Liquid separation, zeolite/polymer

Zeolite/polymer mixed-matrix membranes have been investigated for liquid separations such as purification ofp-xylene [76], separation of ethanol-water mixtures [93-96] and water desalination [83]. 

Another potential application for zeolite/polymer mixed-matrix membranes is the separation of various liquid chemical mixtures via pervaporation. Pervapora-tion is a promising membrane-based technique for the separation of liquid chemical mixtures, especially in azeotropic or close-boihng solutions. Polydime thy 1-siloxane (PDMS), which is a hydrophobic polymer, has been widely used as the continuous polymer matrix for preparing hydrophobic mixed-matrix membranes. To achieve good compatibility and adhesion between the zeolite particles and the PDMS polymer, ZSM-5 was incorporated into the PDMS polymer matrix, the resulting ZS M -5/ P DM S mixed-matrix membranes showed simultaneous enhancement in selectivity and flux for the separation of isopropyl alcohol from water. It was demonstrated that the separation performance of these membranes was affected by the concentration of the isopropyl alcohol in the feed [96]. 

The recovery of petroleum from sandstone and the release of kerogen from oil shale and tar sands both depend strongly on the microstmcture and surface properties of these porous media. The interfacial properties of complex liquid agents—mixtures of polymers and surfactants—are critical to viscosity control in tertiary oil recovery and to the comminution of minerals and coal. The corrosion and wear of mechanical parts are influenced by the composition and stmcture of metal surfaces, as well as by the interaction of lubricants with these surfaces. Microstmcture and surface properties are vitally important to both the performance of electrodes in electrochemical processes and the effectiveness of catalysts. Advances in synthetic chemistry are opening the door to the design of zeolites and layered compounds with tightly specified properties to provide the desired catalytic activity and separation selectivity. 

In the physical separation process, a molecular sieve adsorbent is used as in the Union Carbide Olefins Siv process (88—90). Linear butenes are selectively adsorbed, and the isobutylene effluent is distilled to obtain a polymer-grade product. The adsorbent is a synthetic zeolite, Type 5A in the calcium cation exchanged form (91). UOP also offers an adsorption process, the Sorbutene process (92). The UOP process utilizes a liquid B—B stream, and uses a proprietary rotary valve containing multiple ports, which direct the flow of liquid to various sections of the adsorber (93,94). The cis- and trans-isomers are... 

In gas-solid chromatography, the stationary phase is an active solid. These solids may be inorganic materials, e.g. synthetic zeolite molecular sieve, carbon molecular sieve, silica gel, or graphitised carbon, or they may be oiganic polymers. They are generally used for the separation of low molecular weight materials, i.e. gases and liquids. 

The interest of 2,6-dialkylnaphthalenes as starting materials in the production of polyester fibers and plastics with superior properties [1, 2] and of thermotropic liquid crystal polymers [3] is clearly shown by the increasing number of recent patents relevant to their preparation and separation[3.5]. However, the selective formation of 2,6-dialkylnaphthalenes is not obvious, not only with conventional Friedel-Crafts catalysts [6-8], but also over solid catalysts such as silica-alumina [9-11] or zeolites. 

Liquid-Phase Carbonylation. An incentive for the development of immobilized solid catalysts in liquid-phase carbonylation is to retain the chemical characteristics of the soluble industrial catalysts (6) in the Reppe reaction and reduce the problems of corrosion as well as the separation of catalyst from reaction liquor. Various supporting materials such as active carbon, polymers, zeolites, and amorphous inorganic oxides are used to immobilize homogeneous carbonylation catalysts. 

Some of the available membrane separation processes can already be applied on an industrial scale. Hence, inorganic ceramic membranes (zeolites and their derivatives, e.g. silico aluminophosphates), organic polymer membranes and facilitated transport membranes, which rely on a carrier molecule with high CO2 affinity to achieve selective CO2 transport (such as metallic ions or liquid amines), have been used in separating CO2 from flue gas in post-combustion. As single-stage separation with these membranes is still difficult, new membrane materials are being developed [1]. Typically, the initial separation of carbon dioxide accounfs for 60-80% of the total cost of CO2 sequestration [24,25]. 

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