PDF Publication Title:
Text from PDF Page: 005
46 M. Bjørgen et al. / Applied Catalysis A: General 345 (2008) 43–50 Fig. 1. Nitrogen adsorption and desorption isotherms at 77 K for the three samples. Powder X-ray diffractograms and the results of Pawley refinements are shown in Fig. 2. Simple visual inspection of the diffractograms show that all three samples consist of highly crystalline MFI phase, and this is indeed confirmed by the high quality of the refinements, as seen from the difference plots shown below each diffractogram in Fig. 2. Further details about the samples may also be extracted from the refinement. First, the desilication procedure results in a small but significant reduction in the unit cell volumes (5348 A ̊ 3 for PARENT, 5337 A ̊ 3 for 0.05M, and 5243 A ̊ 3 for 0.20M), in particular for the 0.20M sample. Changes in unit cell parameters are often associated with changes in material composition, and for dry or equally hydrated zeolites, a smaller Si/Al (framework) ratio will typically lead to longer unit cell parameters [29], whereas the opposite trend is observed for the samples studied here—again indicating that a substantial part of the Al content in the treated samples as determined with ICP- AES does not occupy framework positions. However, it should be emphasized that no precautions were taken in order to dry the samples prior to XRD analysis. Further, studies on dealuminated Y zeolites have shown that such correlations between unit cell parameters and compositions depend on the dealumination procedure and that defect sites and healing or replacement of T- atoms influence the results [29]. Also, it cannot be ruled out that the generation of mesopores could lead to unit cell alterations. We identify the detailed study of the dependency of the unit cell parameters and compositions for desilicated samples as a topic for further studies. Second, the background subtracted Rwp figure of merit is slightly better for the 0.20M sample (2.8%) compared to the 0.05M (5.9%) and PARENT (4.2%) samples, indicating improved Fig. 2. X-ray diffractograms and difference plots with respect to Pawley refinement for the three samples. crystallinity. This might be caused by removal of amorphous or less crystalline material present in the PARENT sample. Hence, with respect to XRD, the PARENT and 0.05M samples are quite similar, whereas the 0.20M sample has slightly better overall crystallinity and a reduced unit cell volume. Representative SEM micrographs for the PARENT and 0.20M samples are shown in Fig. 3. All samples consist of prismatic, twinned crystals, typical for the MFI phase. Average crystal size is about 10 mm 15 mm, with some smaller crystallites and larger agglomerates present. Notably, and contrary to some reports [17,20], the NaOH treatment does not lead to any SEM visible differences among the samples in the present case. DRIFTS spectra of the three samples in the n(O–H) region are reported in Fig. 4. The PARENT sample has five well separated bands which can be given the following assignments based on previous studies [30,31]. The sharp well defined component at 3747 cm 1 represents isolated Si–OH groups not interacting significantly with other species. These sites are commonly claimed to be located on the external surface of the zeolite as they are perturbed upon adsorption of steric demanding probe molecules not able to access the micropore system of the zeolite. The intensity of this peak (3747 cm1) has previously been correlated with the external surface area and thus the average crystal size of the zeolite [32,33], and due to the very large crystals studied here, the intensity of this band is quite low. Consequently, bands with maxima at 3726 and 3689 cm1 are clearly visible. These bands have been associated with nearly free Si–OH sites predominantly located inside the structure as they remain virtually unperturbed upon adsorption of large molecules. As expected, the band representing the bridging strongly acidic Al(OH)Si sites respon- sible for the catalytic activity is located at 3610 cm1. Finally, the very broad and unresolved band with a maximum at 3500 cm1 and a shoulder around 3450cm1 is assigned to a variety of internally located Si–OH sites involved in relatively strong hydrogen bonds. The location assignments (internal or external)PDF Image | Methanol to gasoline over zeolite H-ZSM-5
PDF Search Title:
Methanol to gasoline over zeolite H-ZSM-5Original File Name Searched:
Methanol_to_gasoline_over_zeolite_H-ZSM-5_Improved.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 (Standard Web Page)