Shape - Selective Alkylation of Biphenyl Catalyzed by H-Mordenites

Sugi, Yoshihiro 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.1

Liquid phase alkylation of biphenyl was studied over large pore zeolites. Selective formation of the narrowest products, 4,4'-diisopropylbiphenyl (4,4'-DIPB), occurred only over HM among the zeolites with twelvemembered pore openings. These shape-selective catalyses are ascribed to steric restriction of transition state and to entrance of bulky substrates into the pores. The dealumination of HM enhanced catalytic activity and the selectivity of 4,4'-DIPB because of the decrease of coke-deposition, while the activity and the selectivity were low over HM with the low SiO₂/Al₂O₃ ratio. Non-regioselective catalysis occurs on external acid sites because severe cokedeposition deactivates the acid sites inside the pores by blocking pore openings. The selectivity of DIPB isomers was changed with propylene pressure and/or with reaction temperature. 4,4'-DIPB yielded selectively under high propylene pressure ($lt;0.3 MPa) at 250℃, while the selectivity of 4,4'-DIPB decreased under such low propylene pressure as 0.2 MPa. Selective formation of 4,4'-DIPB was observed at moderate temperature such as 250℃, whereas the decrease of the selectivity of 4,4'-DIPB occurred at higher temperature as 300℃. However, 4,4'-DIPB was almost exclusively isomer in the encapsulated DIPB isomers inside the pores under every pressure and temperature. These decreases of the selectivity of 4,4'-DIPB are due to the isomerization of 4,4'-DIPB on the external acid sites. The deactivation of external acid sites of HM was examined to reduce non-regioselective alkylation and isomerization. External acid sites were deactivated by calcination after impregnation of cerium on HM without the decrease in pore radii. Selectivities of 4,4'-DIPB were improved even at high temperatures in the isopropylation of biphenyl because of the suppression of non-regioselective alkylation and isomerization at the external acid sites. The selectivity of 4,4'-diethylbiphenyl (4,4'-DEBP) in the ethylation of biphenyl was much lower than that in the isopropylation. Among the DEBP isomers, 4,4'-DEBP has the highest reactivity for the ethylation to polyethylbiphenyls inside the pores, whereas the isopropylation of 4,4'-DIPB was negligibly low inside the pores. These differences are ascribed to the difference in steric restriction at the transition state composed of substrate, alkylating agent, and acid sites inside the pores.

Shape-Selective Catalysis over Zeolite. An Attempt in the Alkylation of Biphenyl

Yoshihiro, Sugi,Kenichi, Komura,Kim, Jong-Ho 한국공업화학회 2006 공업화학 Vol.17 No.3

The isopropylation of biphenyl over H-mordenite - Roles of 3- and 4-isopropylbiphenyls

Yoshihiro Sugi,Chokkalingam Anand,Tomonori Sugimura,Kenichi Komura,Yoshihiro Kubota,Jong Ho Kim,Gon Seo,Ajayan Vinu 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.5

The isopropylation of biphenyl (BP) and 3- and 4-isopropylbiphenyls (3- and 4-IPBPs) was examined over H-mordenites (MOR) to elucidate the mechanism of shape-selective formation of 4,4'-diisopropylbiphenyl (4,4'-DIPB). The isopropylation of BP occurred predominantly to form 4-isopropylbiphenyl (4-IPBP) from BP and 4,4'-DIPB from 4-IPBP. However, 3-IPBP, a minor isomer from BP, cannot participate effectively in the formation of 3,4'-DIPB due to steric restriction of its isopropyl moiety with MOR channels. Selective formation of 4,4'-DIPB was observed at low to moderate temperatures: 225-275 oC. However, the selectivities for 4,4'-DIPB were decreased at high temperatures,300-350 oC under propene pressure, 0.8MPa, by the isomerization of 4,4'-DIPB at external acid sites. The isomerization of 4,4'-DIPB occurred under low propene pressure even at 250 oC. The roles of 3- and 4-IPBPs in the formation of DIPB isomers were examined in the isopropylation of their mixtures. 4-IPBP was consumed much faster than 3-IPBP in all cases examined. 4-IPBP was an exclusive precursor to DIPB isomers, particularly 4,4'-DIPB. 4,4'-DIPB was also found as a predominant isomer in encapsulated products at all conditions examined. These results show that 4-IPBP can preferentially establish active transition state with propene and acid site in MOR channels, resulting in selective formation of 4,4'-DIPB. It is concluded that the isopropylation of BP over MOR occurs through reactant selectivity mechanism and restricted transition state mechanism, but not through product selectivity mechanism.

Isopropylation of naphthalene over H-mordenite, H-Y, and H-beta zeolites: Roles of isopropylnaphthalene isomers

Yoshihiro Sugi,Yukio Hasegawa,Hiroshi Tamada,Kenichi Komura,Yoshihiro Kubota,김종호 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2

Isopropylation of naphthalene (NP) was examined over H-mordenite (MOR), H-Y zeolite (FAU), and HBeta zeolite (BEA) in order to elucidate roles of isopropylnaphthalene (IPN) isomers during the catalysis. 2-IPN was the predominant isomer over MOR and works as a precursor for the selective formation of β,β-DIPN, particularly, 2,6-DIPN. In contrast, 1-IPN was predominant (with 2-IPN as a minor isomer) over FAU and BEA at low temperatures;dialkylation accompanied by the consumption of 1- and 2-IPN led to predominant formation of α,α- and α,β-DIPN. The formation of β,β-DIPN from 2-IPN was enhanced at higher temperatures. Bulky transition states of 1-IPN in IPN isomers and α,α- and α,β-DIPN among DIPN isomers were hindered by the interaction with MOR channels, resulting in the selective formation of β,β-DIPN, particularly 2,6-DIPN through the less bulky 2-IPN. FAU and BEA allow the formation of α,α- and α,β-DIPN from both of 1- and 2-IPN isomers because their channels are too large to exclude bulky transition states. The catalysis over FAU and BEA occurred under kinetic control at lower temperatures, and thermodynamic control also participates at higher temperatures.

Ceria and lanthana as blocking modifiers for the external surface of MFI zeolite

Jang, Hoi-Gu,Ha, Kwang,Kim, Jong-Ho,Sugi, Yoshihiro,Seo, Gon Elsevier 2014 Applied catalysis. A, General Vol.476 No.-

The ceria-and lanthana-modified MFI zeolites were prepared and extensively investigated to verify the function of lanthanide oxides as blocking modifiers. Their catalytic behavior in the methanol-to-olefin (MTO) conversion was explained by the characterization results regarding crystallinity, agglomeration, porosity, surface composition, and the uptakes of o-xylene and methanol. The ceria impregnated on the MFI formed nano-sized small particles with two oxidation states of +3 and +4 (Ce2O3 and CeO2) on the surface and was located predominantly on the external surface. So, the ceria impregnation maintained the porosity and activity of the MFI, and induced little change in the conversion and product composition of MTO. However, the lanthana impregnated on the MFI dispersed as a single lanthana (La2O3) phase in its micropores, as well as on the external surface. The blocking of the micropores and reduction of acidity by lanthana impregnation lowered the activity of the lanthana-modified MFI in MTO. The ceria located on the external surface of MFI did not have any negative effects on the catalytic performance, while the lanthana dispersed in the micropores lowered the conversion in MTO. The locations and dispersed states of ceria and lanthana were systematically discussed in the relation to their catalytic performance as blocking modifiers. (C) 2014 Elsevier B.V. All rights reserved.

Shape - Selective Alkylation of Isopropylnaphthalene on MCM-22 Zeolite

Seo, Gon,Kim, Jong Ho,Kim, Myung Wan,Sugi, Yoshihiro 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.4

An MCM-22 zeolite with an Si/Al ratio 13 was found to exhibit higher selectivity to β,β-diisopropylnaphthalene in the alkylation of isopropylnaphthalene with isopropylalcohol, as compared with other zeolites such as mordenite, Y and beta having similar Si/Al ratios. This high selectivity is ascribed to the specific pore shape of MCM-22 zeolite. The gradual increase in the selectivity with reaction time is due to its pore modification by coke deposit.

Vapor-Phase Ethylation of Biphenyl over MTW Zeolites

Mulla, Shafeek Abdul Rashid,Waghmode, Suresh B.,Watanabe, Seiji,Maekawa, Hiroyoshi,Komura, Kenichi,Kubota, Yoshihiro,Sugi, Yoshihiro,Kim, Jong-Ho,Seo, Gon The Chemical Society of Japan 2006 Bulletin of the Chemical Society of Japan Vol.79 No.9

<P>Vapor-phase ethylation of biphenyl (BP) with ethanol over the MTW zeolites was examined by using a fixed-bed flow reactor, and compared to the catalyses over MOR and MFI zeolites. Two types of MTW zeolites: MTW-S (small crystal) and MTW-L (large crystal) were synthesized under hydrothermal conditions. The selectivity for 4,4′-diethylbiphenyl (4,4′-DEBP) over the MTW zeolites was the highest among the other zeolites, such as MOR and MFI. The catalytic activity of MTW-S was higher than MTW-L. The selectivities for 4,4′-DEBP at 300 °C were ca. 30% for MTW-S and ca. 22% for MTW-L among the DEBP isomers. The dealumination of the MTW zeolites enhanced the selectivity for 4,4′-DEBP although the catalytic activity was slightly decreased. In particular, the selectivity for 4,4′-DEBP over dealuminated MTW-L by steaming and subsequent refluxing in hydrochloric acid increased from 22 to 42% at 300 °C. The enhancement of the selectivity for 4,4′-DEBP is due to the decrease in non-selective reactions at external acid sites because these sites are removed by the dealumination. The selectivities are higher than those of equilibrium mixtures, and the slimmest isomer. 4,4′-DEBP is preferentially formed due to the steric interaction of reactants and products with acidic sites in the MTW channels. Molecular modeling on the diffusion of products in the MTW channel suggests that 4,4′-DEBP isomer can diffuse most easily among DEBP isomers. 4,4′-DEBP and other isomers easily diffuse inside MOR channel; however, they cannot in the MFI channels. These results show that the formation of 4,4′-DEBP is the most favorable due to the diffusion and the restriction of transition state in the MTW channels.</P>