(25b) Advancement of Catalytic Fast Pyrolysis of Biomass to Produce Renewable Fuels

Catalytic fast pyrolysis (CFP) using bifunctional metal-acid catalysts is a practical approach for converting biomass into high yields of stabilized biocrude (CFP-oil) for either standalone hydrotreating or coprocessing in existing petroleum refineries to produce fuels. We have been developing an integrated fixed-bed CFP technology coupled with hydrotreating (HT) to produce hydrocarbon fuel blendstocks from lignocellulosic biomass^1-2. Experiments conducted in a bench-scale reactor using Pt/TiO₂ with co-fed H₂ demonstrated production of CFP-oils with ≥35% carbon yields and <20wt% oxygen contents on dry basis. The CFP process and Pt/TiO₂ catalyst robustness was demonstrated by evaluating 50% clean pine and 50% forest residue blends and over 100 cycles with the same catalyst bed. Hypothesis-driven modification to the Pt/TiO₂ led to greater than 500% improvement in time-on-stream (2h vs > 15h) per CFP cycle while producing oils with similar carbon yields and oxygen contents. The residual oxygen in the Pt/TiO₂ CFP-oils was reduced to <1wt% using a single-stage standalone hydrotreater that was operated for over 100h to produce hydrocarbon blendstocks. The integrated CFP—HT results were coupled with technoeconomic analysis and achieved a modelled minimum fuel selling price (MFSP) of $3.33/GGE, assuming capture and recovery of coproducts generated during the CFP process. Even though these results were encouraging there are still important research questions that need to be addressed to make the integrated CFP—HT technology cost competitive and to scale up. Recently we demonstrated that capturing CFP-derived coproducts and co-hydrotreating of the Pt/TiO₂ CFP-oil with straight-run diesel can lower MFSP to <$3.00/GGE and reduce GHG emissions by 60% compared to petroleum derived gasoline. This presentation seeks to demonstrate progress made in advancing the integrated CFP—HT process by linking catalyst performance and process development, guided by technoeconomic and life-cycle analyses, and highlighting the importance of computational modeling^3-4 in scaling up the technology.

References

1. Griffin, M. B.; Iisa, K.; Wang, H.; Dutta, A.; Orton, K. A.; French, R. J.; Santosa, D. M.; Wilson, N.; Christensen, E.; Nash, C.; Van Allsburg, K. M.; Baddour, F. G.; Ruddy, D. A.; Tan, E. C. D.; Cai, H.; Mukarakate, C.; Schaidle, J. A., Driving towards cost-competitive biofuels through catalytic fast pyrolysis by rethinking catalyst selection and reactor configuration. Energy & Environmental Science 2018, 11 (10), 2904-2918.
2. French, R. J.; Iisa, K.; Orton, K. A.; Griffin, M. B.; Christensen, E.; Black, S.; Brown, K.; Palmer, S. E.; Schaidle, J. A.; Mukarakate, C.; Foust, T. D., Optimizing Process Conditions during Catalytic Fast Pyrolysis of Pine with Pt/TiO2—Improving the Viability of a Multiple-Fixed-Bed Configuration. ACS Sustainable Chemistry & Engineering 2021, 9 (3), 1235-1245.
3. Pecha, M. B.; Iisa, K.; Griffin, M.; Mukarakate, C.; French, R.; Adkins, B.; Bharadwaj, V. S.; Crowley, M.; Foust, T. D.; Schaidle, J. A.; Ciesielski, P. N., Ex situ upgrading of pyrolysis vapors over PtTiO2: extraction of apparent kinetics via hierarchical transport modeling. Reaction Chemistry & Engineering 2021, 6 (1), 125-137.

4. Adkins, B. D.; Mills, Z.; Parks Ii, J.; Pecha, M. B.; Ciesielski, P. N.; Iisa, K.; Mukarakate, C.; Robichaud, D. J.; Smith, K.; Gaston, K.; Griffin, M. B.; Schaidle, J. A., Predicting thermal excursions during in situ oxidative regeneration of packed bed catalytic fast pyrolysis catalyst. Reaction Chemistry & Engineering 2021, 6 (5), 888-904.