Co-production of active char and hydrogen from Algerian Date Palm Spikelet: Mass and energy balance based on experimental data

Abstract

The industrial deployment of green hydrogen production via biomass gasification is still constrained by high feedstock costs and process complexity. In particular, tar formation in the syngas requires costly gas-cleaning operations and reduces the lifetime of hydrogen separation and purification units, thereby limiting overall economic viability. This study addresses these limitations by valorizing low-cost, non-additive agricultural residues from date palm ( Pheonix dactylifera L.) cultivation in North Africa through a co-production process of hydrogen and activated carbon. The proposed approach decouples biomass pyrolysis from subsequent steam gasification/activation of the resulting char, producing a second-stage gas stream with negligible tar content. Experimental trials conducted in a laboratory-scale rotary kiln to characterize the solid, gaseous, and liquid products of both stages, from which mass and energy balances were established. Depending on operating conditions, 35-44 g of hydrogen and 50-113 g of activated carbons were produced per kilogram of dry feedstock, while 35-40.5% of the initial energy content was recovered as useable heat. The exceptionally low tar content of the gases produced during the activation stage was experimentally confirmed. These results demonstrate the technical advantages of the proposed process over conventional gasification routes and provide a robust experimental basis for further techno-economic and scale-up assessments.