Pyrolysis of oil palm empty fruit bunch biomass pellets using multimode microwave irradiation

Area of Science:

• Biomass Conversion
• Chemical Engineering
• Sustainable Energy

Background:

• Oil palm empty fruit bunch (EFB) is an abundant lignocellulosic waste.
• Pyrolysis offers a promising route for converting biomass into valuable products.
• Microwave heating presents an efficient and rapid method for pyrolysis.

Purpose of the Study:

• To investigate the effect of microwave absorber ratio on the pyrolysis of EFB.
• To analyze the composition and yield of pyrolysis products (bio-oil, char, gas).
• To evaluate the potential of EFB-derived bio-char as an alternative fuel.

Main Methods:

• Pyrolysis of EFB pellets in a multimode microwave system (1 kW, 2.45 GHz).
• Experimentation with varying ratios of biomass to activated carbon (MW absorber).
• Analysis of bio-oil using Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier-Transform Infrared Spectroscopy (FT-IR).
• Determination of bio-char heating value.

Main Results:

• The ratio of biomass to MW absorber significantly influenced temperature profiles and product yields.
• The highest bio-oil yield (approx. 21 wt.%) was achieved with 25% MW absorber.
• Bio-oil was rich in phenolic compounds (60-70 area%).
• Ball lightning (plasma arc) was observed without MW absorber due to residual oils.
• Bio-char exhibited a high heating value of 25 MJ/kg.

Conclusions:

• Activated carbon as a microwave absorber effectively enhances bio-oil yield and quality during EFB pyrolysis.
• Optimized microwave pyrolysis can mitigate issues like plasma arcs and produce valuable bio-products.
• EFB-derived bio-char is a viable alternative fuel source with significant energy content.