In a recent article published in Renewable Energy, researchers explored the potential of biosolids-derived activated biochar as a sustainable carbo-catalyst for upgrading pyrolysis vapors from spent Eucalyptus nicholii (EUC), commonly known as Willow Peppermint biomass.
The aim was to enhance the selective production of valuable phenolic compounds and hydrocarbons, providing an eco-friendly alternative to conventional catalysts and advancing sustainable biomass conversion practices for cleaner energy solutions.
Image Credit: Kseniya.bird/Shutterstock.com
Advancements in Biomass Valorization Technologies
The growing demand for renewable energy has increased interest in biomass as a sustainable alternative to fossil fuels.
Biomass can be converted into valuable products such as fuels, chemicals, and carbon materials. Among various thermochemical conversion methods, pyrolysis stands out for its efficiency and cost-effectiveness in producing bio-oil, biochar, and gases. However, the complex composition of bio-oil often requires further upgrading to improve its quality for practical use.
Catalytic pyrolysis is a promising approach to enhance the yield of high-value compounds. While traditional catalysts like zeolites and metal oxides have shown effectiveness, their high costs and susceptibility to deactivation due to coke formation limit their scalability.
Consequently, scientists are shifting toward more sustainable alternatives, such as activated carbon and biochar derived from agricultural residues and biosolids, to support efficient biomass conversion and advance clean energy technologies.
Investigating Carbo-Catalysts for Enhanced Bio-Oil Production
The authors assessed the catalytic performance of biosolids-derived activated biochar in the pyrolysis of spent EUC biomass. They focused on evaluating how chemical activation using potassium hydroxide (KOH) and phosphoric acid (H3PO4) influenced the biochar's efficacy as a carbo-catalyst.
The feedstock, collected as solid residues following the steam distillation of EUC, was dried, sieved, and then processed through pyrolysis in a quartz tubular reactor at temperatures ranging from 300 to 600 °C. Biosolids sourced from wastewater treatment plants were chemically activated to produce non-activated (BC), KOH-activated (KAC), and H3PO4-activated (PAC) biochars.
The feedstock and catalysts were characterized using thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM).
The resulting bio-oils were analyzed using gas chromatography-mass spectrometry (GC-MS) to determine the distribution of phenolic compounds and hydrocarbons. This study highlighted the dual benefits of biosolid valorization and enhanced catalytic performance in biomass conversion.
Key Findings: Impacts of Utilizing Biochar as a Catalyst
The outcomes demonstrated that biosolids-derived carbo-catalysts significantly influenced the yield and composition of bio-oil during the pyrolysis of EUC biomass.
PAC achieved the best performance among the tested catalysts, producing a bio-oil with 69.7% phenolics and 13.7% hydrocarbons at an optimal pyrolysis temperature of 400 °C.
KAC and BC yielded lower phenolic contents of 58.68% and 62.37%, respectively. PAC's superior performance was attributed to its larger surface area, higher porosity, Brønsted acidic sites, and oxygen-rich groups, facilitating key reactions such as deoxygenation, decarboxylation, and decarbonylation.
While the use of carbo-catalysts slightly reduced the yield of bio-oil, from 35.5 wt% in non-catalytic pyrolysis to 27.7 wt% with BC and around 25-26.2 wt% with PAC and KAC, this also resulted in an increase in gas production due to enhanced cracking reactions.
Gas yield increased from 25.5 wt% without a catalyst to over 33% with catalysts. Catalytic pyrolysis also reduced the activation energy required for biomass breakdown, decreasing it from approximately 150-155 kJ/mol without catalysts to 113-119 kJ/mol with PAC and KAC.
Practical Applications: Toward Sustainable Energy Solutions
This research has significant implications for sustainable energy production.
Using biosolids-derived activated biochar as a catalyst in biomass pyrolysis provides a low-cost and eco-friendly alternative to traditional catalysts. It transforms biosolids, typically viewed as waste, into valuable materials for energy production, supporting waste management and a circular economy.
The improved quality of bio-oil, with higher concentrations of phenolics and hydrocarbons, enhances its utility for biofuel production, helping to decrease reliance on fossil fuels and promoting the transition to renewable energy.
These catalysts can also be applied to various biomass types, encouraging further research into other feedstocks and the broader use of activated biochar in pyrolysis. By improving both the economic and environmental aspects of biomass conversion, this study helps promote cleaner fuel production and better resource utilization.
Conclusion and Future Directions
Biosolids-derived activated biochar, particularly PAC, was crucial in upgrading pyrolysis vapors from spent EUC biomass. It improved bio-oil quality by increasing the production of phenolics and hydrocarbons while lowering the activation energy needed for biomass breakdown. These results highlight the potential of eco-friendly catalysts to support more efficient and sustainable biomass-to-energy conversion.
Using biosolids as catalysts promotes waste reuse, making the process more environmentally friendly. This approach offers a cleaner method for producing valuable chemicals and fuels, reducing reliance on fossil resources and fostering circular economy practices.
Future work should focus on testing these catalysts with various biomass types, optimizing their performance, and assessing their reusability. Conducting life cycle assessments will also be essential to understanding the environmental benefits and supporting the shift toward cleaner and more practical energy solutions.
Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.
Source:
Kaur, R., & et al. Role of carbo-catalyst on upgrading the pyrolysis vapors of spent Eucalyptus nicholii biomass: Towards sustainable phenolics production. Renewable Energy, 122468 (2025). DOI: 10.1016/j.renene.2025.122468, https://www.sciencedirect.com/science/article/pii/S0960148125001302?via%3Dihub