Phosphorous modified ZSM-5: Deactivation and product distribution for MTO

Olefin production by cofeeding methanol and n‐butane: Kinetic modeling considering the deactivation of HZSM‐5 zeolite

“…11,15,16 Catalyst hydrothermal stability has been improved by doping the HZSM-5 zeolite with Fe, 17 and agglomerating with bentonite and alumina. 18,19 The integration of both reactions schematized in Figure 1 is effective for increasing the yield of olefins over those corresponding to the two individual reactions, which is explained by the following findings based on synergies between the kinetic schemes of the two reactions: 20 (i) olefins formed at the initial section of the reactor in n-butane cracking activate the autocatalytic steps for methanol transformation, following the well-established ''hydrocarbon pool'' mechanism originally proposed for SAPO-34 catalyst, which establishes that methylbenzenes are the main reactive species; 12,[21][22][23][24][25] (ii) the incorporation of these olefins in the ''hydrocarbon pool'' maintains the reactivity of methylbenzenes released by the olefins, which delays the formation of polymethylbenzenes that are the precursors of polyaromatic coke; 26,27 (iii) water formation in methanol transformation inhibits the steps for n-butane cracking but also deactivation by coke, given that water adsorption on the active sites competes with coke precursor adsorption in the coke growing steps. 28,29 A further fact to be taken into account is that the heat released ''in situ'' in the dehydration of methanol on the same active sites avoids the presumable energy deficiency in the endothermic cracking step.…”

“…Catalysts prepared based on HZSM-5 zeolites have turned out to be active for paraffin cracking. [7][8][9] Moreover, although the behavior of HZSM-5 zeolite in the transformation of methanol into olefins (MTO process) [10][11][12] is well-known, it is performed on SAPO-34 catalysts due to their higher-selectivity to olefins. Nevertheless, the deactivation of the latter by coke is more rapid, given that H-SAPO34 has a 3-D cage structure with 3.8 Â 3.8 Å framework dimensions, whereas HZSM-5 has a 3-D 10-ring structure with 5.1 Â 5.5 and 5.3 Â 5.6 Å framework dimensions.…”

Conversion of Methanol to Hydrocarbons over Phosphorus-modified ZSM-5/ZSM-11 Intergrowth Zeolites

“…High selectivity of propylene has been obtained on modified ZSM-5 zeolites [2,3]. Phosphorusmodified ZSM-5 has been extensively investigated in methanol conversion [4][5][6][7][8][9][10][11][12][13][14], and catalytic cracking reaction [15][16][17][18][19][20]. The structure of p-modified ZSM-5 has been characterized by many research groups [21][22][23][24][25][26][27].…”

Statistical Optimization for Production of Light Olefins in a Fluidized‐Bed Reactor

“…Interpretation of experimental data derived from fixed-bed reactors for the MTO reaction is complicated due to the possibility of radial and axial gradients of temperature and gasphase composition as well as carbon deposition on the catalyst [10,11]. On the other hand, fluidized beds have been used worldwide in many industrial applications [12,13].…”