Catalytic Pyrolysis of Sewage Sludge for Upgrading Bio-Oil Quality Using Sludge-Based Activated Char as an Alternative to HZSM5
Due to the concerns about the depletion of fossil fuel sources and the deteriorating environment, the attempt to investigate the production of renewable energy will play a crucial role as a potential to alleviate the dependency on mineral fuels. One particular area of interest is generation of bio-oil through sewage sludge (SS) pyrolysis. SS can be a potential candidate in contrast to other types of biomasses due to its availability and low cost. However, the presence of high molecular weight hydrocarbons and oxygenated compounds in the SS bio-oil hinders some of its fuel applications. In this context, catalytic pyrolysis is another attainable route to upgrade bio-oil quality. Among different catalysts (i.e., zeolites) studied for SS pyrolysis, activated chars (AC) are eco-friendly alternatives. The beneficial features of AC derived from SS comprise the comparatively large surface area, porosity, enriched surface functional groups and presence of a high amount of metal species that can improve the catalytic activity. Hence, a sludge-based AC catalyst was fabricated in a single-step pyrolysis reaction with NaOH as the activation agent and was compared with HZSM5 zeolite in this study. The thermal decomposition and kinetics were invested via thermogravimetric analysis (TGA) for guidance and control of pyrolysis and catalytic pyrolysis and the design of the pyrolysis setup. The results indicated that the pyrolysis and catalytic pyrolysis contain four obvious stages and the main decomposition reaction occurred in the range of 200-600 °C. Coats-Redfern method was applied in the 2nd and 3rd devolatilization stages to estimate the reaction order and activation energy (E) from the mass loss data. The average activation energy (Em) values for the reaction orders n = 1, 2 and 3 were in the range of 6.67-20.37 kJ/mol for SS; 1.51-6.87 kJ/mol for HZSM5; and 2.29-9.17 kJ/mol for AC, respectively. According to the results, AC and HZSM5 both were able to improve the reaction rate of SS pyrolysis by abridging the Em value. Moreover, to generate and examine the effect of the catalysts on the quality of bio-oil, a fixed-bed pyrolysis system was designed and implemented. The composition analysis of the produced bio-oil was carried out via gas chromatography/mass spectrometry (GC/MS). The selected SS to catalyst ratios were 1:1, 2:1 and 4:1. The optimum ratio in terms of cracking the long-chain hydrocarbons and removing oxygen-containing compounds was 1:1 for both catalysts. The upgraded bio-oils with HZSM5 and AC were in the total range of C4-C17 with around 72% in the range of C4-C9. The bio-oil from pyrolysis of SS contained 49.27% oxygenated compounds while the presence of HZSM5 and AC dropped to 7.3% and 13.02%, respectively. Meanwhile, generation of value-added chemicals such as light aromatic compounds were significantly improved in the catalytic process. Furthermore, the fabricated AC catalyst was characterized by BET, SEM-EDX, FT-IR and TGA techniques. Overall, this research demonstrated that AC is an efficient catalyst in the pyrolysis of SS and can be used as a cost-competitive catalyst in contrast to HZSM5.Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 377
 A. Zaker, Z. Chen, M. Zaheer-Uddin, Catalytic pyrolysis of sewage sludge with HZSM5 and sludge-derived activated char: A comparative study using TGA-MS and artificial neural networks, Journal of Environmental Chemical Engineering. 9 (2021) 105891. doi:10.1016/j.jece.2021.105891.
 S.S.A. Syed-Hassan, Y. Wang, S. Hu, S. Su, J. Xiang, Thermochemical processing of sewage sludge to energy and fuel: Fundamentals, challenges and considerations, Renewable and Sustainable Energy Reviews. 80 (2017) 888–913. doi:10.1016/j.rser.2017.05.262.
 J. Hu, M. Danish, Z. Lou, P. Zhou, N. Zhu, H. Yuan, P. Qian, Effectiveness of wind turbine blades waste combined with the sewage sludge for enriched carbon preparation through the co-pyrolysis processes, Journal of Cleaner Production. 174 (2018) 780–787. doi:10.1016/j.jclepro.2017.10.166.
 M.S. Ahmad, M.A. Mehmood, S.T.H. Taqvi, A. Elkamel, C.G. Liu, J. Xu, S.A. Rahimuddin, M. Gull, Pyrolysis, kinetics analysis, thermodynamics parameters and reaction mechanism of Typha latifolia to evaluate its bioenergy potential, Bioresource Technology. 245 (2017) 491–501. doi:10.1016/j.biortech.2017.08.162.
 K. Wang, Y. Zheng, X. Zhu, C.E. Brewer, R.C. Brown, Ex-situ catalytic pyrolysis of wastewater sewage sludge – A micro-pyrolysis study, Bioresource Technology. 232 (2017) 229–234. doi:10.1016/j.biortech.2017.02.015.
 A. Zaker, Z. Chen, X. Wang, Q. Zhang, Microwave-assisted pyrolysis of sewage sludge : A review, Fuel Processing Technology. 187 (2019) 84–104. doi:10.1016/j.fuproc.2018.12.011.
 M.C. Samolada, A.A. Zabaniotou, Comparative assessment of municipal sewage sludge incineration, gasification and pyrolysis for a sustainable sludge-to-energy management in Greece, Waste Management. 34 (2014) 411–420. doi:10.1016/j.wasman.2013.11.003.
 Q. Dai, X. Jiang, Y. Jiang, Y. Jin, F. Wang, Y. Chi, J. Yan, A. Xu, Temperature influence and distribution in three phases of pahs in wet sewage sludge pyrolysis using conventional and microwave heating, Energy and Fuels. 28 (2014) 3317–3325. doi:10.1021/ef5003638.
 X. Huang, J.P. Cao, P. Shi, X.Y. Zhao, X.B. Feng, Y.P. Zhao, X. Fan, X.Y. Wei, T. Takarada, Influences of pyrolysis conditions in the production and chemical composition of the bio-oils from fast pyrolysis of sewage sludge, Journal of Analytical and Applied Pyrolysis. 110 (2014) 353–362. doi:10.1016/j.jaap.2014.10.003.
 A. Jaramillo-Arango, I. Fonts, F. Chejne, J. Arauzo, Product compositions from sewage sludge pyrolysis in a fluidized bed and correlations with temperature, Journal of Analytical and Applied Pyrolysis. 121 (2016) 287–296. doi:10.1016/j.jaap.2016.08.008.
 I. Fonts, G. Gea, M. Azuara, J. Ábrego, J. Arauzo, Sewage sludge pyrolysis for liquid production: A review, Renewable and Sustainable Energy Reviews. 16 (2012) 2781–2805. doi:10.1016/j.rser.2012.02.070.
 W. Liu, C. Hu, Y. Yang, D. Tong, G. Li, L. Zhu, Influence of ZSM-5 zeolite on the pyrolytic intermediates from the co-pyrolysis of pubescens and LDPE, Energy Conversion and Management. 51 (2010) 1025–1032. doi:10.1016/j.enconman.2009.12.005.
 M.M. Rahman, R. Liu, J. Cai, Catalytic fast pyrolysis of biomass over zeolites for high quality bio-oil – A review, Fuel Processing Technology. 180 (2018) 32–46. doi:10.1016/j.fuproc.2018.08.002.
 R.N. State, A. Volceanov, P. Muley, D. Boldor, A review of catalysts used in microwave assisted pyrolysis and gasification, Bioresource Technology. 277 (2019) 179–194. doi:10.1016/j.biortech.2019.01.036.
 A. Zaker, Z. Chen, M. Zaheer-Uddin, J. Guo, Co-pyrolysis of sewage sludge and low-density polyethylene - A thermogravimetric study of thermo-kinetics and thermodynamic parameters, Journal of Environmental Chemical Engineering. 9 (2020). doi:10.1016/j.jece.2020.104554.
 H. Persson, I. Duman, S. Wang, L.J. Pettersson, W. Yang, Catalytic pyrolysis over transition metal-modified zeolites : A comparative study between catalyst activity and deactivation, Journal of Analytical and Applied Pyrolysis. 138 (2019) 54–61. doi:10.1016/j.jaap.2018.12.005.
 Y. Shen, P. Zhao, Q. Shao, D. Ma, F. Takahashi, K. Yoshikawa, In-situ catalytic conversion of tar using rice husk char-supported nickel-iron catalysts for biomass pyrolysis/gasification, Applied Catalysis B: Environmental. 152–153 (2014) 140–151. doi:10.1016/j.apcatb.2014.01.032.
 Y. Zhang, H. Lei, Z. Yang, K. Qian, E. Villota, Renewable High-Purity Mono-Phenol Production from Catalytic Microwave-Induced Pyrolysis of Cellulose over Biomass-Derived Activated Carbon Catalyst, ACS Sustainable Chemistry and Engineering. 6 (2018) 5349–5357. doi:10.1021/acssuschemeng.8b00129.
 P. Daorattanachai, W. Laosiripojana, A. Laobuthee, N. Laosiripojana, Type of contribution: Research article catalytic activity of sewage sludge char supported Re-Ni bimetallic catalyst toward cracking/reforming of biomass tar, Renewable Energy. 121 (2018) 644–651. doi:10.1016/j.renene.2018.01.096.
 X. Zhang, H. Lei, L. Zhu, M. Qian, X. Zhu, J. Wu, S. Chen, Enhancement of jet fuel range alkanes from co-feeding of lignocellulosic biomass with plastics via tandem catalytic conversions, Applied Energy. 173 (2016) 418–430. doi:10.1016/j.apenergy.2016.04.071.
 Y. Zhang, D. Duan, H. Lei, E. Villota, R. Ruan, Jet fuel production from waste plastics via catalytic pyrolysis with activated carbons, Applied Energy. 251 (2019) 113337. doi:10.1016/j.apenergy.2019.113337.
 L. Dai, Z. Zeng, X. Tian, L. Jiang, Z. Yu, Q. Wu, Y. Wang, Y. Liu, R. Ruan, Microwave-assisted catalytic pyrolysis of torrefied corn cob for phenol-rich bio-oil production over Fe modified bio-char catalyst, Journal of Analytical and Applied Pyrolysis. 143 (2019) 104691. doi:10.1016/j.jaap.2019.104691.
 F. Guo, X. Li, Y. Liu, K. Peng, C. Guo, Z. Rao, Catalytic cracking of biomass pyrolysis tar over char-supported catalysts, Energy Conversion and Management. 167 (2018) 81–90. doi:10.1016/j.enconman.2018.04.094.
 N. Gao, K. Kamran, C. Quan, P.T. Williams, Thermochemical conversion of sewage sludge: A critical review, Progress in Energy and Combustion Science. 79 (2020) 100843. doi:10.1016/j.pecs.2020.100843.
 D. qing Fu, X. hong Li, W. ying Li, J. Feng, Catalytic upgrading of coal pyrolysis products over bio-char, Fuel Processing Technology. 176 (2018) 240–248. doi:10.1016/j.fuproc.2018.04.001.
 S.R. Naqvi, R. Tariq, Z. Hameed, I. Ali, S.A. Taqvi, M. Naqvi, M.B.K. Niazi, T. Noor, W. Farooq, Pyrolysis of high-ash sewage sludge: Thermo-kinetic study using TGA and artificial neural networks, Fuel. 233 (2018) 529–538. doi:10.1016/j.fuel.2018.06.089.
 A. V. Bridgwater, Review of fast pyrolysis of biomass and product upgrading, Biomass and Bioenergy. 38 (2012) 68–94. doi:10.1016/j.biombioe.2011.01.048.
 S. Sfakiotakis, D. Vamvuka, Study of co-pyrolysis of olive kernel with waste biomass using TGA/DTG/MS, Thermochimica Acta. 670 (2018) 44–54. doi:10.1016/j.tca.2018.10.006.
 D.R. Nhuchhen, P. Abdul Salam, Estimation of higher heating value of biomass from proximate analysis: A new approach, Fuel. 99 (2012) 55–63. doi:10.1016/j.fuel.2012.04.015.
 X. Xiong, I.K.M. Yu, L. Cao, D.C.W. Tsang, S. Zhang, Y.S. Ok, A review of biochar-based catalysts for chemical synthesis, biofuel production, and pollution control, Bioresource Technology. 246 (2017) 254–270. doi:10.1016/j.biortech.2017.06.163.
 X. fei Tan, S. bo Liu, Y. guo Liu, Y. ling Gu, G. ming Zeng, X. jiang Hu, X. Wang, S. heng Liu, L. hua Jiang, Biochar as potential sustainable precursors for activated carbon production: Multiple applications in environmental protection and energy storage, Bioresource Technology. 227 (2017) 359–372. doi:10.1016/j.biortech.2016.12.083.
 T. Sizmur, T. Fresno, G. Akgül, H. Frost, E. Moreno-Jiménez, Biochar modification to enhance sorption of inorganics from water, Bioresource Technology. 246 (2017) 34–47. doi:10.1016/j.biortech.2017.07.082.
 A.U. Rajapaksha, S.S. Chen, D.C.W. Tsang, M. Zhang, M. Vithanage, S. Mandal, B. Gao, N.S. Bolan, Y.S. Ok, Engineered/designer biochar for contaminant removal/immobilization from soil and water: Potential and implication of biochar modification, Chemosphere. 148 (2016) 276–291. doi:10.1016/j.chemosphere.2016.01.043.
 A. Zubrik, M. Matik, S. Hredzák, M. Lovás, Z. Danková, M. Kováčová, J. Briančin, Preparation of chemically activated carbon from waste biomass by single-stage and two-stage pyrolysis, Journal of Cleaner Production. 143 (2017) 643–653. doi:10.1016/j.jclepro.2016.12.061.
 G. Liu, H. Song, J. Wu, Thermogravimetric study and kinetic analysis of dried industrial sludge pyrolysis, Waste Management. 41 (2015) 128–133. doi:10.1016/j.wasman.2015.03.042.
 S.D. Gunasee, B. Danon, J.F. Görgens, R. Mohee, Co-pyrolysis of LDPE and cellulose: Synergies during devolatilization and condensation, Journal of Analytical and Applied Pyrolysis. 126 (2017) 307–314. doi:10.1016/j.jaap.2017.05.016.
 Q. Liu, Z. Xiong, S.S.A. Syed-Hassan, Z. Deng, X. Zhao, S. Su, J. Xiang, Y. Wang, S. Hu, Effect of the pre-reforming by Fe/bio-char catalyst on a two-stage catalytic steam reforming of bio-oil, Fuel. 239 (2019) 282–289. doi:10.1016/j.fuel.2018.11.029.
 P. Hadi, M. Xu, C. Ning, C. Sze Ki Lin, G. McKay, A critical review on preparation, characterization and utilization of sludge-derived activated carbons for wastewater treatment, Chemical Engineering Journal. 260 (2015) 895–906. doi:10.1016/j.cej.2014.08.088.
 A. Zielińska, P. Oleszczuk, B. Charmas, J. Skubiszewska-Zięba, S. Pasieczna-Patkowska, Effect of sewage sludge properties on the biochar characteristic, Journal of Analytical and Applied Pyrolysis. 112 (2015) 201–213. doi:10.1016/j.jaap.2015.01.025.
 Q.H. Lin, H. Cheng, G.Y. Chen, Preparation and characterization of carbonaceous adsorbents from sewage sludge using a pilot-scale microwave heating equipment, Journal of Analytical and Applied Pyrolysis. 93 (2012) 113–119. doi:10.1016/j.jaap.2011.10.006.
 E. Antunes, J. Schumann, G. Brodie, M. V. Jacob, P.A. Schneider, Biochar produced from biosolids using a single-mode microwave: Characterisation and its potential for phosphorus removal, Journal of Environmental Management. 196 (2017) 119–126. doi:10.1016/j.jenvman.2017.02.080.
 R. Shahrokhi-Shahraki, C. Benally, M.G. El-Din, J. Park, High efficiency removal of heavy metals using tire-derived activated carbon vs commercial activated carbon: Insights into the adsorption mechanisms, Chemosphere. 264 (2021) 128455. doi:10.1016/j.chemosphere.2020.128455.
 T.A. Saleh, Naeemullah, M. Tuzen, A. Sarı, Polyethylenimine modified activated carbon as novel magnetic adsorbent for the removal of uranium from aqueous solution, Chemical Engineering Research and Design. 117 (2017) 218–227. doi:10.1016/j.cherd.2016.10.030.
 Q. Bu, H. Lei, M. Qian, G. Yadavalli, A thermal behavior and kinetics study of the catalytic pyrolysis of lignin, RSC Advances. 6 (2016) 100700–100707. doi:10.1039/c6ra22967k.
 Z. Luo, S. Wang, X. Guo, Selective pyrolysis of Organosolv lignin over zeolites with product analysis by TG-FTIR, Journal of Analytical and Applied Pyrolysis. 95 (2012) 112–117. doi:10.1016/j.jaap.2012.01.014.
 A.B. Hernández, F. Okonta, N. Freeman, Thermal decomposition of sewage sludge under N2, CO2 and air: Gas characterization and kinetic analysis, Journal of Environmental Management. 196 (2017) 560–568. doi:10.1016/j.jenvman.2017.03.036.
 Y. Lin, Y. Liao, Z. Yu, S. Fang, Y. Lin, Y. Fan, X. Peng, X. Ma, Co-pyrolysis kinetics of sewage sludge and oil shale thermal decomposition using TGA-FTIR analysis, Energy Conversion and Management. 118 (2016) 345–352. doi:10.1016/j.enconman.2016.04.004.
 J. Lee, K.H. Kim, E.E. Kwon, Biochar as a Catalyst, Renewable and Sustainable Energy Reviews. 77 (2017) 70–79. doi:10.1016/j.rser.2017.04.002.
 M.B. Folgueras, M. Alonso, R.M. Díaz, Influence of sewage sludge treatment on pyrolysis and combustion of dry sludge, Energy. 55 (2013) 426–435. doi:10.1016/j.energy.2013.03.063.
 S.R. Naqvi, R. Tariq, Z. Hameed, I. Ali, M. Naqvi, W.H. Chen, S. Ceylan, H. Rashid, J. Ahmad, S.A. Taqvi, M. Shahbaz, Pyrolysis of high ash sewage sludge: Kinetics and thermodynamic analysis using Coats-Redfern method, Renewable Energy. 131 (2019) 854–860. doi:10.1016/j.renene.2018.07.094.
 Z. Xiang, J. Liang, H.M. Morgan, Y. Liu, H. Mao, Q. Bu, Thermal behavior and kinetic study for co-pyrolysis of lignocellulosic biomass with polyethylene over Cobalt modified ZSM-5 catalyst by thermogravimetric analysis, Bioresource Technology. 247 (2018) 804–811. doi:https://doi.org/10.1016/j.biortech.2017.09.178.
 J. Liang, H.M. Morgan, Y. Liu, A. Shi, H. Lei, H. Mao, Q. Bu, Enhancement of bio-oil yield and selectivity and kinetic study of catalytic pyrolysis of rice straw over transition metal modified ZSM-5 catalyst, Journal of Analytical and Applied Pyrolysis. 128 (2017) 324–334. doi:10.1016/j.jaap.2017.09.018.
 G. Özsin, A.E. Pütün, TGA/MS/FT-IR study for kinetic evaluation and evolved gas analysis of a biomass/PVC co-pyrolysis process, Energy Conversion and Management. 182 (2019) 143–153. doi:10.1016/j.enconman.2018.12.060.
 G. Özsin, A.E. Pütün, Kinetics and evolved gas analysis for pyrolysis of food processing wastes using TGA/MS/FT-IR, Waste Management. 64 (2017) 315–326. doi:10.1016/j.wasman.2017.03.020.
 L. Huang, C. Xie, J. Liu, X. Zhang, K.L. Chang, J. Kuo, J. Sun, W. Xie, L. Zheng, S. Sun, M. Buyukada, F. Evrendilek, Influence of catalysts on co-combustion of sewage sludge and water hyacinth blends as determined by TG-MS analysis, Bioresource Technology. 247 (2018) 217–225. doi:10.1016/j.biortech.2017.09.039.
 Z. Hameed, Z. Aman, S.R. Naqvi, R. Tariq, I. Ali, A.A. Makki, Kinetic and Thermodynamic Analyses of Sugar Cane Bagasse and Sewage Sludge Co-pyrolysis Process, Energy and Fuels. 32 (2018) 9551–9558. doi:10.1021/acs.energyfuels.8b01972.
 Q. Xu, S. Tang, J. Wang, J.H. Ko, Pyrolysis kinetics of sewage sludge and its biochar characteristics, Process Safety and Environmental Protection. 115 (2018) 49–56. doi:10.1016/j.psep.2017.10.014.
 G. Yu, Y. Feng, D. Chen, M. Yang, T. Yu, X. Dai, In Situ Reforming of the Volatile by Char during Sewage Sludge Pyrolysis, Energy and Fuels. 30 (2016) 10396–10403. doi:10.1021/acs.energyfuels.6b01226.
 J. Yang, X. Xu, S. Liang, R. Guan, H. Li, Y. Chen, B. Liu, J. Song, W. Yu, K. Xiao, H. Hou, J. Hu, H. Yao, B. Xiao, Enhanced hydrogen production in catalytic pyrolysis of sewage sludge by red mud: Thermogravimetric kinetic analysis and pyrolysis characteristics, International Journal of Hydrogen Energy. 43 (2018) 7795–7807. doi:10.1016/j.ijhydene.2018.03.018.
 Z. Xiang, J. Liang, H.M. Morgan Jr, Y. Liu, H. Mao, Q. Bu, Thermal behavior and kinetic study for co-pyrolysis of lignocellulosic biomass with polyethylene over Cobalt modiﬁed ZSM-5 catalyst by thermogravimetric analysis, Bioresource Technology. 247 (2018) 804–811.
 R.O. Arazo, D.A.D. Genuino, M.D.G. de Luna, S.C. Capareda, Bio-oil production from dry sewage sludge by fast pyrolysis in an electrically-heated fluidized bed reactor, Sustainable Environment Research. 27 (2017) 7–14. doi:10.1016/j.serj.2016.11.010.
 H. Hassan, J.K. Lim, B.H. Hameed, Recent progress on biomass co-pyrolysis conversion into high-quality bio-oil, Bioresource Technology. 221 (2016) 645–655. doi:10.1016/j.biortech.2016.09.026.
 J. Alvarez, G. Lopez, M. Amutio, M. Artetxe, I. Barbarias, A. Arregi, J. Bilbao, M. Olazar, Characterization of the bio-oil obtained by fast pyrolysis of sewage sludge in a conical spouted bed reactor, Fuel Processing Technology. 149 (2016) 169–175. doi:10.1016/j.fuproc.2016.04.015.
 M. Tomasi Morgano, H. Leibold, F. Richter, D. Stapf, H. Seifert, Screw pyrolysis technology for sewage sludge treatment, Waste Management. 73 (2018) 487–495. doi:10.1016/j.wasman.2017.05.049.
 T.N. Trinh, P.A. Jensen, D.J. Kim, N.O. Knudsen, H.R. Sørensen, Influence of the pyrolysis temperature on sewage sludge product distribution, bio-oil, and char properties, Energy and Fuels. 27 (2013) 1419–1427. doi:10.1021/ef301944r.
 T.L. Liu, J.P. Cao, X.Y. Zhao, J.X. Wang, X.Y. Ren, X. Fan, Y.P. Zhao, X.Y. Wei, In situ upgrading of Shengli lignite pyrolysis vapors over metal-loaded HZSM-5 catalyst, Fuel Processing Technology. 160 (2017) 19–26. doi:10.1016/j.fuproc.2017.02.012.
 Q.L. Xie, P. Peng, S.Y. Liu, M. Min, Y.L. Cheng, Y.Q. Wan, Y. Li, X.Y. Lin, Y.H. Liu, P. Chen, R. Ruan, Fast microwave-assisted catalytic pyrolysis of sewage sludge for bio-oil production, Bioresource Technology. 172 (2014) 162–168. doi:10.1016/j.biortech.2014.09.006.
 S. Liu, Y. Zhang, L. Fan, N. Zhou, G. Tian, X. Zhu, Y. Cheng, Y. Wang, Y. Liu, P. Chen, R. Ruan, Bio-oil production from sequential two-step catalytic fast microwave-assisted biomass pyrolysis, Fuel. 196 (2017) 261–268. doi:10.1016/j.fuel.2017.01.116.
 S. Ren, H. Lei, L. Wang, Q. Bu, S. Chen, J. Wu, Hydrocarbon and hydrogen-rich syngas production by biomass catalytic pyrolysis and bio-oil upgrading over biochar catalysts, RSC Advances. 4 (2014) 10731–10737. doi:10.1039/c4ra00122b.
 Q. Xie, M. Addy, S. Liu, B. Zhang, Y. Cheng, Y. Wan, Y. Li, Y. Liu, X. Lin, P. Chen, R. Ruan, Fast microwave-assisted catalytic co-pyrolysis of microalgae and scum for bio-oil production, Fuel. 160 (2015) 577–582. doi:10.1016/j.fuel.2015.08.020.
 H. Wu, D.M. Quyn, C.-Z. Li, Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part III. The importance of the interactions between volatiles and char at high temperature, Fuel. 81 (2002) 1033–1039. doi:https://doi.org/10.1016/S0016-2361(02)00011-X.