Catalytic pyrolysis of paddy husk in a drop type pyrolyzer for bio-oil production: The role of temperature and catalyst

• Catalytic fast pyrolysis of paddy husk was studied in a lab scale drop type fixed-bed pyrolyzer.
• Bio-oil generated from catalytic pyrolysis had low organic content and high water content.
• Secondary degradation reactions by the catalyst promoted the formation of furans.
• Excess amount of catalyst produced more water and less quality bio-oil.

The present research encompasses the impact of temperature and catalyst on the properties of bio-oils and on product yield for the pyrolysis of rice husk. Fast pyrolysis of paddy husks was conducted in a drop type pyrolyzer to study the influence of pyrolysis temperature 350–600 °C on products yield and properties. In order to investigate the effect of catalyst, experiments were carried out for a wide range of ratios (0.5–2) of biomass at the pyrolysis temperature of 450 °C. The presence of catalyst culminated in less bio-oil yield coupled with higher calorific values and high water contents in comparison to non-catalytic pyrolysis. Furthermore under dehydration and mild pyrolysis conditions the higher amount of catalyst resulted in bio-oil having high water and acidic contents. Oxygen removal degree was used to evaluate the oxygen content transferred from parent biomass to the obtained bio-oil. The ratio 0.5 showed the highest de-oxygenation degree (84.6%). The bio-oil produced at this ratio contained high phenol, phenolic compounds and less carbonyl and acidic contents. The bio-oil characterization (with and without catalyst) was evaluated and reported in terms of CHN/O and GC–MS (phenol, phenol derivatives, ketones, furans and aliphatic compounds).