Valorization of sugar beet pulp via gasification for hydrogen-rich syngas production: Experimental study, optimization, and modeling

Abstract

Hydrogen-rich syngas production through gasification of sugar beet pulp (SBP), a byproduct of sugar processing factories, was investigated in the presence of dolomite-supported Ni and Ni-La catalysts. For this purpose, catalysts with varying metal loadings (10, 20% Ni and 10–1, 10-3% Ni-La by wt%) were synthesized via the impregnation method and characterized by X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET) surface area analysis, and Thermogravimetric Analysis (TGA). Gasification experiments with 10% Ni/Dolomite catalyst examined the effects of gasification temperature (600, 700, and 800 °C), and equivalence ratio (ER = 0.03, 0.09, 0.15), where the highest hydrogen concentration of 23.1 mol% (2.2 mol H₂/kg SBP) was achieved at 700 °C, 0.03 ER. In the subsequent steam gasification experiments, the effects of catalyst type, steam-to-biomass (S:B) ratio, reaction temperature, and gasification duration were studied. Experimental highest hydrogen concentration (61.6%) and syngas calorific value (7535 kJ/m³) were achieved with the 10-3% Ni-La/Dolomite catalyst. Optimization studies were performed using full factorial design, analysis of variance (ANOVA), and Response Surface Methodology (RSM). Modeling of the gasification process employed Artificial Neural Networks (ANN) using Keras model in Python. Optimum gasification conditions were identified as 711.20 °C, 14.58 min, and S:B = 4.99, yielding 57.7 mol% hydrogen for 10% Ni/Dolomite catalyst. This study demonstrates that optimized steam gasification effectively valorizes sugar beet pulp by achieving high hydrogen yields and concentrations.