Solid-phase synthesis method of calcium glycerophosphate catalyst based on carbide slag

Abstract

The invention relates to the technical field of catalytic material synthesis, in particular to a solid-phase synthesis method of a calcium glycerophosphate catalyst based on carbide slag. The method specifically comprises the following steps: mixing carbide slag and glycerol according to the molar ratio of Ca < 2 + > to glycerol being 1: (1-3), carrying out ball-milling reaction at room temperature, washing and drying to obtain the glycerol calcium catalyst for biodiesel transesterification. The invention provides a low-cost, green and efficient solid-phase synthesis path of the glycerol calcium catalyst, and the high-performance glycerol calcium catalyst is rapidly prepared through mechanical ball milling by taking the carbide slag as a raw material under a room temperature condition, so that the energy consumption and the raw material cost are remarkably reduced, and a recyclable and easily-recycled solid base catalyst is provided for biodiesel production; therefore, the biodiesel industry is helped to realize green and sustainable development.

Description

Technical Field

[0001] This invention relates to the field of catalytic material synthesis technology, specifically to a solid-phase synthesis method for a calcium glycerol catalyst based on carbide slag. Background Technology

[0002] Biodiesel, as a green and renewable fuel, has attracted much attention due to its low sulfur and nitrogen content, high oxygen content, and biodegradability. Industrial production of biodiesel mainly involves the transesterification reaction of oils and methanol. Currently, this process often uses homogeneous alkaline catalysts, such as NaOH and KOH, but this process suffers from problems such as difficulty in catalyst recovery and the generation of large amounts of wastewater.

[0003] Heterogeneous solid base catalysts, especially calcium oxide, have become a research hotspot due to their ease of separation and recovery. However, CaO is prone to methanololysis during the reaction, leading to the dissolution of calcium ions, contaminating the product, and causing deactivation. Calcium glycerol, as a novel solid base catalyst, not only has stronger basicity but also significantly inhibits calcium ion dissolution, exhibiting superior catalytic stability.

[0004] Currently, the conventional synthesis method for calcium glycerol catalysts is the liquid-phase method, which typically uses high-purity CaO as a raw material and reacts it under reflux at 60℃~80℃ for more than 4 hours in a mixed solution of methanol and glycerol. This method has disadvantages such as high reaction temperature, long reaction time, the need for a large amount of methanol as a solvent, and high energy consumption, which limits its industrial application. Summary of the Invention

[0005] To address the problems of high reaction temperature, long reaction time, large amount of methanol as solvent, and high energy consumption in conventional synthesis methods of calcium glycerol catalysts, this invention provides a solid-phase synthesis method of calcium glycerol catalyst based on carbide slag. The method of this invention is simple to operate, rapid to react, low in cost, and environmentally friendly. The high catalytic performance of the prepared calcium glycerol catalyst in biodiesel production has also been verified.

[0006] Calcium carbide slag is a large amount of industrial waste generated during acetylene production. Its main component is calcium hydroxide, which is highly alkaline. Improper disposal will pose a serious threat to the environment and ecosystem. Therefore, developing a low-cost, green process for synthesizing calcium glycerol using calcium carbide slag as raw material is beneficial to both the environment and the economy.

[0007] Mechanical ball milling, as a highly efficient solid-phase synthesis technology, can induce chemical reactions through mechanical force, offering advantages such as fast reaction rates, solvent-free operation, low energy consumption, and ease of scale-up. Applying ball milling to the synthesis of calcium glycerol from carbide slag holds promise for overcoming the drawbacks of traditional liquid-phase methods and achieving high-value utilization of solid waste.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows.

[0009] This invention provides a solid-phase synthesis method for a calcium glycerol catalyst based on carbide slag, comprising the following steps: Carbide slag and glycerol were mixed according to Ca... 2+ The mixture was mixed with glycerol at a molar ratio of 1:1 to 3, and ball-milled at room temperature. After washing and drying, a glycerol calcium catalyst was obtained for use in biodiesel transesterification.

[0010] This invention provides a method for preparing calcium glycerol using industrial solid waste calcium carbide slag as raw material through solid-phase synthesis, and applying it as a solid base catalyst in the transesterification reaction of biodiesel. This solves the problems of high cost, high energy consumption and complex process in the traditional calcium glycerol preparation process, while overcoming the pain points of difficult catalyst recovery and serious environmental pollution in biodiesel industrial production, and promoting the development of the biodiesel industry towards a green and sustainable direction.

[0011] Preferably, the particle size of the carbide slag is approximately 325 mesh to 500 mesh. Preferably, the Ca content in the carbide slag... 2+ Content ≥65.27wt%. In this invention, high-purity Ca is selected from the calcium carbide slag. 2+ Using calcium carbide slag with a content of ≥65.27% and medium fineness as raw material is an important material basis for the stable and efficient preparation of high-performance calcium glycerol catalysts by the aforementioned mechanochemical method.

[0012] Preferably, the ball milling step uses two grinding balls of different diameters, including a first grinding ball with a diameter of D1 and a second grinding ball with a diameter of D2, where D1 is 19mm to 20mm, D2 is 9mm to 10mm, and D1 > D2, and the ratio of the number of the first grinding ball to the number of the second grinding ball is 3 to 4:10.

[0013] In this invention, carbide slag and glycerol are reacted according to Ca... 2+ The molar ratio of the ball to glycerol is 1:1 to 3, preferably 1:2. The ball milling is performed using a grinding jar equipped with stainless steel grinding balls of different sizes, arranged in varying quantities to achieve the desired grinding effect. Specifically, the ball milling is carried out in a three-dimensional high-speed vibrating ball mill.

[0014] Preferably, the ball milling process is carried out at a speed of 250 rpm to 300 rpm, and the total ball milling time is 5 minutes to 30 minutes.

[0015] This invention utilizes a high-energy ball mill with a rotation speed of 250-300 rpm as the core power source, combined with a synergistic grinding system consisting of 3-4 large balls and 10 small balls, enabling the reaction to be completed within 5-30 minutes. This configuration achieves a highly efficient combination of macroscopic impact crushing and microscopic shear activation, which is key to the rapid preparation of glycerol-calcium catalysts with high specific surface area, high crystallinity, and porous structure. Through the mechanochemical action of high-energy ball milling, particles with a hierarchical porous structure, uniform size, and rough surface are constructed. The specific surface area of ​​the prepared glycerol-calcium catalyst is approximately 10.4 m². 2 / g, reaching solution-process product (approximately 3.7m) 2 It is nearly 3 times larger than that of g), thus significantly improving the accessibility of active sites and mass transfer efficiency, which is the key structural basis for its significant improvement in catalytic performance.

[0016] Preferably, before the carbide slag undergoes ball milling, it is further subjected to pretreatment to remove sulfide and silicate impurities.

[0017] The preferred method for pretreating carbide slag is as follows: The carbide slag is washed with water 2 to 3 times to remove sulfides and silicate impurities, and then dried to obtain pretreated carbide slag.

[0018] Preferably, during the pretreatment of carbide slag, the drying temperature is 60℃~100℃. The purpose of this drying is to remove free water.

[0019] Preferably, carbide slag and glycerol are mixed according to Ca... 2+ Mix with glycerol at a molar ratio of 1:2.

[0020] This invention effectively overcomes the problems of uneven material mixing and incomplete reaction in traditional solid-phase reactions by optimizing ball milling process parameters, achieving efficient synthesis and industrial-scale preparation of calcium glycerol. Preferably, ball milling for 5 to 10 minutes achieves the optimal balance between reaction efficiency and product performance; the entire ball milling process is carried out at room temperature without external heating or the addition of solvents such as methanol.

[0021] In this invention, under the conditions of maintaining a molar ratio of calcium carbide slag to glycerol of 1:2, ball milling speed of medium to low speed, and room temperature reaction, the volume of the ball mill tank is increased to 5L to 200L, the amount of calcium carbide slag fed in a single batch is 1kg to 1000kg, and the reaction can be completed in 10 to 20 minutes of ball milling; the BET specific surface area of ​​the obtained product fluctuates within a range of no more than 5%, and the catalytic performance is tested by taking 5 consecutive samples. The results are stable and meet the requirements of industrial production for product quality uniformity.

[0022] Preferably, the washing reagent is ethanol or methanol, and the washing is performed 1 to 3 times. The drying temperature is 60℃ to 80℃, and the drying time is 4 to 12 hours.

[0023] This invention relates to the application of the glycerol calcium catalyst prepared by the above method in the catalytic transesterification reaction of oils and fats with short-chain alcohols to produce biodiesel.

[0024] The oil is soybean oil, rapeseed oil, palm oil, corn oil, olive oil, or rice bran oil. The short-chain alcohol is methanol or ethanol.

[0025] The conditions for the transesterification reaction are as follows: the amount of glycerol calcium catalyst is 0.5% to 3% of the mass of the oil, the molar ratio of short-chain alcohol to oil is 6 to 12:1, the reaction temperature is 60℃ to 70℃, and the reaction time is 1 hour to 4 hours.

[0026] The beneficial effects of this invention are: 1. Traditional solution methods require prolonged methanol reflux (≥4 hours) and complex post-treatment, resulting in high energy consumption and solvent costs. This invention uses calcium carbide slag as raw material and induces a chemical reaction at room temperature via mechanical ball milling to prepare a high-performance calcium glycerol catalyst. This invention completes the reaction in just 5-30 minutes using high-energy ball milling under solvent-free, room-temperature conditions, eliminating the need for heating, condensation recovery, and extensive solvent purification. Energy consumption and material costs per unit capacity can be reduced by over 70%, and the process is extremely simple and easily scaled up. This solves the problems of high reaction temperature, long reaction time, large amounts of methanol as solvent, and high energy consumption inherent in conventional methods for synthesizing calcium glycerol catalysts.

[0027] 2. This invention provides a low-cost, green and efficient solid-phase synthesis route for calcium glycerol catalyst, which not only significantly reduces energy consumption and raw material costs, but also provides a recyclable and easily recoverable solid base catalyst for biodiesel production, thereby helping the biodiesel industry achieve green and sustainable development. Attached Figure Description

[0028] Figure 1The figures show the microstructure characteristics of the calcium glycerol catalysts prepared in Examples 1-6, Comparative Examples 1-5, and Examples 7-9. Specifically, (a) shows the X-ray diffraction (XRD) patterns of the calcium glycerol catalysts prepared in Comparative Examples 1-5; (b) shows the XRD patterns of the calcium glycerol catalysts prepared in Examples 1-6; (c) shows the XRD patterns of the calcium glycerol catalysts prepared in Examples 6-8; (d) shows the infrared spectra of the calcium glycerol catalysts prepared in Comparative Examples 3 and 6; (e) shows the Raman spectra of the calcium glycerol catalysts prepared in Comparative Examples 3 and 6; and (f) shows a comparison of the BET surface areas of CaO, the calcium glycerol catalysts prepared in Comparative Examples 1-4, and the calcium glycerol catalysts prepared in Examples 7-8.

[0029] Figure 2 The images show scanning electron microscope (SEM) images of the calcium glycerol catalysts prepared in Example 1 and Comparative Example 3. (a) and (b) are SEM images of the calcium glycerol catalyst prepared in Example 3 at different magnifications; (c) and (d) are SEM images of the calcium glycerol catalyst prepared in Comparative Example 1 at different magnifications.

[0030] Figure 3 The diagram shows a comparison of the catalytic exchange reaction activities of CaO, the calcium glycerol catalysts of Examples 1, 6-8, and Comparative Examples 1-5. Specifically, (a) shows the comparison of the catalytic exchange reaction activities of CaO, the calcium glycerol catalysts of Examples 1, 6-8, and Comparative Examples 1-5; (b) shows the conversion rate curves of the calcium glycerol catalysts prepared in Examples 1 and 3 at different reaction times; (c) shows the conversion rate curves of the calcium glycerol catalysts prepared in Examples 6 and 3 at different reaction times; and (d) shows the conversion rate comparison results of the calcium glycerol catalyst prepared in Example 1 in different types of oils. PO represents palm oil; CO represents corn oil; OO represents olive oil; RO represents rapeseed oil; and RBO represents rice bran oil.

[0031] Figure 4 The images show the X-ray diffraction patterns and conversion rate comparisons of the calcium glycerol catalysts obtained at different ball milling times in Example 9. Specifically, (a) shows the X-ray diffraction patterns of the calcium glycerol catalysts obtained at different ball milling times in Example 9; (b) shows the conversion rate comparison of the calcium glycerol catalyst Scale-up BM:10min obtained after ball milling for 10 minutes in 5 consecutive samplings; (c) shows the conversion rate comparison of the calcium glycerol catalyst Scale-up BM:10min obtained after ball milling for 10 minutes in 8 cycles; and (d) shows the X-ray diffraction pattern of the calcium glycerol catalyst Scale-up BM:10min after 8 cycles. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides a method for preparing calcium glyceroxide using industrial solid waste calcium carbide slag as raw material via solid-phase synthesis, and applying it as a solid base catalyst in the transesterification reaction of biodiesel. This invention aims to solve the problems of high cost, high energy consumption, and complex processes in traditional calcium glyceroxide preparation, while overcoming the pain points of difficult catalyst recovery and severe environmental pollution in biodiesel industrial production, thus promoting the green and sustainable development of the biodiesel industry.

[0035] Biodiesel, characterized by low sulfur and nitrogen content, high oxygen content, and renewability, is considered an ideal alternative fuel to traditional diesel engines. It is primarily produced through the transesterification reaction of vegetable oil and methanol. Currently, industrial applications mostly use homogeneous alkaline catalysts such as sodium hydroxide and potassium hydroxide, which suffer from problems such as difficulty in catalyst recovery and large wastewater discharge, failing to meet the requirements of green chemical development. While calcium oxide (CaO) can be used as a heterogeneous catalyst for transesterification, calcium ion leaching easily occurs in methanol, affecting biodiesel quality. Calcium glycerol, as a new generation of solid alkaline catalyst, not only has stronger alkalinity and higher stability but also effectively inhibits calcium ion dissolution, exhibiting excellent catalytic performance in transesterification reactions; however, its high production cost limits large-scale application. Traditional synthesis of calcium glycerol mainly relies on a liquid-phase method, using high-purity calcium oxide as raw material and refluxing it with a glycerol-methanol mixed solution at 60℃~80℃ for more than 4 hours. The method has the following drawbacks: it requires a large amount of excess methanol (the molar ratio of methanol to precursor is 10:1), the reaction temperature is high, the energy consumption is large, the reflux time is too long, and the production efficiency is low, which restricts its industrial promotion.

[0036] Calcium carbide slag, a large quantity of highly alkaline industrial solid waste generated during acetylene production, poses a threat to the ecological environment, and its high-value resource utilization pathways are still imperfect. Using calcium carbide slag as a calcium source to synthesize calcium glycerol can reduce catalyst costs and achieve resource transformation of solid waste, aligning with the concepts of green chemistry and circular economy.

[0037] While solid-state synthesis methods have applications in materials preparation, there are no reports on their use for the efficient synthesis of calcium glycerol from carbide slag, and on systematically addressing issues related to reaction uniformity, product performance, and process scale-up. This invention, by optimizing ball milling process parameters, effectively overcomes problems such as uneven material mixing and incomplete reaction in traditional solid-state reactions, achieving efficient synthesis and industrial-scale production of calcium glycerol.

[0038] This invention aims to provide a low-cost, green, and efficient solid-phase synthesis route for calcium glycerol. Using carbide slag as raw material, a high-performance calcium glycerol catalyst is rapidly prepared by mechanical ball milling at room temperature. This not only significantly reduces energy consumption and raw material costs, but also provides a recyclable and easily recoverable solid base catalyst for biodiesel production, thereby helping the biodiesel industry achieve green and sustainable development.

[0039] The technical solution of the present invention will be further described below through specific embodiments.

[0040] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.

[0041] The main component of carbide slag is Ca(OH)2, and the Ca(OH)2 content is ≥91.28wt%.

[0042] Example 1 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a ball milling method, carbide slag dried at 60℃ was mixed with glycerol at a concentration of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was milled at 500 rpm for 5 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly (BM, 5 min).

[0043] Example 2 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a ball milling method, carbide slag dried at 60℃ was mixed with glycerol at a concentration of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was then milled at 300 rpm for 10 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly (BM, 10 min).

[0044] Example 3 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a ball milling method, carbide slag dried at 60℃ was mixed with glycerol at a concentration of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was then milled at 300 rpm for 15 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly (BM, 15 min).

[0045] Example 4 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a ball milling method, carbide slag dried at 60℃ was mixed with glycerol at a concentration of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was then milled at 300 rpm for 20 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly (BM, 20 min).

[0046] Example 5 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a ball milling method, carbide slag dried at 60℃ was mixed with glycerol at a concentration of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was then milled at 300 rpm for 25 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly (BM, 25 min).

[0047] Example 6 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a ball milling method, carbide slag dried at 60℃ was mixed with glycerol at a concentration of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was then milled at 300 rpm for 30 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly (BM, 30 min).

[0048] Comparative Example 1 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a solution method, calcined CaO, glycerol, and methanol were placed in a three-necked flask at a molar ratio of 1:2:12 and refluxed at 60°C and 500 rpm for 1 hour. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain the calcium glycerol catalyst, denoted as CaGly (SL, 1h).

[0049] Comparative Example 2 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a solution method, calcined CaO, glycerol, and methanol were placed in a three-necked flask at a molar ratio of 1:2:12 and refluxed at 60°C and 500 rpm for 2 hours with stirring. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain the calcium glycerol catalyst, denoted as CaGly (SL, 2h).

[0050] Comparative Example 3 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a solution method, calcined CaO, glycerol, and methanol were placed in a three-necked flask at a molar ratio of 1:2:12 and refluxed at 60°C and 500 rpm for 4 hours with stirring. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain the calcium glycerol catalyst, denoted as CaGly (SL, 4h).

[0051] Comparative Example 4 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a solution method, calcined CaO, glycerol, and methanol were placed in a three-necked flask at a molar ratio of 1:2:12 and refluxed at 60°C and 500 rpm for 6 hours with stirring. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain the calcium glycerol catalyst, denoted as CaGly (SL, 6h).

[0052] Comparative Example 5 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a solution method, calcined CaO, glycerol, and methanol were placed in a three-necked flask at a molar ratio of 1:2:12 and refluxed at 60°C and 500 rpm for 8 hours. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain the calcium glycerol catalyst, denoted as CaGly (SL, 8h).

[0053] Table 1 Comparison of samples prepared under different conditions Note: "-" indicates none.

[0054] Example 7 A solid-phase synthesis method for a glycerol-calcium catalyst based on hydrated lime includes the following steps: Using a ball milling method, quicklime dried at 60℃ was mixed with glycerol at a ratio of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was then milled at 300 rpm for 30 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly(BM,CH).

[0055] Example 8 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: The carbide residue dried at 60℃ was mixed with glycerol using a ball milling method, with Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was then milled at 300 rpm for 30 minutes to induce a chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst, denoted as CaGly (BM, CS).

[0056] Test 1: X-ray diffraction analysis and BET surface area test.

[0057] X-ray diffraction analysis was performed on the calcium glycerol catalysts prepared in Examples 1-6, Comparative Examples 1-5, and Examples 7-9. The results are as follows: Figure 1 As shown. Standard X-ray diffraction patterns of CaCO3 (PDF#41-1475), CaO (PDF#25-0775), and Ca(OH)2 (PDF#44-1481) were used as controls. The BET specific surface area of ​​CaO, Comparative Examples 1 to 5, and the calcium glycerol catalysts of Examples 1, 6 to 8 were measured.

[0058] Depend on Figure 1 As can be seen from (a) and (b), the CaGly (BM, 5 min) sample showed clear characteristic diffraction peaks of calcium glycerol after ball milling for 5 minutes, and the peak positions were consistent with those of the CaGly (SL, 4 h) sample, proving that the ball milling method used in Examples 1 to 6 of the present invention can rapidly and effectively synthesize calcium glycerol catalysts with good crystallinity.

[0059] Depend on Figure 1 As shown in (c), to further verify the versatility of the solid-phase synthesis method of the calcium glycerol catalyst, a unified grinding scheme was implemented using two calcium sources: quicklime (CH) and carbide slag (CS). The XRD patterns of the obtained products were dominated by CaGly diffraction peaks.

[0060] Depend on Figure 1 As can be seen from (d), after phase analysis, the chemical structure was detected by molecular spectroscopy. Fourier transform infrared spectroscopy shows: 3000 cm⁻¹ -1 ~3600cm -1 An OH stretching vibration peak appears at 2800 cm⁻¹. -1 ~3000cm -1 The presence of a CH stretching vibration peak, consistent with the characteristics of calcium glycerol, confirms that the organic group has been successfully embedded in the crystal lattice structure.

[0061] Depend on Figure 1 As can be seen from (e), the Raman spectrum shows the corresponding CH stretching vibration characteristic peak (approximately 2900). -1 ~3000cm -1 ), and presents 1450cm -1 ~1480cm -1 The CH bending vibration peak at the location supports the XRD-based conclusion that no carbonate impurities were detected within the detection limit.

[0062] Depend on Figure 1 As can be seen from (f), structural characterization confirms that the ball-milled calcium glycerol has a higher specific surface area (13.2 m²) than the solution-synthesized sample. 2 g -1 These superior conformational properties are expected to enhance mass transfer and improve the utilization of active sites in transesterification reactions.

[0063] Test 2: Scanning electron microscopy analysis.

[0064] Scanning electron microscopy analysis was performed on the calcium glycerol catalysts prepared in Example 1 and Comparative Example 3, and the results are as follows: Figure 2 As shown.

[0065] Depend on Figure 2 As can be seen, the CaGly sample of Example 1 (BM, 5 min) exhibits a loose, porous, sponge-like or flocculent structure, composed of micron / submicron-sized fine particles. In contrast, the CaGly sample of Comparative Example 3 (SL, 4 h) is a larger, smooth, dense mass. This indicates that the ball milling method used in Examples 1 to 6 of this invention can construct microstructures with high specific surface area.

[0066] Test 3: Performance evaluation of catalytic transesterification reaction.

[0067] Using the transesterification reaction of soybean oil and methanol as a model, the performance of the glycerol calcium catalysts in Examples 1 to 6 and Comparative Examples 1 to 5 was evaluated.

[0068] Reaction conditions: The amount of calcium glycerol catalyst is 1% of the mass of soybean oil, the molar ratio of methanol to soybean oil is 6:1, the reaction temperature is 60℃, and the stirring speed is 500 rpm.

[0069] The specific method is as follows: Soybean oil, methanol, and calcium glycerol catalyst were subjected to transesterification at 60°C with a stirring speed of 500 rpm for 4 hours. The amount of calcium glycerol catalyst was 1% of the mass of soybean oil, and the molar ratio of methanol to soybean oil was 6:1. The conversion rate at different reaction times was analyzed, and the results are as follows: Figure 3 .

[0070] Combination Figure 3 As shown in (a) to (b), the CaGly(BM,5min) catalyst exhibits extremely high activity in the initial stage of the reaction, with its initial reaction rate being approximately twice that of the CaGly(SL,4h) catalyst. After 240 minutes of reaction, the biodiesel yield under the CaGly(BM,5min) catalysis reaches 77%, higher than the 73% of CaGly(SL,4h). The comparison of initial reaction rates demonstrates that within the first 30 minutes of the reaction, the conversion rate of CaGly(BM,5min) is significantly higher than that of CaGly(SL,4h) and pure CaO, showcasing its superior intrinsic activity.

[0071] Combination Figure 3 As can be seen from (c), the performance difference between the two catalysts in the early stage of the reaction is clearly distinguishable: the solid-state synthesized sample exhibits a higher initial reaction rate and a steeper curve slope, indicating that it has better catalytic initiation performance.

[0072] Combination Figure 3 As shown in (d), the CaGly catalyst synthesized via the solid-state method within 5 minutes can effectively convert palm oil, corn oil, olive oil, rapeseed oil, and rice bran oil as raw materials, demonstrating broad substrate compatibility. In summary, the CaGly catalyst synthesized via the solid-state method not only surpasses traditional methods in activity and synthesis efficiency but also exhibits significant advantages in raw material adaptability, providing strong support for its industrial application in biodiesel production.

[0073] Test 4: Evaluation of the substrate universality of the catalyst.

[0074] Using the calcium glycerol catalyst CaGly (BM, 5 min) prepared in Example 1, transesterification reactions were carried out in different types of oils under the reaction conditions of Test 3; the oils were palm oil (PO), corn oil (CO), olive oil (OO), rapeseed oil (RO), or rice bran oil (RBO); the results are as follows. Figure 3 As shown in (d).

[0075] like Figure 3As shown in (d), despite differences in oil source and fatty acid composition, the conversion rates for different types of oils were highly similar, demonstrating the excellent substrate universality of the calcium glycerol catalyst prepared in Example 1. Similarly, the calcium glycerol catalysts of Examples 2 to 6 also exhibited excellent substrate universality.

[0076] Example 9 A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag includes the following steps: Using a ball milling method, 1 kg of carbide slag dried at 60℃ was mixed with glycerol at a concentration of Ca... 2+ The mixture was prepared with glycerol at a molar ratio of 1:2 and placed in a vibratory ball mill. The mixture was milled at 500 rpm for 5, 10, 20, and 60 minutes to induce the chemical reaction through mechanical force. The reaction product was washed three times with ethanol and dried at 60°C for 6 hours to obtain a white powdery calcium glycerol catalyst.

[0077] Samples were taken at ball milling times of 5, 10, 20, and 60 minutes for X-ray diffraction analysis and conversion rate testing. The results are as follows: Figure 4 As shown in Figure (a) and Table 2.

[0078] Table 2 Comparison of samples with different ball milling times The glycerol-calcium catalyst scale-up BM:10min obtained by ball milling for 10 minutes was used as a model for the transesterification reaction of soybean oil and methanol. The performance of the glycerol-calcium catalyst scale-up BM:10min was evaluated after 5 consecutive samplings. The results are as follows: Figure 4 As shown in (b).

[0079] The glycerol-calcium catalyst scale-up BM:10min obtained by ball milling for 10 minutes was used as a model in the transesterification reaction of soybean oil and methanol to evaluate the performance of the glycerol-calcium catalyst scale-up BM:10min after 8 cycles. The results are as follows. Figure 4 As shown in (c). The X-ray diffraction pattern of the calcium glycerol catalyst scale-up BM after 8 cycles, 10 min, is shown in (c). Figure 4 As shown in (d).

[0080] Reaction conditions: The amount of calcium glycerol catalyst is 1% of the mass of soybean oil, the molar ratio of methanol to soybean oil is 6:1, the reaction temperature is 60℃, and the stirring speed is 500 rpm.

[0081] In Example 7, the amount of calcium carbide slag was increased to 1 kg, and the reaction was carried out in an enlarged ball mill. Samples were taken at 5, 10, 20 and 60 minutes of ball milling for X-ray diffraction analysis. The results showed that clear glycerol-calcium characteristic diffraction peaks could be observed after 10 minutes of reaction, proving that the scaled-up process was still highly efficient.

[0082] The scale-up calcium glycerol catalyst prepared on a large scale was sampled five times consecutively over 10 minutes for activity testing. Figure 4 (b) The results showed that its catalytic activity was comparable to that of the small-scale sample in Example 2, and the results of the five tests were stable and reproducible, which proved that the scale-up process has excellent stability and reliability.

[0083] like Figure 4 (c) Scale-up BM of the glycerol calcium catalyst: after 8 cycles in 10 min, the conversion rates were highly similar, demonstrating that the glycerol calcium catalyst obtained in the embodiments of this invention possesses excellent cycling stability. Figure 4 (d) Clear characteristic diffraction peaks of calcium glycerol were still observed in the calcium glycerol catalyst after 8 cycles, further demonstrating the excellent cycling stability of the calcium glycerol catalyst in Scale-up BM: 10 min.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solid-phase synthesis method for a glycerol-calcium catalyst based on carbide slag, characterized in that, Includes the following steps: Carbide slag and glycerol were mixed according to Ca... 2+ The mixture was mixed with glycerol at a molar ratio of 1:1 to 3, and ball-milled at room temperature. After washing and drying, a glycerol calcium catalyst was obtained for use in biodiesel transesterification.

2. The solid-phase synthesis method of glycerol-calcium catalyst based on carbide slag according to claim 1 is characterized in that, The particle size of carbide slag is 325 mesh to 500 mesh.

3. The solid-phase synthesis method of glycerol-calcium catalyst based on carbide slag according to claim 1, characterized in that, Ca in carbide slag 2+ Content ≥65.27wt%.

4. The solid-phase synthesis method of glycerol-calcium catalyst based on carbide slag according to claim 1, characterized in that, The ball milling process is carried out at a speed of 250 rpm to 300 rpm, and the total ball milling time is 5 minutes to 30 minutes.

5. The solid-phase synthesis method of glycerol-calcium catalyst based on carbide slag according to claim 1, characterized in that, Carbide slag and glycerol were mixed according to Ca... 2+ Mix with glycerol at a molar ratio of 1:

2.

6. The solid-phase synthesis method of glycerol-calcium catalyst based on carbide slag according to claim 1, characterized in that, Before ball milling, the calcium carbide slag undergoes pretreatment to remove sulfide and silicate impurities.

7. The solid-phase synthesis method of glycerol-calcium catalyst based on carbide slag according to claim 6, characterized in that, The method for pretreating carbide slag is as follows: The carbide slag is washed with water 2 to 3 times to remove sulfides and silicate impurities, and then dried to obtain pretreated carbide slag.

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