scholarly journals Catalytic Pyrolysis of Aliphatic Carboxylic Acids into Symmetric Ketones over Ceria-Based Catalysts: Kinetics, Isotope Effect and Mechanism

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 179 ◽  
Author(s):  
Tetiana Kulik ◽  
Borys Palianytsia ◽  
Mats Larsson
Keyword(s):  
Carboxylic Acids ◽  
Isotope Effect ◽  
Catalytic Pyrolysis ◽  
Value Added ◽  
Linear Free Energy ◽  
Kinetic Isotope ◽  
Energy Relationships ◽  
Temperature Programmed ◽  
Aliphatic Carboxylic Acids ◽  
Pyrolysis Of Biomass

Ketonization is a promising way for upgrading bio-derived carboxylic acids from pyrolysis bio-oils, waste oils, and fats to produce high value-added chemicals and biofuels. Therefore, an understanding of its mechanism can help to carry out the catalytic pyrolysis of biomass more efficiently. Here we show that temperature-programmed desorption mass spectrometry (TPD-MS) together with linear free energy relationships (LFERs) can be used to identify catalytic pyrolysis mechanisms. We report the kinetics of the catalytic pyrolysis of deuterated acetic acid and a reaction series of linear and branched fatty acids into symmetric ketones on the surfaces of ceria-based oxides. A structure–reactivity correlation between Taft’s steric substituent constants Es* and activation energies of ketonization indicates that this reaction is the sterically controlled reaction. Surface D3-n-acetates transform into deuterated acetone isotopomers with different yield, rate, E≠, and deuterium kinetic isotope effect (DKIE). The obtained values of inverse DKIE together with the structure–reactivity correlation support a concerted mechanism over ceria-based catalysts. These results demonstrate that analysis of Taft’s correlations and using simple equation for estimation of DKIE from TPD-MS data are promising approaches for the study of catalytic pyrolysis mechanisms on a semi-quantitative level.

scholarly journals Catalytic Pyrolysis of Lignin Model Compounds (Pyrocatechol, Guaiacol, Vanillic and Ferulic Acids) over Nanoceria Catalyst for Biomass Conversion

2021 ◽  
Vol 11 (16) ◽  
pp. 7205
Author(s):  
Nataliia Nastasiienko ◽  
Tetiana Kulik ◽  
Borys Palianytsia ◽  
Julia Laskin ◽  
Tetiana Cherniavska ◽  
...  
Keyword(s):  
Catalytic Pyrolysis ◽  
Biomass Conversion ◽  
Value Added ◽  
Spectroscopic Studies ◽  
Surface Complexes ◽  
General Transformation ◽  
Carboxylate Groups ◽  
Transformation Mechanisms ◽  
Ft Ir ◽  
Temperature Programmed

Understanding the mechanisms of thermal transformations of model lignin compounds (MLC) over nanoscale catalysts is important for improving the technologic processes occurring in the pyrolytic conversion of lignocellulose biomass into biofuels and value-added chemicals. Herein, we investigate catalytic pyrolysis of MLC (pyrocatechol (P), guaiacol (G), ferulic (FA), and vanillic acids (VA)) over nanoceria using FT-IR spectroscopy, temperature-programmed desorption mass spectrometry (TPD MS), and thermogravimetric analysis (DTG/DTA/TG). FT-IR spectroscopic studies indicate that the active groups of aromatic rings of P, G, VA, and FA as well as carboxylate groups of VA and FA are involved in the interaction with nanoceria surface. We explore the general transformation mechanisms of different surface complexes and identify their decomposition products. We demonstrate that decomposition of carboxylate acid complexes occurs by decarboxylation. When FA is used as a precursor, this reaction generates 4-vinylguaiacol. Complexes of VA and FA formed through both active groups of the aromatic ring and decompose on the CeO2 surface to generate hydroxybenzene. The formation of alkylated products accompanies catalytic pyrolysis of acids due to processes of transalkylation on the surface.

scholarly journals Catalytic Pyrolysis of Biomass and Polymer Wastes

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 659 ◽  
Author(s):  
Laibao Zhang ◽  
Zhenghong Bao ◽  
Shunxiang Xia ◽  
Qiang Lu ◽  
Keisha Walters
Keyword(s):  
Catalytic Pyrolysis ◽  
Catalyst Deactivation ◽  
Value Added ◽  
Catalyst Design ◽  
Production Costs ◽  
Practical Utilization ◽  
High Oxygen Content ◽  
Polymer Waste ◽  
Caloric Value ◽  
Pyrolysis Of Biomass

Oil produced by the pyrolysis of biomass and co-pyrolysis of biomass with waste synthetic polymers has significant potential as a substitute for fossil fuels. However, the relatively poor properties found in pyrolysis oil—such as high oxygen content, low caloric value, and physicochemical instability—hampers its practical utilization as a commercial petroleum fuel replacement or additive. This review focuses on pyrolysis catalyst design, impact of using real waste feedstocks, catalyst deactivation and regeneration, and optimization of product distributions to support the production of high value-added products. Co-pyrolysis of two or more feedstock materials is shown to increase oil yield, caloric value, and aromatic hydrocarbon content. In addition, the co-pyrolysis of biomass and polymer waste can contribute to a reduction in production costs, expand waste disposal options, and reduce environmental impacts. Several promising options for catalytic pyrolysis to become industrially viable are also discussed.

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