Sustainable Electrocoupling of the Biogenic Valeric Acid under in Situ Low-Field Nuclear Magnetic Resonance Conditions

Author(s)

Gomes, Bruna Ferreira ^{[1, 2]} ; Holzhaeuser, Fabian Joschka ^[3] ; Silva Lobo, Carlos Manuel ^[1] ; da Silva, Pollyana Ferreira ^[1] ; Danieli, Ernesto ^[4] ; Carmo, Marcelo ^[5] ; Colnago, Luiz Alberto ^[6] ; Palkovits, Stefan ^[3] ; Palkovits, Regina ^[3] ; Bluemich, Bernhard ^[3]

Affiliation

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, Av Trab Sao Carlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[2] Univ Bayreuth, Dept Mat Proc Engn, Univ Str 30, D-95447 Bayreuth - Germany

^[3] Rhein Westfal TH Aachen, Inst Tech & Macromol Chem, Worringerweg 2, D-52074 Aachen - Germany

^[4] Magritek GmbH, Philipsstr 8, D-52068 Aachen - Germany

^[5] Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich - Germany

^[6] Embrapa Instrumentacao, R 15 Novembro, 1452 Ctr, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: ACS SUSTAINABLE CHEMISTRY & ENGINEERING; v. 7, n. 22, p. 18288-18296, NOV 18 2019.
• Web of Science Citations: 1

Abstract

In situ nuclear magnetic resonance (NMR) investigations of a Kolbe electrolysis reaction using a 43 MHz H-1 NMR spectrometer were performed in this work. The electrochemical oxidative decarboxylation of biomass-derived valeric acid into the value-added product n-octane has been monitored. All reactions were conducted in nondeuterated methanolic solution, using KOH as the supporting electrolyte. The working and counter electrodes consisted of Pt wire, and Ag wire was used as a pseudo-reference electrode. The influence of the magnetic field on the reaction kinetics, as well as on mass transfer, has been studied in detail. The findings show that the resulting mass transfer is highly dependent on the magnetic field. The significantly higher reaction velocity for in situ experiments is partly due to the strong Lorentz force, which agitates the solution and reduces the thickness of the electric double layer. The obtained results also suggest a strong influence of the magnetic field on the charge transfer from the electrode to the solution. The total resistance for the electrochemical reaction was significantly reduced by the presence of the magnetic field for all in situ experiments, at all points of the reaction. According to the reaction products, it was found that, at high applied potentials (>5 V) or currents (>15 mA), the reaction velocity can be increased but evaporation and overoxidation phenomena become more apparent. The results presented here show how NMR in situ electrochemistry can help to determine the optimal reaction conditions and improve quantitative analyses by example of a prominent green chemistry application. (AU)

• FAPESP's process: 12/22281-9 - NMR study of the magneto-convective phenomenon on paramagnetic ions during electrodeposition
• Grantee: Bruna Ferreira Gomes Lobo
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 16/01537-6 - Study of the coupling between electrochemistry and low-field, mid-resolution NMR for the in situ and on line analysis of redox reactions of organic compounds and the evaluation of the magnetic field effect on the velocity of the in situ reactions
• Grantee: Bruna Ferreira Gomes Lobo
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)