Reaction pathways of n-pentane cracking on the fresh and regenerated Sr, Zr and La-loaded ZSM-5 zeolites

Catalytic Cracking of Light-naphtha Fraction over Zeolite-based Composites for On-purpose Propylene Production

“…The surface area of the Al-MFI (Si/Al 25 [mol/mol]), the Fe _ Al-MFI (Si/(Fe Al) 25 [mol/mol]) and the Fe _ Ga _ Al-MFI zeolites (Si/(Fe Ga Al) 25 [mol/mol]) were measured by the BET method on the basis of nitrogen adsorption isotherms (Belsorp mini II, MicrotracBEL Corp.). The chemical bonds of aluminum and gallium species in these samples were characterized by the 27 Al-MAS-NMR and the 71 Ga-MAS-NMR measurements (AVANCE300, Bruker Corp.), respectively. The chemical structure of iron species in the Fe _ Al-MFI (Si/(Fe Al) 25 [mol/mol]) and the Fe _ Ga _ Al-MFI (Si/(Fe Ga Al) 25 [mol/ mol]) zeolites were examined by the UV-Vis/DRS (diffuse reflectance spectroscopy) measurement in the wavelength range from 200 to 700 nm with the V-660 spectrometer equipped with the diffuse reflectance accessory (JASCO Corp.).…”

“…In addition, the actual molar ratios of each heteroatom to total heteroatoms in the Fe _ Al-MFI and the Fe _ Ga _ Al-MFI zeolites were calculated as follows: Fe _ Al-MFI; Fe/T 0.5, Al/T 0.5, T Fe Al, Fe _ Ga _ Al-MFI; Fe/ T 0.4, Ga/T 0.3, Al/T 0.3, T Fe Ga Al. Figures 1(B) and 1(C) shows the 27 Al-MAS-NMR spectrum of the Al-MFI, the Fe _ Al-MFI and the Fe _ Ga _ Al-MFI zeolites and the 71 Ga-MAS-NMR spectrum of the Fe _ Ga _ Al-MFI zeolite. The 27 Al-MAS-NMR spectrum included signals at around 50 ppm and around 0 ppm are assigned to the tetrahedral aluminum species located in the zeolite framework and the octahedral aluminum species located in the external framework, respectively.…”

Core‐shell structured HZSM‐5@mesoSiO2 catalysts with tunable shell thickness for efficient n‐butane catalytic cracking

“…Under this background, catalytic cracking of butane could successfully combine the alkenes production with increased butane utilization which would surely have application prospect and economic value in the future 4,5 . On catalysts for catalytic cracking of hydrocarbons, HZSM‐5, showing good activity with its unique channels and proper acid property, still suffers from the diffusion limitation for its single microporosity 6,7 . Much effort has been done to construct hierarchical ZSM‐5 including presynthesis, post‐treatment, and so on, 8,9 to enhance the diffusion property and increase the catalytic performance.…”

Kinetics and reactor modeling of the conversion of n-pentane using HZSM-5 catalysts with different Si/Al ratios

“…These catalytic cracking and aromatization processes are usually carried out over HZSM-5 zeolite (MFI structure) catalysts, 10 where the presence of Al in its framework gives the zeolite Brønsted acidity, which has been found crucial for the selective conversion of n-pentane into olefins. [11][12][13] These olefins can also form aromatic compounds through oligomerization and cyclization-aromatization pathways in the zeolite acid sites. [13][14][15] Remarkable yields of BTX aromatics have recently been reported using Zn-and Ga-modified ZSM-5, 8,9 as well as the important role of the framework and extraframework Al sites in aromatization reactions.…”

“…Predicted contour maps of activity with space time and time on stream for (a) Z15 and (b) Z140 catalysts at 550 ºC, and their projections onto the X axis (τ projection) for (c) Z15 and (d) Z140 catalysts and onto the Y axis (TOS projection) for (e) Z15 and (f) Z140 catalysts As the equation system of Eq. (9) is defined as a function of the time on stream and the catalytic bed length, the simulated space time values were calculated as:(11) …”