(529i) Biomasspyrolysisrefinery: Product Stability of Intermediates and Products

The BiomassPyrolysisRefinery is a dual step
concept for biomass liquefaction and hydrogenation, intending
production of liquid energy carriers. First step of this concept is
liquid phase pyrolysis (LPP). During pyrolysis lignocellulose is
dehydrated to form biochar and pyrolysis oil (Schwaiger et al., 2011,
2012) The LPP process has been scaled up to a capacity of 100 kg/h
biomass (BDI bioCRACK facility) at OMV refinery Schwechat. The second
step of the BiomassPyrolysisRefinery is product upgrading. Pyrolysis
oil can pass a dewatering step to raise the calorific value. It may
also be deoxygenated and hydrogenated. Biochar is separated from the
heat carrier after liquid phase pyrolysis and then hydrogenated.

Figure
1: Stability of selected substances from liquid phase pyrolysis
during storage at ambient temperature

During liquefaction biogenous material passes
several heating and storing steps. Therefore sufficient chemical
stability of intermediates and products is needed. Stability of
pyrolysis oil for storing and upgrading purposes may be very limited
(Fahmi et al., 2008; Kim et al., 2012), because of polymerization.
The molar mass, viscosity and water content may rise significantly.
The storing properties of liquid phase pyrolysis oil, upgraded liquid
phase pyrolysis oil and liquified biochar at ambient temperature was
monitored by GC-MS, GC-TCD, SEC and pH, and TAN analysis. Density and
viscosity were recorded.

Figure
2: Liquid phase pyrolysis oil; molar mass versus storage time

Figure
1 shows the concentration of liquid key substances from liquid phase
pyrolysis. During the first week of storage nearly one third of
highly oxygenated substances vanish, afterwards degradation may
cease. The same trend of property changes in the first days after
pyrolysis is recorded with SEC-analysis. Figure 2 shows stabilization
of molecular mass within day 15.

Figure
3: Viscosity and density at T = 20°C of liquid phase pyrolysis oil

Viscosity and density trends, shown in figure 3,
confirm the findings. Liquid phase pyrolysis oil undergoes ageing
through repolymerization within the first 15 days of storage. After
upgrading stability of pyrolysis oil and liquified biochar is
significantly better. Compared with flash pyrolysis oil the stability
of liquid phase pyrolysis oil is seemingly achieved through
separation from char based particulate matter and inorganics.

Fahmi,
R., Bridgwater, A., Donnison, I., 2008. The effect of lignin and
inorganic species in biomass on pyrolysis oil yields, quality and
stability. Fuel 87, 1230--1240.

Kim,
T.-S., Kim, J.-Y., Kim, K.-H., Lee, S., Choi, D., Choi, I.-G., Choi,
J.W., 2012. The effect of storage duration on bio-oil properties.
Journal of Analytical and Applied Pyrolysis 95, 118--125.

Schwaiger,
N., Feiner, R., Zahel, K., Pieber, A., Witek, V., Pucher, P., Ahn,
E., Wilhelm, P., Chernev, B., Schröttner, H., Siebenhofer, M., 2011.
Liquid and Solid Products from Liquid-Phase Pyrolysis of Softwood.
BioEnergy Research 4, 294--302.

Schwaiger,
N., Witek, V., Feiner, R., Pucher, H., Zahel, K., Pieber, a, Pucher,
P., Ahn, E., Chernev, B., Schroettner, H., Wilhelm, P., Siebenhofer,
M., 2012. Formation of liquid and solid products from liquid phase
pyrolysis. Bioresource technology 124, 90--4.