TY - JOUR
T1 - Intermediate product yield enhancement with a catalytic inorganic membrane
T2 - I. Analytical model for the case of isothermal and differential operation
AU - Harold, M.P.
AU - Zaspalis, V.T.
AU - Keizer, K.
AU - Burggraaf, A.J.
PY - 1993
Y1 - 1993
N2 - A simple model is developed to examine the performance of a supported
catalytic membrane within which occurs the consecutive-parallel reaction
system given by A + B → R, with rate = k1pαA1ApαBB, and A + R → P, with rate = k2pαA2ApαRR.
Closed-form solutions reveal that segregation of reactants A and B to
opposite sides of the membrane is an effective strategy for increasing
the desired product (R) point yield. However, increases in the component
R yield come at the expense of the point catalyst utilization, due, in
part, to depletion of reacting components B and R. The membrane
performance is sensitive to the relative reaction orders with respect to
component A for the special case in which the rates are zeroth-order
with respect to B and R (αB = αR = 0). The segregation strategy is shown to be most beneficial if three requirements are met: (i) αA1 < αA2, (ii) k1, k2
sufficiently large and (iii) active layer sufficiently thin compared to
support. Under favorable conditions [requirements (i)-(iii) met],
component R is selectively produced near the active layer surface, and
diffuses out of the membrane before further reaction to undesired
product (P). The simulations indicate that the fractional increases in
the R yield attained, as the degree of segregation is increased, exceed
the fractional decreases in catalyst utilization. A secondary benefit of
the membrane design is the confinement of reaction products in the bulk
stream on the active layer side, thus reducing the downstream
separation needs.
AB - A simple model is developed to examine the performance of a supported
catalytic membrane within which occurs the consecutive-parallel reaction
system given by A + B → R, with rate = k1pαA1ApαBB, and A + R → P, with rate = k2pαA2ApαRR.
Closed-form solutions reveal that segregation of reactants A and B to
opposite sides of the membrane is an effective strategy for increasing
the desired product (R) point yield. However, increases in the component
R yield come at the expense of the point catalyst utilization, due, in
part, to depletion of reacting components B and R. The membrane
performance is sensitive to the relative reaction orders with respect to
component A for the special case in which the rates are zeroth-order
with respect to B and R (αB = αR = 0). The segregation strategy is shown to be most beneficial if three requirements are met: (i) αA1 < αA2, (ii) k1, k2
sufficiently large and (iii) active layer sufficiently thin compared to
support. Under favorable conditions [requirements (i)-(iii) met],
component R is selectively produced near the active layer surface, and
diffuses out of the membrane before further reaction to undesired
product (P). The simulations indicate that the fractional increases in
the R yield attained, as the degree of segregation is increased, exceed
the fractional decreases in catalyst utilization. A secondary benefit of
the membrane design is the confinement of reaction products in the bulk
stream on the active layer side, thus reducing the downstream
separation needs.
U2 - 10.1016/0009-2509(93)80183-Q
DO - 10.1016/0009-2509(93)80183-Q
M3 - Article
VL - 48
SP - 2705
EP - 2725
JO - Chemical engineering science
JF - Chemical engineering science
SN - 0009-2509
IS - 15
ER -