- The isopropylation of naphthalene over USY zeolite with FAU topology. The selectivities of the products
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The isopropylation of naphthalene (NP) over USY zeolite (FAU06, SiO2/Al2O3 = 6) gave all eight possible diisopropylnaphthalene (DIPN) isomers: β,β- (2,6- and 2,7-), α,β- (1,3-, 1,6-, and 1,7-), and α,α- (1,4- and 1,5-). Th
- Sugi, Yoshihiro,Joseph, Stalin,Ramadass, Kavitha,Indirathankam, Sathish Clastinrusselraj,Premkumar, Selvarajan,Dasireddy, Venkata D.B.C.,Yang, Jae-Hun,Al-Muhtaseb, Alaa H.,Liu, Qing,Kubota, Yoshihiro,Komura, Kenichi,Vinu, Ajayan
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p. 606 - 615
(2021/03/31)
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- Isopropylation of naphthalene by isopropanol over conventional and Zn- and Fe-modified USY zeolites
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Catalytic performances of USY, MOR, and BEA zeolites were compared for the isopropylation of naphthalene by isopropyl alcohol in a high-pressure, fixed-bed reactor. The USY catalyst showed a high conversion of 86% and good stability but a low 2,6-/2,7-DIPN shape selectivity ratio of 0.94. In contrast, over the MOR catalyst, 2,6-DIPN was selectively synthesized with a high 2,6-/2,7-DIPN ratio of 1.75, but low naphthalene conversions and fast deactivation of the catalyst were observed. The USY catalyst was modified by Zn and Fe using the wet impregnation method to enhance the selectivity for 2,6-DIPN. The highest conversion (~95%) and selectivity for 2,6-DIPN (~20%) were achieved with 4% Zn/USY catalyst. It appeared that small metal oxide islands formed in the USY pores to decrease the effective pore size and thus render it mildly shape-selective. Zn loading also decreased the number of strong acid sites responsible for coke formation and increased the number of weak acid sites. The high conversion and stability of Zn-modified catalysts were ascribed to the presence of a suitable admixture of weak and strong acid sites with less coke deposition. The Fe-modified USY catalysts were less effective because the modification increased the number of the strong acid sites.
- Banu, Marimuthu,Lee, Young Hye,Magesh, Ganesan,Lee, Jae Sung
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p. 120 - 128
(2014/01/06)
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- The isopropylation of naphthalene with propene over H-mordenite: The catalysis at the internal and external acid sites
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The isopropylation of naphthalene (NP) with propene over H-Mordenite (MOR) was studied under a wide range of reaction parameters: temperature, propene pressure, period, and NP/MOR ratio. Selective formation of 2,6-diisopropylnaphthalene (2,6-DIPN) was observed at reaction conditions, such as at low reaction temperature, under high propene pressure, and/or with high NP/MOR ratio. However, the decrease in the selectivities for 2,6-DIPN was observed at reaction conditions such as at high temperature, under low propene pressure, and/or with low NP/MOR ratio. The selectivities for 2,6-DIPN in the encapsulated products were remained high and constant under all reaction conditions. These results indicate that the selective formation of 2,6-DIPN occurs through the least bulky transition state due to the exclusion of the bulky isomers by the MOR channels. The decrease in the selectivities for 2,6-DIPN are due to the isomerization of 2,6-DIPN to 2,7-DIPN at the external acid sites, directing towards thermodynamic equilibrium of DIPN isomers.
- Sugi, Yoshihiro,Anand, Chokkalingam,Subramaniam, Vishnu Priya,Stalin, Joseph,Choy, Jin-Ho,Cha, Wang Soo,Elzatahry, Ahmed A.,Tamada, Hiroshi,Komura, Kenichi,Vinu, Ajayan
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p. 543 - 552
(2015/02/19)
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- Shape-selective synthesis of 2,6-diisopropylnaphthalene on H-mordenite catalysts
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To finally dispel any doubts on the shape-selective formation of 2,6-diisopropylnaphthalene (2,6-DIPN) over H-MOR zeolites, naphthalene alkylation was carried out over high-silica H-MOR catalysts with propylene or isopropanol as an alkylating agent and with or without cyclohexane as a solvent. Isomeric composition of DIPN's, determined by one-dimensional GC analysis, was additionally confirmed with advanced two-dimensional GC × GC. Our results proved beyond any doubt shape-selective formation of 2,6-DIPN over these H-MOR catalysts from naphthalene and propylene and without cyclohexane as a solvent. The DIPN mixture contained 60-64% 2,6-DIPN, and the ratio of 2,6-DIPN/2,7-DIPN was in the range 2.5-2.8. We also showed that shape-selective formation of 2,6-DIPN over H-MOR catalyst was depressed by using isopropanol instead of propylene and in the presence of cyclohexane.
- Brzozowski, Robert,Buijs, Wim
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experimental part
p. 181 - 187
(2012/10/07)
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- Shape-selective diisopropylation of naphthalene in H-Mordenite: Myth or reality?
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Selective diisopropylation of naphthalene to 2,6-diisopropylnaphthalene is a challenging goal in sustainable catalysis. Ultrastable Y and H-Mordenite zeolites are the best catalysts reported in the literature with respect to 2,6-diisopropylnaphthalene selectivity. It is generally accepted that in the case of H-Mordenite, shape-selectivity is responsible for the observed 2,6-diisopropylnaphthalene selectivity, while on Ultrastable Y-zeolite, the observed selectivity reflects the internal thermodynamic equilibrium of positional isomers. Revisiting both the experimental and the computational work in this field now leads to the conclusion that shape-selectivity of whatever kind can be ruled out in the case of H-Mordenite. H-Mordenite catalysts produce usually a kinetically controlled mixture of diisopropylnaphthalene isomers which can shift to the direction of a thermodynamical distribution at high reaction temperatures or over more active catalysts.
- Bouvier, Christophe,Buijs, Wim,Gascon, Jorge,Kapteijn, Freek,Gagea, Bogdan C.,Jacobs, Pierre A.,Martens, Johan A.
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scheme or table
p. 60 - 66
(2010/06/19)
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- The alkylation of naphthalene over one-dimensional fourteen-membered ring zeolites. the influence of zeolite structure and alkylating agent on the selectivity for dialkylnaphthalenes
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The alkylation, i.e., isopropylation, s-butylation, and t-butylation, of naphthalene (NP) was examined over one-dimensional fourteen-membered (14-MR) zeolites: CIT-5 (CF1), UTD-1 (DON), and SSZ-53 (SFH), and compared to the results over H-mordenite (MOR)
- Sugi, Yoshihiro,Maekawa, Hiroyoshi,Naiki, Hiroaki,Komura, Kenichi,Kubota, Yoshihiro
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experimental part
p. 1166 - 1174
(2009/05/06)
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- Disproportionation of isopropylnaphthalene on zeolite catalysts
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Disproportionation of isopropylnaphthalene (IPN) was tested over H-mordenite, HY, H-beta zeolites and over amorphous aluminosilicate in the range of 150-300°C. High β,β-selectivity in diisopropylnaphthalene (DIPN) product obtained over zeolites was observed. However, the 2,6-DIPN/2,7-DIPN mole ratio was dependent on the pore structure of the applied zeolite and on the temperature. Over H-mordenites 2,6-DIPN was the most preferred isomer, whereas 2,7-DIPN was favored over HY and H-beta zeolites. Such disproportion in isomer predominating in the DIPN product can be explained by a bimolecular mechanism of disproportionation. Due to the zeolite pore architecture the bent transition-state complex, leading to 2,7-DIPN (HY and H-beta) or more linear, leading to 2,6-DIPN (H-mordenite), was preferred. At high temperatures the monomolecular disproportionation mechanism (dealkylation realkylation) dominated and concealed (simultaneously with side reactions) the shape-selectivity effect. As a result the 2,6-DIPN/2,7-DIPN mole ratio in the product approached equilibrium value.
- Brzozowski, Robert,Skupinski, Wincenty
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- Zeolite pore entrance effect on shape selectivity in naphthalene isopropylation
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Naphthalene alkylation with propylene was studied over various large-pore zeolites and also over amorphous aluminosilicate catalysts. Isomeric distribution of isopropylnaphthalenes (IPN) and diisopropylnaphthalenes (DIPN) were compared at different temperatures. The shape-selectivity effect that occurred in the entrances to the pores could be responsible for high α-selectivity in monoisopropylation and 1NR-selectivity in diisopropylation observed in the naphthalene alkylation over wide pore zeolites. The product was then relatively rich in 1-IPN, 1,3-DIPN, and 1,4-DIPN. This type of shape selectivity suppressed other shape-selectivity effects, e.g., high β-selectivity of reactions occurring inside channels or cavities of the zeolite. High concentration of TIPN in alkylation products could be explained superbly with the help of catalysis in pore entrances. The explanation of such results was proposed to be a specific shape-selectivity effect of alkylation reaction occurring in the entrances to the pores of zeolite.
- Brzozowski,Skupinski
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p. 313 - 318
(2007/10/03)
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- Shape-selective Synthesis of 2,6-Diisopropylnaphthalene over H-Mordenite Catalyst
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2,6-Diisopropylnaphthalene is selectively produced in the liquid phase alkylation of naphthalene with propene or propan-2-ol over H-mordenite catalyst.
- Katayama, Atsuhiko,Toba, Makoto,Takeuchi, Genki,Mizukami, Fujio,Niwa, Shu-ichi,Mitamura, Shuichi
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