PDF Publication Title:
Text from PDF Page: 062
The application of zeolite membranes being quite lucrative for shape-selective hydrogenation of xylene isomers was also reported. As discussed in Section 4.2., MFI zeolites are considered as appropriate candidates for the preparation of membranes, since their pore diameters approximates the size of p-xylene, while the bulkier m- and o-xylene isomer molecules cannot pass the material due to sterical hindrance resulting in significant permselectivity of p-xylene over the other isomers. Coming back, the combination of molecular sieving and hydrogenation of xylene isomers was demonstrated over silicalite-1 coated Pt/Al2O3 catalysts [252]. An excellent para-selectivity was achieved, whereas the hydrogenation of the o- und m-xylene isomers to 1,3-dimethylcyclohexane and 1,2-dimethylcyclohexane was suppressed since almost exclusively p-xylene was passing the membrane to reach the catalytic active sites in the core in order to hydrogenate and produce 1,4-dimethylcyclohexane which diffused across the membrane to the product site. More recently, Zhang et al. [268] has chosen a porous metal-organic framework (MOF), namely zeolitic imidazolate framework-8 (ZIF-8), as a shell enwrapping the Pd/ZSM-5 core. A layer by layer self-assembly of polyelectrolyte was used to overcome the incompatibility between the materials prior to the two-step temperature synthesis employing ice bath for the initial nucleation and temperature of 30 ◦C for further crystallization. The catalytic performance and molecular-size-selectivity of the core-shell structure was evaluated in hydrogenation of 1-hexene and cyclohexene. By applying 1-hexene as a reactant, full conversion was achieved with n-hexane being the only product displaying similar performance as the not enshrouded Pd/ZSM-5 catalyst. On the other hand, the diffusion of cyclohexane into the core catalyst was significantly restrained since its molecular size exceeded the aperture size of ZIF-8 resulting in decreased conversion compared to the Pd/ZSM-5 catalyst. However, the observed conversion of 25.1% was obviously the result of cracks in the ZIF-8 shell. The controlled traffic of reactants providing improved reforming selectivity was demonstrated very recently by Cimenler [242] in the steam reforming of CH4 and C7H8 where the latter represents a model for tar impurity in feed. Applying H-β zeolite membrane shell on the steam reforming Ni/Mg/Ce0.6Zr0.4O2 catalyst led to decreased C7H8 conversion compared to the uncoated catalyst exemplifying the molecular-size selective properties of the membrane. The authors suggested that the shape selective effect could be boosted either by preparing thicker shell membranes or by using dealuminated zeolite. The concept of selective product removal was illustrated for the selective formation of p-xylene in the disproportionation of toluene [245]. Thereby, high p-xylene selectivity was obtained due to the selective permeation of the produced p-xylene through the silicalite membrane coated on the silica-alumina catalyst causing an equilibrium shift. Even so, the activity of the coated catalyst was lower than that 47PDF Image | Zeolite Catalysis
PDF Search Title:
Zeolite CatalysisOriginal File Name Searched:
Zeolite_Catalysis.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |