Selective Removal of Methanol from Humid Air Streams Using a Water-Vapor-Purged Membrane Separator

Abstract

Methanol is an unwanted byproduct of kraft pulping in the pulp and paper industry. More than 50 million tons of kraft pulp is produced in the United States per year, and methanol releases are on the order of pounds per ton of pulp produced. Methanol is released in low concentrations with humid air streams from many sources in a kraft pulp mill. Membrane vapor separation was tested for selective removal of low concentrations of methanol from a humid air stream. The separation studied in this paper was driven by a water-vapor purge stream on the permeate side of a poly(ether amide) block copolymer (PEBAX 2533) membrane. The separation characteristics of the membrane were essentially unchanged when the water-vapor-purge mode was compared to previous single-component measurements. Modeling based on the experiments and for another possible target membrane material is discussed.