Catalytic Pyrolysis of Coconut Fiber with MgCl 2 : Enhancing Thermal Degradation Kinetics and Product Selectivity

Coconut fiber (CCF), a lignocellulosic biomass, presents significant potential for renewable energy production through pyrolysis. This study investigates the catalytic pyrolysis of CCF in a fixed-bed reactor, focusing on the effects of temperature (623-723 K) and magnesium chloride (MgCl2) concentration (0-10%) on product yields and properties. Proximate and elemental analyses were used to characterize CCF's composition, while thermogravimetric analysis (TGA) at heating rates of 20-50 K/min assessed thermal degradation kinetics using the Reparametrized Global Reaction (RGR) model. The kinetic analysis confirmed that MgCl2 reduced activation energy from 56.3 kJ·mol-1 to 29.3 kJ·mol-1, enhancing devolatilization efficiency. Pyrolysis experiments yielded bio-oil, biochar, and gas in the ranges of 47.4-52.4%, 29.7-37.2%, and 15.4-17.9%, respectively, depending on operating conditions. Higher temperatures increased bio-oil yield, peaking at 52.36% at 723 K without MgCl2, while 10% MgCl2 enhanced biochar production to 58.65% with fixed carbon contents up to 62.0% and higher heating values ranging from 22.4 to 25.1 MJ·kg-1. Gas chromatography-mass spectrometry (GC-MS) showed that MgCl2 promoted aldehyde formation (e.g., furfural) via hemicellulose dehydration, whereas higher temperatures favored phenolic compounds from lignin degradation. These findings highlight MgCl2's role in tailoring pyrolysis pathways for optimized bio-oil and biochar production, offering insights into sustainable biomass conversion for energy and carbon sequestration applications.