Microwave assisted pyrolysis of waste from short rotation coppice of poplar

Conference Dates

June 19-24, 2016


Poplar short rotation coppice (SRC) plays an important role in biomass production because they are largely employed both in industry or used as solid fuel [1]. Recently there is a great interest in the below-ground biomass recovery (stump-root system) of poplar SRC because: a) it accounts for about 20% of the total plant dry weight [2] and the average poplar chips can yield 18 ton/ha of root biomass; b) it is easily accessible and harvested (sand-loamy soils); c) the root wood often has higher heating values than tops and branches, and may prove to be a better fuel [3]. Furthermore, the removal of the stump-roots systems does not require the payment of a concession, and using efficient recovery systems, the delivered cost might range from 28 to 66 €/ton[4]. The most common method to dispose waste from forestry biomass is combustion, which is an environmentally unfriendly process. Recently a remarkable interest has been focused on microwave assisted pyrolysis (MAP) of biomass due to the fast and efficient heating and the appealing characteristics of the products obtained [5]. Biomass are able to absorb microwave (MW) and even if a MW absorber is not strictly necessary, it may have some positive effects on the quality of products and pyrolysis time [6]. In this work MAP of residues from SRC of different poplar clones have been studied in a multimode batch oven.. MAP of stump-roots and leaves residues from different poplar clones were thoroughly investigated to produce high quantity and quality of bio-oils. They were obtained with high yield (up to 32.0%) and small water percentage (up to 17.5 %)and showed low density and viscosity and they were fluid at room temperature. Among bio-oils a sample with high acetic acid concentration (543.3 mg/mL) was obtained. Bio-oils were characterized with several analytical techniques: 1H-NMR, IR-ATR, density and viscosity measurements, and an original and innovative quatitative GC-MS method[7, 8]. These techniques let to make possible a detailed study on the bio-oils to define a correlation between their chemical and rheological properties with the parameters of the process.

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