Campus Units
Chemical and Biological Engineering, NSF Engineering Research Center for Biorenewable Chemicals
Document Type
Article
Research Focus Area
Biorenewables, Catalysis and Reaction Engineering
Publication Version
Accepted Manuscript
Publication Date
3-27-2020
Journal or Book Title
Chemical Engineering Journal
First Page
124878
DOI
10.1016/j.cej.2020.124878
Abstract
Catalytic upgrading of pyrolysis vapors from wheat straw over Na2CO3 impregnated γ-Al2O3 was studied as a promising route to biofuels. The Na species were homogenously distributed on the support and created a basicity of ∼0.02 mmol CO2/g catalyst, at 80% lower catalyst acidity. Analytical pyrolysis using a micro-pyrolyzer showed that Na-Al2O3 particularly decreased the yield of acids via ketonization, which was confirmed by feeding carboxylic acid model compounds. The presence of Na decreased the coke yield and catalyzed the coke combustion, decreasing the combustion temperature by ∼100 °C.
Subsequently, 100 g Na-Al2O3 catalyst was tested in an ablative bench scale fast pyrolysis unit where ∼5 kg of wheat straw was pyrolyzed and the vapors passed the catalytic reactor during six reaction/regeneration cycles. In agreement with the micro-pyrolyzer results, Na-Al2O3 was highly effective in reducing the acidity of the bio-oils. Total acid numbers (TAN) as low as ∼1-4 mg KOH/mg could be maintained up to high B:C ratios of ∼13. For a given TAN, this allowed operating to higher B:C ratios and provided higher oil yields compared to using acidic catalysts such as γ-Al2O3 and HZSM-5 zeolite for vapor treatment. At bio-oil energy recoveries of ∼60-70% relative to raw bio-oil, the deoxygenation was comparable to the acidic catalysts. Operation to higher B:C ratios allowed increasing the energy recovery to ∼85% relative to the non-treated bio-oil while still obtaining a good deoxygenation performance of ∼60%. Despite the hydrothermal conditions during reaction and oxidative regeneration, the activity of Na-Al2O3 was regained by coke combustion, the Na remained well dispersed on the support, and the catalyst maintained its capacity for CO2 adsorption at 500 °C after six reaction/regeneration cycles.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Copyright Owner
Elsevier B.V.
Copyright Date
2020
Language
en
File Format
application/pdf
Recommended Citation
Eschenbacher, Andreas; Saraeian, Alireza; Arendt Jensen, Peter; Shanks, Brent H.; Li, Chengxin; Øllgaard Duus, Jens; Lyck Smitshuysen, Thomas Erik; Danvad Damsgaard, Christian; Baltzer Hansen, Asger; Kling, Kirsten Inga; Vie Mentzel, Uffe; Henriksen, Ulrik Birk; Ahrenfeldt, Jesper; and Degn Jensen, Anker, "Deoxygenation of wheat straw fast pyrolysis vapors over Na-Al2O3 catalyst for production of bio-oil with low acidity" (2020). Chemical and Biological Engineering Publications. 417.
https://lib.dr.iastate.edu/cbe_pubs/417
Included in
Bioresource and Agricultural Engineering Commons, Catalysis and Reaction Engineering Commons, Oil, Gas, and Energy Commons, Sustainability Commons
Comments
This is a manuscript of an article published as Eschenbacher, Andreas, Alireza Saraeian, Peter Arendt Jensen, Brent H. Shanks, Chengxin Li, Jens Øllgaard Duus, Thomas Erik Lyck Smitshuysen et al. "Deoxygenation of wheat straw fast pyrolysis vapors over Na-Al2O3 catalyst for production of bio-oil with low acidity." Chemical Engineering Journal (2020): 124878. DOI: 10.1016/j.cej.2020.124878. Posted with permission.