesterification reaction. Simultaneously, the superheated vapor-state methanol can significantly increase the hydrogen supply capacity of methanol, thereby strengthening methylation and hydrogen substitution reactions, thereby obtaining organic acids and hydrocarbons, and improving the quality of the biofuel oil. In conventional transesterification methods for treating waste cooking oil, waste cooking oil and methanol only undergo transesterification reaction, and the main component of the resulting biodiesel is fatty acid esters, which is of lower quality. In the present invention, superheated methanol is used to react with waste cooking oil, thereby simultaneously performing transesterification reaction, methylation reaction, and hydrogen substitution reaction. The main components of the resulting biofuel oil are various hydrocarbon substances, which are similar in composition to petrochemical diesel and are of higher quality.

[0020] Furthermore, the present invention also adds sodium hydroxide during mixing. Using sodium hydroxide as a catalyst and reactant can, on the one hand, catalyze and strengthen the transesterification reaction. On the other hand, the organic acid (oleic acid) reacts with the sodium hydroxide to generate organic sodium acid, thereby promoting the reaction to proceed in the direction of generating the organic sodium acid. The organic sodium acid can be used as a surfactant and is also a high-value product, thereby further improving the resource utilization of waste cooking oil.

[0021] In summary, the method provided by the present invention has a high biofuel oil yield, low energy consumption, and a simple process. In particular, when sodium hydroxide is added, two high-value-added products can be obtained in one step, and low-carbon and efficient recovery of waste cooking oil is achieved, providing a new technical path for the resource utilization of waste cooking oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic flow chart of a method for recovering waste cooking oil using superheated methanol provided by the present invention when sodium hydroxide is added;

[0023] Figure 2 is the mass spectrum of the product obtained from the reaction in Example 1;

[0024] Figure 3 This is a physical picture of sodium oleate samples, which from left to right are Example 2, Example 3 and Example 4;

[0025] Figure 4 This is a physical picture of biofuel oil samples, which from left to right are Examples 1, 2, 3, and 4. DETAILED DESCRIPTION

[0026] The present invention provides a method for recovering waste cooking oil by using superheated methanol, comprising the following steps:

[0027] Mixing waste cooking oil and methanol and reacting them to obtain a product liquid; in the reaction, the methanol is in a superheated vapor state;

[0028] The product liquid is distilled to obtain biofuel oil.

[0029] The present invention mixes waste cooking oil and methanol and reacts them to obtain a product liquid. In the present invention, the acid value of the waste cooking oil is preferably 80 to 120 mgKOH / g; the volume ratio of methanol to waste cooking oil during the mixing is preferably 1:(0.5 to 5), specifically 1:0.5, 1:1, 1:2, 1:3, 1:4 or 1:5; the methanol used during the mixing is liquid methanol, and a superheated vapor state is formed during the reaction; the present invention uses superheated vapor methanol to react with the waste cooking oil, which can improve the mass transfer efficiency of methanol and waste cooking oil, reduce the amount of methanol used, and solve the problem of large methanol usage and high cost in the prior art.

[0030] In the present invention, the mixing preferably also includes adding sodium hydroxide; the quality of the sodium hydroxide is preferably less than or equal to 30% of the waste oil quality, specifically can be 0.1%, 1%, 5%, 10%, 20%, 25% or 30%; the sodium hydroxide is used as a catalyst, and again as a reaction raw material, generates organic acid sodium (sodium oleate) with the organic acid (oleic acid) in the system. When the traditional method adopts the transesterification method to process waste oil, it is necessary to deacidify the waste oil in advance to prevent acid and sodium hydroxide from saponifying. The sodium oleate generated by the saponification reaction has a strong emulsifying ability and can form a stable emulsion at the oil-methanol two-phase interface. The formation of the emulsion can significantly hinder the mass transfer of the oil phase and the methanol phase, causing the transesterification reaction to be difficult to proceed. The present invention adopts superheated steam methanol to react with waste oil, which can strengthen the reaction of grease and methanol. The surfactant generated can not affect the carrying out of the reaction. Before the reaction, there is no need to deacidify the waste oil, and simultaneously, the high-value product of organic acid sodium can be obtained. In addition, the traditional method of recycling waste cooking oil by ester exchange relies on the catalytic reaction of a catalyst, and the amount of catalyst used is large. The present invention uses superheated steam methanol to react with waste cooking oil, which can improve the reaction efficiency and reduce the amount of catalyst used. Figure 1 The figure is a schematic flow chart of a method for recovering waste cooking oil by using superheated methanol provided by the present invention when sodium hydroxide is added.

[0031] In the present invention, the methanol in the reaction is in a superheated vapor state, and the superheat degree of the superheated vapor methanol is preferably 30-200°C, specifically 30°C, 50°C, 80°C, 100°C, 150°C or 200°C.

[0032] In the present invention, the reaction is preferably carried out in a reactor, and the filling degree of the reactor is preferably 1:(5-20), specifically 1:5, 1:10, 1:15 or 1:20.

[0033] In the present invention, the reaction temperature is preferably 180-320°C, specifically 180°C, 200°C, 220°C, 250°C, 300°C or 320°C, the holding time of the reaction is preferably 0-1h, specifically 0, 5min, 10min, 20min, 30min, 50min or 60min (when the holding time is 0, the reaction is terminated when the temperature is raised to the target temperature); the heating rate to the reaction temperature is preferably 3-8°C / min, more preferably 5°C / min; the reaction pressure is preferably 0-3MPa and not 0, specifically 0.1MPa, 0.8MPa, 1.1MPa, 1.5MPa, 1.8MPa, 2MPa, 2.5MPa or 3MPa; the reaction is preferably carried out under a protective atmosphere, preferably argon; the reaction is preferably carried out under stirring, and the stirring speed is preferably ≤100r / min, specifically 10-70r / min. In a specific embodiment of the present invention, the temperature and pressure changes of the reactor are sampled in real time by a sensor and stored in a computer every 2 seconds for determining the state of methanol during the reaction.

[0034] In the present invention, transesterification, methylation, hydrogen substitution and saponification occur simultaneously during the reaction process. The specific reaction principle is as follows: triglyceride in waste cooking oil and methanol undergo transesterification to generate fatty acid methyl ester and glycerol, while the fatty acid methyl ester undergoes methylation and hydrogen substitution to generate organic acid and hydrocarbon substances; the generated organic acid undergoes saponification with sodium hydroxide to generate sodium organic acid.

[0035] In a specific embodiment of the present invention, waste cooking oil, methanol and sodium hydroxide are preferably placed in a reactor and mixed, and then a protective gas is introduced into the reactor, the air is exhausted and the reactor is sealed, and then the temperature is raised to the reaction temperature according to a set program to react; after the reaction is completed, the obtained product liquid is preferably cooled and collected.

[0036] In the present invention, when no sodium hydroxide is added, the product liquid is distilled after the reaction is completed to obtain biofuel oil. In the present invention, the distillation temperature is preferably 40-350°C. The present invention separates heavy oil from light biofuel by distillation.

[0037] In the present invention, when sodium hydroxide is added during mixing, after obtaining a product liquid, the product liquid is subjected to solid-liquid separation to obtain a solid product and a liquid product, and the liquid product is distilled to obtain biofuel oil. In the present invention, the solid-liquid separation method is preferably filtration, preferably performed using a funnel containing filter paper. The solid product is an organic sodium acid, specifically sodium oleate, which can be used as a surfactant. The distillation temperature is consistent with the above-mentioned embodiment and is not further described here.

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] In the following examples, the acid value of waste cooking oil is 100 mgKOH / g.

[0040] Example 1

[0041] 5 mL of waste cooking oil and 5 mL of methanol were placed in a 100 mL reactor. Argon was introduced into the reactor and sealed. The reactor pressure was maintained at 1.8 MPa. Following the programmed procedure, the temperature was raised to 320°C at a rate of 5°C / min and held for 0 min. The reaction was stirred at 70 rpm. After the reaction was complete and the reactor cooled, the product liquid was placed in a storage tank and then distilled to obtain biofuel oil.

[0042] Example 2

[0043] 5mL waste oil, 5mL methyl alcohol and sodium hydroxide (quality of sodium hydroxide is 10% of waste oil quality) are placed in the 100mL reactor, in reactor, feed argon gas and sealing, controlling reactor pressure is 1.5MPa, by the program of setting, be warming up to 180 ℃ with the speed of 5 ℃ / min, be incubated 15min, react, and reaction is carried out under agitation, and speed of agitator is 70r / min.After reaction finishes, after the question response still is cooled, the solid-liquid mixture in the still is transferred to the funnel equipped with filter paper and carries out solid-liquid separation, the solid filtered out is cleaned, and obtains tensio-active agent (sodium oleate).To filter gained liquid and put into storage tank, distill afterwards, finally obtain biofuel oil.

[0044] Example 3

[0045] 5mL waste oil, 5mL methyl alcohol and sodium hydroxide (quality of sodium hydroxide is 10% of waste oil quality) are placed in the 100mL reactor, in reactor, feed argon gas and sealing, controlling reactor pressure is 1.5MPa, by the program of setting, be warming up to 320 ℃ with the speed of 5 ℃ / min, be incubated 30min, react, and reaction is carried out under agitation, and speed of agitator is 70r / min.After reaction finishes, after the question response still is cooled, the solid-liquid mixture in the still is transferred to the funnel equipped with filter paper and carries out solid-liquid separation, the solid filtered out is cleaned, and obtains tensio-active agent (sodium oleate).To filter gained liquid and put into storage tank, distill afterwards, finally obtain biofuel oil.

[0046] Example 4

[0047] 5mL waste oil, 5mL methyl alcohol and sodium hydroxide (quality of sodium hydroxide is 15% of waste oil quality) are placed in the 100mL reactor, in reactor, feed argon gas and sealing, controlling reactor pressure is 1.0MPa, by the program of setting, be warming up to 320 ℃ with the speed of 5 ℃ / min, be incubated 30min, react, and reaction is carried out under agitation, and speed of agitator is 70r / min.After reaction finishes, after the question response kettle is cooled, the solid-liquid mixture in the still is transferred to the funnel equipped with filter paper and carries out solid-liquid separation, the solid filtered out is cleaned and modified surface, obtains surfactant (sodium oleate).Filtering gained liquid is put into storage tank, distills afterwards, finally obtains biofuel oil.

[0048] Example 5

[0049] 5 mL of waste cooking oil and 5 mL of methanol were placed in a 100 mL reactor. Argon was introduced into the reactor and sealed. The reactor pressure was maintained at 0.8 MPa. Following the programmed procedure, the temperature was raised to 220°C at a rate of 5°C / min and held for 0 min (i.e., the reaction was completed after reaching 220°C). The reaction was carried out with stirring at a speed of 70 rpm. After the reaction was completed, the reactor was cooled and the product liquid was placed in a storage tank for distillation to obtain biofuel oil.

[0050] Example 6

[0051] 5mL waste oil, 5mL methyl alcohol and sodium hydroxide (quality of sodium hydroxide is 10% of waste oil quality) are placed in the 100mL reactor, in reactor, feed argon gas and sealing, controlling reactor pressure is 1.5MPa, by the program of setting, be warming up to 220 ℃ with the speed of 5 ℃ / min, be incubated 60min, react, and reaction is carried out under agitation, and speed of agitator is 70r / min.After reaction finishes, after the question response kettle is cooled, the solid-liquid mixture in the still is transferred to the funnel equipped with filter paper and carries out solid-liquid separation, the solid filtered out is cleaned and modified surface, obtains tensio-active agent (sodium oleate).To filter gained liquid and put into storage tank, distill afterwards, finally obtain biofuel oil.

[0052] The biofuel oil yield and surfactant yield of Examples 1 to 6 were calculated as follows: oil yield = mass of biofuel oil / (mass of waste cooking oil + mass of sodium hydroxide), surfactant yield = mass of surfactant (i.e., sodium oleate) / (mass of waste cooking oil + mass of sodium hydroxide). The settlement results are shown in Table 1.

[0053] Table 1 Experimental results of Examples 1 to 6

[0054] project gutter oil Methanol Sodium hydroxide Temperature (℃) Oil yield Surfactant yield Example 1 5mL 5mL 0 320 58.3％ 0 Example 2 5mL 5mL 10％ 180 51.2％ 23.5％ Example 3 5mL 5mL 5％ 320 60.1％ 18.7％ Example 4 5mL 5mL 15％ 320 63.8％ 31.6％ Example 5 5mL 5mL 0 220 45.4％ 0 Example 6 5mL 5mL 10％ 220 56.2％ 28.4％

[0055] According to the results in Table 1, it can be seen that the method provided by the present invention has a high conversion rate of biofuel oil yield, and when sodium hydroxide is added, a surfactant can also be obtained at the same time, thereby achieving efficient resource utilization of waste cooking oil.

[0056] Figure 2 This is the mass spectrum of the biofuel oil obtained in Example 1. Figure 2 It can be seen that the present invention uses superheated methanol and waste cooking oil to react and indeed produces hydrocarbons. The mass spectrometry of the biofuel oils obtained in other examples was tested and the results showed that hydrocarbons were produced in all of them.

[0057] Figure 3 This is a physical picture of sodium oleate samples, which from left to right are Example 2, Example 3 and Example 4; Figure 4 The following is a sample of biofuel oil, which includes Examples 1, 2, 3, and 4 from left to right. Figures 3-4 It can be seen that, in the case of adding sodium hydroxide, the present invention can obtain two products, the active agent and the biofuel oil, through a one-step reaction.

[0058] In summary, the present invention uses superheated steam methanol to recover waste cooking oil, converting it into high-quality fuel oil and surfactants in a one-step process. The method provided by the present invention has a simple process flow and achieves the output of higher-quality fuel oil and surfactants. It overcomes the drawbacks of traditional processes such as low fuel quality, complex preparation processes, large catalyst and methanol usage, and high costs, meeting the original intention of low-carbon energy conservation and emission reduction, and achieving low-carbon and high-efficiency recovery of waste cooking oil.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for recovering waste cooking oil using superheated methanol, characterized in that: The following steps are involved: Mixing waste cooking oil and methanol and reacting them to obtain a product liquid; in the reaction, the methanol is in a superheated vapor state; The product liquid is distilled to obtain biofuel oil.

2. The method according to claim 1, characterized in that The volume ratio of methanol to waste cooking oil during the mixing is 1:(0.5-5).

3. The method according to claim 1 or 2, characterized in that The mixing further comprises adding sodium hydroxide; the mass of the sodium hydroxide is less than or equal to 30% of the mass of the waste cooking oil.

4. The method according to claim 3, characterized in that When sodium hydroxide is added to the mixture, after obtaining the product liquid, the method further includes subjecting the obtained product liquid to solid-liquid separation to obtain a solid product and a liquid product; distilling the liquid product to obtain biofuel oil; and the solid product is organic acid sodium.

5. The method according to claim 1, wherein In the reaction, the superheat degree of the superheated steam methanol is 30-200°C.

6. The method according to claim 1, characterized in that The reaction is carried out in a reactor, and the filling degree of the reactor is 1:(5-20).

7. The method according to claim 1, characterized in that The reaction temperature is 180-320° C., and the insulation time is 0-1 h.

8. The method according to claim 1 or 7, characterized in that The reaction pressure is 0-3 MPa and is not zero.

9. The method according to claim 1 or 7, characterized in that The reaction was carried out under protective atmosphere.

10. The method according to claim 1 or 7, characterized in that The heating rate to the reaction temperature is 3 to 10° C. / min.

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