(205e) Transformation of Chitin into Value-Added Chemicals

Chitin is the world second most abundant biopolymer widely existed in the exoskeleton of shellfish and insects containing 7 wt% of biologically fixed nitrogen. This sustainable biomass has an underestimated but remarkable potential for the production of industrially important chemicals especially nitrogen containing compounds. To date, the direct conversion of chitin into high value chemicals with high yield has yet to be demonstrated. [1] In this presentation, we will show case some of our efforts in the catalytic transformation of chitin into N-containing chemicals (Scheme 1). Several strategies, including dehydration, liquefaction, hydrogenolysis and hydrothermal treatment, will be described in detail. The direct, one-pot conversion of chitin into a N-containing furan derivative with 7.5 % yield was achieved in both organic and ionic liquid solvents, by using boric acid and metal chlorides/HCl additives.[2, 3] The boron-sugar complex intermediate formed during the reaction was probed by NMR analysis, which is the key intermediate in the reaction. Chitin liquefaction, which transforms solid biomass into oils, was demonstrated in ethylene glycol under the catalysis of sulphuric acid.[4] After liquefaction, the crystalline structure of chitin was efficiently damaged. The total yield of liquefied monomers was around 30 %. Moreover, chitin monomer has been converted to its corresponding amide/amino substituted sugar alcohols, over noble metal catalysts in the presence of hydrogen in water.[5] By using Ru/C catalyst, 71.9% C6 polyols (N-containing) 8.7% N-acetylmonoethanolamine (NMEA) and 6.1% C4 polyols were obtained. [6] Kinetic studies revealed four major parallel reaction pathways that lead to these various products. In an effort to enhance the product yields, a comparative, systematic investigation of chitin treatment by various methods was studied and the structure-reactivity correlation has been identified. The yield of dehydration product was increased to 4-fold as previous by ball mill treatment. This series of work demonstrated that chitin is indeed an attractive starting materials for the manufacturing of certain value added chemicals.

REFERENCES

[1] N. Yan and X. Chen, Nature, 524 (2015) 155.

[2] X. Chen, S.L. Chew, F.M. Kerton and N. Yan, Green Chem., 16 (2014) 2204.

[3] X. Chen, Y. Liu, F.M. Kerton and N. Yan, RSC Adv., 5 (2015) 20073.

[4] Y. Pierson, X. Chen, F.D. Bobbink, J. Zhang and N. Yan, ACS Sustainable Chem. Eng., 2 (2014) 2081.

[5] F.D. Bobbink, J. Zhang, Y. Pierson, X. Chen and N. Yan, Green Chem., 17 (2015) 1024.

[6] X. Chen, Y. Gao, L. Wang, H. Chen and N. Yan, ChemPlusChem, 80 (2015) 1565.