(117b) A Novel Experimental Technique for Study of Isothermal Pyrolysis of Cellulose

Fast pyrolysis of biomass converts solid biopolymers into a valuable liquid product (bio-oil) which can be further upgraded to fuels or chemicals. Much effort has been dedicated to developing processes and catalysts which maximize efficiency, throughput and/or bio-oil quality (e.g., [1-2]). While these efforts are important to developing thermochemical biorefineries of the future, the complex chemistry by which the biomass feedstock breaks down is still largely unknown. Global reaction kinetics for the pyrolysis of cellulose have been published (e.g., [3]), but the accuracy of these models is debated [4]. Additionally, recent work has indicated both indirectly (e.g., [5]) and directly [6] that solid biomass pyrolysis proceeds through a high temperature intermediate liquid before volatilizing into the final bio-oil constituents. In order to maximize the accuracy of pyrolysis experiments and prevent device-dependent results, it is important that mass and heat transport rates within the solid biomass and intermediate liquid be faster than the intrinsic reaction kinetics. In this work, we demonstrate an experimental technique whereby biomass pyrolysis can be studied in a kinetically-limited manner. By reducing the size of and controlling shape of biomass, we can eliminate composition and thermal gradients. Additionally, volatiles, gases and char are all characterized in a single pyrolysis run with multi-dimensional analytical techniques. The mechanism of cellulose pyrolysis is investigated by comparing the product distributions of several short-chain cellulose oligomers to cellulose (degree of polymerization equal to 250). We find that oligomers have different product distributions compared to cellulose. Additionally, the production of furans (e.g., HMF, furfural) is maximized for cellobiose. Interestingly, a maximum in char is also observed at cellobiose, indicating that char and furan production are connected.

1.             Vispute, T.P., et al., Renewable Chemical Commodity Feedstocks from Integrated Catalytic Processing of Pyrolysis Oils. Science, 2010. 330(6008): p. 1222.

2.             Agblevor, F.A., et al., Fractional Catalytic Pyrolysis of Hybrid Poplar Wood. Ind. Eng. Chem. Res., 2010. 49(8): p. 3533.

3.             Bradbury, A.G.W., et al., KINETIC-MODEL FOR PYROLYSIS OF CELLULOSE. Journal of Applied Polymer Science, 1979. 23(11): p. 3271.

4.             Varhegyi, G., et al., IS THE BROIDO-SHAFIZADEH MODEL FOR CELLULOSE PYROLYSIS TRUE. Energy & Fuels, 1994. 8(6): p. 1345.

5.             Boutin, O., et al., Radiant flash pyrolysis of cellulose - Evidence for the formation of short life time intermediate liquid species. Journal of Analytical and Applied Pyrolysis, 1998. 47(1): p. 13.

6.             Dauenhauer, P.J., et al., Reactive boiling of cellulose for integrated catalysis through an intermediate liquid. Green Chemistry, 2009. 11(10): p. 1555.