Bio-Oil Produced via Catalytic Pyrolysis of the Solid Digestates from Anaerobic Co-Digestion Plants †
National Research and Development Institute for Chemistry and Petrochemistry ICECHIM, 202 Spl Independentei St., Bucharest 060021, Romania
*
Author to whom correspondence should be addressed.
†
Presented at the 15th International Symposium “Priorities of Chemistry for a Sustainable Development” PRIOCHEM, Bucharest, Romania and 30 October–1 November 2019.
Proceedings 2019, 29(1), 89; https://doi.org/10.3390/proceedings2019029089
Published: 16 October 2019
(This article belongs to the Proceedings of Priorities of Chemistry for a Sustainable Development-PRIOCHEM)
Digestate, the residue following anaerobic digestion, has attracted great attention recently as a potential feedstock for pyrolysis. Pyrolysis is regarded as a technology with great potential to treat wastes. Related studies have found over 91% of the digestate energy was transferred into products of bio-oil, solid, and gaseous [1]. Digestate pyrolysis oil shows promise as a biofuel source for engine applications [2]. However, related studies on the components of pyrolysis oil are still lacking.
In this context, the objective of this study was to investigate the pyrolysis process of the solid fraction from anaerobic co-digestion plants digestate in the presence of a nanostructured catalyst based on Mn, and the characterization of a bio-oil fraction produced in the pyrolysis process.
The digestate was obtained from anaerobic digestion in a laboratory. Composition analysis and thermogravimetric analysis were conducted. Experiments were undertaken to investigate the impact of the reaction temperature and pressure on the digestate pyrolysis, as well as characterizing the yield and quality of the bio-oil product. Further objectives were to propose the optimum reaction from digestate to bio-oil, and find a feasible foundation of the digestate decomposition mechanism for further utilization.
Experimental
The catalysts were obtained using a soft template method via the evaporation self-assembly (EISA) method, using salts of Mn precipitated in the presence of polymeric anti-agglomerates as Pluronic P123. The prepared catalysts were characterized by isothermal sorption measurements using a NOVA 2200e-Quantachrome Analyzer porosimeter (the specific surface was calculated from the linear portion of the adsorption isotherm using the B.E.T. equation), Fourier-transform infrared spectroscopy (Jasco FTIR-6300 with ATR Specac Golden Gate) and X-ray diffraction (XRD) analysis with X-ray diffractometer SmartLab (Rigaku). The acid strength distribution was performed by a method of thermal desorption of diethylamine on a Thermogravimetric Analyzer [3].
The experimental tests have been carried out in a laboratory-scale tubular reactor in inert gas. The tubular reactor made of stainless steel was heated in an electric furnace provided with a temperature control system. The solid digestate used as feedstock for pyrolysis were obtained from a laboratory biogas plant. The suspension obtained from the mixture of conditioned solid digestate, lipid fraction from algae biomass, and a catalyst in various mixed ratios was continuously fed into the reactor. A gas-liquid separator was used to separate the condensed liquids and gas products. The liquid and gas products were analyzed using a GC/MS Triple Quad Agilent Technology gas chromatograph. The structural characterization of the resulted bio-char was made by textural analysis and determination of the ash content.
The catalyst characterization data indicates the obtaining of an amorphous hydrous nanostructured MnO2. The results show that the amorphous hydrous nanoparticles with the mean particle size of 10–30 nm were obtained and the BET specific surface areas were 130 m2/g.
The catalytic activity of synthesized MnO2 nanoparticles was evaluated in the pyrolysis of anaerobic co-digestion plants digestate solid suspension. The reaction parameters studied for the pyrolysis process were: temperature 450–520 °C, atmospheric pressure, and catalyst concentration 1–10 wt.%. The obtained results showed that the catalyst concentration had an important effect over liquid yield. The liquid yield reached a maximum value at the pyrolysis temperature of 460 °C in the presence of 0.75 wt. % based on the feedstock amount. The analysis of the liquid fractions obtained on the nanostructured Mn catalysts highlights the presence of a large number of linear and branched aliphatic hydrocarbon components, unsaturated compounds, alcohols, carbonyl compounds, and carboxylic acids, with boiling temperatures ranging over a wide range. Meanwhile, the textural analysis of the separate coal from the catalytic pyrolysis reveals a low pore volume and implicitly a small specific surface, specific to the non-activated coal.
The nanostructured Mn catalyst was successfully obtained by a soft templating method using salts of Mn by precipitation in the presence of Pluronic P123. The pyrolysis of biogas solid digestate results shows that the yield and composition of the liquid fraction are dependent on the catalyst concentration and residence time.
Acknowledgments
The authors gratefully acknowledge the financial support of the UEFISCDI, Romania, in the framework of PN-III-P1-1.2-PCCDI-2017, financing contract no. 32 PCCDI/2018.
References
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MDPI and ACS Style
Ghimis, S.-B.; Vasilievici, G.; Radu, E.; Velea, S.; Fierascu, R. Bio-Oil Produced via Catalytic Pyrolysis of the Solid Digestates from Anaerobic Co-Digestion Plants. Proceedings 2019, 29, 89. https://doi.org/10.3390/proceedings2019029089
AMA Style
Ghimis S-B, Vasilievici G, Radu E, Velea S, Fierascu R. Bio-Oil Produced via Catalytic Pyrolysis of the Solid Digestates from Anaerobic Co-Digestion Plants. Proceedings. 2019; 29(1):89. https://doi.org/10.3390/proceedings2019029089
Chicago/Turabian StyleGhimis, Simona-Bianca, Gabriel Vasilievici, Elena Radu, Sanda Velea, and Radu Fierascu. 2019. "Bio-Oil Produced via Catalytic Pyrolysis of the Solid Digestates from Anaerobic Co-Digestion Plants" Proceedings 29, no. 1: 89. https://doi.org/10.3390/proceedings2019029089
