日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

NGK have first prepared DDR-type zeolite membranes, and has thereafter revealed its molecular sieving effect through measurements of single gas permeation of various gas species. Recently, we have succeeded in scaling up this DDR-type zeolite membrane into a large multichanneled structure with a diameter and length of 180 mm and 1000 mm, respectively, realizing a membrane area of 12 m² within a single membrane. This membrane was developed for aiming large-scale applications with high throughput, such as natural gas purification. Taking this application for example, the performance of our membrane is discussed through the separation of CO₂ from CO₂/CH₄ mixtures, which is a reference index for natural gas purification. Our membrane exhibited a high CO₂ permeance and selectivity of >5×10⁻⁷ mol/m² s Pa and >160, respectively, for equimolar mixtures of CO₂ and CH₄ at a total feed pressure of 3 bars. We expect that this high performance shall be promising for industrial applications. Application to other binary systems including H₂ separation from H₂/CH₄ and CO₂ separation from CO₂/H₂ mixtures was also confirmed to be possible. Another beneficial feature of our DDR-type zeolite membrane is its remarkably low aluminium content. In general, zeolites with lower aluminium content are more chemically stable and thus our membrane is expected to have high acidic resistance, suitable for dehydration applications. The dehydration performance of our membrane has been actually tested in several organic solvent/water systems using pervaporation method. Our membrane showed high performance and excellent stability for more than 200 hrs in dehydration of 90% acetic acid solution at 90°C. Enhanced dehydration performance has also been observed in other solvents including phenol, ester and alcohol solutions.