Feasibility of an Electrochemical Membrane Reactor for the Partial Oxidation of n-Butane to Maleic Anhydride

Abstract

The feasibility of n-butane partial oxidation to maleic anhydride (MA) over vanadium phosphorus oxide catalysts in an electrochemical membrane reactor in which an oxygen-ion-conducting electrolyte was used as the membrane was studied. Butane oxidation and oxygen separation were carried out simultaneously on the opposite surfaces of the membrane, and the oxygen flux transferred across the membrane was controlled by the external current between the two electrodes. At 751 K and with a current of 40 mA, the conversion of butane was 15−16%, and the selectivity to MA was about 39%. The selectivity and yield of MA increased with increasing applied current. The optimal reaction temperature was 750 ± 5 K, as a compromise among the ionic conductivity of the membrane, the polarization resistances of the electrodes, and the selectivity and the yield of MA.

Solid Electrolyte Membrane Reactors

“…From the above considerations, one can then conclude that, under the given operation conditions (Ye et al , 2004 ), the electrochemical MA synthesis can be practically divided into two locally separated reaction steps. The fi rst step comprises all charge transport processes and the electrochemical charge transfer reactions within the SE membrane and a narrow surface region of the electrodes.…”

“…The partial oxidation of n -butane to maleic anhydride, on the one hand, is still the only industrial application of the direct partial oxidation of alkanes (Centi, Cavani, and Trifi ro, 2001 ) and, on the other hand, it exhibits the typical properties of selective oxidations. In our laboratory we (Ye et al , 2004 ) studied experimentally the feasibility of electrocatalytic synthesis for this reaction. However, theoretical analysis and model simulations are necessary in order to evaluate the reactor performance and to provide an effi cient design and optimal operation conditions.…”

“…The details of the experimental setup are given by Ye et al ( 2004 ) and Ye ( 2006 ). The experimental data published by Ye et al (2004 ) were used to determine the conductivity constant, C SE , and the activation enthalpy, E A SE , by a least square fi t of the modifi ed Arrhenius -type equation (7.11) . Table 7.2 lists the obtained parameter values; Figure 7.8 shows the experimental data and the simulated conductivity as a function of the inverse temperature.…”

“…The characteristic isothermal current -voltage behavior obtained from oxygenpumping experiments (Ye et al ., 2004 ) were used in order to determine the unknown kinetic parameters for the electrochemical reactions ( 7.12 , 7.13 ). The experimental setup did not include a reference electrode and therefore the cathodic and the anodic charge transfer processes could not be measured separately.…”

Alternative Reaction Engineering Concepts in Partial Oxidations on Oxidic Catalysts

“…In the partial oxidation of n-butane to maleic anhydride, the potential of an electrochemical membrane reactor has been investigated recently (100). A vanadium phosphorous oxide catalyst on gold has been used as a catalytically active anode, and the oxygen flux was controlled by the external applied current.…”