Selective Production of 2-Phenylhexane from Benzene and n-Hexane Over Pt- and Ga-Modified Zeolites

Abstract

Alkylation of benzene with n-hexane was performed over H-ZSM-5 and monometallic Ga-and Pt-and bimetallic Ga-and Pt-modified ZSM-5. The influence of the particle size and the method of incorporation of Ga (during hydrothermal synthesis, by solid-state ion exchange, or by liquid-state ion exchange) was determined. The presence of Pt and well-dispersed extraframework Ga in H-ZSM-5 increased the selectivity in alkylation and suppressed cracking reactions. Well-dispersed Pt particles led to better catalytic performance. The method of Ga incorporation played an important role in obtaining higher selectivity to alkylation products and in the suppression of side reactions. Up to 93% selectivity in alkylation (of which [95% was to 2-phenylhexane) was reached over 2 wt% Pt/H-Ga f ZSM5, in which Ga occupied framework positions. We propose that the close proximity of very small Pt nanoparticles and Ga-(OH)-Si acid sites results in the optimal bifunctional catalyst for selective production of 2-phenylhexane from benzene and n-hexane. During the reaction, the catalyst deactivated, most probably due to the sintering of the Pt particles.

Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

“…Noble‐metal‐containing zeolites have mainly been used as catalysts for the direct alkylation of benzene with alkanes at high temperatures . The alkylation of benzene with propane and ethane have been reported using metal‐modified zeolites, such as Pt and Pd/H‐ZSM‐5, at 300–500 °C with 10–20 % benzene conversions .…”

“…For alkylation with n ‐hexane, Pt‐modified ZSM‐5 showed 30 % conversion and 50 % total selectivity for hexyl benzenes, including 1‐phenylhexane and 2‐phenylhexane at 205 °C . Pt‐Ga bimetallic ZSM‐5 has also been reported as a highly selective catalyst for 2‐phenylhexane production . Several examples of catalysts without noble metals have also been reported; however, the main problem with such systems is their low selectivity toward the desired alkylated benzenes due to high reaction temperatures.…”

“…Several examples of catalysts without noble metals have also been reported; however, the main problem with such systems is their low selectivity toward the desired alkylated benzenes due to high reaction temperatures. The reaction of n ‐hexane with benzene using proton‐type zeolites such as H‐ZSM‐5 affords a low selectivity toward alkylated products, with large amounts of cracking and/or higher alkylated products . Only the homogeneous, super‐strong acid HF‐SbF 5 can promote the reaction selectively at room temperature .…”

“…[2] Pt-Ga bimetallic ZSM-5 has also been reported as a highly selective catalyst for 2-phenylhexane production. [3] Several examples of catalysts without noble metals have also been reported; however, the main problem with such systems is their low selectivity toward the desired alkylated benzenes due to high reaction temperatures. The reaction of n-hexane with benzene using proton-type zeolites such as H-ZSM-5 affords a low selectivity toward alkylated products, with large amounts of cracking and/or higher alkylated products.…”

New theoretical insight on the acid sites distribution, their local structures and acid strength of the SAPO‐11 molecular sieve

“…In general the interaction energy increases with the type of functional used, according to the trend xB97X-D > B3LYP. The results show that ONIOM methodology seems to be suited to investigate the acid sites in SAPO-11.acid sites, adsorption, xB97X-D, ONIOM, SAPO-11 1 | I N TR ODU C TI ON Silicoaluminophosphates (SAPOs) materials have been used widely in the hydroisomerization of n-paraffins, [1][2][3] methanol-to-hydrocarbons (MTH) and methanol-to-olefin (MTO) conversion, [4][5][6][7][8] alkylation reactions, [9] and many others reactions. [3,10,11] Different types of silicoaluminophosphates molecular sieves have been investigated and synthetized such as 3,5,9] SAPO-11 molecular sieve is highly active and selective for the skeletal isomerization of n-paraffins.…”