Octanes, cracking

Barthomeuf and Beaumont (25) have found that the activity for iso-octane cracking remains unchanged for NaHY zeolites in which up to 33 percent of Al has been extracted with chelating agents. This corresponded to a dealumination from 56 to 37 Al/u.c. Further dealumination resulted in a decrease in... 

Iso-octane Cracking Activity of Aluminum-Deficient Na, H—Y Zeolites (300°C, Hi... 

Activity of H-GaMFI catalyst with and without silica binder (50 wt%) in iso-octane cracking (at 400°C) and toluene disproportionation (at SOO C) reactions [amount of catalyst 0.05 g (without binder) or 0.1 g (with binder) pulse size 0.4 pi carrier gas (N2) flow rate 20 cm min ]. 

Conditions of a step for template molecule removal affected strongly the concentration of very strong acid site in HZSM-5. Treatment with ammonia water at ca 373 K was also studied as a procedure to affect the solid acidity, and a similarity of acid sites created by both methods was identified. From the quantitative measurements of acid sites, it was found that the very strong acid site consisted of two A1 cations. Catalytic activity for octane cracking was enhanced by the presence of very strong acid site. 

To investigate the detailed structures and energetics of the initiation reaction for a larger system, the four possible reaction pathways to break the C-C bonds in an octane molecule have been studied (Goldstein et al. 1996 Xiao et. al. 1997). Table 3 shows the reaction scheme for octane cracking with four pairs of products—methyl and heptyl, ethyl and hexyl, propyl and pentyl, and butyl and butyl radicals. The calculated BDEs of these homolytic C-C scission at the MP2/6-31G, PMP2/6-31G, B3LYP/6-31G, and CBS-4 levels, are also listed in Table 3. 

The preceding information indicates the paths to follow in order to obtain stocks of high octane number by refining. The orientation must be towards streams rich in aromatics (reformate) and in isoparaffins (isomerization, alkylation). The olefins present essentially in cracked gasolines can be used only with moderation, considering their low MONs, even if their RONs are attractive. 

Ecole Nationale Superieure du Petrole et des Moteurs Formation Industrie end point (or FBP - final boiling point) electrostatic precipitation ethyl tertiary butyl ether European Union extra-urban driving cycle volume fraction distilled at 70-100-180-210°C Fachausschuss Mineralol-und-Brennstoff-Normung fluid catalytic cracking Food and Drug Administration front end octane number fluorescent indicator adsorption flame ionization detector... 

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