Resumen
The present work demonstrated the sustainable and renewable approach of thermochemical conversion specifically for pyrolysis of rice hull through renewable catalytic pyrolysis utilizing calcined eggshell (ES) and natural limestone (LS) for syngas production. LS has a potential to be developed as an effective and cheap CaO derived heterogeneous catalyst for thermochemical conversion technologies. Meanwhile, ES waste has the potential to be used as low cost and high supply catalyst worldwide in enhancing the production of different compounds. This study investigates the thermodynamic and kinetic parameters of rice hull (RH) pyrolysis with the presence of two different types of renewable catalysts i.e. LS and ES using thermogravimetric analysis coupled with mass spectrometer (TGA-MS) equipment. Both LS and ES are calcined at temperature of 1123K in a furnace for a duration of 4 hours to remove any organic matter and to convert the composition of CaCO3 to CaO in these materials. Approximate 10% weight ratio of biomass to catalyst sample is pyrolyzed at different heating rates within the range of 10-100 K/min from temperature range of 323K and 1173K under nitrogen environment flow of 100 mL/min. A pyrolysis mechanism of both catalysts had shown significant effect on the degradation of RH. Model free kinetic of iso-conversional method (Flynn-Wall-Ozawa) and multi-step reaction model (Distributed Activation Energy Model) were employed into present study. The average activation energy was found in the range of 175.4 ? 177.7 kJ/mol (RH), 123.3 ? 132.5 kJ/mol (RH-LS), and 96.1 ? 100.4 kJ/mol (RH-ES) respectively. Furthermore, the syngas composition had increased from 60.05 wt% to 63.1 wt% (RH-LS) and 63.4 wt% (RH-ES). However, the CO2 content had decreased from 24.1 wt% (RH) to 20.8 wt% (RH-LS) and 19.9 wt% (RH-ES). This study draws a main conclusion that ES has better catalytic effect compared to LS for optimizing syngas yield.