Application of solid waste for acetylene production in catalytic preparation of biodiesel

Abstract

The invention discloses application of solid waste for producing acetylene in catalytic preparation of biodiesel, and the solid waste for producing acetylene is upstream solid waste lime powder before reaction or a mixture of the upstream solid waste lime powder before reaction and downstream solid waste carbide slag after reaction. The specific method is as follows: under the catalytic action of solid waste, grease (vegetable oil and animal oil) and low-carbon alcohol (methanol, ethanol and the like) are subjected to transesterification to prepare the biodiesel. The yield of the obtained biodiesel (fatty acid methyl ester) is more than 95%, and the catalyst can be centrifugally separated after reaction and can be repeatedly used. Compared with a pure solid base catalyst, the solid waste is cheap and easy to obtain, compared with other solid waste-based catalysts, the solid waste is simple in pretreatment and stable in source, the problem that the solid waste is difficult to treat in acetylene production enterprises can be effectively solved, and the method has important significance on recycling of waste resources and development of a green chemical process.

Description

Technical Field

[0001] The present invention belongs to the technical fields of solid waste treatment, recycling and biodiesel preparation, and specifically relates to the application of upstream and downstream solid wastes of acetylene production as catalysts in the ester exchange reaction between various oils and low-carbon alcohols to prepare biodiesel. Background Art

[0002] Energy is the lifeblood of a country's development. At present, the overexploitation and utilization of global oil resources has put it at risk of resource depletion. Many conflicts are caused by oil resources, and the exhaust pollution of petrochemical fuels has also become a huge challenge facing mankind. Seeking renewable, green and environmentally friendly new energy is an important strategic direction for achieving sustainable social development. At the 2020 Central Economic Work Conference, China proposed to reduce the proportion of fossil energy consumption, vigorously develop renewable clean energy, and make efforts to do a good job in "carbon peak and carbon neutrality" one of the key tasks in 2021. Under this vision, China's energy system will undergo a profound and leapfrog transformation, that is, gradually shifting from black and high-carbon to green and low-carbon, and from fossil energy to non-fossil energy represented by renewable energy.

[0003] As an important alternative to petrochemical energy, biodiesel has great development potential. It is a long-chain fatty acid methyl ester made by transesterification of animal and vegetable oils, waste oils and other raw materials with alcohols such as methanol or ethanol under the action of a catalyst. Biodiesel has the characteristics of high cetane number, low sulfur and aromatic content, high flash point, good lubricity, renewable and environmentally friendly. In recent years, it has been widely studied as an excellent alternative to fossil energy and has good development prospects. Biodiesel prepared from vegetable oil or waste cooking oil as a fuel, the amount of CO2 released into the atmosphere during combustion is balanced with the amount of CO2 absorbed from the atmosphere during its formation process, which can achieve "zero growth" in carbon emissions.

[0004] There are many methods for preparing biodiesel. At present, the transesterification method is one of the most commonly used methods for preparing biodiesel. It uses oil crops such as soybeans and rapeseed, oil palm and Pistacia chinensis fruits, oil aquatic plants such as engineered microalgae, and natural oils such as animal fats, waste cooking oil, and organic waste in industrial and agricultural production as raw materials, and is obtained through transesterification reaction. The by-product is glycerol. The transesterification method completely changes the chemical structure of the raw oil, converting the macromolecular raw oil into biodiesel with low density and strong fluidity through chemical reactions, creating favorable conditions for its later storage, transportation and use. Since the transesterification reaction is a reversible step-by-step equilibrium reaction, the reaction process is quite complicated. The use of catalytic technology is an effective means to increase the reaction rate and increase the yield. The catalytic systems reported in the literature include homogeneous acid or base catalysts (such as H2SO4, NaOH, NaOCH3, sodium carbonate, etc.), bioenzyme catalysts (such as lipase), and catalyst-free supercritical transesterification technology. Conventional homogeneous acid or base catalytic systems are relatively mature and are used in many industrial productions. However, the homogeneous catalytic method has the disadvantages of easy saponification side reactions, corrosiveness, difficulty in separating reaction products, non-reusable catalysts, and high product costs. Both enzyme catalysis and supercritical synthesis methods face the problem of harsh reaction conditions or high costs. The heterogeneous catalytic method for synthesizing biodiesel is environmentally friendly, the catalyst can be reused and there is no serious corrosion to the reaction equipment, and the product purification process is simple. Therefore, the heterogeneous base catalytic method for synthesizing biodiesel is one of the research directions with great development potential at this stage. The key scientific problem facing the ester exchange method for synthesizing biodiesel is the high cost of biodiesel, and improving catalyst performance and reducing catalyst cost are effective ways to solve this key problem.

[0005] Pure CaO catalyst has good catalytic activity for preparing biodiesel by transesterification reaction, but its catalyst preparation has the disadvantages of expensive raw materials, high energy consumption and environmental unfriendliness. The literature reports some methods of preparing calcium oxide-based solid base catalysts using waste materials such as eggshells, shrimp shells, oyster shells, etc., but the source of raw materials is unstable and needs to be specially collected, and the preparation needs to go through pre-treatment calcination processes such as de-inner membrane, washing and high-temperature calcination (>800°C), which increases economic cost and technical complexity. Patent CN102430400A reports a method for preparing solid base catalysts using natural calcium-based materials, using natural calcium-based material powder rich in calcium and magnesium carbonate as raw materials, and roasting after heating reaction to obtain solid base catalysts, which are used for transesterification reaction of biodiesel, and the yield of biodiesel obtained can reach 98%. Patent CN118527152A reports a method for preparing inorganic particle catalysts containing CaO and using it to catalyze biodiesel transesterification reaction, and the yield of biodiesel transesterification reaches 95%. The patent obtains inorganic ash by roasting or extracting and then roasting the residue of direct coal liquefaction, and adds a binder, an extrusion aid and a diluent to the inorganic ash to obtain an inorganic particle catalyst. Patent CN109663588A reports a preparation method of a dolomite composite cerium solid base catalyst, which is immersed in a cerium salt solution after calcining the dolomite powder and fully stirred, and then heated in a water bath, dried, and calcined twice to obtain a dolomite composite cerium solid base catalyst, which has a good catalytic effect in the biodiesel transesterification reaction, and the yield can reach 98%. Patent CN108187650A reports a preparation method of a solid base biodiesel catalyst with coal slime biochar as a carrier, which is pyrolyzed in a nitrogen atmosphere to obtain coal slime biochar, and the obtained coal slime biochar is activated with potassium hydroxide, composited with calcium hydroxide, and calcined to obtain a solid base biodiesel catalyst with coal slime biochar as a carrier. The catalyst is used to catalyze the transesterification reaction of biodiesel, and a biodiesel yield of 93% can be obtained. From the above, it can be seen that this calcium oxide-based catalyst prepared from natural raw materials, although it avoids the disadvantage of unstable sources of solid waste (eggshells, mollusk shells, etc.)-based catalysts, has the disadvantages of expensive raw materials and high preparation costs.

[0006] The upstream solid waste lime powder and downstream solid waste carbide slag in the industrial production of acetylene are mainly composed of calcium oxide, calcium hydroxide, calcium carbonate, and also contain a small amount of SiO2, MgO, Al2O3 and other components. Directly discharging them into the environment has a great harm to the environment. How to efficiently treat them has become a difficulty for the industry and academia. Summary of the invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a new use for solid waste from industrial production of acetylene.

[0008] The present invention provides the use of solid waste from industrial production of acetylene in catalytic preparation of biodiesel. The solid waste from acetylene production is lime powder of upstream solid waste before reaction or a mixture of lime powder of upstream solid waste before reaction and carbide slag of downstream solid waste after reaction. The specific method of using solid waste from acetylene production for catalytic preparation of biodiesel is as follows: using solid waste from acetylene production as catalyst, making oil and low-carbon alcohol undergo ester exchange reaction to prepare biodiesel, centrifugation after the reaction, removing excess low-carbon alcohol from the upper solution by rotary evaporation to obtain biodiesel, and reusing the solid waste from acetylene production in the lower layer by precipitation.

[0009] The above-mentioned oil is any one of vegetable oils or animal oils such as soybean oil, rapeseed oil, peanut oil, cottonseed oil, sesame oil, olive oil, etc.

[0010] The above-mentioned low-carbon alcohol is any one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and the like.

[0011] The amount of reactants used will affect the reaction equilibrium shift, and an excess of low-carbon alcohols can shift the reaction equilibrium in a positive direction, resulting in a higher yield. Further, the volume ratio of the oil to the low-carbon alcohol is preferably 4:1 to 4:3.

[0012] The amount of catalyst used will directly affect the reaction effect, including conversion rate and yield. Further, it is preferred that the amount of solid waste used to produce acetylene is 3wt% to 9wt% of the mass of the oil.

[0013] The reaction temperature will affect the biodiesel yield and conversion rate. Furthermore, it is preferred that the reflux temperature of the transesterification reaction is 55 to 80° C. and the reaction time is 1 to 9 hours.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention uses solid waste produced from acetylene as a catalyst in the process of preparing biodiesel by oil ester exchange. The yield of biodiesel obtained by catalyzing the ester exchange reaction between vegetable oil and animal oil by the upstream solid waste lime powder and the downstream solid waste carbide slag (fresh or stored for more than one year) can reach more than 95%, and the catalyst has good reapplicability. After being reused for 3 times, it still has high catalytic activity, showing good catalytic activity and stable performance. The catalyst source is stable and can be used directly without pretreatment, avoiding the shortcomings of unstable source and high processing cost of solid waste (eggshell, mollusk shell, etc.)-based catalysts reported in the literature, and also avoiding the shortcomings of expensive raw materials and high preparation cost of catalysts prepared from natural raw materials. It can fully utilize solid waste and significantly reduce the production cost of biodiesel, reflecting the green environmental protection concept of waste recycling. The catalyst after the reaction can be separated by centrifugation or filtration, which is of great significance to the recycling of waste and the development of green chemical processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 These are the XRD spectra of a fresh sample of lime powder, an upstream solid waste in acetylene production, and one year after it was stored.

[0017] Figure 2 This is the XRD spectrum of carbide slag, a downstream solid waste in the production of acetylene.

[0018] Figure 3 The performance of the lime powder of Examples 1 to 5 catalyzed the transesterification reaction of different oils and fats and was reused three times. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0020] The lime powder and carbide slag, the upstream solid wastes of acetylene production used in the following examples, were first analyzed by Bruker D8 Advance powder X-ray diffractometer. Fresh lime powder and lime powder and carbide slag after one year were placed in an electric constant temperature dryer, the temperature was set at 150°C, and dried for 2 hours for XRD detection. The main parameters were: light tube type: Cu target, ceramic X-ray tube; light tube power: 2.2kW; scanning mode: θ / θ goniometer; high precision: small step angle 0.0001°; angle reproducibility 0.0001°; goniometer: dual positioning using optical encoder technology and stepper motor; detector: LynxEye array detector tube voltage 40kV, tube current 40mA, scanning angle 5°~80°.

[0021] The XRD spectrum of white ash powder is as follows Figure 1 As shown. Figure 1It can be seen that the 2θ angle has diffraction peaks at 32.2°, 37.4°, 53.8°, 64.1° and 67.4°. These diffraction peaks are characteristic peaks of CaO, corresponding to the 111, 200, 220, 311, and 222 crystal planes of CaO, respectively, indicating that the main component of lime powder is CaO. After one year of storage, in addition to its main component CaO, new diffraction peaks appear at 18.2°, 28.7°, 34.2°, 47.4° and 51.1°. These diffraction peaks correspond to the characteristic diffraction peaks of Ca(OH)2, corresponding to the 001, 100, 011, 012, and 110 crystal planes of Ca(OH)2, respectively, indicating that after one year of storage of lime powder, part of the CaO is deteriorated to form Ca(OH)2. The XRD spectrum of carbide slag is shown in the figure. Figure 2 As shown, there are diffraction peaks at 2θ angles of 18.2°, 28.7°, 34.2°, 47.4° and 51.1°, which are the characteristic peaks of Ca(OH)2, corresponding to the 001, 100, 011, 012, and 110 crystal planes of Ca(OH)2, respectively. The diffraction peaks at 34.1°, 39.4°, 43.2°, 63.1°, and 64.7° correspond to the diffraction peaks of CaCO3, corresponding to the 110, 113, 202, 125, and 300 crystal planes of CaCO3, respectively, indicating that the main components of carbide slag are Ca(OH)2 and CaCO3.

[0022] Example 1

[0023] 12mL peanut oil, 6mL methanol and 0.7g ash powder, the upstream solid waste of acetylene production, were added to a flask. Under the condition of magnetic stirring at a speed of 450rpm, the temperature of the magnetic stirrer was controlled to rise to 80℃. The reaction was stopped after 3h of reaction at a reflux temperature of 65℃. After cooling to room temperature, the sample was transferred to a 50mL centrifuge tube and centrifuged at a speed of 8000r / min for 5min. The upper layer was the biodiesel phase, the lower layer was the glycerol phase, and the bottom was the ash powder for recycling. The upper clear liquid was transferred to a flask and rotary evaporated for 5min in a 40℃ water bath to obtain biodiesel. The analysis results showed that the yield of biodiesel was 99%.

[0024] Example 2

[0025] 12mL olive oil, 6mL methanol and 0.7g ash powder, the upstream solid waste of acetylene production, were added to the flask. Under the condition of magnetic stirring at a speed of 450rpm, the temperature of the magnetic stirrer was controlled to rise to 80℃. The reaction was stopped after 3h of reaction at a reflux temperature of 65℃. After cooling to room temperature, the sample was transferred to a 50mL centrifuge tube and centrifuged at a speed of 8000r / min for 5min. The upper layer was the biodiesel phase, the lower layer was the glycerol phase, and the bottom was the ash powder for recycling. The upper clear liquid was transferred to a flask and rotary evaporated for 5min in a 40℃ water bath to obtain biodiesel. The analysis results showed that the yield of biodiesel was 97%.

[0026] Example 3

[0027] 12mL sunflower oil, 6mL methanol and 0.7g ash powder, the upstream solid waste of acetylene production, were added to a flask. Under the condition of magnetic stirring at a speed of 450rpm, the temperature of the magnetic stirrer was controlled to rise to 80℃, and the reaction was stopped after 3h at a reflux temperature of 65℃. After cooling to room temperature, the sample was transferred to a 50mL centrifuge tube and centrifuged at a speed of 8000r / min for 5min. The upper layer was the biodiesel phase, the lower layer was the glycerol phase, and the bottom was the ash powder for recycling. The upper clear liquid was transferred to a flask and rotary evaporated in a 40℃ water bath for 5min to obtain biodiesel. The analysis results showed that the yield of biodiesel was 98%.

[0028] Example 4

[0029] 12mL rapeseed oil, 6mL methanol and 0.7g of white ash powder, an upstream solid waste for acetylene production, were added to a flask. Under the condition of magnetic stirring at a speed of 450rpm, the temperature of the magnetic stirrer was controlled to rise to 80℃, and the reaction was stopped after 3h at a reflux temperature of 65℃. After cooling to room temperature, the sample was transferred to a 50mL centrifuge tube and centrifuged at a speed of 8000r / min for 5min. The upper layer was the biodiesel phase, the lower layer was the glycerol phase, and the bottom was the white ash powder for recycling. The upper clear liquid was transferred to a flask and rotary evaporated in a 40℃ water bath for 5min to obtain biodiesel. The analysis results showed that the yield of biodiesel was 98%.

[0030] Example 5

[0031] 12mL cottonseed oil, 6mL methanol and 0.7g of ash powder, an upstream solid waste for acetylene production, were added to a flask. Under the condition of magnetic stirring at a speed of 450rpm, the temperature of the magnetic stirrer was controlled to rise to 80℃. The reaction was stopped after 3h of reaction at a reflux temperature of 65℃. After cooling to room temperature, the sample was transferred to a 50mL centrifuge tube and centrifuged at a speed of 8000r / min for 5min. The upper layer was the biodiesel phase, the lower layer was the glycerol phase, and the bottom was the ash powder for recycling. The upper clear liquid was transferred to a flask and rotary evaporated in a 40℃ water bath for 5min to obtain biodiesel. The analysis results showed that the yield of biodiesel was 99%.

[0032] The lime powder obtained by centrifugation in Examples 1 to 5 above was added back into the flask, and the reusability test was performed according to the method of the corresponding Example. Figure 3 As shown, the lime powder was reused three times under the conditions of catalyzing different oils and fats, and the biodiesel yield was above 95%.

[0033] Example 6

[0034] 12mL edible lard, 6mL methanol and 0.7g ash powder, the upstream solid waste of acetylene production, were added to the flask. Under the condition of magnetic stirring at a speed of 450rpm, the temperature of the magnetic stirrer was controlled to rise to 80℃. The reaction was stopped after the reaction was carried out at a reflux temperature of 65℃ for 3h. After cooling to room temperature, the sample was transferred to a 50mL centrifuge tube and centrifuged at a speed of 8000r / min for 5min. The upper layer was the biodiesel phase, the lower layer was the glycerol phase, and the bottom was the ash powder. The upper clear liquid was transferred to a flask and rotary evaporated in a 40℃ water bath for 5min to obtain biodiesel. The analysis results showed that the yield of biodiesel was 98%. The ash powder at the bottom was recycled.

[0035] This example adopts the same method and uses the upstream solid waste lime powder of acetylene production that has been stored for one year as a catalyst. The analysis results show that the biodiesel yield is 97%, indicating that the lime powder catalyst that has been stored for one year still has high catalytic activity.

[0036] Example 7

[0037] 12mL edible lard, 6mL methanol and 0.65g of a mixture of upstream solid waste lime powder and downstream solid waste carbide slag in a mass ratio of 8:1 were added to a flask. Under the condition of magnetic stirring at a speed of 450rpm, the temperature of the magnetic stirrer was controlled to rise to 80℃, and the reaction was stopped after reflux temperature of 65℃ for 5h. After cooling to room temperature, the sample was transferred to a 50mL centrifuge tube and centrifuged at a speed of 8000r / min for 5min. The upper layer was biodiesel phase, the lower layer was glycerol phase, and the bottom was lime powder. The upper clear liquid was transferred to a flask and rotary evaporated in a 40℃ water bath for 5min to obtain biodiesel. The analysis results showed that the yield of biodiesel was 99%. The lime powder at the bottom was recycled.

[0038] In addition, this embodiment also explores the use of upstream solid waste lime powder and downstream solid waste carbide slag in a mass ratio of 6:1, 4:1, and 2:1 for catalytic transesterification, and the biodiesel yield is greater than 97%.

Claims

1. Use of solid waste from acetylene production in catalytic preparation of biodiesel, wherein the solid waste from acetylene production is lime powder of upstream solid waste before reaction or a mixture of lime powder of upstream solid waste before reaction and carbide slag of downstream solid waste after reaction.

2. The use of solid waste from acetylene production in catalytic preparation of biodiesel according to claim 1, characterized in that: Using solid waste from acetylene production as a catalyst, oil and low-carbon alcohol undergo an ester exchange reaction to prepare biodiesel. After the reaction is completed, centrifugal separation is performed, and the upper solution is used to remove excess low-carbon alcohol by rotary evaporation to obtain biodiesel. The solid waste from acetylene production in the lower layer is precipitated and reused.

3. The use of solid waste from acetylene production in catalytic preparation of biodiesel according to claim 2, characterized in that: The oil is any one of soybean oil, rapeseed oil, peanut oil, cottonseed oil, sesame oil, olive oil and animal oil.

4. The use of solid waste from acetylene production in catalytic preparation of biodiesel according to claim 2, characterized in that: The low-carbon alcohol is any one of methanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol.

5. The use of solid waste from acetylene production in catalytic preparation of biodiesel according to claim 2, characterized in that: The volume ratio of the oil to the low-carbon alcohol is 4:1 to 4:

3.

6. The use of solid waste from acetylene production in catalytic preparation of biodiesel according to claim 2, characterized in that: The amount of the solid waste used in producing acetylene is 3wt% to 9wt% of the mass of the oil.

7. The use of solid waste from acetylene production in catalytic preparation of biodiesel according to claim 2, characterized in that: The reflux temperature of the transesterification reaction is 55-80°C.

8. The use of solid waste from acetylene production in catalytic preparation of biodiesel according to claim 2, characterized in that: The reaction time of the transesterification reaction is 1 to 9 hours.

Images