Microporous membrane has shown great potential for the separation of carbon dioxide from the gas mixture. Beside the membrane performance, the membrane preparation method is a factor to be concerned in this technique. In this work, pure silica DDR zeolite membranes on silica porous substrate were synthesized from an economical and environmentally efficient process. Porous silica substrate was fabricated using a low cost material. The membrane growth reaction used a minimum amount of chemical, produced no waste generation. Part of the reactant is supplied from porous substrate. The membrane quality is strongly dependent on the exposed faces of seed crystals and the pH value of the template solution. The obtained membranes show very high permeance and selectivity for CO2 from a CO2/CH4 gas mixture in both dry and humid conditions and hot gas flow. The membrane maintains stability in high performance with the separation factor of 440–500 for a test period of one week. Display omitted •Pure silica DDR zeolite membrane on low cost porous silica support.•Gelless secondary growth of pure silica DDR zeolite membrane.•Membrane quality dependent on the pH of template solution and exposed faces of seed crystals.•High performance on CO2/CH4 gas mixture separation in both dry and humid conditions.•Environmental friendly in both membrane preparation and membrane performance.