(311b) Biofuels from Pyrolysis Oil: A Two-Step Hydrodeoxygenation Process

BIOFUELS FROM PYROLYSIS OIL:

A TWO-STEP HYDRODEOXYGENATION PROCESS

H. Pucher, N. Schwaiger, R. Feiner, L. Ellmaier*, P. Pucher*, M. Siebenhofer
Graz University of Technology, Institute of Chemical Engineering and Environmental
Technology, *BDI-BioEnergy International AG
Non-renewable energy resources such as oil and coal will not suffice the increasing demand of energy in the future. It is assumed that renewable resources such as biomass are able to fill this dawning gap because they have been considered as the most promising energy sources in the next century [1]. In addition the European Commission has released a directive to increase the volume of renewable biofuels for transportation to 10% by 2020 [2].
To fill the upcoming gap and meet the requirements of the directive a biomass liquefaction concept from renewable resources has been developed. This concept consists of two main process steps. In the first step lignocellulosic biomass like wood and straw, is converted in pyrolysis oil and pyrolysis char through liquid phase pyrolysis. In the second step these intermediate products are upgraded. Two promising upgrading technologies were investigated: hydrodeoxygenation [3], [4] of pyrolysis oil, and hydrogenation of liquid phase pyrolysis char.
The main focus of this project was to investigate and optimize upgrading of liquid phase pyrolysis oil to maximize the output of the carbon rich fraction, raise stability and identify potential fields of application. Investigations were carried out in lab size batch mode. To minimize coke formation and catalyst deactivation, a two-step hydrodeoxygenation process was developed [5]. This process was able to convert the polar, highly acidic, water and oxygen rich liquid phase pyrolysis oil into an appropriate, carbon rich, oxygen poor and water poor biofuel like product phase.
The operation parameters for each process step, like hydrogen pressure, temperature, reaction time, catalyst and carrier to pyrolysis oil ratio, were determined. Table 1 shows representative results.

Table 1: Comparison of Liquid Phase Pyrolysis Oil, Pyrolysis Oil after the 1 Step, Pyrolysis Oil after the 2 Step and Diesel Fuel.

28 percent of the organic carbon of the liquid phase pyrolysis oil was transferred to a carbon rich biofuel like product phase (2 step pyrolysis oil). This product phase has an oxygen content of about 2%, a high lower calorific value and a fuel like density and viscosity.
In conclusion trough the developed two-step hydrodeoxygenation process a biofuel like product phase is produced. Composition and characterization of all products were determined by SEC, GC-MS, elemental analysis, Karl Fischer Titration, TAN, SimDist and NDIR continuous gas analysis.
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1 At 20°C.

2 At 15°C.