title: The Dilemma of Supporting Electrolytes for Electroorganic Synthesis: A Case Study on Kolbe Electrolysis.
abstract: Remarkably, coulombic efficiency (CE, about 50 % at 1 Farad equivalent), and product composition resulting from aqueous Kolbe electrolysis are independent of reactor temperature and initial pH value. Although numerous studies on Kolbe electrolysis are available, the interrelations of different reaction parameters (e.g., acid concentration, pH, and especially electrolytic conductivity) are not addressed. A systematic analysis based on cyclic voltammetry reveals that solely the electrolytic conductivity impacts the current-voltage behavior. When using supporting electrolytes, not only their concentration, but also the type is decisive. We show that higher concentrations of KNO3 result in reduced CE and thus in significant increase in electric energy demand per converted molecule, whereas Na2 SO4 allows improved space-time yields. Pros and cons of adding supporting electrolytes are discussed in a final cost assessment.
authors.affiliation: UFZ-Helmholtz-Centre for Environmental Research, Department of Environmental Microbiology, Permoserstraße 15, 04318, Leipzig, Germany), Fax: (+49) 341-235-1351.
authors.forename: Carolin
authors.initials: C
authors.lastname: Stang
authors.affiliation: UFZ-Helmholtz-Centre for Environmental Research, Department of Environmental Microbiology, Permoserstraße 15, 04318, Leipzig, Germany), Fax: (+49) 341-235-1351. falk.harnisch@ufz.de.
authors.forename: Falk
authors.initials: F
authors.lastname: Harnisch
mesh_terms: D002384:Catalysis; D060326:Chemistry Techniques, Synthetic / Q000379:methods*; D004563:Electrochemistry; D004566:Electrodes; D004572:Electrolysis / Q000379:methods*; D004573:Electrolytes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000737:chemistry; D010421:Pentanoic Acids / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D013696:Temperature
chemical_list: D004573:Electrolytes; D009566:Nitrates; D010421:Pentanoic Acids; D017680:Potassium Compounds; D013431:Sulfates; C012036:sodium sulfate; D010984:Platinum; C038780:n-pentanoic acid; C023844:potassium nitrate
keywords: cyclic voltammetry; electrochemical oxidation; electrolytes; electrolytic conductivity; electroorganic synthesis