F:Flammable;
108-20-3Relevant articles and documents
Dehydration of 2-propanol over molybdenum oxide treated with hydrogen
Matsuda, Takeshi,Hirata, Yasuyoshi,Sakagami, Hirotoshi,Takahashi, Nobuo
, p. 1261 - 1262 (1997)
Dehydration of 2-propanol was carried out at 398 K using molybdenum oxides as a catalyst. The parent MoO3 exhibited a low activity. H2 reduction at 623 K increased the dehydration activity. After the reduction for 4 h, the MoO3 became more active than USY zeolites, although the catalytic activity of MoO3 declined with time on stream. We suggest that the acidity of MoO3 was enhanced by H2 reduction at 623 K.
A FTIR spectroscopy study of isopropanol reactivity on alkali-metal-doped MoO3/TiO2 catalysts
Martin, Cristina,Martin, Ines,Rives, Vicente,Grzybowska, Barbara,Gressel, Irena
, p. 733 - 740 (1996)
The transformation of isopropanol on MoO3/TiO2 catalysts doped with alkali-metal cations has been studied by the pulse technique. The FTIR studies have provided evidence of the dissociative adsorption of isopropanol and the formation of isopropoxide species which decompose at higher temperatures to acetone. Catalytic measurements have shown that the addition of alkali-metal cations leads to a drastic decrease in the yield of propene, owing to the elimination of Bronsted centres originally existing on the catalyst surface, whereas the rate of dehydrogenation to acetone is affected only slightly. The extent of the changes observed depends on the nature of the doping alkali-metal cation.
Catalytic dehydration of propan-2-ol by lanthanum-Y zeolite
Rudham, Robert,Spiers, Andrew I.
, p. 1445 - 1448 (1997)
Catalytic dehydration of propan-2-ol has been investigated over the range 353 to 407 K on a series of LaY zeolites containing up to 9.5 lanthanum atoms per unit cell. Zero-order kinetics were obeyed, with mean activation energies of 128.5 and 139.5 kJ mol-1, respectively, for diisopropyl ether and propene formation. These activation energies, which were independent of both the temperature of catalyst activation and the extent of lanthanum exchange, are identical to those for the reaction on HY zeolites made from the same NaY starting material. Reaction is thus considered in terms of the same single Bronsted acid-site mechanism, where differences in activity arise from differences in the concentration of active sites. Progressive poisoning experiments with pyridine assess the total concentration of acid sites, which generally exceeds that which is accessible to propan-2-ol and active in catalysis.
Catalytic properties of carbon nanotubes-supported heteropolyacids in isopropanol conversion
Kirpsza,Lalik,Mordarski,Micek-Ilnicka
, p. 254 - 262 (2018)
The technique of catalytic flow microreactor has been combined with the gas flow-through microcalorimetry to correlate the catalytic activity of supported heteropolyacids with both the acid strength of protons as well as the protons’ accessibility. Multiwall carbon nanotubes (CNT) were used as a support for Keggin (H3PW12O40) and Wells-Dawson (H6P2W18O62) structured heteropolyacids, in order to produce catalysts combining high acidity from the parent acids with the inherent microporosity of the support. Prior to the catalytic tests, the obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and Raman spectroscopies as well as by the nitrogen adsorption-desorption analysis (BET). The latter technique confirmed overall improved porosity of the obtained materials. Upon testing for activity in the isopropyl alcohol dehydration, the supported Wells-Dawson catalysts turned out to be superior to both the Keggin-based materials, as well as to the unsupported H6P2W18O62. It has been found that the improvement of catalytic performance in the isopropanol conversion is mostly related to the increase of the accessibility of protons, rather than to the changes in the acid strengths.
Catalytic properties of H2-reduced MoO3 with noble metal for the conversions of heptane and propan-2-ol
Uchijima, Fumiko,Takagi, Tomoaki,Itoh, Hidenobu,Matsuda, Takeshi,Takahashi, Nobuo
, p. 1077 - 1083 (2000)
Effects of H2 reduction on the catalytic properties of MoO3 with Pt, Pd, Rh, Ir, or Ru for the conversions of heptane and propan-2-ol were studied. The catalytic activity of MoO3 with noble metal for the isomerization of heptane was strongly dependent on the period of H2 reduction at 623 K. This behavior was almost the same as that of MoO3 without noble metal. Among the catalysts tested, Pt/MoO3 was the most active for this reaction. The catalytic activities of MoO3 for dehydration and dehydrogenation of propan-2-o1 also increased in proportion with the period of H2 reduction. In the case of MoO3 with noble metal, a higher dehydration activity was obtained by a longer period of H2 reduction, while the dehydrogenation activity was almost independent of the reduction period. Pt/MoO3 exhibited a high dehydration activity compared with the other catalysts, indicating the most acidic property of Pt/MoO3. We conclude from these results that the high isomerization activity of Pt/MoO3 can be attributed to its high acidity as well as to the hydrogenative and dehydrogenative properties of Pt metal.
Effect of H2 reduction on the catalytic properties of MoO3 with noble metals for the conversions of pentane and propan-2-ol
Matsuda, Takeshi,Uozumi, Shuhei,Takahashi, Nobuo
, p. 665 - 672 (2004)
The catalytic properties of H2-reduced MoO3 with noble metals for the conversions of pentane and 2-propanol were investigated. There was no appreciable difference in the pentane isomerization activity and in the 2-propanol dehydration activity among Pt, Pd, Rh, and Ir/MoO3 catalysts after reduction at 773 K for 12 hr. The isomerization and dehydration activities of H2-reduced Ru/MoO3 were lower than those of the other catalysts. The isomerization and the dehydration activities of H2-reduced Pt/MoO3 varied very little with amount of Pt. However, in the case of H2-reduced Ru/MoO3, the isomerization and dehydration activities increased and the dehydrogenation activity was lowered by an increase in the Ru amount. The isomerization activity of H2-reduced MoO3 with noble metals could be determined by the ability to act as an acid catalyst. The reduction process of Ru/MoO3 was affected by the Ru amount. MoO2 formation was suppressed and of HxMoO3 was promoted by an increase in the Ru amount. By contrast, reduction of Pt/MoO3 involved the formation of a hydrogen molybdenum bronze, HxMoO3, irrespective of the Pt amount. The active phase for pentane isomerization and 2-propanol dehydration could generate from reduction of HxMoO3.
Bimolecular chemistry of dimethylcarbene
Likhotvorik, Igor R.,Tippmann, Eric,Platz, Matthew S.
, p. 3049 - 3051 (2001)
A new non-nitrogenous precursor of dimethylcarbene has been synthesized. Photolysis of 10,10′-dimethyltricyclo[4.3.1.01,6]deca-2,4-diene in solution with 254 nm light produces dimethylcarbene. Previously unknown intermolecular reactions of dimethylcarbene have been observed.
Acid and Basic Properties of Titania-Alumina Mixed Oxides; Active Sites for Propan-2-ol Dehydration
Lahousse, Christophe,Mauge, Francoise,Bachelier, Jean,Lavalley, Jean-Claude
, p. 2907 - 2912 (1995)
TiO2-Al2O3 mixed oxides have been prepared by cohydrolysis of Ti(4+) and Al(3+) isopropoxides.Textural and acid-base properties were investigated using nitrogen physisorption, adsorption of probe molecules followed by FTIR spectroscopy, and test-reactions.Catalysts were found to exhibit high surface areas and pore volumes.Results obtained from adsorbed CO2 probe molecules and COS hydrolysis activity agreed well and showed that the hydroxy basicity of mixed oxides was lower than that of the two oxide components.Pyridine and 2,6-dimethylpyridine were used to titrate Lewis and Broensted acidic sites, respectively.A linear increase of the number of strong Lewis acid sites with alumina content was observed, whereas the number of Broensted acid sites reached a maximum for 30percent TiO2-70percent Al2O3 compared with that expected from the composition and the activity of pure oxides.Comparison between probe-molecule adsorption and test reaction, points out that both types of site are involved in propan-2-ol dehydration.A transformation of Lewis acid sites into Broensted sites is proposed when propan-2-ol is chemisorbed on Lewis acid sites.
The Active Hydrogen Electrochemically or Thermally Generated on Pd/H3PO4/Pd Catalysts
Otsuka, Kiyoshi,Yamanaka, Ichiro
, p. 1945 - 1948 (1987)
Hydrogenation of 2-propanol into propane was caused by the hydrogen atoms electrochemically generated on Pd-black of the electrocatalytic cell Pd/H3PO4/Pd.The reaction was also caused by the hydrogen generated through spillover and reverse spillover between Pd and H3PO4.Under closed circuit conditions, the latter hydrogenation over the anode Pd was retarded because of the inhibition of the reverse spillover.
Hydrocarbonylation of linear and branched aliphatic C2-C4 alcohols catalyzed by cobalt-ruthenium systems. A comparative study.
Jenner, Gerard
, p. 237 - 252 (1988)
In an extension of studies of the hydrocarbonylation of C2-C4 alcohols in the presence of a bimetallic catalyst system at high Syngas pressures to yield the next higher homologue, the effect of the catalytic system based on cobalt and ruthenium compounds promoted by iodine or iodides has been examined.For the optimal Co/Ru ratio the selectivity for the higher alcohol is highest because of a large decrease in the extent of hydrocarbon and ether formation.Neither this ratio nor the optimal pressure depends on the structure of the alcohol.It is suggested that the synergism observed in Co-Ru-catalyzed hydrocarbonylation of alcohols is due to a cocatalytic effect of the Ru catalyst involving reaction of ruthenium hydrides with acyl-cobalt complexes.The mechanism is consistent with the suggestion that there is an intermediate olefin that undergoes hydroformylation in a subsequent step.
Howard,Brown
, p. 1026 (1961)
Thermostable sulfated 2-4 nm tetragonal ZrO2 with high loading in nanotubes of SBA-15: A superior acidic catalytic material
Landau,Titelman,Vradman,Wilson
, p. 594 - 595 (2003)
The high-loaded (48-60 wt.%) 2-4 nm tetragonal ZrO2 phase inserted in mesostructured silica SBA-15 by chemical solution decomposition (CSD) of Zr(n-PrO)4 and activated at 873 K displayed ～ 3 times higher capacity for surface sulfate ions and, respectively, 1.5-2.2 times higher catalytic activity per gram of SO4-ZrO2/SBA-15 composite in condensation of MeOH with t-BuOH and dehydration of isopropanol compared with the regular bulk sulfated zirconia material.
Catalytic properties of new ternary Nb-Sb-V oxide - A comparative study with mechanical mixture of single oxides and binary systems
Ziolek, Maria,Golinska-Mazwa, Hanna,Filipek, Elzbieta,Piz, Mateusz
, p. 159 - 167 (2012)
The study presents a comparative analysis of catalytic properties of new Nb2SbVO10 ternary oxide against those of a mechanical mixture of single oxides and a mixture of single with binary oxide, all of the same chemical composition. Moreover, the material without antimony (Nb 9VO25) was tested. Acid-base and redox properties were studied in the following test reactions: 2-propanol decomposition, acetonylacetone (AcOAc) cyclisation and methanol oxidation. The properties of ternary oxide and the mechanical mixture of single oxides are not significantly different. The main difference is in the generation of more active Lewis acid-base pairs in ternary oxide, which is demonstrated by the higher production of ether in the intermolecular dehydration of 2-propanol. Acidic/basic and redox properties of the oxide catalysts containing Nb, Sb, V, O (atomic ratio: 2:1:1:10) strongly depend on the presence of binary oxide, which significantly enhances the basicity of the catalysts. The highest basicity was found for pure binary oxide Nb9VO25 but this catalyst without Sb exhibits much lower activity in the transformation of both alcohols.
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Ashdown,Harris,Armstrong
, p. 850 (1936)
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Acidity of co-precipitated SiO2-ZrO2 mixed oxides in the acid-catalyzed dehydrations of iso-propanol and formic acid
Pyen, Seunghee,Hong, Eunpyo,Shin, Mi,Suh, Young-Woong,Shin, Chae-Ho
, p. 71 - 77 (2018)
SiO2-ZrO2 is an interesting class of binary mixed oxide systems, but its acidity has not been intensively linked to the catalytic activity in the dehydration reactions. Thus, SiO2-ZrO2 mixed oxides with the Si/(Si + Zr) ratio ranging from 0 to 1 were synthesized via a coprecipitation method and their physicochemical properties including acid characteristics were investigated. As a result of pyridine adsorbed FT-IR and iso-propanol (IPA)-TPD, the type, quantity, concentration, and strength of acid site were largely dependent on the molar composition of SiO2-ZrO2 mixed oxides, where they reached maximum at the Si/(Si + Zr) molar ratio of 0.7. Furthermore, it was found that the catalytic activity was proportional to the acid strength in the decomposition of IPA, while the quantity of Br?nsted acid sites was a principal contributor to the activity in the decomposition of formic acid.
Synthesis and Crystal Structure of . Hydrogenation-Dehydrogenation Reactions of Dienes and Alcohols with Heterogeneous Catalysts derived from
Castagno, Fabrizio,Castiglioni, Mario,Sappa, Enrico,Tiripicchio, Antonio,Camellini, Marisa Tiripicchio,et al.
, p. 1477 - 1482 (1989)
The complex 2(μ-Cu(PPh3))(CO)9> has been synthesized in tetrahydrofuran (thf) by reaction of the anion 2(CO)9>-, generated in situ from 3(CO)9> and NaH, with 4>.Its structure has been determined by X-ray methods.Crystals are triclinic, space group P(*) with Z = 2 in a unit cell of dimensions a = 13.643(7), b = 14.120(6), c = 9.504(4) Angstroem, α = 94.88(3), β = 105.77(4), and γ = 102.15(3) deg.The structure has been solved from diffractometer data by direct and Fourier methods and refined by full-matrix least squares to R = 0.0462 for 2 191 observed reflections.The metal cluster can be described as a NiOs3 tetrahedron with an Os-Os edge bridged by the Cu atom from the Cu(PPh3) group.This complex, supported on Chromosorb and thermally activated under H2, forms a heterogeneous catalyst for the hydrogenation-dehydrogenation of several substrates, in particular alcohols.The behaviour of this catalyst is significantly different from that of systems derived from the parent cluster or from .In particular, it shows high dehydrogenation ability.
Effect of preparation protocol on the surface acidity of molybdenum catalysts supported on titania and zirconia
Lamine, Nacéra,Benadda, Amel,Djadoun, Amar,Barama, Akila,Blanchard, Juliette
, p. 157 - 165 (2016)
Molybdenum catalysts supported on titania and zirconia have been prepared via the impregnation on the corresponding hydroxides and oxides. The solids have been characterized by surface area measurements, XR-Fluorescence analysis, XRD and Raman Spectroscopy. The isopropanol decomposition reaction has been used to probe their acidic properties. These analyses revealed that introduction of molybdenum on the surfaces of the hydroxides and the oxides results in an increase of the specific surface area. Impregnation on the hydroxide leads to a comparatively better molybdenum dispersion and to a greater surface acidity. This indicates that the acid sites on hydroxide derived solids are stronger and more numerous than on their oxide derived counterpart.
HIGH-PRESSURE CATALYTIC HYDRATION OF OLEFINS OVER VARIOUS PROTON-EXCHANGED ZEOLITES
Eguchi, Koichi,Tokiai, Takeo,Kimura, Yoshio,Arai, Hiromichi
, p. 567 - 570 (1986)
Catalytic hydration of ethylene, propylene, and 1-butene to alcohol was investigated at high pressures using proton-exchanged zeolites.All the zeolites more or less exhibited the hydration activities.Pentasil- and ferrierite-type zeolites were the most active among the zeolite catalysts.The activities of zeolite catalysts are correlated with the amount of adsorbed water, indicating that hydrophobic acid sites are effective for olefin hydration.
Characterization of CrAPO-5 materials in test reactions of conversion of 2-methyl-3-butyn-2-ol and isopropanol
Zadrozna, Gabriela,Souvage, Emmanuelle,Kornatowski, Jan
, p. 270 - 275 (2002)
CrAPO-5 materials with various amounts of Cr(III) stably incorporated into the framework positions were tested in the reactions of conversion of 2-methyl-3-butyn-2-ol (MBOH) and isopropanol. The results were compared with those obtained over similar materials containing extraframework chromium species and over nonsubstituted AlPO4-5. The products of the reactions indicated an increased acidity of catalytic sites in CrAPO-5 compared to that in AlPO4-5. The yield of conversion depends mainly on the amount of chromium and its distribution. The multivalent extraframework Cr species yielded similar catalytic effects as framework Cr centers. However, their activity dropped very quickly due both to the hindrances to alcohol molecules in accessing the catalytic sites in the pores clogged by these species and to the faster coking.
Sulfated titania [TiO2/SO42-]: A very active solid acid catalyst for the esterification of free fatty acids with ethanol
Ropero-Vega,Aldana-Pérez,Gómez,Ni?o-Gómez
, p. 24 - 29 (2010)
Sulfated titanias were prepared by using ammonium sulfate and sulfuric acid as sulfate precursors. Depending on the sulfation method, important effects on the acidity, textural properties as well as on activity were found. After ammonium sulfate was used, a large amount of S{double bond, long}O linked to the titania surface was observed by FTIR spectroscopy. The acidity strength determined with Hammett indicators showed strong acidity in the sulfated samples. The FTIR-pyridine adsorption spectra evidenced the presence of Lewis and Br?nsted acid sites in the catalysts sulfated with ammonium sulfate, while in the titania sulfated with sulfuric acid, only Lewis-type sites were observed. The sulfated titanias showed very high activity for the esterification of fatty acids with ethanol in a mixture of oleic acid (79%). Conversions up to 82.2% of the oleic acid and selectivity to ester of 100% were reached after 3 h of reaction at 80 °C. The results showed that sulfated titanias are promising solid acid catalysts to be used in the esterification of free fatty acids with ethanol.
Linde,Freeman
, p. 4417 (1970)
Compensation effect in isopropanol dehydration over heteropoly acid catalysts at a gas-solid interface
Bond, Geoffrey C.,Frodsham, Sarah J.,Jubb, Paul,Kozhevnikova, Elena F.,Kozhevnikov, Ivan V.
, p. 158 - 164 (2012)
Kinetics of isopropanol dehydration at a gas-solid interface over a range of bulk and supported Bronsted acid catalysts based on H3PW 12O40 (HPW) Keggin-type heteropoly acid was studied in a continuous flow fixed-bed reactor in the temperature range of 55-135 °C and isopropanol partial pressure of 0.94-5.52 kPa. The bulk catalysts included HPW itself and its Cs acid salts CsnH3-nPW 12O40 (CsnH3-nPW). The supported catalysts comprised of 15 wt.% HPW supported on SiO2, TiO2, ZrO2 and Nb2O5. Under the conditions studied, the reaction was found to be of zero order in isopropanol. The turnover rate decreased in the order HPW > Cs2.5H 0.5PW ≈ Cs2HPW > HPW/SiO2 > HPW/TiO2 > HPW/Nb2O5 ≈ HPW/ZrO 2, which is in line with the acid strength of these catalysts. The true activation energies E and pre-exponential factors A obtained from zero-order kinetics, were found to exhibit a compensation linear relationship ln A = mE + c. Moreover, the bulk and supported catalysts exhibited different compensation plots. This is suggested to be due to the different chemical structure of Bronsted acid sites in these catalysts, resulting in differing reaction mechanisms. The bulk catalysts possess strong surface H+ sites located on peripheral (bridging) oxygen atoms in the Keggin unit, whereas supported HPW catalysts have weaker H+ sites probably located on oxygen atoms of support. Consequently, on the bulk catalysts, isopropanol dehydration is suggested to occur via E1 elimination pathway, whereas on the supported catalysts it might also involve a contribution of E2 elimination pathway.
Conversion of Alcohols (α-Methylated Series) on AlPO4 Catalysts
Campelo, J. M.,Garcia, A.,Herencia, J. F.,Luna, D.,Marinas, J. M.,Romero, A. A.
, p. 307 - 314 (1995)
The conversion (dehydration/dehydrogenation) of alcohols in α-methylated series (methanol, ethanol, 2-propanol, and tert-butanol) on AlPO4 catalysts differently prepared has been studied by microcatalytic pulse reactor technique at different temperatures and flow rates.The kinetic parameters have been obtained by analysis of the data through the Basset-Habgood equation.Dehydration to ether and/or olefin is the major reaction process.Dehydrogenation product was only scarcely found in 2-propanol conversion.The influence of the reaction temperature upon the conversion of alcohols and the selectivities of the products was investigated.Activities increases as a function of surface acidity of the AlPO4 catalyst as well as with the α-substitution in the alcohol.Moreover, selectivity studies indicated that ethanol and 2-propanol dehydration follows a combination pathway of parallel and consecutive reactions.A good correlation between the results of dehydration conversion and acid properties, gas-chromatographically measured through the irreversible adsorption of pyridine (473 and 573 K) and 2,6-dimethylpyridine (573 K), is observed.Also, activity poisoning results indicated that Broensted acid sites of AlPO4 catalyst participated in dehydration processes, thus strengthening the carbenium ion reaction pathway in AlPO4 catalysts.
Direct benzyl alcohol and benzaldehyde synthesis from toluene over keggin-type polyoxometalates catalysts: Kinetic and mechanistic studies
Djaouida, Allam,Sadia, Mansouri,Sma?n, Hocine
, (2019/02/05)
The catalytic activity of various Keggin polyoxometalate catalysts has been investigated in the gas-phase partial oxidation of toluene to produce benzyl alcohol and benzaldehyde. The catalyst systems HPMo12O40, HPMo11VO40, FePMo12O40, and PMo11FeO39 were prepared and characterized by FT-IR, UV-visible, SEM, XRD, TGA, and cyclic voltammetry. The acid/base properties were evaluated using the decomposition of isopropanol. Catalytic studies were carried under atmospheric pressure and over the temperature range 200°C-350°C, using carbon dioxide as a mild oxidant. Toluene conversion and product distribution depend mainly on the catalyst composition and operating conditions. In addition to benzaldehyde, benzyl alcohol is obtained with a high selectivity on the PMo11FeO39 catalyst. The kinetic data show that the reoxidation of the reduced catalyst is the rate-limiting step for the partial oxidation reaction of toluene.
