Characterization of biomass pyrolysis tars produced in the relative absence of extraparticle secondary reactions

Fraga, Ana-Rita; Gaines, Alec F.; Kandiyoti, R.

doi:10.1016/0016-2361(91)90186-e

Cited by 76 publications

(44 citation statements)

References 20 publications

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“…At low temperatures more residence time is available for vapour-solid interactions and autocatalysis take place whereas at high temperatures the tar decomposition reactions take place. Fraga et al [36] in their investigation of biomass pyrolysis tars show that extensive modification of primary pyrolysis tars takes place by means of intraparticle (heterogeneous) secondary reactions, the reactions being intensified by increasing heating rates. The chain growth model takes both the volatiles retention time and cracking and repolymerization reactions of the vapours with the decomposing solid as well as autocatalysis into consideration.…”

Section: Resultsmentioning

confidence: 98%

A model for primary and heterogeneous secondary reactions of wood pyrolysis

1996

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A chain growth model for heterogeneous secondary reactions is developed for the pyrolysis of large wood particles and the parameters determined by nonlinear optimization. The model takes both the volatile retention time and cracking and repolymerization reactions of the vapours with the decomposing solid as well as autocatalysis into consideration. The extent of the secondary reactions is strongly influenced by the time and the ratio of the autocatalytic (propagation) reaction rate to noncatalytic (initiation) reaction rate. The wood which has a higher value of the autocatalytic/noncatalytic ratio also has a higher exothermic heat of reaction and yields a higher amount of final char residue. This fact confirms that the heterogeneous secondary reactions lead to carbon enrichment of the final residue and are accompanied with an exothermic heat of reaction. The lower activation energies of the initiation and propagation reactions as compared to primary reactions (competitive reaction model consisting of weight loss and char forming reactions) confirm autocatalysis in large particles. The sealed reactor studies of small quantities of fine wood samples show that heterogeneous secondary reactions and not lower heating rates in large particles are the main source of char formed during the thermal decomposition of large wood particles. The model predictions are in agreement with the weight loss and temperature versus time curves over a wide range of particle size and furnace temperatures.

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Section: Resultsmentioning

confidence: 98%

A model for primary and heterogeneous secondary reactions of wood pyrolysis

1996

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“…For example, lignin in RDF represents a potential precursor for PAH formation, due to the aromatic nature of this polymer [40]. Analogously, sulphur is released as hydrogen sulphide (H 2 S) and a myriad of compact and relatively stable molecules such as methanthiole, COS, carbon disulphide (CS 2 ), thiophene, and benzothiophene ( Table 5).…”

Section: Tar and Organosulphur Conversionmentioning

confidence: 99%

Reforming of tars and organic sulphur compounds in a plasma-assisted process for waste gasification

Materazzi

Lettieri

Mazzei

et al. 2015

Fuel Processing Technology

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“…Consequently, scientists designed various other reactors to study the kinetics and reaction features of biomass pyrolysis. The typical ones include the mesh reactor [8,9], self-stirred tank reactor [10], fluidized bed reactor [11,12] and fixed bed reactor [13,14] in millimeters of inner diameter. These reactors, however, do not have standardized configurations and suffer still the limitations caused by gas mixing and gas diffusion that are present inevitably in such reactors.…”

Section: Introductionmentioning

confidence: 99%