By linking biomass structure to thermal reaction pathways, the research reveals how mannan-rich materials can be selectively transformed into industrially relevant compounds such as levomannosan and 5-hydroxymethylfurfural, offering a sustainable route for waste valorization.
Agricultural and artisanal wastes are often regarded as low-value residues, yet many contain highly ordered carbohydrates with significant potential for conversion into value-added chemicals. Biomass is widely recognized as a renewable and carbon-neutral resource for producing fuels and chemicals, and among thermochemical technologies, pyrolysis has attracted considerable attention for its ability to convert solid biomass into oxygen-rich liquid bio-oil. However, selectively steering pyrolysis toward high-value products remains challenging due to the structural and compositional diversity of biomass feedstocks. Palm-derived handicraft materials, such as tagua nut and bodhi root, are particularly promising because they are rich in holocellulose, low in lignin and ash, and dominated by mannan, a hemicellulose capable of yielding valuable anhydrosugars and furan derivatives—though the structure–reaction relationship has remained poorly understood.
A study (DOI:10.48130/een-0025-0020) published in Energy & Environment Nexus on 15 January 2026 by Ji Liu’s & Qiang Lu’s team, North China Electric Power University, elucidates the structure–reaction–product relationship of mannan-rich palm handicraft wastes, providing a scientific basis for their selective conversion into high-value anhydrosugars through optimized pyrolysis.
The study employed a comprehensive, multi-technique experimental approach to systematically link feedstock structure with pyrolysis behavior and product formation. First, ultimate and proximate analyses, component analysis, and scanning electron microscopy (SEM) were used to characterize the elemental composition, ash characteristics, carbohydrate distribution, and surface morphology of tagua nut and bodhi root. These methods revealed that both materials are carbohydrate-rich, with exceptionally high holocellulose contents and mannan-dominated monosaccharide profiles. Thermogravimetry coupled with infrared spectroscopy (TG-FTIR) was then applied to track thermal decomposition and volatile evolution during controlled heating under nitrogen, while in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) monitored structural transformations in the solid phase. To resolve product distribution and temperature effects, pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) provided rapid, online identification of volatile products, and complementary lab-scale fixed-bed pyrolysis experiments quantified solid, liquid, and gas yields under longer residence times. Results showed that both feedstocks decomposed through three stages, with rapid mannan degradation occurring between 180 and 380 °C and maximum mass-loss rates at ~301–302 °C, consistent with mannan-type hemicellulose. High volatile contents promoted liquid formation, while higher ash levels in bodhi root enhanced secondary cracking and gas production. Py-GC/MS revealed that anhydrosugars and furans dominated the product spectrum, with levomannosan (LM) accounting for over 90% of anhydrosugars and reaching maximum yields of 11.2 wt% for tagua nut (600 °C) and 10.9 wt% for bodhi root (500 °C). Fixed-bed pyrolysis confirmed that bio-oil yields peaked at 600 °C, and that prolonged high-temperature exposure reduced LM via secondary decomposition while favoring gas formation. Mechanistically, mannan depolymerization and transglycosylation produced LM as a key intermediate, followed by dehydration and bond cleavage to form furans and gases. Together, these results establish a clear structure–reaction–product relationship and identify optimal temperature windows for selectively producing LM from mannan-rich palm wastes.
The findings establish a clear structure–reaction–product relationship for mannan-rich biomass. Palm handicraft wastes, often discarded or underutilized, can serve as efficient feedstocks for producing high-value platform chemicals. Levomannosan and 5-hydroxymethylfurfural are important intermediates for biobased polymers, resins, solvents, and fuel additives. This work highlights a practical pathway to integrate waste management with green chemical production.
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References
DOI
10.48130/een-0025-0020
Original Source URL
https://doi.org/10.48130/een-0025-0020
Funding information
This work was supported by National Natural Science Foundation of China (Grant Nos 52276189, 52436009, 52376182), and Fundamental Research Funds for the Central Universities (Grant No. 2024JG001).
About Energy & Environment Nexus
Energy & Environment Nexus is a multidisciplinary journal for communicating advances in the science, technology and engineering of energy, environment and their Nexus.