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Vapor-phase Stabilization of Biomass Pyrolysis Vapors Using Mixed-metal Oxide Catalysts

preprint
revised on 26.02.2019 and posted on 27.02.2019 by Charles W. Edmunds, Calvin Mukarakate, Mengze Xu, Yagya N. Regmi, Choo Hamilton, Joshua A. Schaidle, Nicole Labbé, Stephen Chmely
Mixed-metal oxides possess a wide range of tunability and show promise for catalytic stabilization of biomass pyrolysis products. For materials derived from layered double hydroxides, understanding the effect of divalent cation species and divalent/trivalent cation stoichiometric ratio on catalytic behavior is critical to their successful implementation. In this study, four mixed-metal oxide catalysts consisting of Al, Zn, and Mg in different stoichiometric ratios were synthesized and tested for ex-situ catalytic fast pyrolysis (CFP) using pine wood as feedstock. The catalytic activity and deactivation behavior of these catalysts were monitored in real-time using a lab-scale pyrolysis reactor and fixed catalyst bed coupled with a molecular beam mass spectrometer (MBMS), and data were analyzed by multivariate statistical approaches. In comparing Mg- and Zn-Al catalyst materials, we demonstrate that the Mg-Al materials possessed greater quantities of basic sites, which we attribute to their higher surface areas, and they produced upgraded pyrolysis vapors which contained less acids and more deoxygenated aromatic hydrocarbons such as toluene and xylene. However, detrimental impacts on carbon yields were realized via decarbonylation and decarboxylation reactions and coke formation. Given that the primary goals of catalytic upgrading of bio-oil are deoxygenation, reduction of acidity, and high carbon yield, these results highlight both promising catalytic effects of mixed-metal oxide materials and opportunities for improvement.

Funding

DOE EERE DE-EE0006639

USDA Hatch Project 1012359

DOE DE-AC36-08GO28308

History

Email Address of Submitting Author

schmely@utk.edu

Institution

University of Tennessee Institute of Agriculture

Country

United States

ORCID For Submitting Author

0000-0002-2637-9974

Declaration of Conflict of Interest

The authors declare no conflicts of interest

Version Notes

Version 02- response to reviewer comments

Exports