Mp. Harold et C. Lee, INTERMEDIATE PRODUCT YIELD ENHANCEMENT WITH A CATALYTIC INORGANIC MEMBRANE .2. NONISOTHERMAL AND INTEGRAL OPERATION IN A BACK-MIXED REACTOR, Chemical Engineering Science, 52(12), 1997, pp. 1923-1939
The catalytic membrane reactor (CMR) offers added flexibility over its
conventional reactor counterparts. In this study a model is developed
to examine the performance of a completely back-mixed CMR for the con
secutive-parallel reaction system given by 1 A + B --> R 2 A + R --> P
+ Q where the desired product is the intermediate R. The effect of se
gregating reactants to opposite sides of the nonpermselective membrane
is examined with regard to the conversion of the main reactants A and
B and the integral yield of R. The conversions and yield are shown to
be sensitive functions of the degree of segregation. Several factors
are identified which contribute to: the intrinsic kinetics and catalyt
ic activity (e.e. apparent reaction orders), the degree of mixing of t
he reactants A and B between the characteristic flow, transmembrane di
ffusion, and reaction time), the proximity of the active layer to both
of the reactants, and the relative extents and stoichiometries of the
two reactions. For a fixed conversion of B and fixed overall B/A feed
ratio, and for the case in which the rate of reaction 2 has a higher
apparent reaction order with respect to A than reaction 1, the integra
l yield of R exceeds that for a mixed feed if A is concentrated on the
support side and B is concentrated on the active layer side. The memb
rane in this case serves as a diffusional barrier to reactant A, there
by controlling the effective B/A ratio at the catalytic layer. The yie
ld increase is achieved at the expense of contact time (or reactor vol
ume). The analysis shows that it is possible to realize the same yield
increase with a mixed feed by adjusting the B/A feed ratio. (C) 1997
Elsevier Science Ltd.