Extractive Catalytic Oxidative Deoxygenation of Model Fuels Catalyzed by a Vanadium-Substituted Heteropolyacid and Molecular Oxygen

Abstract

Extractive catalytic oxidative deoxygenation (ECODO) completes extractive catalytic oxidative desulfurization (ECODS) and extractive catalytic oxidative denitrogenation by removing organic oxygen from fuels. This is particularly necessary for renewable fuels to make them more stable and efficient. In ECODO, compounds such as cresol, furan, and their derivatives could be completely oxidized under oxygen at 20 bar and 120 °C using an aqueous heteropolyacid catalyst solution. The oxidation products were separated in situ in the three-phase process, either as CO 2 or CO in the gas phase or as water-soluble organic acids like formic and acetic acid as well as acetone. In the case of stable dibenzofuran (DBF), the conversion could be drastically increased from only 27% to above 50% by tuning the reaction conditions and optimizing the catalyst loading by a design of experiment. Moreover, the amount of oxygen in the gas phase could be drastically reduced from 20 to 4 bar operating in 20 bar of synthetic air without limiting the performance of the catalyst. Furthermore, it could be shown that the parallel ECODS in the presence of an oxygenate like DBF leads to better desulfurization of model gasoline than without. The ECODO therefore offers a potential alternative to the classical hydrodeoxygenation, which is not only more energy-efficient but also replaces the expensive hydrogen with cheap air and avoids additional unit operations for fuel cleaning.

Extraction-Coupled Oxidative Desulfurization (ECODS) of n-Tetradecane as Model Oil under Moderate Conditions Using Molecular Oxygen

“…This approach is called extraction-coupled oxidative desulfurization (ECODS). ,− The ECODS process operates in a biphasic mode where water is used as a second phase. Herein, the catalyst, a P-V-Mo Keggin polyoxometalate, is dissolved in the aqueous phase and transforms the sulfur compounds into highly water-soluble products that are extracted in situ into the aqueous catalyst phase.…”

Revealing the nitrogen reaction pathway for the catalytic oxidative denitrification of fuels

“…The sulfur containing fuel components are oxidized after diffusion from the organic fuel phase into the aqueous catalyst phase, to form highly polar products such as H 2 SO 4 and carboxylic acids, which are thereby extracted from the organic fuel phase and accumulate in the aqueous phase. [24][25][26][27] In contrast to the inhibiting properties of the basic nitrogen compounds in hydrotreating, the oxidative desulfurization improves with simultaneous denitrification in this system (ECODN; extractive catalytic oxidative denitrogenation). 26 The reaction pathway of ECODS has already been well studied.…”