Molecular sieving silica membrane fabrication process

DETAILED DESCRIPTION It is an object of this invention to provide a process for producing molecular sieving silica membranes which overcomes the potential disadvantages of traditional approaches to producing such membranes as discussed hereinabove.
It is an object of this invention to provide a process for producing gas separation membranes having high selectivity achieved by having small pore sizes and narrow pore size distributions, and high permeance, defined as flux/pressure drop, achieved by having a large volume fraction porosity and a very thin selective layer.
It is yet another object of this invention to provide a process for producing molecular sieving silica membranes using fugitive organic ligands as micropore templates.
In this approach, organic templates are introduced in a dense inorganic matrix and then removed oxidatively or hydrolytically to create a microporous channel system that exhibits molecular sieving and/or molecular recognition characteristics.
Ideally, the organic ligand volume fraction is used to control porosity enhanced flux, independently of selectivity, which depends on the ligand size and shape.
In order to successfully implement this approach, several criteria must be satisfied.
The organic ligands must be uniformly incorporated in the inorganic matrix without aggregation or phase separation to avoid creating pores larger than the size of the individual ligands; the synthesis and processing conditions should result in a dense embedding matrix so that pores are created only by template removal; and template removal should be achieved without collapse of the matrix, so that the pores created preserve the original size and shape of the template.
These and other objects of this invention are achieved by a process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the organic constituent of the hybrid organic-inorganic polymer, forming a porous film