Experimental and CFD investigation of thermo-catalytic conversion of toluene as tar model in a fixed bed of date stone and spent coffee ground chars

• Published in: Biomass conversion and biorefinery 2024, Vol.14 (21), p.27767-27786
• Main Authors: Benhalilou, Mohamed Rachid, Ouerhani, Mohamed, Largeau, Jean-François, Tazerout, Mohand
• Format: Article
• Language: English
• Subjects: Activated carbon; Biotechnology; Catalytic converters; Energy; Engineering Sciences; Fixed beds; Original Article; Parameter identification; Renewable and Green Energy; Residence time distribution; Stainless steels; Stone; Tars; Temperature; Toluene
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-022-03425-w

In this paper, the aim is to avoid clogging and fouling of the equipment, by transforming the tars into lighter gas molecules and thus increasing the yield of pyrolytic gas. Thus, a thermal conversion of a tar model, toluene, in a fixed bed of two biochar prepared in the lab (spent coffee ground char (SCG-C) and date stone char (DS-C)) was studied. Experiments were done at medium temperatures (T) from 500, 600, 700, to 800 °C and carried out for two residence times (RT) of 0.6 and 1.2 s. A species transport model was developed for a dual purpose: first, to investigate toluene conversion in function of various parameters (medium, residence time, temperature, and bed height); secondly, to identify the configurations {temperature, residence time} allowing to get a full conversion of toluene (90–100%) and consequently lets us exceed the capacities of the experimental reactor in terms of temperature (900 and 1000 °C) and residence time (0.9 and 1.5 s). DS-C and SCG-C bed results were compared with commercial activated carbon (CAC) bed as a high-performed catalytic char and a stainless-steel ball (SSB) bed as a thermal conversion way. The originality of this work is its concern on the validation of the relevance of a CFD tool with a transport model for the prediction of conversion of tar in a fixed bed with different media. Thus, a possible extension of the experimental plan by numerical results researching full conversion and investigating the chemistry inside the reactor.