Molasses-based catalyst, preparation method thereof and application of molasses-based catalyst in synthesis of biodiesel

Abstract

The invention discloses a molasses-based biomass sulfonated carbon catalyst preparation method, which comprises: grinding and mixing solid molasses and sodium hydroxide, calcining at 500-650 DEG C in an inert atmosphere to obtain activated carbon, and carrying out a sulfonation reaction on the activated carbon and concentrated sulfuric acid to obtain the catalyst. According to the method, by-product molasses in the sugar industry is taken as a raw material, a carbon source is rich in source, low in price and easy to obtain, the process is simple, the catalyst has relatively high specific surface area and conversion rate, the by-product can be utilized in a high-valued manner, and the method has certain industrial practical value.

Description

Technical Field

[0001] The present invention belongs to the field of application of biodiesel and biomass resource, and particularly relates to a molasses sulfonated carbon catalyst, a preparation method thereof, and an application thereof in the synthesis of biodiesel. Background Art

[0002] With the rapid development of the global economy and the sharp increase in energy consumption, there have been many environmental problems such as the depletion of petroleum fuels and greenhouse gas emissions. There is an urgent need to find a renewable and clean energy to replace fossil energy. Biodiesel is a green and clean energy with rapid development and great potential. Compared with petroleum fuels, biodiesel is considered an ideal substitute for traditional fossil energy because of its advantages such as renewability, biodegradability, high flash point, high combustion efficiency, high cetane number, low sulfur content, and less environmental damage.

[0003] At present, homogeneous catalysts are mainly used in the esterification reaction for synthesizing biodiesel. The production of biodiesel using homogeneous catalysts has advantages such as high yield and fast reaction rate. However, the production of biodiesel using homogeneous catalysts has disadvantages such as difficult separation, non-recyclability, equipment corrosion, and environmental pollution. Compared with homogeneous catalysts, solid acid and base catalysts have advantages such as easy separation, recyclability, and non-corrosiveness. Therefore, the use of solid acids and bases as catalysts for the production of biodiesel has become a research hotspot.

[0004] Molasses-based carbon solid acid catalysts are a type of solid materials with acidity. They are formed by the combination of acidic functional groups and activated carbon, and have advantages such as chemical stability and renewability. They have broad practical application potential. Applying them to the catalytic esterification reaction of oleic acid and methanol to prepare biodiesel is of great significance for the green catalytic synthesis of biodiesel. Summary of the Invention

[0005] Aiming at the problems of the above-mentioned existing technologies, the present invention provides a molasses-based biomass sulfonated carbon catalyst, a preparation method thereof, and an application thereof in the synthesis of biodiesel. Its carbon source is rich and cheap, the process is simple, and the catalyst has a high specific surface area and catalytic conversion rate.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A preparation method of a molasses-based biomass sulfonated carbon catalyst, comprising the following steps:

[0008] (1) Grind and mix solid molasses with sodium hydroxide, and then calcine at 500°C to 650°C under an inert atmosphere to obtain activated carbon;

[0009] (2) Perform a sulfonation reaction on the activated carbon obtained in step (1) with sulfuric acid to obtain the catalyst.

[0010] Preferably, the solid molasses described in step (1) is obtained by the following method: drying molasses in a vacuum drying oven, drying at 50 °C for 8 h, 60 °C for 8 h, and 70 °C for 8 h in sequence, and then taking it out and grinding to obtain it.

[0011] Preferably, in step (1), the mass ratio of the solid molasses to sodium hydroxide is 1.0:1 to 2.0:1. More preferably, it is 1.6:1.

[0012] Preferably, in step (1), it is calcined at 550 °C.

[0013] Preferably, the calcination time in step (1) is 2 to 6 h, more preferably 4 h.

[0014] Preferably, the inert gas described in step (1) is N2.

[0015] Preferably, step (1) further includes the steps of washing, drying, and pulverizing after calcination.

[0016] Preferably, the sulfuric acid described in step (2) is concentrated sulfuric acid. Specifically, it is concentrated sulfuric acid with a concentration of 98%.

[0017] Preferably, the temperature of the sulfonation reaction described in step (2) is 90 to 130 °C, more preferably 110 °C.

[0018] Preferably, the time of the sulfonation reaction described in step (2) is 2 to 10 h, more preferably 8 h.

[0019] Preferably, step (2) further includes the steps of washing and drying after the sulfonation reaction. More preferably, the drying temperature is 80 to 110 °C, and the drying time is 12 to 24 h. The drying is carried out using a drying oven or an oven.

[0020] The second object of the present invention is to provide a molasses-based biomass sulfonated carbon catalyst prepared by the above method.

[0021] The third object of the present invention is to provide the application of the above molasses-based biomass sulfonated carbon catalyst in the synthesis of biodiesel.

[0022] Preferably, the application is: catalyzing the esterification reaction of oleic acid and methanol.

[0023] More preferably, the molar ratio of oleic acid to methanol is 1:8 to 1:16, more preferably 1:12.

[0024] More preferably, in the esterification reaction, the addition amount of the catalyst is 1 to 9 wt%, preferably 5 wt%.

[0025] The time of the esterification reaction is 1 to 5 h, preferably 4 h.

[0026] The temperature of the esterification reaction is 60 to 100 °C, preferably 80 °C.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) The molasses-based biomass sulfonated carbon catalyst of the present invention is obtained by sulfonation using an activated carbon carrier as the carrier and has a mesoporous structure.

[0029] (2) The preparation process of the molasses-based biomass sulfonated carbon catalyst of the present invention is simple, the raw material molasses is easily available and inexpensive, it can be reused, and it can be highly valued with high economic benefits.

[0030] (3) When the molasses-based biomass sulfonated carbon catalyst of the present invention is used to catalyze the esterification reaction of oleic acid and methanol to prepare biodiesel, it has better catalytic performance and higher catalytic activity. After being reused five times, the catalytic activity changes little. Description of the Drawings

[0031] Figure 1 XRD patterns of different TM-SO3H / C catalysts in the test examples;

[0032] Figure 2 SEM images of TM-550-C (a) and TM-SO3H / C catalyst (b) in the test examples.

[0033] Figure 3 Adsorption-desorption curves and pore size distribution diagrams of different TM-SO3H / C catalysts in the test examples. Detailed Description of the Invention

[0034] The present invention will be described in more detail below with reference to the examples, which do not limit the scope of protection of the present invention.

[0035] Example 1

[0036] (1) Preparation of TM-550-C:

[0037] Solid molasses and the activator sodium hydroxide were uniformly mixed at a mass ratio of 1.6:1, placed in a tubular furnace, heated to 550 °C under a N2 atmosphere, and kept warm for 4 h. After cooling to room temperature, it was washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain TM-550-C. The SEM of the prepared TM-550-C is as Figure 2 (a) shown.

[0038] (2) Preparation of TM-SO3H / 550-C:

[0039] Weigh 4 g of the TM550-C carrier, place it in a three-necked flask, add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, heat it in a water bath at 110 ° C for 8 h to carry out sulfonation reaction, cool it to room temperature after the reaction is completed, add deionized water to wash it until it is neutral, place it in an oven at 100 ° C for 12 h, and grind it to obtain TM-SO3H / 550-C. The XRD pattern of the prepared TM-SO3H / 550-C is shown in Figure 1 As shown; the SEM of the prepared TM-SO3H / 550-C is as shown Figure 2 (b) shows; the N2 adsorption-desorption curve of the prepared TM-SO3H / 550-C is shown in Figure 3 As shown, its N2 adsorption-desorption curve belongs to the H3 type isotherm, indicating that TM-SO3H / 550-C is a typical mesoporous material. The specific surface area, pore volume and pore size of the SO3H / 550-C catalyst are shown in Table 2.

[0040] (3) Catalyst performance evaluation:

[0041] 0.565 g of TM-SO3H / 550-C catalyst was placed in a 50 mL three-necked flask, and 11.30 g of oleic acid and 15.38 g of methanol were added. The flask was sealed and heated. When heated to 80 °C, the reaction was stirred for 4 h. After the reaction, samples were taken and tested by acid-base titration. The conversion rate of oleic acid was 99.80%. In order to evaluate the repeatability of the catalyst, the catalyst was recovered after each experiment, washed with ethanol, and dried in a vacuum drying oven for the next reaction. The catalyst was reused 5 times, and the conversion rate of oleic acid remained at about 98%, and the activity of the catalyst did not decrease significantly.

[0042] Example 2

[0043] (1) Preparation of TM-600-C:

[0044] Solid molasses and activator sodium hydroxide were uniformly mixed in a mass ratio of 1.6:1, and then placed in a tube furnace and heated to 600 °C in a N2 atmosphere for 4 h. After cooling to room temperature, it was washed with deionized water until neutral, placed in an oven at 100 °C for 12 h, and ground to obtain TM-600-C.

[0045] (2) Preparation of sulfonated carbon:

[0046] Weigh 4 g of the above-mentioned TM-600-C support, place it in a three-necked flask, add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, heat it in a water bath at 110 °C for 8 h for sulfonation reaction. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, dry it in an oven at 100 °C for 12 h, and grind it to obtain TM-SO3H / 600-C. The XRD pattern of the prepared TM-SO3H / 600-C is as shown in Figure 1 ; The N2 adsorption-desorption curve of the prepared TM-SO3H / 600-C is as shown in Figure 3 . Its N2 adsorption-desorption curve belongs to the H3-type isotherm, indicating that TM-SO3H / 600-C belongs to a typical mesoporous material. The specific surface area, pore volume and pore diameter of the TM-SO3H / 600-C catalyst are shown in Table 2.

[0047] (3)Catalyst performance evaluation:

[0048] Load 0.565 g of TM-SO3H / 600-C catalyst into a 50 mL three-necked flask, then add 11.30 g of oleic acid and 15.38 g of methanol, seal it, start heating. When it is heated to 80 °C, start stirring and reacting for 4 h. After the reaction is completed, take a sample and detect it by acid-base titration. The conversion rate of oleic acid is 94.04%. In order to evaluate the repeatability of the catalyst, after each experiment, the catalyst is recovered, washed with ethanol, and dried in a vacuum drying oven for the next reaction. The catalyst is reused 5 times, and the conversion rate of oleic acid still remains at about 93%, and the activity of the catalyst has no obvious decrease.

[0049] Example 3

[0050] (1)Preparation of TM-650-C:

[0051] After uniformly mixing solid molasses and the activator sodium hydroxide according to a mass ratio of 1.6:1, place it in a tubular furnace and heat it to 650 °C under a N2 atmosphere for 4 h. After cooling to room temperature, wash it with deionized water until neutral, dry it in an oven at 100 °C for 12 h, and grind it to obtain TM-650-C.

[0052] (2)Preparation of TM-SO3H / 650-C:

[0053] Weigh 4 g of the above-mentioned TM-650-C support, place it in a three-necked flask, add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, and heat it in a water bath at 110 °C for 8 h for sulfonation reaction. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, place it in an oven and dry it at 100 °C for 12 h, and then grind it to obtain TM-SO3H / 650-C. The XRD pattern of the prepared TM-SO3H / 650-C is as shown in Figure 1 ; The N2 adsorption-desorption curve of the prepared TM-SO3H / 650-C is as shown in Figure 3 . Its N2 adsorption-desorption curve belongs to the H3-type isotherm, indicating that TM-SO3H / 650-C belongs to a typical mesoporous material. The specific surface area, pore volume and pore diameter of the SO3H / 650-C catalyst are shown in Table 2.

[0054] (3) Catalyst performance evaluation:

[0055] Load 0.565 g of TM-SO3H / 650-C catalyst into a 50 mL three-necked flask, then add 11.30 g of oleic acid and 15.38 g of methanol, seal it, start heating, and when it is heated to 80 °C, start stirring and reacting for 4 h. After the reaction is completed, take a sample and detect it by acid-base titration. The conversion rate of oleic acid is 92.53%. In order to evaluate the repeatability of the catalyst, after each experiment, the catalyst is recovered, washed with ethanol, and dried in a vacuum drying oven for the next reaction. The catalyst is reused 5 times, and the conversion rate of oleic acid still remains at about 91%, and the activity of the catalyst has no obvious decrease.

[0056] Example 4

[0057] (1) Preparation of TM-500-C:

[0058] The preparation of solid molasses is the same as that in Example 1. After uniformly mixing solid molasses and the activator sodium hydroxide according to a mass ratio of 1.6:1, place it in a tubular furnace and heat it to 500 °C under a N2 atmosphere for 4 h. After cooling to room temperature, wash it with deionized water until neutral, place it in an oven and dry it at 100 °C for 12 h, and then grind it to obtain TM-500-C.

[0059] (2) Preparation of TM-SO3H / 500-C:

[0060] Weigh 4 g of the above-mentioned TM-500-C support and place it in a three-necked flask. Add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL. Carry out the sulfonation reaction by heating in a water bath at 110 °C for 8 h. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, place it in an oven and dry at 100 °C for 12 h. After grinding, TM-SO3H / 500-C is obtained. The XRD pattern of the prepared TM-SO3H / 500-C is as shown in Figure 1 ; The N2 adsorption-desorption curve of the prepared TM-SO3H / 500-C is as shown in Figure 3 . Its N2 adsorption-desorption curve belongs to the H3-type isotherm, indicating that TM-SO3H / 500-C belongs to a typical mesoporous material. The specific surface area, pore volume and pore diameter of the TM-SO3H / 500-C catalyst are shown in Table 2.

[0061] (3) Catalyst performance evaluation:

[0062] Load 0.565 g of the TM-SO3H / 500-C catalyst into a 50 mL three-necked flask, then add 11.30 g of oleic acid and 15.38 g of methanol, seal it, start heating. When heated to 80 °C, start stirring and reacting for 4 h. After the reaction is completed, take a sample and detect it by acid-base titration. The conversion rate of oleic acid is 81.28%. In order to evaluate the repeatability of the catalyst, after each experiment, the catalyst is recovered, washed with ethanol, and dried in a vacuum drying oven for the next reaction. The catalyst is reused 5 times, and the conversion rate of oleic acid still remains at about 80%, and the activity of the catalyst has no obvious decrease.

[0063] Comparative Example 1

[0064] (1) Preparation of TM-450-C:

[0065] Dry molasses in a vacuum drying oven for 24 h, with a drying temperature of 50 °C for 8 h, 60 °C for 8 h, and 70 °C for 8 h. Then take it out and grind it to obtain solid molasses. After uniformly mixing the solid molasses with the activator sodium hydroxide according to a mass ratio of 1.6:1, place it in a tube furnace and heat it to 450 °C in an N2 atmosphere, and keep it warm for 4 h. After cooling to room temperature, wash it with deionized water until neutral, place it in an oven and dry at 100 °C for 12 h. After grinding, TM-450-C is obtained.

[0066] (2) Preparation of TM-SO3H / 450-C:

[0067] Weigh 4 g of the above-mentioned TM-450-C support and place it in a three-necked flask. Add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, and heat it in a water bath at 110 °C for 8 h for sulfonation reaction. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, place it in an oven and dry it at 100 °C for 12 h, and then grind it to obtain TM-SO3H / 450-C. The XRD of the prepared TM-SO3H / 450-C is as shown in Figure 1 shown; the N2 adsorption-desorption curve of the prepared TM-SO3H / 450-C is as shown in Figure 3 shown. Its N2 adsorption-desorption curve belongs to the H3-type isotherm, indicating that SO3H / 450-C belongs to a typical mesoporous material. The specific surface area, pore volume and pore diameter of the TM-SO3H / 450-C catalyst are shown in Table 2.

[0068] (3)Catalyst performance evaluation:

[0069] Load 0.565 g of TM-SO3H / 450-C catalyst into a 50 mL three-necked flask, then add 11.30 g of oleic acid and 15.38 g of methanol, seal it, start heating, and when it is heated to 80 °C, start stirring and reacting for 4 h. After the reaction is completed, take a sample and detect it by acid-base titration. The conversion rate of oleic acid is 78.46%.

[0070] Comparative Example 2

[0071] (1)Preparation of JG-550-C:

[0072] Mix the straw and the activator sodium hydroxide evenly according to the mass ratio of 1.6:1, place it in a tubular furnace and heat it to 550 °C in an N2 atmosphere, and keep it warm for 4 h. After cooling to room temperature, wash it with deionized water until neutral, place it in an oven and dry it at 100 °C for 12 h, and then grind it to obtain JG-550-C.

[0073] (2)Preparation of JG-SO3H / 550-C:

[0074] Weigh 4 g of the above-mentioned JG-550-C support and place it in a three-necked flask. Add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, and heat it in a water bath at 110 °C for 8 h for sulfonation reaction. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, place it in an oven and dry it at 100 °C for 12 h, and then grind it to obtain JG-SO3H / 550-C. The specific surface area, pore volume and pore diameter of the prepared GD-SO3H / 550-C catalyst are shown in Table 2.

[0075] (3)The catalyst performance evaluation is the same as that in Example 1, except that the catalyst is JG-SO3H / 550-C. The conversion rate of oleic acid obtained is 83.26%.

[0076] Comparative Example 3

[0077] (1) Preparation of HS-550-C:

[0078] The peanut shell powder and the activator sodium hydroxide were uniformly mixed at a mass ratio of 1.6:1, and then placed in a tubular furnace and heated to 550 °C under a N2 atmosphere for 4 h. After cooling to room temperature, it was washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain HS-550-C.

[0079] (2) Preparation of HS-SO3H / 550-C:

[0080] Weighed 4 g of the above HS-550-C support, placed it in a three-necked flask, added 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, and heated it in a water bath at 110 °C for 8 h for sulfonation reaction. After the reaction was completed, it was cooled to room temperature, washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain HS-SO3H / 550-C. The specific surface area, pore volume and pore diameter of the prepared HS-SO3H / 550-C catalyst are shown in Table 2.

[0081] (3) The performance evaluation of the catalyst was the same as that in Example 1, except that the catalyst was HS-SO3H / 550-C. The conversion rate of oleic acid was 75.97%.

[0082] Comparative Example 4

[0083] (1) Preparation of ZZ-550-C:

[0084] The bamboo powder and the activator sodium hydroxide were uniformly mixed at a mass ratio of 1.6:1, and then placed in a tubular furnace and heated to 550 °C under a N2 atmosphere for 4 h. After cooling to room temperature, it was washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain ZZ-550-C.

[0085] (2) Preparation of ZZ-SO3H / 550-C:

[0086] Weighed 4 g of the above ZZ-550-C support, placed it in a three-necked flask, added 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, and heated it in a water bath at 110 °C for 8 h for sulfonation reaction. After the reaction was completed, it was cooled to room temperature, washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain ZZ-SO3H / 550-C. The specific surface area, pore volume and pore diameter of the prepared ZZ-SO3H / 550-C catalyst are shown in Table 2.

[0087] (3) The catalyst performance evaluation was the same as in Example 1, except that the catalyst was ZZ-SO3H / 550-C. The conversion rate of oleic acid was 81.02%.

[0088] Comparative Example 5

[0089] (1) Preparation of BLK-550-C:

[0090] Chestnut shells and the activator sodium hydroxide were uniformly mixed at a mass ratio of 1.6:1, then placed in a tube furnace and heated to 550 °C under a N2 atmosphere for 4 h. After cooling to room temperature, it was washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain BLK-550-C.

[0091] (2) Preparation of BLK-SO3H / 550-C:

[0092] Weigh 4 g of the above BLK-550-C support, place it in a three-necked flask, add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, and heat it in a water bath at 110 °C for 8 h for sulfonation reaction. After the reaction ended, it was cooled to room temperature, washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain BLK-SO3H / 550-C. The specific surface area, pore volume, and pore diameter of the prepared BLK-SO3H / 550-C catalyst are shown in Table 2.

[0093] (3) The catalyst performance evaluation was the same as in Example 1, except that the catalyst was BLK-SO3H / 550-C. The conversion rate of oleic acid was 82.95%.

[0094] Comparative Example 6

[0095] (1) Preparation of TCJ-550-C:

[0096] First, the sugar beet was dried, then the sugar beet and the activator sodium hydroxide were uniformly mixed at a mass ratio of 1.6:1, and then placed in a tube furnace and heated to 550 °C under a N2 atmosphere for 4 h. After cooling to room temperature, it was washed with deionized water until neutral, dried in an oven at 100 °C for 12 h, and ground to obtain TCJ-550-C.

[0097] (2) Preparation of TCJ-SO3H / 550-C:

[0098] Weigh 4 g of the above-mentioned TCJ-550-C support and place it in a three-necked flask. Add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL. Carry out the sulfonation reaction by heating in a water bath at 110 °C for 8 h. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, place it in an oven and dry at 100 °C for 12 h. After grinding, TCJ-SO3H / 550-C is obtained.

[0099] (3)The performance evaluation of the catalyst is the same as that in Example 1, except that the catalyst is TCJ-SO3H / 550-C. The conversion rate of oleic acid is 81.34%.

[0100] Comparative Example 7

[0101] (1)Preparation of ZT-550-C:

[0102] After uniformly mixing sucrose and the activator sodium hydroxide according to a mass ratio of 1.6:1, place it in a tubular furnace and heat it to 550 °C under a N2 atmosphere for 4 h. After cooling to room temperature, wash it with deionized water until neutral, place it in an oven and dry at 100 °C for 12 h. After grinding, ZT-550-C is obtained.

[0103] (2)Preparation of ZT-SO3H / 550-C:

[0104] Weigh 4 g of the above-mentioned ZT550-C support and place it in a three-necked flask. Add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL. Carry out the sulfonation reaction by heating in a water bath at 110 °C for 8 h. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, place it in an oven and dry at 100 °C for 12 h. After grinding, ZT-SO3H / 550-C is obtained.

[0105] (3)Catalyst performance evaluation:

[0106] Load 0.565 g of ZT-SO3H / 550-C catalyst into a 50 mL three-necked flask, then add 11.30 g of oleic acid and 15.38 g of methanol, seal it, start heating. When it is heated to 80 °C, start stirring and reacting for 4 h. After the reaction is completed, take a sample and detect it by acid-base titration. The conversion rate of oleic acid is 92.80%. In order to evaluate the repeatability of the catalyst, after each experiment is completed, the catalyst is recovered, washed with ethanol, and dried in a vacuum drying oven for the next reaction. This catalyst is reused 5 times, and the conversion rate of oleic acid still remains at about 91%, and the activity of the catalyst has no obvious decrease.

[0107] From the performance evaluations of Example 1, Comparative Example 6, and Comparative Example 7, it can be seen that among the three sulfonated carbon catalysts prepared with sucrose, TM-SO3H / 550-C has the highest conversion rate. This is because molasses contains a certain amount of metal components as shown in Table 1. Under the action of sodium hydroxide and high temperature, metal - O - C bonds are formed. These oxides react with the water generated in the esterification reaction to form bases. Therefore, there are both acid and base active centers on the activated carbon carrier. Under the same catalytic action of acid and base, the conversion rate of TM-SO3H / 550-C for catalyzing the esterification of oleic acid into methyl oleate is the highest.

[0108] Table 1 Metal Ion Content in Molasses

[0109] Item Cobalt Copper Iron Manganese Zinc Potassium Sodium Content (mg / kg) Not detected 0.98 83.97 13.6 4.88 0.73 222.8

[0110] Comparative Example 8

[0111] (1) Preparation of DF-400-C:

[0112] First, mix amylose and the activator sodium hydroxide evenly at a mass ratio of 1.6:1, then place them in a tubular furnace and heat to 400 °C in an N2 atmosphere, and keep the temperature for 4 h. After cooling to room temperature, wash with deionized water until neutral, dry in an oven at 100 °C for 12 h, and grind to obtain DF-400-C.

[0113] (2) Preparation of DF-SO3H / 400-C:

[0114] Weigh 4 g of the above DF-550-C carrier, place it in a three-necked flask, add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL, and carry out the sulfonation reaction by heating in a water bath at 110 °C for 8 h. After the reaction is completed, cool to room temperature, add deionized water to wash until neutral, dry in an oven at 100 °C for 12 h, and grind to obtain DF-SO3H / 400-C.

[0115] (3) The performance evaluation of the catalyst is the same as that in Example 1, except that the catalyst is DF-SO3H / 400-C. The conversion rate of oleic acid obtained is 68.13 %.

[0116] Comparative Example 9

[0117] (1) Preparation of PTT-400-C:

[0118] First, mix glucose and the activator sodium hydroxide evenly at a mass ratio of 1.6:1, then place them in a tubular furnace and heat to 400 °C in an N2 atmosphere, and keep the temperature for 4 h. After cooling to room temperature, wash with deionized water until neutral, dry in an oven at 100 °C for 12 h, and grind to obtain PTT-400-C.

[0119] (2) Preparation of PTT-SO3H / 400-C:

[0120] Weigh 4 g of the above PTT-550-C support and place it in a three-necked flask. Add 60 mL of concentrated sulfuric acid according to the ratio of activated carbon to concentrated sulfuric acid of 1 g:15 mL. Carry out the sulfonation reaction by heating in a water bath at 110 °C for 8 h. After the reaction is completed, cool it to room temperature, add deionized water to wash until neutral, dry it in an oven at 100 °C for 12 h, and grind it to obtain PTT-SO3H / 400-C.

[0121] (3) The evaluation of the catalyst performance is the same as that in Example 1, except that the catalyst is PTT-SO3H / 550-C. The conversion rate of oleic acid is 70.83%.

[0122] Test Example

[0123] Characterize the catalysts prepared in the above examples and comparative examples. The XRD characterization and SEM characterization are shown in Figure 1 、 2 , and the adsorption-desorption performance is shown in Figure 3 . The specific surface area and pore size characterization are shown in Table 2.

[0124] Table 2 Specific Surface Area, Pore Volume and Pore Size of the Materials

[0125] Samples <![CDATA[S BET (m 2 / g)]]> <![CDATA[Pore Volume (cm 3 / g)]]> Pore size (nm) Example 1 <![CDATA[TM-SO3H / 550-C]]> 113.83 0.49 4.89 Example 2 <![CDATA[TM-SO3H / 600-C]]> 96.27 0.10 6.35 Example 3 <![CDATA[TM-SO3H / 650-C]]> 139.18 0.11 4.60 Example 4 <![CDATA[TM-SO3H / 500-C]]> 52.32 0.06 8.27 Comparative Example 1 <![CDATA[TM-SO3H / 450-C]]> 31.75 0.06 14.33 Comparative Example 2 <![CDATA[JG-SO3H / 550-C]]> 127.67 0.26 13.53 Comparative Example 3 <![CDATA[HS-SO3H / 550-C]]> 157.61 0.20 7.79 Comparative Example 4 <![CDATA[ZZ-SO3H / 550-C]]> 120.67 0.27 14.39 Comparative Example 5 <![CDATA[BLK-SO3H / 550-C]]> 118.52 0.22 12.43

Claims

1. A preparation method of a molasses-based biomass sulfonated carbon catalyst, characterized in that, It includes the following steps: (1) After grinding and mixing solid molasses with sodium hydroxide, calcine it at 500°C to 650°C under an inert atmosphere to obtain activated carbon; (2) Carry out a sulfonation reaction on the activated carbon obtained in step (1) with sulfuric acid to obtain the catalyst.

2. The preparation method according to claim 1, wherein In step (1), the mass ratio of the solid molasses to sodium hydroxide is (1.0 - 2.0):

1.

3. The preparation method according to claim 1, characterized in that, In step (1), calcine at 550°C.

4. The preparation method according to claim 1, characterized in that, In step (1), the calcination time is 2 - 6 h, more preferably 4 h.

5. The preparation method according to claim 1, wherein The sulfuric acid in step (2) is concentrated sulfuric acid.

6. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the sulfonation reaction is 90 - 130°C, more preferably 110°C.

7. The preparation method according to claim 1, characterized in that, In step (2), the time of the sulfonation reaction is 2 - 10 h, more preferably 8 h.

8. The preparation method according to claim 1, wherein Step (2) also includes the steps of washing and drying after the sulfonation reaction; more preferably, the drying temperature is 80 - 110°C, and the drying time is 12 - 24 h; the drying is carried out by blowing drying or vacuum drying.

9. A molasses-based biomass sulfonated carbon catalyst prepared by the preparation method according to any one of claims 1 - 8.

10. Application of the molasses-based biomass sulfonated carbon catalyst prepared by the preparation method according to any one of claims 1 - 8 in the synthesis of biodiesel.

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