Composition, biomass woody species

In addition to the variations in the LHC composition that occur from species to species, each species has its extractives, which include resins and waxes. These constituents are capable of interfering with cellulose hydrolysis because of their hydrophobic nature. Tannins and other highly reactive materials are constituents of some woody species. When LHC is obtained from nonwoody (herbaceous) species, the range of interfering constituents increases greatly. Sugars, starches, dextran, carotenoids, and many isoprenoids are to be found. Operators of a cellulose hydrolysis process that uses municipal solid waste as its biomass resource may experience seasonal variations in composition and chance inclusion of crankcase oil and other products that inhibit enzymes or kill yeast. 

The traditional pulp/paper composition metrics (e.g. specific lignin and cellulose contents) are based on chemical reaction (depolymerization) of the native biomass into fractions. Each separated fiaction is then independently pyrolysed, and the pyrolysis yields are fit to models, and the composite used to predict other woody species ... 

Variations in Product Due to Feedstock. While process-related differences in product composition have been evident, extensive study of the effect of feedstock on product composition has never been undertaken. Some limited comparative tests can be gleaned from the literature however, most process research in direct liquefaction of biomass has been performed with woods of various species. Table I provides some of the results available in the literature for non-woody feedstocks. Significant differences in heteroatom content are evident, but only limited chemical analysis is available in most cases. 

---