NOVELTY - Producing a structure for molecular separations, comprises: providing many template materials including biomolecules, biopolymers and/or polymers; providing a sieve material suitable for producing a structure for molecular separations around the template materials; positioning the template materials in an arrangement for leaving pores suitable for molecular separations; and removing the template materials to leave pores in the sieve material.    USE - The process is useful for producing catalyst, which is useful as a molecular sieve. The process, assembly and the membrane are useful for producing a structure for molecular separations (all claimed), preferably for separating gases from their mixtures, and chemicals from a liquid, alcohol/water separation, dewatering, sugar concentration, desalination, water purification, carbon monoxide remediation and syngas production. The membrane is also useful in industries including oil and petrochemical, coal gasification, pulp and paper and natural gas producers. The catalyst is useful in fuel cells, and in catalytic converters and as a coating for proton exchange membranes.    ADVANTAGE - The process provides the catalyst with lower cost, and primarily in energy savings. The method provides improved dispersal of the catalyst and the ability to create well-defined binary or ternary or higher complexity catalysts with very unique properties. The back pressure or pressure drop across the membrane is very low, and the molecules have an easy path through the membrane.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) an assembly (10) comprising a substrate (16), template materials on the substrate, and the sieve material positioned on the substrate around the template materials;    (2) a membrane comprising a membrane made from the sieve material, and having opposed major surfaces, and pores in at least one of the major surfaces, where the pores have a diameter of 5-30 Angstrom ; and    (3) producing a catalyst, comprising attaching catalytic materials e.g. transitions metals to template materials, positioning a catalyst substrate material around the template materials and removing the template materials to leave pores in the catalyst substrate material, with the catalytic materials attached to or positioned in the pores.    DESCRIPTION OF DRAWING(S) - The figure shows a side view of the assembly for producing a ceramic membrane for molecular separations.    Assembly (10)    DNA molecules (14)    Substrate (16)    Sol-gel (18)