Abstract: In this paper, furfural residue acid hydrolysis experiments take levulinic acid, furfural residue to determine the preparation of levulinic acid optimum process conditions as follows: reaction temperature 200 ℃, reaction time 40min, sulfuric acid concentration of 6%, solid-liquid ratio 1:20, when the levulinic acid yield 51.9mol%.
Key words: furfural residue; levulinic acid; Yield
Our capable of producing millions of tons per year of furfural slag contains large amounts of cellulose, in the promotion of resource conservation today, should make full use of furfural residue of cellulose to produce high value-added chemical products. Preparation of levulinic acid can be used to a variety of chemical products, used widely. Therefore, the study will waste furfural hydrolysis conversion of levulinic acid preparation is important [1].
This paper investigated the impact of each of reaction conditions on the yield of levulinic acid, finding the optimal process conditions, furfural residue acid hydrolysis of levulinic acid amplification process optimization and research foundation.
1 Experimental
1.1 Experimental Materials & Equipment
Furfural residue taken from the laboratory resulting corncob furfural, 98% H2SO4, levulinic acid were commercially available analytical grade. Experimental use 100ml batch autoclave (British Yu Gongyi City Yuhua Instrument Factory); DZ-2BC vacuum oven (Tianjin Teste Instrument Co., Ltd.); FA2004 electronic balance (Shanghai flat Instruments Inc.); GC- 14B gas chromatograph (Shimadzu Seisakusho).
1.2 Principle of step
Furfural slag mainly composed of cellulose, cellulose furfural slag at high temperature catalytic hydrolysis can generate glucose, and then dehydrated to form 5-hydroxymethyl furfural, 5-hydroxymethyl furfural last decarboxylation can generate levulinic acid [2 ].
The amount of furfural residue after drying and a percentage of an aqueous solution of sulfuric acid was added to the magnetic rotor 100ml autoclave, a certain time the reaction was cooled after heating. After cooling, the reaction solution suction filtration and the separated solid residue, the amount of the reaction mixture analyzed by gas chromatography levulinic acid. After washing and drying the residue weighed solid phase residue quality. By Van Soest method [3] analyzing the composition of furfural and levulinic acid residue.
1.3 Analysis Method
To analyze the content of the liquid after the reaction of levulinic acid by gas chromatography. GC conditions were set as follows: capillary column, flame ionization detector; temperature program: initial column temperature column temperature 100 ℃, holding 3 min, then 10 ℃ / min rate was raised to 210 ℃, maintained for 10 min; vaporization room temperature is 240 ℃; detector temperature was 250 ℃; injection volume 1 μL, split injection; high purity nitrogen carrier gas.
Levulinic acid yield (mol%) =;
Weight loss rate (%) =.
2 Results and discussion
By Van Soest method for the determination of furfural residue in the cellulose content of 54.4%, furfural residue in order to maximize the cellulose is converted to levulinic acid, sulfuric acid concentration, temperature, reaction time and other factors were examined. The results are as follows:
2.1 Effect of sulfuric acid concentration of levulinic acid yield
Great from the literature [4] found that acid hydrolysis of cellulose material than the impact of the solid-liquid ratio 1:20, temperature 200 ℃, time 40min under the conditions of change in the concentration of sulfuric acid aqueous solution with the following results:
It can be seen with increasing concentration of sulfuric acid, the weight loss rate is gradually increased from 1, the cellulose hydrolysis rate increased. In the sulfuric acid concentration increased from 2% to 6% of the process, the molar yield of hydrolyzate of levulinic acid is also increasing, and then increase the concentration of sulfuric acid, levulinic acid yield tends to be stable, because when there is no after hydrolysis of the cellulose chain molecules shaped area is completed, the crystalline acid molecules less accessible areas, so the hydrolysis rate becomes slow and gradually stabilized, so levulinic acid yields have stabilized.
2.2 Effect of temperature on the yield of levulinic acid
In the solid-liquid ratio 1:20, 6% aqueous solution of sulfuric acid concentration, time of 40min conditions, varying the reaction temperature, the following results:
When it can be seen from Figure 2 when the temperature rises, the yield of levulinic acid starting material and the weight loss rate is gradually increased, the reaction temperature was 200 deg.] C, the highest yield of levulinic acid was 51.97mol%; continuing to increase the temperature of the reaction of levulinic acid yield declined slightly, while the rate of weight loss is essentially the same. This is because in a certain temperature range, the higher the temperature, the faster the electron transfer reaction system, the faster the reaction, the shorter the time required for hydrolysis. The temperature continues to rise, furfural slag cellulose is almost completely decomposed, the reaction intermediate is generated in the other polymerization by-products at a high temperature to produce levulinic acid will decompose at high temperatures, so that the production of levulinic acid the rate of decline [5].
2.3 Effect of reaction time on the yield of levulinic acid
Reaction temperature 200 ℃, solid-liquid mass ratio of 1:20, the acid concentration of 6%, reaction time was changed the following results:
Figure 3 shows the reaction time is increased to increase the yield of levulinic acid, and the weight loss rate remained stable, the reaction time is within the scope of the cellulose almost completely decomposed. The reaction time is 40min, the levulinic acid yield up to 51.977mol%; continue to increase the yield of acetyl acid reaction time decreased slightly. This is probably because the reaction time is too short, the reaction equilibrium is not reached, generating less amount of levulinic acid, and the reaction time, the byproduct gradually increased, so that the yield of levulinic acid decreased.
2.4 The solid-liquid ratio of levulinic acid Yield
6% acidity, temperature 200 ℃, 40min reaction conditions, changing the solid-liquid ratio, results are as follows:
As can be seen from Figure 4, the solid-liquid ratio is increased, reducing weight loss, levulinic acid yields decreased, indicating that the more dilute the concentration of the solid phase reaction system, hydrolysis of cellulose sulfate and hydrogen ions and serotonin the probability of contact with methyl furfural and other intermediate products increased significantly, thus better able to catalyze the hydrolysis of cellulose and can quickly be intermediate in the catalytic conversion of levulinic acid.
3 summary
In this paper, furfural levulinic acid residue acid hydrolysis experiments were studied influence of reaction conditions on the yield of levulinic acid can be obtained at a reaction temperature of 200 ℃, sulfuric acid concentration of 6%, the reaction time was 40min, solid to liquid ratio 1:20, the highest yield of levulinic acid for 51.9mol%.
references:
[1] Yang Rui. Furfural residue comprehensive utilization of new exploration [D]. South China University of Technology, 2005.
Acid hydrolysis of levulinic acid [D] [2] Liu Kai straw hypertension. Northeast Forestry University, 2007.
[3] Chen Xian love, business Jin, Song Huifang, etc. Several procedures straw cellulose / hemicellulose and lignin contrast [J]. Chinese Society of Agricultural Engineering Academic Annual Meeting Proceedings 2011, 2011.
[4] Zhang Jianli. Process of starch and sawdust as raw material levulinic acid [D]. Zhengzhou University, 2006.
. [5] Yang Jing plant cellulose hydrolysis of levulinic acid production and comprehensive utilization of slag lignin activated carbon [J] Chemical Engineering Progress, 1996 (0l):. 4-42.
