Comprehensive Study of the Liquid Products from Slow Pyrolysis of Crambe Seeds: Bio-oil and Organic Compounds of the Aqueous Phase

The present work addresses the detailed structural elucidation by high resolution techniques of both liquid pyrolysis products from slow pyrolysis of crambe seeds. Bio-oil and aqueous phase were obtained at 400 degrees C with 32% and 15.8% (w/w) yield and were separated by density difference. Lyophilization was applied to concentrate the organic compounds present in aqueous phase (OCAP). Bio-oil and the OCAP were analyzed by comprehensive bidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC x GC-TOFMS) and positive and negative-ion electrospray (ESI) high resolution Orbitrap mass spectrometry (HRMS). For the bio-oil, 1,400 analytes were identified by GC x GC-TOFMS and the most abundant classes were hydrocarbons (448.6 mg g(-1)) and N-containing compounds (172.2 mg g(-1)). In the bio-oil ESI-( + ) Orbitrap HRMS data, the N2 class was the most abundant (79.9%). In the negative mode, ca. 87.6% of assigned peaks corresponded to O2 class for bio-oil. The major compounds identified by GC x GC-TOFMS in the OCAP were oxygenated (49.8%) and NO containing compounds (45.9%). ESI ( - ) Orbitrap HRMS analysis for OCAP presented high percentage of O2 (57.2%) and NO (28.3%) classes, while ESI ( + ) Orbitrap MS of N2 (51.8%) and NO (28.8%) classes. The aqueous fraction composition profile indicates a potential biological activity due to the presence of N-heterocyclic compounds and the bio-oil (38.9 MJ kg(-1); 5.4% H2O) has the potential to be used as a second generation (ASTM D7544) or hydrotreated to improve fuel quality.