527-84-4Relevant academic research and scientific papers
Novel approach towards Al-rich AFI for catalytic application
Zhou, Yong,?ilková, Nadě?da,Shamzhy, Mariya,Avadhut, Yamini,Hartmann, Martin,?ejka, Ji?í,Opanasenko, Maksym
, p. 62 - 68 (2019)
A new germanosilicate structural analogue of AFI zeolite (Ge-AFI) was hydrothermally synthesized. One- and two-step alumination of the Ge-AFI zeolites were used to modify their structure and acidic properties traced using XRD, N2 adsorption, ICP-OES, 27Al NMR, and FTIR spectroscopy. Two-step aluminated sample (deGe-Al-AFI) provided a higher Al content, stronger acid sites and a higher micropore volume than one-step aluminated sample (Al-AFI). Extensive evaluation of the catalytic performance of these AFI zeolites compared with reference conventional zeolite catalysts for alkylation of toluene with isopropyl alcohol showed that deGe-Al-AFI exhibited relatively high toluene conversion and selectivity to valuable p-cymene due to the optimized textural and acidic properties.
Electrophilic Aromatic Substitution. 9. A Kinetic Study of the Friedel-Crafts Isopropylation Reaction in Nitromethane
DeHaan, Franklin P.,Delker, Gerald L.,Covey, William D.,Ahn, Jeffrey,Cowan, Robert L.,et al.
, p. 1587 - 1590 (1986)
The kinetics of the aluminum chloride catalyzed reaction between isopropyl chloride and benzene or toluene were determined in solvent nitromethane by using vacuum-line techniques.The reaction at 25 deg C was first order in isopropyl chloride and in aromatic hydrocarbon and first order in initial catalyst concentration.Noncompetitive results are kT/kB = 2.0 +/- 0.7 with the following toluene product isomer distribution: percent ortho, 45.3 +/- 1.5; percent meta, 22.7 +/- 1.1; percent para, 32.0 +/- 1.0.For competitive runs kT/kB was 2.3 +/- 0.1 with the same isomer distribution.Rate constants at 25, 15, 0, -15, and -27 deg C yielded Ea = 78 +/- 4 kJ/mol, ΔH = 76 +/- 4 kJ/mol, Δ = -13 +/- 14 J/mol deg.The results are consistent with a ? complex-like transition state and a predominantly ionic mechanism.
Catalytic Property of Calcined Iron Sulfate Treated with Hydrogen Chloride in Alkylation of Toluene and Benzene with Alkyl Chlorides
Arata, Kazushi,Hino, Makoto,Yabe, Katsumasa
, p. 6 - 9 (1980)
Alkylation was carried out at room temperature over catalysts prepared by calcination of FeSO4, Fe2O3, and Fe(OH)3 in the air at various temperatures and subsequent exposure to HCl at room temperature for 20 min.The FeSO4-HCl catalysts heat-treated at 700 and 750 deg C showed very high activity and selectivity, the other catalysts except for the sulfate treated at 800 deg C being almost inactive.The FeSO4(700 deg C)-HCl catalyst was found to consist of FeCl3 and α-Fe2O3 by means of Moessbauer effect, the absorption peak areas being 14 and 86percent for portions of iron based on the chloride and oxide, respectively.The results of DTA and TGA experiments suggest that the coordinate bond of water molecule on FeCl3 of the FeSO4(700 deg C)-HCl catalyst is stronger than that on FeCl3 of the FeSO4 (600, 800, and 900 deg C)-HCl and commercial FeCl3.The FeSO4(700 deg C)-HCl catalyst showed a much higher activity than pure FeCl3.The iron(III) chloride formed by reaction of HCl and α-Fe2O3 obtained by thermal decomposition of the sulfate at 700 or 750 deg C was found to be a very strong Lewis acid catalyst.
Continuous, ionic liquid-catalysed propylation of toluene in a liquid-liquid biphasic reaction mode using a loop reactor concept
Ladnak, Viktor,Hofmann, Norbert,Brausen, Nicole,Wasserscheid, Peter
, p. 719 - 726 (2007)
Acidic ionic liquids of the type [cation] [bis(trifluoromethanesulfonyl) imide anion]/aluminium trichloride {[cation] [(CF3SO 2)2N]/AlCl3} have been applied to realise for the first time a continuous Friedel-Crafts alkylation reaction in liquid-liquid biphasic reaction mode using a loop reactor concept. Exemplified for the continuous propylation of toluene we have proved that the acidic catalyst layer is successfully immobilised over at least 18 h in the loop reactor. After 8 h time-on-stream, a steady state has been reached followed by at least 10 h time-on-stream without any loss of activity or change in selectivity. Our results reveal the high potential of this class of acidic ionic liquids in continuous arene functionalisation reactions.
The Acidic Property and Catalytic Activity of MoO3-SiO2-Al2O3
Sabu, Kuzhunellil Raghavan Pillai,Rao, Kalur Vijayachandra C.,Nair, Chandrathil Govindan Ramacha.
, p. 1926 - 1932 (1991)
The ternary oxide system MoO3-SiO2-Al2O3 was prepared by coprecipitation method.The pH of coprecipitation has been varied from pH = 2 to pH = 8 and its effect on the acidic properties of the ternary oxide acidic system was studied by butylamine titration.The MoO3-SiO2-Al2O3 prepared from highly acidic solution has low acid strength.The total acid amount of the ternary oxide decreased considerably at higher pH (>6) of coprecipitation.It was found that the total acid amount of MoO3-SiO2-Al2O3 containing 9.7 percent (by weight) of MoO3 and silica to alumina molar ratio 16.6 is very high compared with that of SiO2-Al2O3 of the same silica to alumina molar ratio.The acid strength of SiO2-Al2O3 is reduced by the incorporation of MoO3.Increase in calcination temperature increased the acid strength.The catalytic activity of MoO3-SiO2-Al2O3 was found to be very high for the alkylation of toluene with 2-propanol.The products are found to be o-cymene, p-cymene, and three isomers of diisopropyltoluenes.Reaction temperature >200 deg C, higher liquid hourly space velocity, and higher alcohol content in the feed decreased the total conversion of 2-propanol to isopropyltoluenes.The acidic property and catalytic activity of MoO3-SiO2-Al2O3 are not considerably reduced up to four successive regeneration cycles.
Alkylation of Toluene with 2-Propanol over Titania-Silica-Alumina Catalysts
Rao, K. V. C.,Sabu, K. R.,Nair, C. G. R.
, p. 2657 - 2661 (1989)
The alkylating activity of titania supported on silica-alumina has been reported earlier (V.G.Kumar, T.S.Shoba, and K.V.C.Rao, Tetrahedron Lett., 26, 3281 (1985)).Further investigations to synthesize such a catalyst with optimum alkylation activity resulted in the coprecipitation of the catalyst from a solution of pH 4-the test reaction selected being the alkylation of toluene with 2-propanol in a fixed bed tubular reactor.The product mixtures at different reaction times are analyzed to have a view on the variation of yields of different alkylated products with reaction time.The alkylated products are o-cymene, p-cymene, and diisopropyltoluenes (DIT).The presence of titania exerts a synergistic effect upon the alkylating activity of silica-alumina.Also the catalytic activity is governed by the physical caracteristics of the catalyst like surface area and porosity.The trend of para-rich isomer distribution observed in the product mixture is attributed to the steric factors.It has been observed that o-cymene is formed at a constant rate whereas p-cymene formation decreased with reaction time.Increased formation of diisopropyltoluenes are observed with the passing of reaction time.Alkylation studies in the temperature range 165-240 degC have been done to find the effect of reaction temperature on the product distribution.Thus a decrease in the ortho to para molar ratio with increase in reaction temperature and increased formation of diisopropyltoluenes at lower temperatures are observed.No considerable reduction in the alkylation activity has been noticed up to five regeneration cycles.
Identification by GC-MS of cymene isomers and 3,7,7-trimethylcyclohepta-1, 3,5-triene in essential oils
Romanenko,Tkachev
, p. 699 - 701 (2006)
Retention indices of cymene isomers published in popular GC-MS atlases were found to be erroneous by analyzing synthetic samples. The following retention indices (RI) were found using a nonpolar phase (diphenyl: dimethylpolysiloxane, 5:95) for four essential-oil components with indistinguishable mass spectra: 3,7,7-trimethylcyclohepta-1,3,5-triene (RI = 970), m-cymene (RI = 1022), p-cymene (RI = 1024), and o-cymene (RI = 1039). The relative distributions of these compounds were evaluated based on the analysis of about 1000 essential oils. Simple methods were given for preparing standard mixtures of isomeric compounds for identification by GC-MS.
Production of p -cymene from crude sulphate turpentine with commercial zeolite catalyst using a continuous fixed bed reactor
Linnekoski, Juha A.,Asikainen, Martta,Heikkinen, Harri,Kaila, Reetta K.,R?s?nen, Jari,Laitinen, Antero,Harlin, Ali
, p. 1468 - 1475 (2014)
Crude sulphate turpentine (CST), containing -pinene, 3-carene, other terpene isomers, and organic sulphur compounds, was used as feedstock in the production of cymenes with commercial zeolite catalysts. The catalysts used were not sensitive to sulphur, and the desulphurisation step was not needed prior to cymene synthesis. The experiments were performed in a continuous fixed bed reactor. Promising results were obtained after initial optimization at temperatures close to 300 °C with faujasite Y zeolite under 5 bar N2 pressure. Cymenes were produced with 54% yields from model compound -pinene and with 28% yields from CST. The mechanistic route of the reaction can be divided into three steps: (1) ring opening, (2) rearrangement, and (3) dehydrogenation. The final step in the formation of p-cymene can occur via dehydrogenation or disproportion; here the effect of reaction conditions and catalyst plays a crucial role.
Facile fabrication of aluminum-promoted vanadium phosphate: A highly active heterogeneous catalyst for isopropylation of toluene to cymene
Behera, Gobinda Chandra,Parida,Das
, p. 190 - 198 (2012)
Vanadium phosphate is well known as a heterogeneous catalyst in gas phase oxidation reactions. To date, there has been little interest in carrying out liquid-phase reactions with vanadium phosphate as catalyst. Herein, we report the catalytic activity of vanadium phosphate and aluminum-promoted vanadium phosphate toward liquid-phase isopropylation of toluene to cymene. The catalysts were unambiguously characterized by X-ray diffraction, N2 adsorption-desorption, FT-IR technique, UV-vis DRS, and FE-SEM. The total acid sites were estimated by an NH3 TPD analyzer. XPS was used as a powerful tool to know the electronic environment of the catalysts. The optimization of the reaction was carried out by varying temperature from 75 to 150 °C and molar ratio (toluene: isopropanol) from 1:1-1:3. Under optimum reaction conditions, 5 wt.% aluminum-promoted vanadium phosphate showed 90% conversion with 85% selectivity to p-cymene.
Alkylation of Toluene with Isopropanol on Lantanum Modified ZSM-5 Zeolite
Abdullaeva,Voskressenskii,Akhmedova,Mamedov
, p. 190 - 197 (2020/12/17)
Abstract: The effect of lanthanum concentration on the physicochemical and catalyticproperties of HZSM-5 zeolite in a reaction of toluene alkylation withisopropanol was studied in a temperature range of 250–350°C. Based on the dataobtained by X-ray diffraction analysis, low-temperature nitrogen adsorption (BETmethod), and IR spectroscopy, it was shown that an increase in lanthanumconcentration in HZSM-5 from 1.0 wt % to 7.0 wt % reduces both the specificsurface area and the pore volume of the zeolite despite the retention of itscrystalline structure. This also results in redistribution of acid sites,specifically decreases the concentration of strong Br?nsted acid sites (B) andincreases that of moderate Lewis acid sites (L), thus decreasing the B/L ratiofrom 3.53 to 0.20. All these occurrences have a crucial effect on theselectivity of reaction products and, in particular, on the p-isopropyl toluene (4-IPT) selectivity. Maximumselectivity, making up 72.4%, is achieved by a zeolite containing 5.0 wt %lanthanum at a B/L ratio of 0.25.
