- Synthesis of Nanosized ZSM-5 Zeolites by Different Methods and Their Catalytic Performance in the Alkylation of Naphthalene
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Abstract: Three nanosized ZSM-5 zeolites were successfully prepared from reactive gelswith the same Si/Al ratios by different synthetic procedures that included theuse of tetrapropylammonium hydroxide or n-butylamine as a template and a seedingmethod that did not use an organic additive. The effect of the synthetic methodon the physicochemical properties of the prepared samples was investigated byXRD, XRF, XPS, N2 physisorption, SEM, TEM,27Al MAS NMR, NH3-TPD, andPy-FTIR. The catalytic performance of thenanosized ZSM-5 zeolites in the alkylation of naphthalene with methanol wascompared. The prepared samples were phase-pure, highly crystalline ZSM-5zeolites, but they had different bulk and surface Si/Al ratios as well astextural and acidic properties. The study of the prepared catalysts innaphthalene methylation revealed that both the acid characteristics of the ZSM-5nanosized zeolites and their textural properties were responsible for theiractivity in the reaction. A difference in the composition ofmonomethylnaphthalenes and dimethylnaphthalenes was attributed to the ability ofthe catalyst to isomerize the primary reaction products on acid sites located onthe external surface of the zeolite crystals. 2,7-DMN was found to be thepreferred reaction product over 2,6-DMN when formed at pore entrances to ZSM-5channels due to the differences in their dimensions. In contrast,2,6-dimethylnaphthalene could be produced on weaker external Br?nsted acidsites, which are hydroxyls attached to octahedral Al atoms. The presentedresults show that the method used to synthesize nanoscale ZSM-5 zeolites is acritical factor that determines the physicochemical properties and catalyticperformance of the resulting crystals.
- Wang, Yongchao,Kikhtyanin,Li, Cheng,Su, Xiaofang,Bai, Xuefeng,Wu, Wei
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p. 394 - 406
(2021/02/26)
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- Methylation of 2-methylnaphthalene over metal-impregnated mesoporous MCM-41 for the synthesis of 2,6-triad dimethylnaphthalene isomers
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2,6-Dimethylnaphthalene (2,6-DMN) is one of the key intermediates for the production of polyethylene naphthalate (PEN), which demonstrates superior properties compared with the polyethylene terephthalate. However, the complex synthesis procedure of 2,6-DMN increases the production cost and decreases the commercialisation of PEN. In this study, selective synthesis of 2,6-triad DMN isomers (1,5-DMN, 1,6-DMN and 2,6-DMN) has been investigated by the methylation of 2-methylnaphthalene (2-MN) over mesoporous Cu/MCM-41 and Zr/MCM-41 zeolite catalysts. On the contrary of other DMN isomers, 2.6-triad isomers can effectively be converted to be profitable 2,6-DMN with an additional isomerisation reaction, which is a new approach to reach higher 2,6-DMN yield. The methylation reactions of 2-MN were investigated in a fixed-bed reactor at 400?°C and weight hourly space velocity of 1–3?h?1. The results showed that the activity of MCM-41 on the methylation of 2-MN has been enhanced with the impregnation of Cu. The conversion increased from about 17% to 35 wt% with the impregnation of Cu. Similarly, the 2,6-triad DMN selectivity and 2,6-/2,7-DMN ratio reached the maximum level (48 wt% and 1.95, respectively) over Cu-impregnated MCM-41 zeolite catalyst.
- Niftaliyeva, Aysel,Güle?, Fatih,Karaduman, Ali
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p. 2403 - 2416
(2020/02/11)
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- Selective synthesis of 2,6-triad dimethylnaphthalene isomers by disproportionation of 2-methylnaphthalene over mesoporous MCM-41
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2,6-Dimethylnaphthalene (2,6-DMN) is one of the crucial intermediates for the synthesis of polybutylenenaphthalate and polyethylene naphthalate (PEN). The complex synthesis procedure and the high cost of 2,6-DMN production significantly reduce the commercialisation of PEN even though PEN demonstrates superior properties compared with polyethylene terephthalate. 2,6-DMN can be produced by methylation of 2-methylnaphthalene (2-MN) and/or naphthalene, disproportionation of 2-MN, and/or isomerisation of dimethylnaphthalenes (DMNs). In this study, synthesis of 2,6-triad DMN isomers consisting of 2,6-DMN, 1,6-DMN, and 1,5-DMN have been investigated with the disproportionation of 2-MN over unmodified and Zr-modified mesoporous MCM-41 zeolite catalysts. In contrast to other DMN isomers, both 1,5-DMN and 1,6-DMN can be effectively isomerised to be profitable 2,6-DMN. The disproportionation of 2-MN experiments were carried out in a catalytic fixed-bed reactor in the presence of 1?g of catalyst at a temperature range of 350–500?°C and weight hourly space velocity between 1 to 3?h?1. The results demonstrated that mesoporous MCM-41 zeolite catalyst has a selective pore shape for 2,6-triad DMN isomers, which may allow a decrease in the production cost of 2,6-DMN. Additionally, 2,6-DMN was successfully synthesised by the disproportionation of 2-MN over MCM-41 zeolite catalyst. Furthermore, both the conversion of 2-MN and the selectivity of 2,6-DMN were considerably enhanced by the Zr impregnation on MCM-41.
- Güle?, Fatih,Niftaliyeva, Aysel,Karaduman, Ali
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p. 7205 - 7218
(2018/08/22)
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- Methylation of naphthalene on MTW-type zeolites. Influence of template origin and substitution of Al by Ga
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Two templates, methyltriethylammonium bromide (MTEA) and tetraethylammonium bromide (TEA) were used to synthesize aluminosilicate ZSM-12 zeolites. Additionally, zeolites isomorphously substituted (partially or totally) by gallium were prepared with MTEA.
- Wu, Wei,Wu, Weiguo,Kikhtyanin,Li, Lingfei,Toktarev,Ayupov,Khabibulin,Echevsky,Huang, Juan
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experimental part
p. 279 - 288
(2010/11/18)
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- Method for producing dimethylnaphthalene using a metal catalyst
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Disclosed herein is a process of producing high purity and high yield dimethylnaphthalene by dehydrogenating a dimethyltetralin isomer using a metal catalyst for dehydrogenation. The metal catalyst contains a carrier selected from alumina (Al2O3), silica (SiO2), a silica-alumina mixture and zeolite. The metal catalyst also contains 0.05 to 2.5 % by weight of platinum (Pt), 0.1 to 3.0 % by weight of tin (Sn) or indium (In), 0.5 to 15.0 % by weight of at least one selected from the group consisting of potassium (K), magnesium (Mg) and cesium (Cs), 0.3 to 3.0 % by weight of chlorine, and 0.01 to 3.0 % by weight of zinc (Zn) or gallium (Ga) as active components based on an element weight of the final catalyst.
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Page/Page column 7
(2008/06/13)
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- Dehydrogenation process of dimethylnaphthalene using metal catalyst
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Disclosed herein is a process of producing high purity and high yield dimethylnaphthalene by dehydrogenating a dimethyltetralin isomer using a metal catalyst for dehydrogenation. The metal catalyst contains a carrier selected from alumina (Al2O3), silica (SiO2), a silica-alumina mixture and zeolite. The metal catalyst also contains 0.05 to 2.5% by weight of platinum (Pt), 0.1 to 3.0% by weight of tin (Sn) or indium (In), 0.5 to 15.0% by weight of at least one selected from the group consisting of potassium (K), magnesium (Mg) and cesium (Cs), 0.3 to 3.0% by weight of chlorine, and 0.01 to 3.0 % by weight of zinc (Zn) or gallium (Ga) as active components based on an element weight of the final catalyst.
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Page/Page column 5-6
(2008/06/13)
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- Method for obtaining 2,6-dimethylnaphthalene using isomerization and crystallization processes
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The present invention relates to a method for preparation, separation and purification of high-purity 2,6-dimethylnaphthalene. The method according to the present invention comprises a step of subjecting a dimethylnaphthalene isomer mixture rich in 1,5-dimethylnaphthalene, high boiling point materials, unreacted 1,5-dimethyltetralin, and low boiling point materials, which are produced from a dehydrogenation reaction of 1,5-dimethyltetralin, to separation, using a distillation column;a step of subjecting the dimethylnaphthalene mixture separated by the distillation column to liquid state isomerization in the presence of an isomerization catalyst;a first crystallization step (melt crystallization process) of cooling the product of liquid state isomerization with a refrigerant without a solvent to form crystals; anda second crystallization step (solution crystallization process) of mixing the product of the first crystallization step with a solvent to form crystals.
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Page/Page column 8-9
(2008/06/13)
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- Process for producing organic compounds by catalysis of imide compounds
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A process produces an organic compound by catalysis of an imide compound of Formula (1): wherein R1 and R2 are each an alkyl group, aryl group, cycloalkyl group, etc., where R1 and R2 may be combined to form a double bond, or an aromatic or non-aromatic ring; and X is an oxygen atom or a hydroxyl group. In this process, the imide compound catalyst is added in installments to the reaction system to perform a reaction. Such reactions include, for example, oxidation reactions, carboxylation reactions, nitration reactions, sulfonation reactions, and carbon-carbon bond formation reactions. This process can produce a target compound with a higher conversion or selectivity in the production of the organic compound by catalysis of the imide compound catalyst such as N-hydroxyphthalimide.
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- Characterization of the combustion products of polyethylene
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Polyethylene (PE) was burned in a tube-type furnace with an air flow at a temperature of 600~900°C. Combustion products were collected with glass wool, glass fiber filter, and XAD-2 adsorbent. The analysis of the products was performed with GC-FID and GC-MSD. At low temperature, hydrocarbons were the major components, while at higher temperature the products were composed of polycyclic aromatic hydrocarbons. With the high performance of the Hewlett-Packard 6890GC-5973MSD, more compounds were identified in comparison with previous studies.
- Piao, Mingjun,Chu, Shaogang,Zheng, Minghui,Xu, Xiaobai
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p. 1497 - 1512
(2007/10/03)
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- Synthesis of peri-cyclobutarenes by thermolysis of [methoxy(trimethylsilyl)methyl]arenes
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[Methoxy(trimethylsilyl)methyl]arenes are readily prepared by reactions of chlorotrimethylsilane with (α-methoxy)arenylmethyllithium reagents as obtained from (methoxymethyl)arenes and t-BuLi. The [methoxy(trimethylsilyl)methyl]arenes eliminate methoxytrimethylsilane at 525-675 °C/0.05-0.10 mm to yield peri-cyclobutarenes as derived from arenylcarbenes. Of importance is the fact that the initial arenylcarbenes generated insert into adjacent peri C-H bonds and/or isomerize to other arenylcarbenes that insert into their peri C-H bonds to give peri- cyclobutarenes. Thus, flash-vacuum pyrolysis of 1- [methoxy(trimethylsilyl)methyl]naphthalene (13) at 575-675 °C/0.05-0.10 mm yields 1H-cyclobuta[de]naphthalene (6, up to 39%) in practical quantities. 2- [Methoxy(trimethylsilyl)methyl]naphthalene (23) also affords 6 as a major thermolysis product. At 510 °C/0.05-0.10 mm 4-methoxy-1- [methoxy(trimethylsilyl)methyl]naphthalene (29) decomposes to 4-methoxy-1H- cyclobuta[de]naphthalene (31, 46%). Under similar conditions, 2-methoxy-1- [methoxy(trimethylsilyl)methyl]naphthalene (33) converts to 1,2- dihydronaphtho[2,1-b]furan (35, 64%) and naphtho[2,1-b]furan (36, 31%), presumably by insertion of 2-methoxy-1-naphthylcarbene (34) into a C-H bond of its o-methoxy group and then dehydrogenation of the resultant dihydrofuran. Further, 1-[methoxy(trimethylsilyl)methyl]-6-methylnaphthalene (39) pyrolyzes (510 °C/0.10-0.20 mm) to 6-methyl-1-naphthylcarbene (40), which isomerizes in part to 7-methyl-1-naphthylcarbene (49); carbenes 40 and 49 then undergo peri C-H insertion to give 3-methyl-1H- cyclobuta[de]naphthalene (41) and 2-methyl-1H-cyclobuta[de]naphthalene (42) in an 8:1 ratio and a combined yield of 44%. The pyrolytic method is particularly valuable for preparing higher peri single carbon atom bridged arenes such as 4H-cyclobuta[jk]phenanthrene (53, 65%) and 3H- cyclobuta[cd]pyrene (59, 86%).
- Engler, Thomas A.,Shechter, Harold
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p. 4247 - 4254
(2007/10/03)
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- The first helical-chiral phosphane ligands: rac-[5]- and rac-[6]-heliphos
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The syntheses of two helical, chiral phosphanes in their racemic forms are described. Their helicene backbone was built up using an improved photocyclization approach. The phosphorus functionalities were introduced in the last step. Up to now, separation of the enantiomers of the helicene phosphanes could be achieved analytically but not on a preparative scale.
- Terfort, Andreas,Goerls, Helmar,Brunner, Henri
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- SHAPE SELECTIVE DISPROPORTIONATION OF METHYLNAPHTHALENE ON ZSM-5 CATALYST
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The conversion of 2-methylnaphthalene (2-MN) was studied at atmospheric pressure in a flow-type fixed bed reactor using H-Y, H-beta, H-mordenite, H-ZSM-5, H-ZSM-11 and H-ZSM-48 as catalysts.H-Y and H-beta exhibited high activities for disproportionation and isomerization of 2-MN.H-Mordenite and zeolites having medium size pores were active for the conversion of 2-MN which was mainly isomerized to 1-MN.The low disproportionation activities of these zeolites resulted from their shape selective properties.Disproportionation of 2-MN on the zeolite catalysts gave 2,6- and 2,7-dimethylnaphthalenes (DMN) in higher proportions than the thermodynamically attainable level.H-ZSM-5 was the most selective catalyst to produce these DMN isomers among the zeolite catalysts tested, although 2,7-DMN was formed in a higher proportion than 2,6-DMN.On H-mordenite catalyst, 2,6-DMN was more selectively formed than 2,7-DMN.The selectivity for 2,6-DMN against 2,7-DMN increased with increasing SiO2/Al2O3 ratio of H-mordenite.It is suggested that the composition of DMN isomers produced by disproportionation of 2-MN depends on the acid strength as well as on the shape selective properties of zeolites used.
- Kikuchi, Eiichi,Mogi, Yasuhiro,Matsuda, Takeshi
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p. 909 - 919
(2007/10/02)
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- Shape Selective Catalysis by ZSM-5 in Disproportionation of 2-Methylnaphthalene
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Disproportionation of methylnaphthalene (MN) was carried out on ZSM-5 catalysts.The external acid sites were eliminated by dealumination with (NH4)2SiF6.The dealuminated ZSM-5 gave 2,6- and 2,7-dimethylnaphthalene (DMN) from disproportionation of 2-methylnaphthalene (MN), due to its shape selective property.
- Matsuda, Takeshi,Yogo, Katsunori,Mogi, Yashuhiro,Kikuchi, Eiichi
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p. 1085 - 1088
(2007/10/02)
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- Studies of Aromatic Sesquiterpenes. III. The Synthesis of 4-Methoxyisocadalene
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Starting from p-cresol, the title sesquiterpene was synthesized through 4-methoxy-1,6-dimethylnaphthalene as a key intermediate.
- Adachi, Kazuo,Taniguchi, Naoki
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p. 1655 - 1656
(2007/10/02)
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