The new bio-crude: a renewable substitute for petroleum?

The rapid thermal processing (RTP/sup TM/) technology developed by ENSYN produces bio-crude (or bio-oil) from the fast pyrolysis (rapid cracking) of waste biomass materials. In this process biomass is heated to high temperature (400-650/spl deg/C) for a short residence time (usually less than 0.5 s) at atmospheric pressure in the absence of oxygen. The rapid heating causes fragmentation of the biomass structure thus producing the liquid bio-crude. This liquid is not petroleum. Bio-crude, essentially, is a mixture of oxygenated chemicals resulting from the degradation of complex structures. The three major components are: water, depolymerised lignin and carbonyls. Other chemical groups include carboxylic acids, carbohydrates, lignin-derived phenolics and alcohols. In order to use the bio-crude for any application it is necessary to characterize it thoroughly for its pH, viscosity, water content, ash content, alkali content, elemental composition, heating value, surface tension, stability behavior and its distillation characteristics. The objective of the present work was to determine these properties for a typical bio-crude and examine how it is different from a typical petroleum crude. In this investigation, a bio-crude produced from commercial oak sawdust (at 515/spl deg/C and 700 msec) was characterized. The distillation results showed that the amount of distillate increased with temperature (50, 100 and 200/spl deg/C, 172 Pa) and ranged from 17-67 wt.%. The distillate consisted of both water and oxygenated compounds such as acids, aldehydes, esters, ketones and phenols.