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).