Catalytic Pyrolysis of Coconut Fiber with MgCl₂: 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.