Catalytic influence of mineral compounds on the reactivity of cellulose-derived char in O2-, CO2-, and H2O-containing atmospheres. (1st March 2021)

• Record Type: Journal Article
• Authors: Pflieger, Christin; Lotz, Katrin; Hilse, Nikoline; Berger, Cornelius M.; Schiemann, Martin; Debiagi, Paulo; Hasse, Christian; Scherer, Viktor; Muhler, Martin
• Is Part Of: Fuel. Volume 287(2021)
• Publication Date: 2021-03-01
• Subjects: Biomass-derived char -- Minerals -- Catalytic effect -- Oxyfuel combustion -- Char conversion; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2020.119584
• Languages: English
• ISSNs: 0016-2361

Abstract

Abstract: The catalytic effects of mineral compounds on the conversion of a biomass-derived char in air- and oxyfuel-related atmospheres were investigated by thermogravimetric analysis at atmospheric pressure. The applied char originated from the hydrothermal carbonization (HTC) of cellulose followed by pyrolysis at 1073 K and subsequent mixing with 20 wt% of minerals by grinding to achieve tight contact. The reactivities of the mineral-loaded HTC chars were evaluated based on isothermal experiments in O2 -, CO2 -, and H2 O-containing atmospheres as a function of their composition applying a magnetic suspension balance. The reactivity sequence K2 CO3 > Na2 CO3 ≫ Fe2 O3 > CaO > MgO ≥ mineral-free was derived consistently for char oxidation in O2 /inert as well as for char gasification in diluted H2 O and CO2 mixtures. In addition to this qualitative assessment, the kinetic experiments were first modelled based on a simple global n th -order power-law rate expression. Then, the more complex Carbon Burnout Kinetics (CBK/G) model and the PoliMi model were applied. All three modeling approaches enabled a systematic quantification of the catalytic effects and led to a comparable lowering in the apparent activation energy. In combination with the kinetic parameters determined for the mineral-free char, the lowered apparent activation energies specific for the applied mineral and atmosphere facilitate the implementation of catalytic effects on the conversion of biomass-derived char into combustion models.