Chemical evaluation of chars produced by thermochemical conversion (gasification, pyrolysis and hydrothermal carbonization) of agro-industrial biomass on a commercial scale

• Published in: Biomass & bioenergy Vol. 59; pp. 264 - 278
• Main Authors: Wiedner, Katja, Rumpel, Cornelia, Steiner, Christoph, Pozzi, Alessandro, Maas, Robert, Glaser, Bruno
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2013; Elsevier
• Subjects: 13C NMR; Agronomy. Soil science and plant productions; biochar; bioenergy; Biological and medical sciences; biomass; Black carbon; carbon; cation exchange capacity; edaphic factors; elemental composition; Environmental Sciences; Fundamental and applied biological sciences. Psychology; Gasification; General agronomy. Plant production; hydrochars; Hydrothermal carbonization; Life Sciences; nuclear magnetic resonance spectroscopy; pollutants; Polycyclic aromatic hydrocarbons; production technology; Pyrolysis; scanning electron microscopy; Use of agricultural and forest wastes. Biomass use, bioconversion; X-radiation; Pyrolysis; Gasification; Hydrothermal carbonization; Polycyclic aromatic hydrocarbons; 13C NMR; Black carbon; Thermochemical treatment; Agricultural industry; NMR spectrometry; Biomass; Surface structure; Persistent organic pollutant; Characterization; Carbonization; Hydrothermal treatment; Chemical composition; Carbon 13; Scanning electron microscopy; Carbon black; Hydrocarbon; C NMR; Polycyclic aromatic compound; Biochar; Solid state; Energy-dispersive X-ray spectrometry; Morphology; C-13 NMR
• DOI: 10.1016/j.biombioe.2013.08.026
• ISSN: 0961-9534

Technologies for agro-industrial feedstock utilization such as pyrolysis, gasification and hydrothermal carbonization at industrial scale develop rapidly. The thermochemically converted biomasses of these production technologies have fundamentally different properties controlled by the production technology. This is reflected by general properties such as pH or elemental composition. The 13C NMR spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy and black carbon results confirmed these observations showing that hydrochars have lower proportions of aromatic compounds than biochars (less stable) but are rich in functional groups (higher cation exchange capacity) than biochars. Analyses of pollutants indicate that polycyclic aromatic hydrocarbons as well as dioxin contents of most samples were under the threshold values recommended by International Biochar Initiative and European Biochar Certificate. In conclusion, biochars and hydrochars are entirely different from each other and these materials will probably have a complementary reaction in a soil environment. •Production technologies influences fundamentally chemical properties of chars.•Carbonized materials have different behaviour in soil environment.•Environmental risk of chars is low with respect to PAH and dioxin contents.•Certification standard for biochars is not suitable for hydrochars.•Commercial scale reactors are able to produce high quality biochars according to the regulations of the EBC or IBI.