Hydroisomerization of n-Octane over Bifunctional Ni−Pd/HY Zeolite Catalysts

Abstract

Bifunctional catalysts containing 0.1−0.5 wt % nickel and 0.1 wt % palladium supported on HY zeolite were prepared through incipient wetness impregnation (IWI) and characterized by X-ray diffraction (XRD), Brunauer−Emmett−Teller (BET) surface area, temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Hydroisomerization of n-octane was carried out between 200 and 450 °C under 1 atm of pressure, and it was found that Ni addition up to 0.3 wt % over 0.1 wt % Pd/HY zeolite enhanced the n-octane conversion and isomerization selectivity with a low percentage of cracked products. As the Ni amount exceeds the threshold values, the conversion decreases with an increase in cracked products, and also, the selectivity of mono- and dibranched isomers was improved, suggesting the operation of a protonated cyclopropane (PCP) intermediate mechanism. As a conclusion, the bimetallic catalysts were more selective toward the formation of dibranched isomers containing higher octane number. The role of noble metal over HY zeolite and recyclability of the catalyst were also studied.

Hydroisomerization of n-alkanes over Pt-modified micro/mesoporous materials obtained by mordenite recrystallization

“…To assess the influence of chain length on the activity and selectivity of Pt/MOR in hydroisomerization, the conversion of C 6 , C 8 and C 16 alkanes is plotted versus reaction temperature and the hydroisomerization selectivity -versus conversion (Fig. 9).…”

“…Among the large number of the catalysts studied zeolites Y [3][4][5][6][7][8]16], BEA [17][18][19], ZSM-22, -23 [20] and zeotypes SAPO-11, -31, -41 [20][21][22] were found to be the most active and selective in hydroisomerization of n-heptane and n-octane. These results pointed that zeolites modified with nobel metals are among the most perspective catalysts for hydroisomerization n-alkanes with more than six carbon atoms.…”

“…Numerous studies were devoted to the investigation of the influence of zeolite structure, pore geometry and acidity on the hydroisomerization activity [16][17][18][19][20][21][22]. Among the large number of the catalysts studied zeolites Y [3][4][5][6][7][8]16], BEA [17][18][19], ZSM-22, -23 [20] and zeotypes SAPO-11, -31, -41 [20][21][22] were found to be the most active and selective in hydroisomerization of n-heptane and n-octane.…”

Effect of phosphomolybdic acid on the catalytic behavior of bifunctional Pt‐Cr/nanocrystalline Y zeolite in hydroisomerization of n‐octane

“…The metallic sites such as Pt and Cr convert the normal octane into the corresponding alkene. In the next step, the Brønsted acid sites are responsible for the isomerization of the linear octane through the formation of the secondary carbenium ion and its rearrangement into the tertiary carbenium ion, which is likely to release the iso‐octane …”

Catalysis in the Upgrading of Fischer–Tropsch Syncrude

“…281 Bifunctional Ni-Pd/HY zeolite catalysts containing 0.1-0.5 mass% Ni and 0.1 mass% Pd prepared by incipient wetness impregnation were used for the HIS of n-octane between 200 and 450 1C at atmospheric pressure. 282 It was found that Ni addition up to 0.3 mass% to the Pd/HY zeolite increased n-octane conversion and HIS selectivity. At the same time, the yield of cracked products was decreased.…”