Mild template removal of SAPO-34 zeolite membranes in wet ozone environment

Abstract

The thermal stress associated with traditional high temperature calcination for the template removal of zeolite membranes leads to the formation of defects and thus poor selectivity. Mild template removal under ozone environment is effective in producing high quality ZSM-5 and DDR membranes by minimizing thermal stress. Template removal of SAPO-34 membranes, limited by thermal stress and incomplete template removal using conventional high temperature calcination method, was carried out under wet ozone. The addition of water in ozone substantially accelerated the oxidization of template molecules. SAPO-34 membranes with high permeance and selectivity for CO2-CH4 separation were obtained, which can be attributed to the mild calcination condition and high template removal efficiency associated with wet ozone. The combination of ozone and water vapor led to the formation of hydroxyl radicals, which can diffuse into the zeolite porosity and oxidize the template molecules effectively.