60-29-7

Ethylation of Ethanol in the Gas Phase

Audier, H. E.,Monteiro, C.,Robin, D.

, p. 146 (1989)

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Study of the Ethylation of Ethanol by Using a Dual-cell Fourier Transform Mass Spectrometer

Bjarnason, Asgeir

, p. 847 - 848 (1989)

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Heterogeneous Parahydrogen-Induced Polarization of Diethyl Ether for Magnetic Resonance Imaging Applications

Salnikov, Oleg G.,Svyatova, Alexandra,Kovtunova, Larisa M.,Chukanov, Nikita V.,Bukhtiyarov, Valerii I.,Kovtunov, Kirill V.,Chekmenev, Eduard Y.,Koptyug, Igor V.

, p. 1316 - 1322 (2021)

Magnetic resonance imaging (MRI) with the use of hyperpolarized gases as contrast agents provides valuable information on lungs structure and function. While the technology of 129Xe hyperpolarization for clinical MRI research is well developed, it requires the expensive equipment for production and detection of hyperpolarized 129Xe. Herein we present the 1H hyperpolarization of diethyl ether vapor that can be imaged on any clinical MRI scanner. 1H nuclear spin polarization of up to 1.3 % was achieved using heterogeneous hydrogenation of ethyl vinyl ether with parahydrogen over Rh/TiO2 catalyst. Liquefaction of diethyl ether vapor proceeds with partial preservation of hyperpolarization and prolongs its lifetime by ≈10 times. The proof-of-principle 2D 1H MRI of hyperpolarized diethyl ether was demonstrated with 0.1×1.1 mm2 spatial and 120 ms temporal resolution. The long history of use of diethyl ether for anesthesia is expected to facilitate the clinical translation of the presented approach.

THE SURFACE STRUCTURE AND CATALYTIC PROPERTIES OF ONE-ATOMIC LAYER AMORPHOUS NIOBIUM-OXIDE ATTACHED ON SiO2

Asakura, Kiyotaka,Twasawa, Yasuhiro

, p. 859 - 862 (1986)

A SiO2-attached one-atomic layer amorphous niobium-oxide catalyst was prepared by the two-stage attaching reaction between silanol groups and Nb(OC2H5)5 followed by chemical treatments with H2O and O2.The one-atomiclayer Nb oxide catalyst was found to be active and selective for ethene formation from ethanol.

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Skaerblom

, (1928)

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Solvent effects in liquid-phase dehydration reaction of ethanol to diethylether catalysed by sulfonic-acid catalyst

Vanoye, Laurent,Zanota, Marie-Line,Desgranges, Audrey,Favre-Reguillon, Alain,De Bellefon, Claude

, p. 276 - 280 (2011)

The liquid-phase dehydration of ethanol to diethylether over heterogeneous sulfonic-acid catalysts was carried out in a stirred batch reactor. The different Amberlyst catalysts were found to have similar activities for this reaction; even though Amberlyst 70 showed a lower acid capacity compensated by a higher specific activity. By comparing the conversion of ethanol as a function of reaction mixture composition, it was found that reaction rates greatly depended on ethanol concentration but also on reaction mixture polarity. The swelling of the used resins could not explain the observed variations of initial reaction rate since this effect was observed both with resins and with homogeneous catalyst, i.e. p-toluenesulfonic acid. The initial ethanol concentration has a complex effect on initial reaction rates that could not be correlated by usual kinetic models. Taking account of the intrinsic reactivity trends of the SN2 etherification reaction, a strong dependence was found between solvent properties and initial reaction rate.

Conversion of ethanol and glycerol to olefins over the Re- and W-containing catalysts

Zharova,Chistyakov,Zavelev,Kriventsov,Yakimchuk,Kryzhovets,Petrakova,Drobot,Tsodikov

, p. 337 - 345 (2015)

The catalytic conversion of a mixture of ethanol and glycerol over the Re - W/Al2O3 catalysts was studied. The Re - W binary system exhibits a non-additive cocatalytic effect in the conversion of ethanol and its mixture with glycerol into the fraction of olefins C4 - C9. The non-additive increase in the catalytic activity is associated with the specific structure of the binuclear metallocomplex precursors, due to which the supported metals are arranged in the immediate vicinity from each other on the support surface and intensively interact to form Re7+. The study of the combined conversion of ethanol and glycerol made it possible to find an optimum ratio of the reactants in the initial mixture. The yield of target hydrocarbons attains 50 wt.% based on the amount of carbon passed through the reactor.

Catalytic activity of heteropoly tungstate catalysts for ethanol dehydration reaction: Deactivation and regeneration

Verdes, Orsina,Sasca, Viorel,Popa, Alexandru,Suba, Mariana,Borcanescu, Silvana

, p. 123 - 132 (2021)

The pure and palladium doped 12-tungstophosphoric acid - H3PW12O40 (HPW) and its cesium salts CsxH3-xPW12O40 (x = 1, 2, 2.25 and 2.5) were prepared and characterized by thermal analysis, FTIR, XRD, BET and XPS methods. In this paper were determined the optimal reaction temperature and the effect of palladium on the coke content during the dehydration of ethanol in the temperature range of 200?350 °C. Above 300 °C, a strong deactivation of the catalysts was caused by coke formation. The catalytic tests demonstrate that by supporting the HPW and PdyPW (y = 0.15, 0.2 and 0.25) on mesoporous molecular sieve SBA-15 the catalytic activity in ethanol dehydration reaction was improved. Palladium doping of HPW/SBA-15 significantly decreases the formation of coke deposit. The formation of coke during the ethanol dehydration does not affect the Keggin structure which led us to conclude that such catalysts can be regenerated in air and regain their catalytic activity for a short time.

An Unusually Acidic and Thermally Stable Cesium Titanate CsxTi2- yMyO4 (x = 0.67 or 0.70; M = vacancy or Zn)

Maluangnont, Tosapol,Wuttitham, Boonyawat,Hongklai, Panisa,Khunmee, Pongsatorn,Tippayasukho, Sorawat,Chanlek, Narong,Sooknoi, Tawan

, p. 6885 - 6892 (2019)

Proton-free, alkali-containing layered metal oxides are thermally stable compared to their protonic counterparts, potentially allowing catalysis by Lewis acid sites at elevated temperatures. However, the Lewis acidic nature of these materials has not been well explored, as alkali ions are generally considered to promote basic but to suppress acidic character. Here, we report a rare example of an unusually acidic cesium-containing oxide CsxTi2-yMyO4 (x = 0.67 or 0.70; M = Ti vacancy or Zn). These lepidocrocite-type microcrystals desorbed NH3 at >400 °C with a total acidity of 410 μmol g-1 at a specific surface area of only 5 m2 g-1, without the need for lengthy proton-ion exchange, pillaring, delamination, or restacking. The soft and easily polarized Cs+ ion essentially drives the formation of the Lewis acidic site on the surfaces as suggested by IR of sorbed pyridine. The two-dimensional layered structure was preserved after the oxide was employed in the ethanol conversion at 380 °C, the temperature at which the protonic form could have converted to anatase. The structure was also retained after the NH3 temperature-programmed desorption measurement up to 700 °C. The production of ethylene from ethanol, well-known to occur over acid sites, unambiguously confirmed the acidic nature of this cesium titanate.

Gilman et al.

, p. 1034,1038,1039 (1954)

A study of commercial transition aluminas and of their catalytic activity in the dehydration of ethanol

Phung, Thanh Khoa,Lagazzo, Alberto,Rivero Crespo, Miguel Angel,Sanchez Escribano, Vicente,Busca, Guido

, p. 102 - 113 (2014)

Conversion of ethanol was investigated over four commercial aluminas prepared by different industrial procedures and one commercial silica-alumina. Characterization was performed by TEM, XRD, SBET and porosity measurements, and IR spectroscopy of the surface OH groups and of adsorbed CO and pyridine. Different features are attributed to different phases (γ-, δ-, θ-Al2O3) and different impurities (Na +, Cl-). Total conversion of ethanol with >99% selectivity to ethylene is achieved at 623 K over the purer Al2O 3 catalyst (Na 3+ sites in a tetrahedral environment located on edges and corners of the nanocrystals. Ethanol adsorbs dissociatively on Lewis acid-base pair sites but may also displace water and/or hydroxyl groups from Lewis acidic Al3+ sites forming the active intermediate ethoxy species. Surface ethoxy groups are supposed to be intermediate species for both diethyl ether and ethylene production. Silica-alumina also works as a Lewis acid catalyst. The slightly lower activity on surface area basis of silica-alumina than aluminas attributed to the lower density of Lewis acid sites and the absence of significant basicity.

Catalytic activity of LiZr2(PO4)3 nasicon-type phosphates in ethanol conversion process in conventional and membrane reactors

Ilin, Andrey B.,Orekhova, Natalia V.,Ermilova, Margarita M.,Yaroslavtsev, Andrey B.

, p. 29 - 36 (2016)

In this paper synthesis and catalytic properties of new catalysts based on double lithium-zirconium phosphate (LiZr2(PO4)3) with monoclinic NASICON-type structure, doped by indium, niobium and molybdenum are discussed. The obtained samples with particle size of 50-300 nm were characterized by X-ray diffraction, scanning electron microscopy and X-ray microanalysis. The synthesized samples exhibit catalytic activity in the dehydration and dehydrogenation reactions of ethanol conversion. The main products were acetaldehyde, diethyl ether, hydrogen, C2- and C4-hydrocarbons. Indium- and molibdenum-doped samples were characterized by high activity in dehydrogenation processes, while niobium-doped was more active in dehydration processes. The highest selectivity in diethyl ether formation was achieved for LiZr2(PO4)3 and Nb-doped samples (90 and 60% at 300°C). The highest hydrogen yield (up to 60%) was obtained with the use of In-doped catalyst. LiZr2(PO4)3 and Mo-doped samples are also noticeable for high C4-hydrocarbons formation, selectivity to which reaches 60% at 390°C. Use of a 100% hydrogen selective palladium-ruthenium alloy membrane increases hydrogen yield by 20%.

Novel synthesis of homogenous CsxWO3 nanorods with excellent NIR shielding properties by a water controlled-release solvothermal process

Guo, Chongshen,Yin, Shu,Zhang, Peilin,Yan, Mei,Adachi, Kenji,Chonan, Takeshi,Sato, Tsugio

, p. 8227 - 8229 (2010)

Nanosize homogenous rod-like tungsten bronze CsxWO3 with excellent NIR shielding ability was successfully synthesized by a novel and facile water controlled-release solvothermal process (WCRSP).

Calingaert,Soroos,Hnizda

, p. 392 (1942)

Rigid Arrangements of Ionic Charge in Zeolite Frameworks Conferred by Specific Aluminum Distributions Preferentially Stabilize Alkanol Dehydration Transition States

Bates, Jason S.,Di Iorio, John R.,Gounder, Rajamani,Hibbitts, David,Hoffman, Alexander J.,Nimlos, Claire T.,Nystrom, Steven V.

, p. 18686 - 18694 (2020)

Zeolite reactivity depends on the solvating environments of their micropores and the proximity of their Br?nsted acid sites. Turnover rates (per H+) for methanol and ethanol dehydration increase with the fraction of H+ sites sharing six-membered rings of chabazite (CHA) zeolites. Density functional theory (DFT) shows that activation barriers vary widely with the number and arrangement of Al (1–5 per 36 T-site unit cell), but cannot be described solely by Al–Al distance or density. Certain Al distributions yield rigid arrangements of anionic charge that stabilize cationic intermediates and transition states via H-bonding to decrease barriers. This is a key feature of acid catalysis in zeolite solvents, which lack the isotropy of liquid solvents. The sensitivity of polar transition states to specific arrangements of charge in their solvating environments and the ability to position such charges in zeolite lattices with increasing precision herald rich catalytic diversity among zeolites of varying Al arrangement.

A new method for quantifying iodine in a starch-iodine matrix

Manion, Bruce A.,Holbein, Bruce E.,Marcone, Massimo F.,Seetharaman, Koushik

, p. 2698 - 2704 (2010)

A rapid and sensitive method for quantifying iodine in intact starch granules using gas chromatography is described with detection limits as low as 0.2% (w/w) iodine in starch. Sample preparation includes NaBH4 reduction of the various iodine species associated with starch to the colorless soluble iodide ion, followed by its quantitative derivatization to EtI using Et3O+BF4- in CH2Cl2. Identification and quantification of EtI is carried out by extraction and injection of the EtI so generated in CH2Cl2 into a gas chromatography-mass spectrometer (GC-MS). Routine quantification of EtI was then performed using GC with a flame ionization detector (GC-FID). Results for different iodine:potassium iodide ratios of the initially bound iodine and for seven different starch matrices showed that in all cases regression coefficients for the standards were high (R2 >0.96).

Alvorado

, p. 790 (1928)

EFFECT OF THE NATURE OF THE CARRIER AND REDUCTION CONDITIONS ON THE PROPERTIES OF RHENIUM CATALYSTS OF HYDROGENATION OF ETHYL ACETATE

Avaev, V. I.,Ryashentseva, M. A.,Minachev, Kh. M.

, p. 15 - 19 (1988)

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Direct conversion of ethanol into ethylene oxide on gold-based catalysts: Effect of CeOx and Li2O addition on the selectivity

Lippits,Nieuwenhuys

, p. 142 - 149 (2010)

Results are presented concerning the behavior of alumina-supported gold catalysts and the effects of addition of Li2O and CeOx on the oxidation, dehydrogenation and dehydration reactions of ethanol. Pure alumina mainly acts as an acidic catalyst and produces diethyl ether and ethylene. Gold particles play an important role in converting ethanol into ethylene oxide and acetaldehyde. Addition of Li2O influences the selectivity by suppressing the formation of diethyl ether and ethylene. With the Au/Li2O/Al2O3 catalysts, a high selectivity toward ethylene oxide can be obtained. The influence of the oxygen concentration on the gas flow is investigated. It is suggested that at low concentrations, the role of oxygen is mainly to prevent coke formation on the catalytic surface.

Ethanol dehydration and dehydrogenation on γ-Al2O3: Mechanism of acetaldehyde formation

DeWilde, Joseph F.,Czopinski, Christopher J.,Bhan, Aditya

, p. 4425 - 4433 (2014)

Steady state kinetics and measured pyridine inhibition of ethanol dehydration and dehydrogenation rates on γ-alumina above 623 K show that ethanol dehydrogenation can be described with an indirect hydrogen transfer mechanism to form acetaldehyde and ethane and that this mechanism proceeds through a shared surface intermediate with ethylene synthesis from ethanol dehydration. Ethane is produced at a rate within experimental error of acetaldehyde production, demonstrating that ethane is a coproduct of acetaldehyde synthesis from ethanol dehydrogenation. Steady state kinetic measurements indicate that acetaldehyde synthesis rates above 623 K are independent of co-fed water partial pressure up to 1.7 kPa and possess an ethanol partial pressure dependence between 0 and 1 (Pethanol = 1.0-16.2 kPa), consistent with ethanol dehydrogenation rates being inhibited only by ethanol monomer surface species. The surface density of catalytically active sites for ethylene and diethyl ether production were estimated from in situ pyridine titration experiments to be ～0.2 and ～1.8 sites nm-2, respectively, at 623 K. Primary kinetic isotope effects for ethylene and acetaldehyde are measured only when the C-H bonds of ethanol are deuterated, verifying that C-H bond cleavage is kinetically limiting for both products. The proposed indirect hydrogen transfer model for acetaldehyde synthesis is consistent with experimentally observed reaction rate dependences and kinetic isotope effects and highlights the complementary role of hydrogen adatom removal pathways in the formation of aldehydes on Lewis acidic systems. (Chemical Equation Presented).

A comparative study of direct versus post-synthesis alumination of mesoporous FSM-16 silica

Zimowska,Michalik-Zym,Kry?ciak-Czerwenka,Dula,Socha,Pamin,Bazarnik,Bahranowski,Olejniczak,Lityńska-Dobrzyńska,Serwicka

, p. 623 - 631 (2016)

Al-FSM-16 mesoporous silicas were synthesized either by direct method, from Al-kanemite (Al-FSM-16/D), or by post-synthesis impregnation of purely siliceous FSM-16 with Al(NO3)3 (Al-FSM-16/P) and characterized with XRD, XRF, SEM, TEM, nitrogen sorption isotherms, 27Al and 29Si MAS NMR, FTIR, XPS, NH3-TPD, FTIR of pyridine adsorption and catalytic decomposition of ethanol. Only substitutional Al sites exist in Al-FSM-16/D, while in Al-FSM-16/P some Al remains in extra-lattice positions. Upon transformation of Al-FSM-16/D into hydrogen form a certain amount of extra-framework Al is formed. Direct alumination introduces a higher degree of structural disorder. In Al-FSM-16/D, Al is preferentially accumulated at inner pore walls, while in Al-FSM-16/P external surface is Al-rich. Post-synthesis alumination is more efficient in introducing acid sites into FSM-16. The generated acidity is of Br?nsted and Lewis nature, the latter being stronger than the former.

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Clark,Graham,Winter

, p. 2753 (1925)

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Method for quantifying redox site densities in metal oxide catalysts: Application to the comparison of turnover frequencies for ethanol oxidative dehydrogenation over alumina-supported VOx, MoOx, and WOx catalysts

Nair, Hari,Baertsch, Chelsey D.

, p. 1 - 4 (2008)

Isothermal anaerobic titration with ethanol as a probe molecule is proposed as an accurate technique to quantify active redox site densities in supported metal oxide catalysts. It is shown that the number of active redox sites for VOx-Al2O3, MoOx-Al2O3, and WOx-Al2O3 catalysts is a function of both the metal atom and its oxide surface density, but the intrinsic redox rate per active site is independent of both of these factors. Thus, the difference in steady-state redox rates per metal atom is due only to differences in the number of redox sites under reaction conditions.

Nanocrystalline h-rth zeolite: An efficient catalyst for the low-temperature dehydration of ethanol to ethene

Lee, Jeong Hwan,Lee, Sujin,Hong, Suk Bong

, p. 2035 - 2039 (2018)

The low-temperature dehydration of bioethanol is an environmentally benign route to ethene production. Here we compare the catalytic properties of a series of cage-based small-pore zeolites with different framework structures, acid strengths, and/or crystallite sizes for ethanol dehydration at 200 8C under wet conditions (H2 O/EtOH = 0.2). Among the zeolites studied here, nanocrystalline H-RTH was found to be considerably more effective than H-mordenite, the best catalyst for this reaction known to date, which can be rationalized by product shape selectivity. Whereas the acidity of this zeolite also plays a crucial role in selectively forming ethene, its nanocrystallinity is primarily responsible for the observed high catalyst durability.

Sulfated zirconia foams synthesized by integrative route combining surfactants, air bubbles and sol-gel transition applied to heterogeneous catalysis

Alves-Rosa, Marinalva A.,Martins, Leandro,Hammer, Peter,Pulcinelli, Sandra H.,Santilli, Celso V.

, p. 6686 - 6694 (2016)

Sulfated zirconia ceramic foams were produced by the sol-gel process using air-liquid foam and surfactants as dual pore templates. The results showed the presence of high porosity (until 93%) and surface area (105 m2 g-1), and a hierarchical structure of pore sizes in the range of macro (between 10 and 76 μm), and meso-scales (?6 nm). The hierarchical porous structure and pore wall texturization of ceramic foams produced by this process, besides the presence of strong acid sites, certify these materials as heterogeneous catalysts for dehydration reactions.

Dehydrogenative ester synthesis from enol ethers and water with a ruthenium complex catalyzing two reactions in synergy

Ben-David, Yehoshoa,Diskin-Posner, Yael,Kar, Sayan,Luo, Jie,Milstein, David,Rauch, Michael

supporting information, p. 1481 - 1487 (2022/03/07)

We report the dehydrogenative synthesis of esters from enol ethers using water as the formal oxidant, catalyzed by a newly developed ruthenium acridine-based PNP(Ph)-type complex. Mechanistic experiments and density functional theory (DFT) studies suggest that an inner-sphere stepwise coupled reaction pathway is operational instead of a more intuitive outer-sphere tandem hydration-dehydrogenation pathway.

Transition Metal-Free Direct Hydrogenation of Esters via a Frustrated Lewis Pair

Sapsford, Joshua S.,Csókás, Dániel,Turnell-Ritson, Roland C.,Parkin, Liam A.,Crawford, Andrew D.,Pápai, Imre,Ashley, Andrew E.

, p. 9143 - 9150 (2021/07/31)

"Frustrated Lewis pairs"(FLPs) continue to exhibit unique reactivity for the reduction of organic substrates, yet to date, the catalytic hydrogenation of an ester functionality has not been demonstrated. Here, we report that iPr3SnNTf2 (1-NTf2; Tf = SO2CF3) is a more potent Lewis acid than the previously studied iPr3SnOTf; in an FLP with 2,4,6-collidine/2,6-lutidine (col/lut), this translates to faster H2 activation and the catalytic hydrogenolysis of an ester bond by a main-group compound, furnishing alcohol and ether (minor) products. The reaction outcome is sensitive to the steric and electronic properties of the substrate; CF3CO2Et and simple formates (HCO2Me and HCO2Et) are catalytically reduced, whereas related esters CF3CO2nBu and CH3CO2Et show only stoichiometric reactivity. A computational case study on the hydrogenation of CF3CO2Et and CH3CO2Et reveals that both share a common mechanistic pathway; however, key differences in the energies of a Sn-acetal intermediate and transition states emerge, favoring CF3CO2Et reduction. The alcohol products reversibly inhibit 1-NTf2/lut via formation of resting-state species 1-OR/[1·(1-OR)]+[NTf2]- however, the extra energy required to regenerate 1-NTf2/lut exacerbates the unfavorable reduction energy profile for CH3CO2Et, ultimately preventing turnover. These findings will assist the design of future main-group catalysts for ester hydrogenation, with improved performance.