(645c) Hydrogen Production from Thermal and Catalytic Gasification of Biomass in a Fluidized CREC-Riser Simulator: Thermodynamic Modeling and Experimental Results

Biomass gasification is an alternative path of critical future value. It produces synthesis gas, a mixture of hydrogen and carbon monoxide, the first one being an energetic vector. ^{(1, 2)}

Gasification of several biomasses was performed in a CREC Riser Simulator reactor. Thermal experiments were performed at 550 °C and 600 °C with broza, bark and CANMET Pellets, under helium or CO₂. On the other hand, catalytic experiments were developed using glucose and metoxy-phenol. Temperature, steam/biomass ratio, catalyst loading and reaction time were changed in a wide range of operating conditions. Two fluidizable catalysts were used: 20%Ni/5%La₂O₃/g-Al₂O₃ and 15%Ni-5%CeO₂/γ-Al₂O₃. They were synthesized via incipient wetness impregnation and characterized using PSD, DA, TPD, TPR and BET. ⁽²⁾

Thermal conversion showed that hydrogen increases with temperature, with this being consistent for the three feedstocks employed (Broza, Canmet Pellet and Bark). Furthermore, the gasifying agent influences hydrogen production, with maximum yields obtained for hydrogen at 600 C, under inert atmospheres (helium). As well, higher temperatures led to a decrease in the H₂ /CO ratio for “Broza”. For the “Canmet Pellet”, it showed a slight H₂ /CO increase, while for “bark” remained almost constant. The maximum value of the ratio H₂ / CO was obtained at 550 °C, being 5.88.

Regarding the catalytic experiments with fluidizable methoxy-phenol (representing lignin) were used. It was shown hydrogen production increased with temperature. The change with temperature was more notorious from 600 °C to 650 °C than from 650 °C a 700 °C. Hydrogen production augmented as well, with reaction time, with a major change observed in the 10 and 20 second range.

Concerning reaction equilibrium eight chemical reactions were first considered⁽¹⁾. The Gauss- Jordan procedure was applied to identify five independent equations. On this basis a thermodynamic model, with five algebraic nonlinear equations and five unknowns was considered. The equations were solved with Newton-Raphson method. Experimental hydrogen production was systematically compared with chemical equilibrium values and this for H₂, CO, CO₂ and CH₄. An experimental maximum hydrogen molar fraction of 0.54 for S/B = 2.5 was observed. A similar situation was noticed with CO₂ produced with however, CO and methane being reduced at those conditions.

(1) Salaices E., Serrano B. de Lasa H. “Steam Gasification of a Cellulose Surrogate Over Fluidizable Ni/alpha alumina: A Kinetics Model” AIChEJ Vol.58, Issue 5, 1588–1599 (2012), IF: 2.03

(2) Mazumder, A., de Lasa H. Fluidizable La₂O₃ Promoted Ni/ γ-Al₂O₃ Catalyst for Steam Gasification of Biomass: Effect of Catalyst Preparation Conditions. Applied Catalysis B, Vol.169-169, 250-265 (2015). IF:3.42