Hydrogen is receiving considerable interest as a sustainable and renewable alternative to fossil fuels. Of the techniques available to synthesize hydrogen sustainably, the gasification of biomass shows promise as being of sufficient scale to satisfy future energy demand. We have developed a novel thermochemical conversion process coupling catalytic biomass gasification with in situ CO₂ capture using a CaO derived sorbent to maximise the H₂ output from the gasifier. The ultimate objective of this project is to be able to feed the H₂ rich gas directly to a fuel cell, without the expense of intermediate gas cleaning or upgrading.
We investigated the role of highly active steam reforming and water-gas shift catalysts, crucial for the successful operation of industrial biomass gasifiers; these reduce the formation of tars and hence increase the production of a H₂-rich synthesis gas by altering the fundamental reaction kinetics. The output of H₂ is further promoted by using CaO derived sorbents for in situ CO₂ capture.
To facilitate catalyst and sorbent screening, we developed a methodology using a thermogravimetric analyser coupled with mass spectrometer (TG-MS). We then used this technique to assess the performance of 15 targeted catalysts and catalyst/sorbent combinations by studying reaction kinetics and product distribution. Different active agents were investigated involving Group VIII metals, Platinum Group metals and Alkali Earth metal oxides. We also investigated the influence of catalyst substrate material and structure, including the use of novel, hierarchically structured mesoporous substrates. Catalyst/sorbent combinations displaying the greatest activity for hydrogen were subsequently identified.