목질계 바이오매스는 조성분간의 결합이 치밀하고 높은 함량의 리그닌을 포함하여 전처리 공정이 필수적이다. 전처 리 용매 중 테트라하이드로퓨란(THF)은 유기용매로 재사용이 가능하다는 장점이 있다. THF는 가격이 저렴하고 다양 한 반응 조건에서 선택적으로 리그닌을 제거하고 물 혹은 이온성 액체와 공용매로 사용된다. 수산화 나트륨(Sodium hydroxide)은 바이오매스 내 ether결합을 파괴하여 리그닌을 우선적으로 용해시키며 셀룰로오스와 헤미셀룰로오스의 표면적을 확장시키는 역할을 한다. 본 연구에서는 NaOH/THF 공용매 전처리 공정을 적용하여 효과적 리그닌을 제거 를 위한 전처리 특성을 파악하고 후속 공정인 산촉매 전환 공정을 통해 최적의 레불린산 전환 수율을 얻었다. 전처리 공정은 NaOH/THF 공용매 비율을 16가지 부피 비율로 수행되었으며 반응조건은 180℃에서 60분으로 고정하였다. 최 적의 공용매 조건은 NaOH(5 wt%)/THF 공용매 90:10(v/v%)이였으며 76.8% 글루칸을 수득과 함께 90.1%의 리그닌을 제거하였다. 전처리 후속 공정인 산촉매 전환 공정은 반응시간 30~90분, 반응온도 160~200 ℃로 수행하였을 때, 산촉 매 전환 공정의 최적 조건은 180 ℃에서 반응시간 60분이었며, 이 때의 레불린산 전환수율은 84.7%이다.

Lignocellulosic biomass is essential to pretreatment because of having rigid structures and a lot of lignin. Among methods of pretreatment, using THF solvents has the advantage of being easy to reuse. THF (Tetrahydrofuran) used as a co-solvent with water or ionic solvent that is inexpensive and can remove lignin over a wide range of reaction conditions. NaOH (Sodium hydroxide) has been demonstrated to preferentially solvate lignin from cellulose. Thus, NaOH was used as a pretreatment co-solvent for the fractionation of lignin by destroying the ether bond to amend for hydrolysis and expand the surface area of cellulose and hemicellulose. In this experiment, lignin was removed by the NaOH/THF co-solvent pretreatment process to characteristics for the pretreatment and obtain the optimal levulinic acid conversion yield through the acid catalyst conversion process. the NaOH/THF co-solvent system was conducted in various ratios of co-solvent under a total of 16 conditions. And the temperature was 180 ℃ during to 60 mins. The optimum condition of co-solvent is NaOH 5 wt%/THF 90:10(v/v%), 76.8% glucan content was obtained through this co-solvent pretreatment, and 90.1% lignin was removed. In the acid catalyst conversion process, which is a subsequent pretreatment process, the experiment was conducted under the conditions of 30 to 90 min of reaction time and 160 ℃ to 200 ℃ reaction temperature. The optimum condition of acid catalyst conversion process is 60min reaction time under of 180 ℃, and it obtained 84.7% of levulinic aicd conversion yield.

Lignocellulosic biomass CELF Co-solvent Pretreatment THF NaOH Levulinic acid

1. Kumar, Abhinandan, Singh, P., Raizada, P., and Hussain, C. M.,“Impact of COVID-19 on Green-house Gases Emissions: A Critical Review,” Science of The Total Environment, 806(1), 150349(2022).
2. Esfandabadi, Z. S., Ranjbari, M. and Scagnelli, S. D., “The Imbalance of Food and Biofuel Markets Amid Ukraine-Russia Crisis: A Systems Thinking Perspective,” Biofuel Research Journal, 34, 1640-1647(2022).
3. Kumar, P., Barrett, D. M., Delwiche, M. J. and Stroeve, P., “Methods for Pretreatment of Lignocellulosic Biomass for Efficient Hydrolysis and Biofuel Production,” Industrial & Engineering Chemistry Research, 48(8), 3713-3729(2009).
4. Lay, C. H., Dharmaraja, J., Shobana, S., Arvindnarayan, S., Priya, R. K., Saratlae, R. and Kumar, G., “Lignocellulose Biohydrogen
Towards Net Zero Emission: A Review on Recent Developments,” Biore- source Technology, 364, 128084(2022).
5. Park, J. H., Kim, T. H. and Kim, J. S., “The Effect of Enzymatic Hydrolysis by Ethanol Organosolv Pretreatment of Corn Stover,”
Korean Chemical Engineering Research, 54(4), 448-452(2016).
6. Chen, W. H., Nižetić, S., Sirohi, R., Huang, Z., Luque, R., Papadopoulos, A. M. and Hoang, A. T., “Liquid Hot Water as Sustainable Biomass Pretreatment Technique for Bioenergy Production:A Review,” Bioresource Technology, 344, 126207(2022).
7. Kim, J. S., “Enhancement of Enzymatic Hydrolysis of Cellulosic Biomass by Organosolv Pretreatment Using High Concentration
of Ethanol,” Korean Chemical Engineering Research, 59(1), 54-59(2021).
8. Deng, W., Feng, Y., Fu, J., Guo, H., Guo, Y., Han, B. and Zhou,H., “Catalytic Conversion of Lignocellulosic Biomass Into Chemicals and Fuels,” Green Energy & Environment (2022).
9. Mirmohamadsadeghi, S., Chen, Z. and Wan, C., “Reducing Biomass Recalcitrance via Mild Sodium Carbonate Pretreatment,”
Bioresource Technology, 209, 386-390(2016).
10. Cai, C. M., Zhang, T., Kumar, R. and Wyman, C. E., “THF cosolvent Enhances Hydrocarbon Fuel Precursor Yields from Lignocellulosic Biomass,” Green Chemistry, 15(11), 3140-3145 (2013).
11. Patri, A. S., Mohan, R., Pu, Y., Yoo, C. G., Ragauskas, A. J.,Kumar, R. and Wyman, C. E., “THF co-solvent Pretreatment Prevents Lig-nin Redeposition from Interfering with Enzymes Yielding Pro-longed Cellulase Activity,” Biotechnology for Biofuels, 14(1), 1-13(2021).
12. Dharmaraja, J., S., Arvindnarayan, S., Francis, R. R., Jeyakumar, R. B., Saratale, R. and Kumar, G., “Lignocellulosic Biomass
Conversion via Greener Pretreatment Methods Towards Biorefinery Applications,” Bioresource Technology, 369, 128328(2022).
13. Meng, X., Parikh, A., Seemala, B., Kumar, R., Pu, Y., Christopher,P. and Ragauskas, A. J., “Chemical Transformations of Poplar
Lignin During Cosolvent Enhanced Lignocellulosic Fractionation Pro-cess,” ACS Sustainable Chemistry & Engineering, 6(7),8711-8718(2018).
14. Rihko-Struckmann, L. K., Oluyinka, O., Sahni, A., McBride, K.,Fachet, M., Ludwig, K. and Sundmacher, K., “Transformation of Remnant Algal Biomass to 5-HMF and Levulinic Acid: Influence of a Biphasic Solvent System,” RSC Advances, 10(42), 24753-24763(2020).
15. Sluiter, A., Hames, B., Ruiz, R., Scarlata, C., Sluiter, J., Templeton,D. and Crocker, D. L. A. P., “Determination of Structural Carbohydrates and Lignin in Biomass,” Laboratory Analytical Procedure, NREL(2008).
16. Kim, J. S., “Production of Levulinic Acid from Gelidium amansii Using Two Step Acid Hydrolysis,” Korean Chemical Engineering Research, 51(4), 438-442(2013).
17. Han, S., Lee, S. M. and Kim, J. S., “Kinetic Study of Glucose Conversion to 5-hydroxymethylfurfural and Levulinic Acid Catalyzed by Sulfuric Acid,” Korean Chemical Engineering Research,60(2), 193-201(2022).