Inter-conversion of light olefins on ZSM-5 in catalytic naphtha cracking condition

Thermodynamic equilibrium distribution of light olefins in catalytic pyrolysis

“…It is reported that light olefin distributions are quite similar regardless of catalyst types and reaction conditions in catalytic naphtha cracking, indicating inter-conversion of light olefins occurs simultaneously together with naphtha cracking, and therefore, it is difficult to control the selectivity of ethene and propene in catalytic naphtha cracking [13]. One reason for this phenomenon is that the selectivity of ethene and propene was restricted by the thermodynamic equilibrium.…”

Reaction pathway and kinetics of C3–C7 olefin transformation over high-silicon HZSM-5 zeolite at 400–490°C

“…Particularly, catalytic oligomerization is more relevant in processes that upgrades light olefinic gases into hydrocarbons in the gasoline (C 5 -C 10 ) and diesel (C 10 -C 20 ) ranges, such as the MOGD process (mobile olefin to gasoline and distillate) [6]. However, in processes whose target products are ethylene and propylene, such as naphtha cracking [7] and MTO/MTP (methanol to olefin/propylene) [1], cracking reactions are preferred. Better understanding of the olefin transformation pattern can help select catalysts and operating conditions for a higher product yield.…”

Active intermediates formed on phosphorous-modified MTW zeolites in methanol to olefin conversion: An ESR study

“…S5. Aluminum atoms of P(x)-MTW exhibited two 27 Al MAS NMR peaks at 54 and −2 ppm; the former peak was attributed to the aluminum atoms with tetrahedral coordination and the latter peak to those with octahedral coordination [25,27]. The negligibly small latter peak indicated that most aluminum atoms of P(0.0)-MTW were located in its framework with a tetrahedral coordination.…”

“…The increase in the amount of phosphorous induced the increase in the relative intensity of the peaks at 1 and −5 ppm, while that of the peak at −11 and −18 ppm decreased considerably. The peaks at −11 and −18 ppm is attributed to the phosphorous atoms of Al O P bonds, while those at 1 and −5 ppm are from the phosphorous atoms of phosphorous oxides located in the zeolite pores [25,27]. When the amount of phosphorous was small, most phosphorous atoms were combined to aluminum atoms through oxygen atoms.…”

“…The 31 P MAS NMR spectra, at a spinning rate of 11.0 kHz, were recorded on the same spectrometer at a 31 P frequency of 202.450 MHz. The 31 P chemical shifts were referenced to H 3 PO 4 solution [25].…”