Membrane Fabrication Methods Using Organosilica Materials And Uses Thereof (ExxonMobil)

CATEGORY: MEMBRANES
Membrane Fabrication Methods Using Organosilica Materials And Uses Thereof (ExxonMobil)
United States Patent Application 20160168485
LI; Quanchang ;   et al.   June 16, 2016
Assignee: ExxonMobil Research and Engineering Company
Abstract
Methods for fabricating a membrane with an organosilica material which is a polymer comprising independent units of Formula [Z.sup.3Z.sup.4SiCH.sub.2].sub.3 (I), wherein each Z.sup.3 represents a hydroxyl group, a C.sub.1-C.sub.4 alkoxy group or an oxygen atom bonded to a silicon atom of another unit or an active site on the support and each Z.sup.4 represents a hydroxyl group, a C.sub.1-C.sub.4 alkoxy group, a C.sub.1-C.sub.4 alkyl group, an oxygen atom bonded to a silicon atom of another unit or an active site on the support are provided. Methods of removing a contaminant from a hydrocarbon stream are also provided.
FIELD OF THE INVENTION
[0004] The present invention relates to methods of fabricating membranes using organosilica materials and processes for liquid separation.
BACKGROUND OF THE INVENTION
[0005] Membranes have various potential industrial applications including gas, water and hydrocarbon separations. However, to be more competitive with other separation processes, such as distillation, adsorption and cryogenic separations, membranes have to demonstrate economical scalability and stability in harsh chemical, thermal and mechanical environments. While membranes exist for natural gas and water desalination applications, there is a lack of suitable membranes for hydrocarbon and crude oil separations (e.g., liquid separations) due to challenges such as low flux, poor economics and fouling potential of the membranes. For example, performance of polymeric membranes, such as polytetrafluoroethylene (PTFE) and polyimides, is limited by low flux and low operating temperatures. Furthermore, such polymers are prone to plasticize (i.e., swell) upon exposure to aromatic/naphthenic liquids at high-pressure, thereby making them unselective. Carbon molecular sieve membranes, offer much higher selectivity and the materials do not plasticize when compared to conventional polymeric membranes for separations; however, carbon molecular sieve membranes can suffer from scalability challenges and low permeability due to sub-structure collapse during pyrolysis. Sintered metals provide chemical, thermal and mechanical robustness, but cost of manufacturing such membranes remains prohibitively high.
[0006] Further, microporous and mesoporous silica materials have challenges with hydrothermal stability, and require a surfactant-templated route which is cost and energy intensive. Conventional ceramic membranes (TiO.sub.2, Al.sub.2O.sub.3) have been proposed for these challenging applications since they provide stability and selectivity, however to fabricate membranes of small pore sizes (2-10 nm) require multiple intermediate layers which reduce their flux (productivity) and the fabricated membranes have a low surface area/volume. Also, surface defects on the ceramic membranes cause low selectivity for separation work, and limit their applications. Thus, it remains highly desirable to develop a membrane with chemical, thermal and mechanical robustness with high rejection (selectivity), flux (productivity), tunable surface properties while still being economically scalable.
[0007] Therefore, there is a need for improved methods of fabricating improved membranes using organosilica materials that can be prepared by a method that can be practiced in the absence of a structure directing agent, a porogen or surfactant.
SUMMARY OF THE INVENTION
[0008] It has been found that membranes with chemical, thermal and mechanical robustness with high rejection (selectivity), flux (productivity) and tunable surface properties can be successfully fabricated using organosilica materials without the need for a structure directing agent, a porogen or surfactant.
[0009] Thus, in one aspect, embodiments of the invention provide a method method for fabricating a membrane, the method comprising: adding at least one compound of Formula [Z.sup.1Z.sup.2SiCH.sub.2].sub.3 (Ia) into an aqueous mixture that contains essentially no structure directing agent or porogen to form a solution, wherein each Z.sup.1 represents a hydroxyl group, a C.sub.1-C.sub.4 alkoxy group or an oxygen bonded to a silicon atom of another compound and each Z.sup.2 represents, a hydroxyl group, a C.sub.1-C.sub.4 alkoxy group, a C.sub.1-C.sub.4 alkyl group or an oxygen bonded to a silicon atom of another compound; coating the solution onto a support to form a coated support; aging the coated support; and drying the coated support to obtain a membrane comprising an organosilica material which is a polymer comprising independent units of Formula [Z.sup.3Z.sup.4SiCH.sub.2].sub.3 (I), wherein each Z.sup.3 represents a hydroxyl group, a C.sub.1-C.sub.4 alkoxy group or an oxygen atom bonded to a silicon atom of another unit or an active site on the support and each Z.sup.4 represents a hydroxyl group, a C.sub.1-C.sub.4 alkoxy group, a C.sub.1-C.sub.4 alkyl group, an oxygen atom bonded to a silicon atom of another unit or an active site on the support.
[0010] In still another aspect, embodiments of the invention provide a membrane made according to the methods described herein.
[0011] In still another aspect, embodiments of the invention provide a method of removing microcarbon residue from a crude oil, the method comprising filtering a crude oil through the membrane of claim 38.
[0012] Other embodiments, including particular aspects of the embodiments summarized above, will be evident from the detailed description that follows.
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