Researchers have demonstrated that biochar-supported catalysts can efficiently convert biomass tar into hydrogen-rich gas at significantly lower temperatures than conventional processes, in findings that could reduce the cost and energy demands of biomass gasification.
The study, published in the journal Biochar, tested a series of metal catalysts using toluene as a representative tar compound, with biochar derived from wood chip gasification serving as a low-cost support material. Of the metals tested, which were nickel, cobalt, and iron, nickel-based catalysts showed the strongest performance in breaking down tar compounds.
Introducing lanthanum as a promoter element produced the standout result. A lanthanum-promoted nickel biochar catalyst achieved a hydrogen yield of 87% and a tar conversion rate of 93% at just 400°C. This is the temperatures at which conventional catalysts typically fall well short of comparable efficiency.
The researchers attribute the performance gains to improved metal dispersion, higher surface basicity, and the creation of oxygen vacancies that facilitate chemical reactions. Durability testing showed the catalyst maintained stable hydrogen production over extended operation, resisting the carbon build-up that typically degrades conventional catalysts.
Biomass gasification is widely regarded as a viable renewable energy route, but tar formation has long been a significant operational challenge, clogging equipment and reducing system efficiency. Converting that tar into useful hydrogen has been a key research goal.
The use of biochar as a catalyst support adds a further sustainability dimension. Produced from biomass residues, it is both inexpensive and carbon-rich, and its porous structure makes it well suited to hosting active metal particles, aligning the approach with circular economy principles.
Biochar catalyst achieves high hydrogen yields from biomass tar at low temperatures
