Chromatographic characterization of bio-oils from fast pyrolysis of sugar cane residues (straw and bagasse) from four genotypes of the Saccharum Complex

Abstract

Residues of four different genotypes of sugarcane (Saccharum sp., Saccharum Robustum, Miscanthus sp. and Erianthus sp.), belonging to the Germplasm Bank of the Saccharum Complex (BAGCANA) from EMBRAPA, were subjected to a pyrolysis process and the bio-oils produced were analyzed by GC and GC×GC. The main objective was to start the studies in the integrated use of these residues (sugarcane straw and sugarcane bagasse) in view of a bio-refinery. The species Robustum, Miscanthus and Erianthus were compared with the cultivated variety of sugarcane (Saccharum sp.) because they are candidate to application as “energy-cane”, which is a sugarcane with higher amount of cellulose being cultivated for energetic purposes. The residues (straw and bagasse) are not adequately used and tend to be inadequately discarded, causing environmental impacts. However, if these residues be re-processed by pyrolysis, the produced bio-oil can be found many potential uses.The goal of this paper is to compare the amount and quality of bio-oils produced from these residues (bagasse and straw), intending to aggregate value to these materials and to indicate their best uses. The bio-oils were analyzed by GC×GC coupled to mass spectroscopy, allowing the detection and identification of their major constituents. Phenols were the main classes of identified compounds that can indicate the use of the bio-oil as alternative source of raw material for chemical industries. It is important to highlight that not only the straw but also the bagasse produced similar bio-oils, differing only in the relative amount of these compounds in the bio-oil, allowing an integrated utilization of these materials. The goal of this paper is to compare the amount and quality of bio-oils produced from these residues (bagasse and straw), intending to aggregate value to these materials and to indicate their best uses. The bio-oils were analyzed by GC×GC coupled to mass spectroscopy, allowing the detection and identification of their major constituents. Phenols were the main classes of identified compounds that can indicate the use of the bio-oil as alternative source of raw material for chemical industries. It is important to highlight that not only the straw but also the bagasse produced similar bio-oils, differing only in the relative amount of these compounds in the bio-oil, allowing an integrated utilization of these materials. The identified compounds are approximately the same in all the samples, differing only in the relative amount of these compounds in the bio-oils. The major compounds were slightly different in the studied bio-oils, but they can be represented by benzofuran-2,3-dihydro, 4-vinyl-guaiacol, syringol and 5-hydroxy-methyl-furfural. The aldehyde contents increased significantly in the Miscanthus and Erianthus bio-oils samples, mainly due to furfural derivatives, which are not found in the other samples. In addition, only the species Erianthus sp. presented yield in bio-oil superior to the commercial specie, which may indicate its use in the production of furfural and derivatives.