Hydrogen production from microwave catalytic pyrolysis of spruce sawdust

•Microwave catalytic pyrolysis of spruce sawdust has been studied.•Presence of metallic catalyst had strong effect on the hydrogen production.•Catalysts prepared using microwave heating have a suitable surface characteristic.

The production of energy from wood biomass is as old as humanity itself. In the last 20 years there has been enormous progress in research of torrefaction, pyrolysis and mainly gasification of biomass. Products from conventional pyrolysis of biomass are gas known as pyrolysis gas, a liquid condensate known as bio-oil and char named bio-char. Most of the articles dealing with convectional pyrolysis of biomass are focused on the production of bio-oil. Only some works deal with the possibility of producing high-quality syngas (H2 + CO) or hydrogen itself. For this purpose, the technology of microwave pyrolysis could be suitable. Microwaves can generate microplasma and hot spots, which promote heterogeneous catalytic reactions and produce a greater concentration of hydrogen in the resulting gas than convectional pyrolysis. In this work, an experimental study of spruce sawdust microwave pyrolysis was performed in the presence of catalysts to maximize the yield of hydrogen or syngas. Experiments were carried out in a microwave reactor with a power of 400 W. As catalysts char from sawdust, or sawdust char-doped with metal ions (Ni, Co, Fe) were used. Ions of metals were used to increase the yield of hydrogen (e.g. Nickel is widely used in the catalytic cracking of methane). The influence of the catalyst on the quantity of products (gas, liquid and solid) was studied, as well as the amount of hydrogen generated in the pyrolysis gas, or the amount of waste water in the liquid condensate.

Graphical abstractDownload high-res image (180KB)Download full-size image