Pyrolysis of Hibiscus Rosa Sinensis under catalytic and non-catalytic conditions: Kinetics, thermodynamic parameters and product profiles

The pyrolysis of stem and leaves of Hibiscus rosa sinensis was performed with and without Zeolite-5A using thermogravimetric analysis under nitrogen atmosphere for 125-to-1000-μm particles and 5–20 °C min−1 heating rate. The decomposition rates of hemicellulose, cellulose, and lignin were obtained by deconvolution of differential thermogravimetric data. Activation energy for catalytic pyrolysis was ∼25 % lower than non-catalytic pyrolysis and was higher for lignin pyrolysis, due to a higher ratio of volatile matter to fixed carbon. The best-fit models for hemicellulose, cellulose, and lignin decomposition were nth-order, random-scission, and nucleation-A4. The pre-exponential factors were estimated from the fundamental rate expression using the best-fit model and activation energy, while thermodynamic parameters were estimated using the Eyring equation. A lab-scale fixed-bed reactor was used to measure the product profiles under catalytic and non-catalytic conditions in the decomposition range of individual constituents. The liquid product yield was 15 % higher for catalytic conditions.