(81d) Liquid Phase Pyrolysis of Biogenic Feedstock

Pyrolytic conversion of biogenic feedstock has become a high priority task due to declining crude oil reserves.

This project focuses on pyrolytic conversion of CHO-feedstock such as fir chips under liquid phase operation conditions. From liquid phase pyrolysis improved convective heat transfer is expected, enabling fast pyrolysis conditions at ambient pressure. Investigations may be classified as isothermal. Operation temperature is limited to a range of less than 650 K.

The process is operated in a lab scale reactor in the semi-batch mode. The rate of degradation for nearly monodisperse feed is recorded. The feed quantity is limited to an amount which causes a deviation of the reactor temperature of less than 2 K each feed cycle because of the energy surplus of the reaction mass. The effect of temperature on product distribution is investigated. For comparison dry pyrolysis has been carried out for quasi isothermal conditions. Additionally, the influence of the heating rate on the mechanism and rate of pyrolytic degradation was analyzed.

The gaseous, liquid and solid products were characterized by GC-MS, NMR-spectroscopy and elemental analysis. Reproducibility was checked with replicates.

Figure 1 representatively shows the temperature dependency of water formation.

Figure 1: Temperature dependency of water formation

The ratio of water formed during pyrolytic degradation increases with increasing temperature, passing a maximum, while formation of CHO-products linearly correlates with the operation temperature. Carbon transfer from feed to gaseous and liquid product phase also linearly correlates with the temperature.