Objective 1: Develop thermochemical and/or catalytic, carbon efficient biomass conversion processes to produce bio-oils and bio-gas containing fractions suitable for use towards advanced commercially viable bio-fuels (jet, diesel, and gasoline carbon ranges). This includes co-conversion of biomass with other carbon sources (e.g., plastics from both agricultural and environmental waste) to enhance carbon efficiency. [NP306, C3, PS3A] Objective 2. Develop pre- and post-process thermo-catalytic depolymerization, distillation and extraction technologies to produce renewable chemicals and biocarbon materials from biomass, biochar, lignin and/or condensed phase bio-oils (furans, phenolics, chiral anhydrosugars, aromatics, biocoke fibers). [NP306, C3, PS3A] Objective 3: Identify and develop new feedstocks and accompanying technologies to produce biodiesel, renewable hydrocarbon diesel and biojet fuels from fats and oils. [NP306, C3, PS3A] Objective 4. Accurately estimate the economic values of thermolysis conversion processes to produce bio-based fuels and chemicals. [NP306, C3, PS3C]
Efficient processes will be developed for the thermo-catalytic conversion of lignocellulosic biomass and alternative fats and oils into advanced biofuels and renewable chemicals. For lignocellulose, advanced pyrolysis processes will be developed that balance deoxygenation and carbon efficiency for thermochemical biomass conversion in multifaceted ways. Processes that reduce the severity of deoxygenation during pyrolysis and produce stable, mid-level oxygen (~20-25 wt%) content (MLO) bio-oil will be developed. Some oxygen containing species can be valuable products in the petrochemicals space. Additionally, processes will be developed that achieve a high level of deoxygenation (= 10 wt%) at a higher carbon efficiency than the current state of the art to target nearly finish drop-in fuels. This effort will include reactive pyrolysis methods to recapture carbon and hydrogen that is generally lost to gaseous products. Methods involving co-processing of biomass with waste plastics (polyolefins) will be explored, exploiting the high H/C and low O/C properties of the plastic to increase the efficiency of the biomass conversion. Separations and refining processes for the produced bio-oils and other biorefinery feedstocks will be also be studied. A research goal is to enhance production of 1) phenol, alkyl phenols and aromatic hydrocarbons 2) furans, anhydrosugars and other oxygenates 3) renewable calcined coke and coal-tar alternatives for aluminum smelting applications, and other carbonaceous solids via conversion of lignin, biomass pyrolysis oils and pyrolysis oil distillation residues. Finer separations processes for bio-oils are also needed to improve the quality of the synthesized coproducts. Finer separation of the whole oils (low and/or medium oxygenated oils) based on oxygenated species may lead to 1) increased downstream process yields and 2) increase the quality of calcined coke coproduct (chemical and/or physical properties). Alternative lipids sources such as fats, oils and greases from brown grease lipids (BGL), poultry fat, tallow, distillers’ corn oil and other sources will be converted to biodiesel via transesterification and renewable hydrocarbon diesel (RHD) via catalytic hydrotreatment and isomerization. These feedstocks have not been proven as suitable for either biodiesel or renewable hydrocarbon diesel. Elevated sulfur content in these feedstocks results in biodiesels or RHD that do not meet the ASTM specification for sulfur. A combined approach to sulfur removal will be taken, involving distillation and selective adsorption, will be employed and we will evaluate the process of converting fatty acids derived BGL into RHD. Techno-economic analysis (TEA) and life cycle analysis (LCA) models will be developed to advise the economic viability of the processes developed in this project.
Objective 1: 1) We continued experiments started in the previous reporting period on depolymerizing lignin via solvent liquefaction. In addition to the variables previously tested (temperature, concentration, and use of low and high boiling solvents), the effect of treating various fractions of lignin separately was evaluated. Lignin was first fractionated via solvent extraction with ethyl acetate and then methanol, creating three fractions. It was found that these fractions had different depolymerization rates. We also developed a diffusion nuclear magnetic resonance (NMR) based method to determine the average molecular weight of the bio-oils produced. This allowed for the analysis of the depolymerization rate of the lignins without interference from solvent-based impurities, which is impossible with the GPC method of determining average molecular weight. 2) We also continued analytical scale experiments using biochar as a catalyst for the production of mid-level oxygen (MLO) content bio-oil from biomass and biomass/polyolefin mixtures via catalytic pyrolysis. We have previously reported the effectiveness of rice-hull-derived biochar for the production of MLO bio-oil. Further experiments are needed to optimize conditions to achieve MLO with very high carbon efficiency. 3) We continued high throughput studies to discover catalysts for co-processing of biomass with plastic waste. Carbon-based and some metal oxide catalysts look promising. Furthermore, we conducted preliminary experiments on biomass-assisted depolymerization of polyethylene under hydrothermal conditions, finding metal oxide catalysts effective for aiding in depolymerization efficiency. Objective 2: 1) We successfully demonstrated the continuous calcination of blends of biocoke and petroleum coke. A tube furnace conveyed sized coke solids, and elemental characterization of the products demonstrated a reduction in metallic impurities, sulfur impurities and also maintenance of necessary crystalline properties. 2) Using bio-oil distillation residues and oils produced as side products from biomass liquefaction, we demonstrated the synthesis of renewable versions of coal tar pitch. The product was obtained by taking bio-oil distillation residues from continuous flash distillation and removing the toluene insoluble, then heating the solubles to particular temperatures. We produced a biopitch product with nearly 50 wt% coking value relatively low amounts of toluene insolubles (~32 wt), and trace amounts of quinoline insoluble. Objective 3: 1) Brown grease lipids (BGL) in the form of trap grease and sewage scum grease, collected from local municipal underground grease traps and wastewater treatment plants, respectively, were converted to biodiesel in collaboration with Environmental Fuels LLC. Other oil-bearing sources that have been identified include Chinese Tallow Tree seeds received from Louisiana State University (MTA ID 15918) and yellow beans received from Delaware State University (MTRA Agreement 58-8072-9-021). The yellow beans have been extracted and subjected to lipid and fatty acid composition analysis. The Chinese Tallow Tree Seeds have only been received. 2) In collaboration with Environmental Fuels, LLC, protocols to purify brown grease lipids and reduce them to FFA were developed. Conversion of the FFAs to biodiesel or biojet fuels has not been initiated. Objective 4: 1) In collaboration with Drexel University, we performed life cycle analysis (LCA) calculations on scaled-up versions of the continuous biocoke calcination process, using the data obtained from continuous experiments. If scaled and adopted by the industry, we found that this process would reduce GHG emissions by 54% and acidification potential (due to sulfur) by 27%.
Elkasabi, Y.M., Mullen, C.A. 2021. Progress on biobased industrial carbons as thermochemical biorefinery coproducts. Review Article. https://doi.org/10.1021/acs.energyfuels.1c00182?rel=cite-as&ref=PDF&jav=VoR.
Elkasabi, Y.M., Omolayo, Y., Spatari, S. 2021. Continuous calcination of biocoke/petcoke blends in a rotary tube furnace. ACS Sustainable Chemistry & Engineering. 9:695-703. https://doi.org/10.1021/acssuschemeng.0c06307?ref=pdf.
Spatari, S., Larnaudie, V., Mannoh, I., Wheller, M.C., Macken, N.M., Mullen, C.A., Boateng, A.A. 2020. Environmental, exergetic and economic tradeoffs for catalytic and fast pyrolysis-to-renewable diesel. Renewable Energy. 162:371-380. https://doi.org/10.1016/j.renene.2020.08.042.
Raymundo, L.M., Mullen, C.A., Boateng, A.A., Desisto, W.J., Trierweiler, J.O. 2020. Production of partially deoxygenated pyrolysis oil from switchgrass via Ca(OH)2, CaO and Ca(COOH)2 co-feeding. Energy and Fuels. 34:12616-12625. https://doi.org/10.1021/acs.energyfuels.0c01784.
Patel, M., Mullen, C.A., Gunukula, S., Desisto, W.J. 2020. Fast pyrolysis of lignin pre-treated with magnesium formate and magnesium hydroxide. Energies. 13:4995.
Isah, S., Zhang, J., Biresaw, G., Strahan, G.D., Nunez, A., Wyatt, V.T., Ngo, H, Ozbay, G. 2021. Synthesis of Dimer Acid 2-Ethylhexyl Esters and their Physicochemical Properties as Biolubricant Base Stock and their Potential as Additive in Commercial Base Oils. Journal of the American Oil Chemists' Society. 98(6):683–695. https://doi.org/10.1002/aocs.12455.