Equilibrium shift in reactors with a permselective wall

摘要

The objective of this study is to obtain a fundamental understanding of the behavior of reactors with a permselective wall (membrane reactors) in terms of design parameters (reactor length, membrane thickness) operating variables (pressure ratio, feed flow rate, feed temperature), physical properties (rate constant, permeability of fast gas, permselectivity, equilibrium constant, heat of reaction), and flow patterns (recycle, cocurrent, countercurrent). Pure feed reacts on the high pressure side of the membrane, and the product(s) formed are continuously removed to the low pressure side so that thermodynamic equilibrium is never reached.;It is shown by simulation that equilibrium shift can be enhanced by: recycling unconverted reactant; shifting feed location in plug flow membrane reactors to separate products; and maintaining high permeation rates to reduce backreaction. It is shown that the choice between cocurrent flow and countercurrent flow depends on the system parameters. It is also shown that diffusional resistance will degrade performance at high permeation fluxes and/or high aspect ratios (diameter/length).