(612b) Progress in Liquefaction of Biochar

Nowadays there is a great effort to commercialise pyrolysis of biomass for biofuel production. Pyrolysis of biomass produces significant amounts of biochar up to 40%, depending on the pyrolysis process and the type of biogenous feedstock [1], [2]. The renewable resource pyrolysis char often referred to as biochar, produced by pyrolysis or hydrothermal carbonization [3], [4], has promising properties for advanced upgrade. Technologies for the conversion of biochar to biofuels may therefore contribute to suffice the growing demand for fuel. Direct liquefaction of biochar is a conceivable way of producing biofuels. Direct liquefaction of biochar was carried out catalytically and non-catalytically in a 450ml batch reactor at a temperature of 425°C with the hydrogen donor solvent tetralin. For each experiment 30g of dried and milled biochar was used. After 30min reaction time non-catalytic biochar liquefaction showed a conversion of 84% and an oil yield of 72% [5], catalytic biochar liquefaction even showed 100% conversion and 95% oil yield. Compared to fossil coal liquefaction the hydrogenation of biochar leads to a diverse product distribution with more oil products and less intermediates. In process modelling intermediates as well as products and residues of similar product properties were identified according to their solubility in different organic solvents. Based on this product classes the kinetics of biochar liquefaction was investigated. Re-hydrogenation of spent hydrogen donor is possible and was investigated in a Design of Experiment study. Analysis of the oil product was carried out with size exclusion chromatography (SEC).

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[2]       N. Schwaiger, V. Witek, R. Feiner, H. Pucher, K. Zahel, A. Pieber, P. Pucher, E. Ahn, B. Chernev, H. Schroettner, P. Wilhelm, and M. Siebenhofer, “Formation of liquid and solid products from liquid phase pyrolysis.,” Bioresour. Technol., vol. 124, pp. 90–94, 2012.

[3]       D. Ciolkosz and R. Wallace, “A review of torrefaction for bioenergy feedstock production,” Biofuels, Bioprod. Biorefining, vol. 5, pp. 317–329, 2011.

[4]       A. Funke and F. Ziegler, “Hydrothermal carbonization of biomass: a summary and discussion of chemical mechanisms for process engineering,” Biofuels, Bioprod. biorefining, vol. 4, no. 2, pp. 160–177, 2010.

[5]       R. Feiner, N. Schwaiger, H. Pucher, L. Ellmaier, P. Pucher, and M. Siebenhofer, “Liquefaction of pyrolysis derived biochar: a new step towards biofuel from renewable resources,” RSC Adv., vol. 3, pp. 17898–17903, 2013.