Na₂ZrO₃ as an Effective Bifunctional Catalyst–Sorbent during Cellulose Pyrolysis

Na₂ZrO₃ was tested as bifunctional catalyst sorbent using cellulose as model biomass under pyrolytic conditions. Thermogravimetric analyzer connected to a mass spectrometer (TG-MS) was used to study the influence of Na₂ZrO₃ on the gas evolution from cellulose pyrolysis. The weight loss data and gas evolution was analyzed over a temperature range of 200–800 °C. Na₂ZrO₃ showed a clear catalytic influence during cellulose pyrolysis, and it was actively catalyzing tar cracking and reforming reactions at elevated temperatures. A comparison with CaO was conducted under identical conditions and results showed that Na₂ZrO₃ mixed samples were able to produce higher yield of hydrogen from cellulose, mainly due to participating in tar-cracking and reforming reactions at lower temperatures than CaO (500 °C for Na₂ZrO₃, compared to 600 °C for CaO). The study showed that Na₂ZrO₃ can act as catalyst for pyrolysis reactions of cracking and reforming, and subsequently remove CO₂ produced in situ. The results suggest that Na₂ZrO₃ has potential to participate in the gasification of biomass as an effective bifunctional catalyst–sorbent, which may enhance hydrogen yield.