High Selectivity Production of Propylene from n-Butene: Thermodynamic and Experimental Study Using a Shape Selective Zeolite Catalyst

Abstract

Propylene production by n-butene catalytic cracking was studied. Thermodynamic analysis and experimental results showed that a shape-selective catalyst, SAPO-34, with a small pore diameter and weak external acidic sites, can increase the propylene yield and selectivity to 48% and 66%, respectively, from the values of 31% and 36% over a ZSM-5 zeolite by inhibiting the formation of isobutene and other hydrocarbons whose dynamic diameters are larger than isobutene. The optimal temperature for the maximum equilibrium yield of propylene decreases from 600 to 550°C. The effect of temperature, weight hourly space velocity and time-on-stream in the n-butene cracking process were also studied.

CO2hydrogenation using bifunctional catalysts based on K-promoted iron oxide and zeolite: influence of the zeolite structure and crystal size

“…41,42 It is interesting how the small pore crystalline structure limits formation of isobutene and isobutane, resulting in an increase of the C2 and C3 fractions (see Table S1). 43 However, the high Al content of this zeolite results in the formation of ethane and propane during the initial stages of the reaction (see Figure 6d), due to hydrogen transfer reactions, especially favored within the cavities of the CHA structure. As in the case of combination of the FTS catalyst with zeolite beta, the presence of chabazite results in total conversion of the -olefins (see Figure S5).…”

Theta-1 zeolite catalyst for increasing the yield of propene when cracking olefins and its potential integration with an olefin metathesis unit

“…(6)(7)(8)(9)(10)(11)(12)(13). On the other hand, highly olefinic streams have been recognized as a suitable feed to increase propene production by catalytic cracking, particularly the cracking of butene (14)(15)(16)(17)(18), but also pentene (19,20), hexene (21,22) or octene (23).…”

Propene Production by Butene Cracking. Descriptors for Zeolite Catalysts

“…Taking into account the reaction mechanism described above, the optimal catalyst should be the one that, while being stable toward deactivation, will promote the propene selectivity by minimizing the reactions leading to side products, such as aromatics and alkanes. When cracking 1-butene, the thermodynamic equilibrium yield of propene and ethene increases with increasing reaction temperature and decreasing total pressure. ,,,,, When catalyzed by ZSM-5, optimum yields are obtained at reaction temperatures in the range of 500–580 °C and at butene partial pressure of 0.02–0.05 MPa, or at higher temperatures if partial pressure is increased. This is expected because increasing the reaction temperature favors the endothermic cracking steps over the exothermic hydrogen transfer reactions, while increasing pressure will favor kinetically the bimolecular reactions leading to hydrogen transfer.…”

“…Then, a mixture of 16 vol.% 1butene (99.6 %, Praxair Spain) in nitrogen was fed to the reactor. The contact time was varied by changing the total flow and/or the amount of catalyst in order to obtain different The butene isomerization rate at 550 ºC in the presence of an acid ZSM-5 catalyst is very fast and the butene isomer distribution rapidly reaches the equilibrium concentrations 46 .…”