Slow steam pyrolysis of Arundo donax is proposed as possible process for the recovery of a solid material suitable to be used as biochar. In view of the evaluation of the feasibility of such a process, products yields, char properties and energetic content of gaseous and liquid products (bio-oils), needed to assist energetically the process, are relevant data to be evaluated in dependence on process operating conditions and biomass characteristics. Biomass main components (hemicellulose, cellulose and lignin) contribute to a different extent to the determination of products yield and characteristics both for their own intrinsic chemical nature and for the onset of possible interactions due to their simultaneous presence in a real biomass. Moreover, it is known that inorganic elements present in the biomass can affect pyrolysis mechanisms and consequently products yields and characteristics. The investigation of combustion behavior of bio-oils cannot disregard the analysis of their chemical composition responsible of their peculiar chemical and physical properties: chemical instability, high density, viscosity and surface tension, low pH and calorific value, a wide evaporation range represent critical aspects for their utilization in the traditional combustion systems. Definitely, the chemical characterization of pyrolysis derived bio-oils is fundamental to investigate their reactivity in view of the exploitation of their energetic content. In the present paper the influence of inorganic species and of possible interactions between biomass main components on bio-oil derived from pyrolysis of Arundo donax has been studied. To this aim steam assisted pyrolysis tests have been carried out on untreated and demineralized samples of Arundo donax canes in a proper experimental apparatus up to 973 K, at pressure 5×105 Pa and heating rate 5 K/min. As reference test, a mixture of xylan (one of the major hemicellulose component in hardwoods), cellulose and lignin resembling the composition of Arundo donax canes has been processed in the same experimental apparatus at the same operating conditions. Bio-oils composition has been compared to the data computed by the superimposition of the results obtained from pyrolysis tests on the single biomass components. Given the high chemical complexity typical of these liquids, the application of different experimental approaches and analytical techniques has been required for an overall characterization and for tailoring specific analytical procedures to face the high dilution of pyrolysis liquid in process water.
BIO-OILS PRODUCED BY STEAM ASSISTED PYROLYSIS OF Arundo donax AND A XYLAN, CELLULOSE AND LIGNIN MIXTURE: A PRELIMINARY STUDY ON SALT EFFECT
VALENTINA GARGIULO;PAOLA GIUDICIANNI;MICHELA ALFE';RAFFAELE RAGUCCI
2014
Abstract
Slow steam pyrolysis of Arundo donax is proposed as possible process for the recovery of a solid material suitable to be used as biochar. In view of the evaluation of the feasibility of such a process, products yields, char properties and energetic content of gaseous and liquid products (bio-oils), needed to assist energetically the process, are relevant data to be evaluated in dependence on process operating conditions and biomass characteristics. Biomass main components (hemicellulose, cellulose and lignin) contribute to a different extent to the determination of products yield and characteristics both for their own intrinsic chemical nature and for the onset of possible interactions due to their simultaneous presence in a real biomass. Moreover, it is known that inorganic elements present in the biomass can affect pyrolysis mechanisms and consequently products yields and characteristics. The investigation of combustion behavior of bio-oils cannot disregard the analysis of their chemical composition responsible of their peculiar chemical and physical properties: chemical instability, high density, viscosity and surface tension, low pH and calorific value, a wide evaporation range represent critical aspects for their utilization in the traditional combustion systems. Definitely, the chemical characterization of pyrolysis derived bio-oils is fundamental to investigate their reactivity in view of the exploitation of their energetic content. In the present paper the influence of inorganic species and of possible interactions between biomass main components on bio-oil derived from pyrolysis of Arundo donax has been studied. To this aim steam assisted pyrolysis tests have been carried out on untreated and demineralized samples of Arundo donax canes in a proper experimental apparatus up to 973 K, at pressure 5×105 Pa and heating rate 5 K/min. As reference test, a mixture of xylan (one of the major hemicellulose component in hardwoods), cellulose and lignin resembling the composition of Arundo donax canes has been processed in the same experimental apparatus at the same operating conditions. Bio-oils composition has been compared to the data computed by the superimposition of the results obtained from pyrolysis tests on the single biomass components. Given the high chemical complexity typical of these liquids, the application of different experimental approaches and analytical techniques has been required for an overall characterization and for tailoring specific analytical procedures to face the high dilution of pyrolysis liquid in process water.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
