No abstract

No abstract

No abstract

No abstract

This study describes tar conversion on olivine in fluidized-bed gasification conditions. A laboratory-scale reactor (Aligator) was used to characterize phenol conversion to higher tars, before adding a sand and olivine bed to investigate heterogeneous steam reforming and the cokefaction of these tars. H2 and H2O atmospheres were tested both separately and together to characterize tar conversion on olivine. Catalytic activity in steam reforming was shown to be much improved by the presence of H2. In the absence of H2O in the reactive atmosphere, olivine caused a high cokefaction of tars. With 10% H2O and 20% H2, olivine became highly active in steam reforming of tars. Carbon deposition on the catalysts was quantified by temperature-programmed oxidation (TPO), and optical photographs of olivine were taken after tar conversion.

No abstract

Torrefaction is a mild thermal pretreatment which improves biomass properties and releases condensable species. Condensable species released during torrefaction of pine, ash wood, miscanthus and wheat straw at 250, 280 and 300 °C were investigated. A fixed-bed reactor was used for the laboratory scale experiments. A micro-GC, Karl Fischer titrator and GC-MS were used to analyse incondensable gases, water and other condensable species, respectively. The overall mass balance ranged from 96 to 103 wt.%. The quantification rate of condensable species was on average 77 wt.%. In addition to the major species usually reported in the literature – water, acetic acid, 2-propanone,1-hydroxy- – we show that large amounts of some anhydrosugars were produced. Additionally, 85 condensable species were identified. Among these species, many terpenes and terpenoids in pine were identified by adsorption on SPME fibre. Finally, the influence of temperature and of the nature of biomass on the yields of condensable species was highlighted. (Résumé d'auteur

This work examines the effect of both absolute pressure (range 1−6 bar) and peak temperature (range 350−800 °C) during pyrolysis of acacia wood in a macro-TG on the yield and CO 2 gasification reactivity of the resulting charcoal. A central composite design was used for the experiments. The results of statistical analyses showed satisfactory agreement between the experimental results (charcoal yield and charcoal CO 2 gasification reactivity) and model predictions. Both charcoal yield and reactivity decreased with an increase in temperature but increased with an increase in pressure. An increase in pyrolysis pressure increased charcoal yield and decreased reactivity. The temperature had a more significant effect on charcoal reactivity than pressure, and their interaction was not significant. The optimal conditions for the preparation of reductant charcoal were found to be a peak pyrolysis temperature of 617 °C and an absolute pressure of 6 bar.