Zeolite poly

Quaternary ammonium bromides and hydroxides (quats) are applied as templates in the synthesis of zeolites with relatively high Si/Al ratio. Examples will be given of the use of mon-, di-, poly- and associated quats as templates in zeolite growth. Templated zeolites of the MFI-type can be grown in a lateral or in an axial way onto metal supports, providing promising composite systems, for separation and catalysis, respectively. 

Zeolite based ceramics as catalysts for wet hydrogen peroxide catalytic oxidation of phenol and poly-phenols... 

In the present work, a Cu-13X zeolite sample was ceramized and used as a catalyst for the wet oxidation of phenol solutions and olive oil mill wastewaters (OOMW). The material showed good catalytic activity for the abatement of phenol and poly-phenols, excellent stability and no leaching of the active species. In this way a real heterogeneously catalyzed reaction was performed. Moreover, the catalyst was reused without special reactivation treatments for different consecutive reaction cycles. 

Besides di- and poly-saccharides, zeolites have been applied for hydrolysis of simple glycosides as described by Le Strat and Morreau.132 Methyl a- and /i-D-glucopyrano-sides were treated with water in the presence of dealuminated HY faujasite with an Si/Al ratio of 15, at temperatures ranging between 100 and 150 °C. It was observed that the reaction rate for the (i glycoside was about 5-6 times higher than that for the oc anomer, a result that might arise from the shape-selective properties of the zeolite and stereoelectronic effects on the surface of the solid. 

Midforming [Middle-range distillate forming] A process for converting lower olefins to transport fuels. The catalyst is either a ZSM-5-type zeolite in which some of the aluminum has been replaced by iron, or a hetero-poly acid. Developed in the 1980s by the National Chemical Laboratory, Pune, India. To be piloted by Bharat Petrochemical Corporation, Bombay, and Davy Poweigas. 

PDMS nanocomposites with layered mica-type silicates were also reported.374 A two-step sol-gel process of the in situ precipitation of silica led to the development of siloxane-based nanocomposites with particularly high transparencies.3 5 Some unusual nanocomposites prepared by threading polymer chains through zeolites, mesoporous silica, or silica nanotubes were reviewed.3 6 Poly(4-vinylpyridine) nanocross-linked by octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane was reported.377... 

Up to now, a variety of non-zeolite/polymer mixed-matrix membranes have been developed comprising either nonporous or porous non-zeolitic materials as the dispersed phase in the continuous polymer phase. For example, non-porous and porous silica nanoparticles, alumina, activated carbon, poly(ethylene glycol) impregnated activated carbon, carbon molecular sieves, Ti02 nanoparticles, layered materials, metal-organic frameworks and mesoporous molecular sieves have been studied as the dispersed non-zeolitic materials in the mixed-matrix membranes in the literature [23-35]. This chapter does not focus on these non-zeoUte/polymer mixed-matrix membranes. Instead we describe recent progress in molecular sieve/ polymer mixed-matrix membranes, as much of the research conducted to date on mixed-matrix membranes has focused on the combination of a dispersed zeolite phase with an easily processed continuous polymer matrix. The molecular sieve/ polymer mixed-matrix membranes covered in this chapter include zeolite/polymer and non-zeolitic molecular sieve/polymer mixed-matrix membranes, such as alu-minophosphate molecular sieve (AlPO)/polymer and silicoaluminophosphate molecular sieve (SAPO)/polymer mixed-matrix membranes. 

Glassy polymers with much higher glass transition temperatures and more rigid polymer chains than rubbery polymers have been extensively used as the continuous polymer matrices in the zeolite/polymer mixed-matrix membranes. Typical glassy polymers in the mixed-matrix membranes include cellulose acetate, polysul-fone, polyethersulfone, polyimides, polyetherimides, polyvinyl alcohol, Nafion , poly(4-methyl-2-pentyne), etc. 

Another type of mixed-matrix membranes for alcohol/water pervaporation applications was developed utilizing hydrophiUc poly(vinyl alcohol) (PVA) and ZSM-5. The ZSM-5/PVA mixed-matrix membranes demonstrated increased selectivity and flux, compared to pure PVA, for the water/isopropyl alcohol separation [97]. This type of mixed-matrix membranes, however, may have membrane swelling issue due to the hydrophilic nature of the PVA polymer. Mixed-matrix membranes comprising modifled poly(vinyl chloride) and NaA zeolite have shown both enhanced flux and selectivity for the ethanol/water separation at high NaA loadings [98]. 

G. (1989) A zeolite/polymer membrane for separation of ethanol-water azeotrope. /. Appl. Poly. Sci., 37 (7), 1791-1800. 

Homogeneous catalysts have a very low selectivity for 2,6-dialkyl-p-benzoquinone (I), whereas zeolites combine high activities with high selectivities towards formation of (I). The formation of poly(2,6-dialkyl-l,4-phenylene ether) (III) is suppressed on zeolites by steric constraints. The formation of 3,3, 5,5 -tetraalkyl-4,4 -diphenoquinone (II) is suppressed in the supercages, but promoted by high concentrations of phenol. 

Many other polymerization processes have been patented, but only some of them appear to be developed or under development in 1996. One large-scale process uses an acid montmorrillonite clay and acetic anhydride (209) another process uses strong perfluorosulfonic acid resin catalysts (170,210). The polymerization product in these processes is a poly(tetramethylene ether) with acetate end groups, which have to be removed by alkaline hydrolysis (211) or hydrogenolysis (212). If necessary, the product is then neutralized, eg, with phosphoric acid (213), and the salts removed by filtration. Instead of montmorrillonite clay, other acidic catalysts can be used, such as Fullers earth or zeolites (214—216). 

Irradiation of poly(ethylene glycol) labeled at the chain terminal with two 2-naphthyl groups 337 in NaY zeolite leads to formation of intramolecular photo-cyclomers 338 to the exclusion of intermolecular products [325] (Scheme 93). These results are explained in terms of the compartmentalization of the guest molecules in the supercages of NaY zeolite. Thus, this work demonstrates the util-... 

---