HYDROPHOBIC ZEOLITES FOR ADSORPTION PROCESSES

The use of zeolites for adsorptive waste gas purification and solvent recovery was limited by the preferential uptake of water by conventional zeolites. Recently developed zeolites produced by sophisticated synthesis and dealumination techniques combine extreme hydrophobicity and high temperature- and acid resistance. These zeolites are, therefore, suitable for selective adsorption of organic solvents from moist waste gas streams. Since zeolites are nonflammable, sorbent ignition is inherently prevented. Higher desorption temperatures result in lower specific energy costs and facilitates the adsorption and desorption of polymerizing and high boiling products. The low water uptake reduces the energy required for treating high humidity waste gas streams and allows the recovery of solvents with low water concentrations. Using appropriate binding substances zeolites can be pelletized to hollow cylinders with low pressure drop or can be used for coating honeycomp rotors.