F:Flammable;1634-04-4Relevant articles and documents
Heteropoly Acids Supported on Acidic Ion-exchange Resin as Highly Active Solid-acid Catalysts
Baba, Toshihide,Ono, Yoshio,Ishimoto, Tadao,Moritaka, Shun-ichi,Tanooka, Seiichi
, p. 2155 - 2156 (1985)
Heteropoly acids supported on a macroreticular acidic ion-exchange resin shows much higher activity than those supported on activated carbon for the synthesis of methyl t-butyl ether and the esterification of acetic acid with 1-pentanol.This high activity can plausibly be attributed to the interaction of heteropoly anions with substrates which are protonated by the protons of the acidic resin.
Activity of Polymeric and Zeolite-Containing Catalysts in Production of Methyl tert-Butyl Ether
Koval',Bazhina,Safronova,Perevezentsev,Kosukhin,Erofeev,Ryabov
, p. 71 - 73 (2001)
The effect of structural and acid characteristics of catalysts of various nature (sulfonic cation exchangers of the KU-23 type and high-silica zeolite of the ZSM-5 type) on their activity and selectivity in production of methyl tert-butyl ether from isobutylene and methanol was studied.
High-pressure heat-flow calorimeter. Determination of the enthalpy of reaction for the synthesis of methyl t-butyl ether from methanol and 2-methylpropene
Arntz, H.,Gottlieb, K.
, p. 967 - 972 (1985)
A high-pressure heat-flow calorimeter suitable for measuring enthalpies of reaction and heat capacities is described.With the calorimeter, thermodynamic properties can be studied from 290 to 600 K and from 0.1 to 10 MPa.The reaction enthalpy for the synthesis of methyl t-butyl ether from methanol and 2-methylpropene using an acidic ion-exchange-resin catalyst was measured at 319 K and 1.6 MPa.The molar reaction enthalpy is given by ΔrHm(319 K, 1.6 MPa) = -(39.8 +/- 0.4)kJ.mol-1.The corresponding standard molar enthalpy of formation of methyl t-butyl ether is ΔfHm0(l, 298.15 K) = -315.4 kJ.mol-1.
Gas phase synthesis of MTBE on triflic-acid-modified zeolites
Nikolopoulos,Kogelbauer,Goodwin Jr.,Marcelin
, p. 76 - 82 (1996)
The gas phase synthesis of MTBE (methyl tert-butyl ether) was studied using three series of triflic acid (TFA)-modifled zeolites, the parent materials being HY, H-mordenite, and HZSM-5. Impregnation with TFA was found to enhance MTBE synthesis activity only for the large-pore zeolite Y and only up to a certain extent of modification. A high level of TFA modification caused a reduction in activity, apparently due to blockage of the active sites by TEA molecules and extra-lattice Al formed during the modification process. The mechanism of activity enhancement by TEA modification appears to be related to the formation of extra-lattice Al rather than the direct presence of TFA.
Gas phase synthesis of MTBE from methanol and isobutene over dealuminated zeolites
Collignon,Mariani,Moreno,Remy,Poncelet
, p. 53 - 66 (1997)
Gas phase synthesis of MTBE from methanol and isobutene has been investigated over different zeolites. It is shown that bulk Si/Al ratio has a marked influence on the formation of MTBE. H-beta zeolite was found to be as active as acid Amberlyst-15 (reference catalyst), and noticeably superior to non- and dealuminated forms of H-Y, H-ZSM-5, zeolite omega, and H-mordenites. Screening test results obtained over other catalysts (SAPOs and pillared clays) are briefly commented. The contribution of the external surface of the zeolites to the reaction is discussed. In the case of H-Y zeolites, it is shown that extraframework Al species (27Al NMR signal at 30 ppm) have a detrimental effect on the reaction.
On Anchimerically Assisted Homolysis via Sulphide Functions
Lawson, Alexander J.
, p. 1238 - 1239 (1981)
In contrast to O-O fission, anchimeric assistance from sulphide functions in the rate of unimolecular fission of the N-O bond is only marked for heterolysis reactions; analogous homolyses are very much less accelerated, although bridged radical intermediates are involved.
Determination of adsorption and kinetic parameters for methyl tert-butyl ether synthesis from tert-butyl alcohol and methanol
Ray,Ziyang,Hidajat
, p. 209 - 221 (2001)
Synthesis of MTBE by direct reaction between methanol and tert-butyl alcohol (TBA) on acid ion-exchange resin, Amberlyst 15, packed in a reactor was studied at 318-328 K and at different flow rates. A mathematical model based on a quasi-homogeneous kinetics was developed, assuming the reaction in the polymer phase to be homogeneous. H2O traveled more slowly than MTBE. The reaction rate increased with increasing reaction temperature, and the conversion of the limiting reactant, TBA, was favored at high temperatures and at low flow rates of TBA. The adsorption constant of H2O was almost 10 times greater than that of MTBE and as a result, the desired product MTBE always elutes faster than H2O. The effects of temperature on forward reaction constant, and reaction equilibrium constant were also explored. The activation energy for the reaction was 130.1 kJ/mole. The fitted parameters obtained for enthalpy and entropy of adsorption from Arrhenius plots were consistent with thermodynamics when the standard states were changed to liquid at 1 mole to pure gas at 1 atm. The accuracy of the proposed mathematical model was further verified when it was observed that the model could predict experimental results at different feed concentrations and flow rates quite well.
Kinetics of liquid phase synthesis of methyl tert-butyl ether from tert-butyl alcohol and methanol catalyzed by ion exchange resin
Matouq,Goto
, p. 825 - 831 (1993)
Synthesis of methyl tert-butyl ether (abbreviated as MTBE) from methanol (MeOH) and tert-butyl alcohol (TBA) in the liquid phase was studied by using Amberlyst 15 in the H+ form as an acid catalyst. Experiments were carried out in a stirred batch reactor at different temperatures (313, 318, and 323 K) under atmospheric pressure. It was found that catalyst sizes and rotation speeds had no significant effects on reaction rates. Mechanism studies showed that three reactions took place simultaneously. It was also found that dehydration of TBA could not be neglected. The experimental concentration profiles with time could be simulated well by simple kinetics. Finally, rate constants could be expressed by Arrhenius equations.
Strong influence of the polyanion structure on the secondary structure of solid heteropolyacids and their catalytic activity; methyl tert-butyl ether synthesis in the pseudo-liquid phase of heteropolyacids
Shikata, Sawami,Misono, Makoto
, p. 1293 - 1294 (1998)
It has been shown that the high catalytic activity of a Dawson-type heteropolyacid for gas-phase methyl tert-butyl ether synthesis at low temperatures is attributable to its amorphous secondary structure, which brings about a flexible pseudo-liquid phase and facilitates rapid absorption and desorption of molecules.
Catalysis in a porous molecular capsule: Activation by regulated access to sixty metal centers spanning a truncated icosahedron
Kopilevich, Sivil,Gil, Adria,Garcia-Rates, Miquel,Bonet-Avalos, Josep,Bo, Carles,Mueller, Achim,Weinstock, Ira A.
, p. 13082 - 13088 (2012)
The 30 cationic {MoV2O4(acetate)} + units linking 12 negatively charged pentagonal "ligands," {(MoVI)MoVI5O21(H 2O)6}6- of the porous metal-oxide capsule, [{MoVI6O21(H2O)6} 12{MoV2O4(acetate)} 30]42- provide active sites for catalytic transformations of organic "guests". This is demonstrated using a well-behaved model reaction, the fully reversible cleavage and formation of methyl tert-butyl ether (MTBE) under mild conditions in water. Five independent lines of evidence demonstrate that reactions of the MTBE guests occur in the ca. 6 × 10 3 A3 interior of the spherical capsule. The Mo atoms of the {MoV2O4(acetate)}+ linkers - spanning an ca. 3-nm truncated icosahedron - are sterically accessible to substrate, and controlled removal of their internally bound acetate ligands generates catalytically active {MoV2O4(H 2O)2}2+ units with labile water ligands, and Lewis- and Bronsted-acid properties. The activity of these units is demonstrating by kinetic data that reveal a first-order dependence of MTBE cleavage rates on the number of acetate-free {MoV2O 4(H2O)2}2+ linkers. DFT calculations point to a pathway involving both Mo(V) centers, and the intermediacy of isobutene in both forward and reverse reactions. A plausible catalytic cycle - satisfying microscopic reversibility - is supported by activation parameters for MTBE cleavage, deuterium and oxygen-18 labeling studies, and by reactions of deliberately added isobutene and of a water-soluble isobutene analog. More generally, pore-restricted encapsulation, ligand-regulated access to multiple structurally integral metal-centers, and options for modifying the microenvironment within this new type of nanoreactor, suggest numerous additional transformations of organic substrates by this and related molybdenum-oxide based capsules.
