Improving bio-oil properties through the fast co-pyrolysis of lignocellulosic biomass and waste tyres.

Pinewood sawdust and the waste rubber from truck tyres have been co-pyrolysed in order to improve the properties of bio-oil for its integration in oil refineries. In addition, an analysis has been conducted of the effect the interactions between these two materials' pyrolysis reactions have on product yields and properties. Biomass/tyre mixing ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 by weight percentage have been pyrolysed in continuous mode at 500 °C in a conical spouted bed reactor, obtaining oil yields in the 55.2-71.6 wt% range. Gaseous, oil and solid fractions have been characterised for the 50/50 biomass/tyre mixture, paying special attention to the oil fraction by determining its detailed composition, elemental analysis and calorific value. Co-processing enables the stabilization of the liquid, as the co-pyrolysis oil has a stable single phase, being composed mainly of water, aromatic hydrocarbons and phenols in concentrations of 14.5, 11.1 and 9.7 wt%, respectively. Adding tyre rubber to the biomass in the pyrolysis feed improves the oil's properties, as a liquid with higher carbon content and lower oxygen and water is obtained, even if sulphur content is also increased.