Flow Behavior and Aging of Pyrolysis Oils from Different Feedstocks

Abstract

This work focuses on the flow behavior and accelerated aging of pyrolysis oils produced in a screw reactor from different feedstocks. Beech wood, wheat straw, chicken manure, and sewage sludge were pyrolyzed at 350, 400, 450, and 500 °C, and the viscosity of the corresponding oils was measured at four different temperatures between 20 and 80 °C, with values up to 1 Pa s at 20 °C. Newtonian flow behavior was observed, except for wheat straw pyrolysis oils at temperatures below 50 °C. Absolute viscosity values as well as flow activation energies (EA), covering a range from 38 to 57 kJ mol–1, turned out to be independent of the pyrolysis temperature, except for beech wood oil. In this latter case, a peak in viscosity and activation energy was found at a pyrolysis temperature of 450 °C and is attributed to the low water content of the oil obtained at this temperature. Accelerated aging experiments were conducted for 24 h at 40 and 80 °C. For the latter temperature, the effect of a free surface and an inert ga...