Incorporation of Complex Reaction Sequences in Engineering Models of Electrolytic Cells: I . Paired Synthesis of Propylene Oxide in an Undivided Cell

Abstract

A reaction sequence involving 11 chemical species was incorporated into a mathematical model of an electrolytic cell consisting of an undivided parallel-plate reactor operating under steady, continuous flow conditions. The set of coupled, nonlinear, stiff differential equations was solved numerically by dynamic simulation. The technique was applied to the paired synthesis of propylene oxide from propylene-saturated bromide electrolyte. For this system, the eigenvalues associated with the jacobian ranged over ten orders of magnitude. The effect of pH, [Br-], mass transfer, space time, and current density were explored to understand their influence on yield, selectivity, conversion, current efficiency, and cell voltage. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 141.217.58.200 Downloaded on 2015-04-08 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 141.217.58.200 Downloaded on 2015-04-08 to IP Vol. 132,No. 8 COMPLEX REACTION SEQUENCES ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 141.217.58.200 Downloaded on 2015-04-08 to IP Vol. 132, No. 8 COMPLEX REACTION SEQUENCES ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 141.217.58.200 Downloaded on 2015-04-08 to IP

Mass Transfer Requirements for Alternating Polarity, Alternating Voltage Synthesis

“…Homogeneous side reactions.--A detailed discussion of side reactions is available (35). Organic side reactions occur from the reaction of bromine and propylene, since the bromonium ion intermediate is available for nucleophiles other than water.…”

“…Propylene oxide is susceptible to attack by water since the epoxide ring is readily attacked eve n by weak nucleophiles. In basic solutions, the SN1 and SN2 hydroxide ioncatalyzed reactions are the dominant mechanisms of glycol formation (36,37) O \ OH CH3CH / CH2 + H20--~ CH3 CH--CH2OH [7] Bromodydrin can be quantitatively converted to oxide, owing to the large rate difference between the bromohydrin-oxide and oxide-glycol reactions (35). Bromine may form polybromides Br3-and Brs-.…”

“…[2], is 1.23 x 1017 (35) Atx=~: c=0 [16] Nondimensional equations.--The model equations were made dimensionless with reference quantities. Concentrations were scaled against the bromide ion concentration.…”

Economics of Electrolytic Processing

“…Despite the applicability of these mechanisms to numerous reac- (23) has been developed, in accessible form, only for the simplest redox reaction, i.e., Ox + ne-= Red. The recent work of AIkire and Lisius (27) demonstrates that complex reaction sequences can be incorporated into engineering models of electrolytic cells. Progress in electrochemical reactor design will greatly clarify the applicability of the e]ectrosynthetic method and lead to new applications.…”

Theoretical analysis of the effects of operational and designed parameters on the performance of a flow-through porous electrode

“…There have been several treatments and models of the three dimensional porous electrode developed over the years [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. A one dimensional mathematical model was proposed by Sun and Scott [3] to describe the distributions of concentration and current density, the overall cell polarization and the effective factors.…”