Catalytic Conversion Of Alcohols Research Articles

Enhanced Photoelectrocatalytic Activities for CH3OH‐to‐HCHO Conversion on Fe2O3/MoO3: Fe‐O‐Mo Covalency Dominates the Intrinsic Activity

AbstractThe catalytic conversion of alcohols under mild conditions is a great challenge because it is constrained by low selectivity and low activity. Herein, we demonstrate a hollow nanotube Fe2O3/MoO3 heterojunction (FeMo‐2) for the photoelectrocatalytic conversion of small‐molecule alcohols. Experimental and theoretical analyses reveal that the optical carrier transfer rate is enhanced by constructing interfacial internal electric fields and Fe‐O‐Mo charge transfer channels. For the formox process, heterojunctions possess superior HCHO‐selective reaction paths and free energy transitions, optimizing the selectivity of HCHO and enhancing the reactivity. FeMo‐2 shows a greatly improved performance compared to single Fe2O3; the photocurrent density of FeMo‐2 reaches 0.66 mA cm−2, which is 3.88 times that of Fe2O3 (0.17 mA cm−2), and the Faraday efficiency of the CH3OH‐to‐HCHO conversion is 95.7 %. This work may deepen our understanding of interfacial charge separation and has potential for the production of HCHO and for conversion reactions of other small‐molecule alcohols at cryogenic temperatures.

Enhanced Photoelectrocatalytic Activities for CH3 OH-to-HCHO Conversion on Fe2 O3 /MoO3 : Fe-O-Mo Covalency Dominates the Intrinsic Activity.

The catalytic conversion of alcohols under mild conditions is a great challenge because it is constrained by low selectivity and low activity. Herein, we demonstrate a hollow nanotube Fe2 O3 /MoO3 heterojunction (FeMo-2) for the photoelectrocatalytic conversion of small-molecule alcohols. Experimental and theoretical analyses reveal that the optical carrier transfer rate is enhanced by constructing interfacial internal electric fields and Fe-O-Mo charge transfer channels. For the formox process, heterojunctions possess superior HCHO-selective reaction paths and free energy transitions, optimizing the selectivity of HCHO and enhancing the reactivity. FeMo-2 shows a greatly improved performance compared to single Fe2 O3 ; the photocurrent density of FeMo-2 reaches 0.66 mA cm-2 , which is 3.88 times that of Fe2 O3 (0.17 mA cm-2 ), and the Faraday efficiency of the CH3 OH-to-HCHO conversion is 95.7 %. This work may deepen our understanding of interfacial charge separation and has potential for the production of HCHO and for conversion reactions of other small-molecule alcohols at cryogenic temperatures.

ChemInform Abstract: Catalytic Conversion of Alcohols into Carboxylic Acid Salts in Water: Scope, Recycling, and Mechanistic Insights.

AbstractThe low to excellent product yield strongly depends on the substrates′ substituents.

Catalytic Conversion of Alcohols into Carboxylic Acid Salts in Water: Scope, Recycling, and Mechanistic Insights

AbstractInvited for this month′s cover are the groups of Franck Dumeignil and Régis Gauvin at the University of Lille. The image illustrates the oxidation of alcohols by ruthenium complexes in and by water, with release of hydrogen as the only co‐product. The Full Paper itself is available at 10.1002/cssc.201600243.

Cover Picture: Catalytic Conversion of Alcohols into Carboxylic Acid Salts in Water: Scope, Recycling, and Mechanistic Insights (ChemSusChem 12/2016)

Cover Picture: Catalytic Conversion of Alcohols into Carboxylic Acid Salts in Water: Scope, Recycling, and Mechanistic Insights (ChemSusChem 12/2016)

Catalytic Conversion of Alcohols into Carboxylic Acid Salts in Water: Scope, Recycling, and Mechanistic Insights.

The catalytic conversion of alcohols into carboxylic acid salts in water was performed in the presence of ruthenium complexes supported by aliphatic PNP pincer ligands preformed or formed in situ. High activity toward a wide substrate scope was achieved with turnover number values of up to 4000. The air-stable catalytic system can be recycled by using toluene as a catalyst-immobilizing phase; the activity is maintained after five consecutive runs. Finally, mechanistic studies allowed some fundamental aspects related to water activation to be unveiled and to the mechanism postulated.

Catalytic conversion of alcohols over alumina–zirconia mixed oxides: Reactivity and selectivity

The amorphous and crystalline mixed 25, 50 and 75 wt.% Al 2O 3–ZrO 2 composites were prepared by means of sol–gel method using aluminum iso-propoxide and zirconyl nitrate precursors. Physicochemical properties were determined using XRD, BET, NH 3-TPD, TGA, SEM, and FT-IR spectroscopy. Catalytic activity and selectivity were investigated for the dehydration of 2-octanol and 1,2-diphenyl-2-propanol (DPP). Al 75Zr 25 composite is more selective than other forms for the conversion of 2-octanol. The selectivity of DPP for 1-alkene formation was increased over Al 25Zr 75 catalyst. The crystalline 50 wt.% catalyst dehydrated tertiary alcohol (DPP) selectively in the presence of 2-octanol. The amorphous 50 wt.% catalyst dehydrated DPP predominately to 1-alkene isomer. The crystalline catalyst favored the formation of E-2-alkene.

Effect of Catalytic Alcohol Conversion on the Mechanical Strength of Porous ZrO2 and ZrO2 + Y2O3 Materials

The surface and bulk properties of ZrO2 and ZrO2 + Y2O3 powder compacts are studied by x-ray diffraction, x-ray electron spectroscopy, electron spin resonance, and Raman scattering spectroscopy. Heat treatment in air at 450–800°C and catalytic conversion of methanol and ethanol on the surface of the compacts are found to have a significant effect on their mechanical strength. The results offer some insight into the nature of surface diffusion, which reduces the area of intergranular contacts, thereby raising the mechanical strength of the material, and provide indirect evidence that similar molecular mechanisms underlie the strengthening of metal and oxide powder compacts by heat treatment and catalytic reactions.

Catalytic conversion of alcohols and amines using metal nitride catalysts

High surface area metal nitrides of Mo, W and V are very active and selective alcohol dehydration catalysts and retain the bulk nitride structure even after 30 hours or longer exposure to water generated during alcohol dehydration. Unlike some of the corresponding metal oxides, the nitrides are not selective for any particular octene isomer. These catalysts were much less active for the analogous reaction of deamination of 2-octylamine to produce ammonia and octenes; furthermore, condensation to produce di- and tri-octylamines was more rapid than alkene production. These catalysts were very inactive, in comparison to typical Pt-SiO 2 catalysts, for dehydrogenating cyclohexene.

Catalytic conversion of alcohols: XXVIII. Product selectivities for 2-methylcyclohexanol conversion with metal oxide catalysts

Metal oxides exhibit a range of selectivities (dehydration percentage, alkene distribution and alcohol isomerization) for the conversion of a 2-methylcyclohexanol isomer. For many metal oxide catalysts, trans-2-methylcyclohexanol produces a predominance of the less stable 3-methylcyclohexene isomer. The grouping of metal oxides based on the production of the less stable alkene isomers from 2-octanol is similar to that for trans-2-methylcyclohexanol. It is proposed that the same catalytic properties determine the selectivity for both reactants: for smaller metal cations the product selectivity is determined by steric crowding in the transition state, and for the larger cations the product selectivity is determined by the basicity of the oxygen anion and the relative acidity of the β-hydrogens that are eliminated to produce water.

Catalytic conversion of alcohols: The impact of inductive effect for secondary alcohol dehydration

To produce high-purity 1-octene, the dehydration of 1-octanol was performed over a dual-bed catalytic system comprising Al2O3 and Ba/Al2O3 catalysts. The influence of the catalyst weight on the activities of Al2O3 and Ba/Al2O3 single-bed systems was initially investigated at liquid hourly space velocities (LHSVs) of 7–168 h−1 at 400 °C. For the Al2O3 single-bed system, the 1-octene selectivity decreased with an increase in the catalyst weight. Although the 1-octene selectivity of Ba/Al2O3 increased owing to the anti-Saytzeff effect, its yield was limited due to a low 1-octanol conversion. The efficiency of the dual-bed catalytic system was subsequently investigated by varying the catalyst bed ratio (i.e., xAl–yBa). The 40Al-60Ba catalytic system afforded a higher conversion (95.3%) and productivity than the Ba/Al2O3 single-bed system at an LHSV of 56 h−1. Moreover, the 10Al-90Ba catalytic system with a high Ba/Al2O3 catalyst ratio exhibited a high 1-octene productivity at LHSVs of 7–28 h−1, while also yielding a high-purity product. The single-bed system exhibited a lower selectivity toward 1-octene than the dual-bed system, and after 100 h, the 10Al-90Ba dual-bed system offered a stable catalytic performance regardless of the small reductions in the 1-octene selectivity and yield.

Catalytic conversion of alcohols. Relation of hafnium-zirconium mixed oxide catalytic selectivity to surface composition measured by Raman spectroscopic methods

The Raman spectra obtained for a series of mixed Hf-Zr oxide catalysts, prepared by coprecipitation, indicate that the surface composition is similar to the bulk composition. Hf, impregnated on calcined zirconia, remains on the surface following calcination at 600/sup 0/C but migrates into the bulk if calcination is effected at 1000/sup 0/C. The catalytic selectivity abruptly changes from that of pure hafnia to that of pure zirconia at a composition corresponding to Hf:Zr = ca. 1:9 rather than that undergoing a gradual change that follows the surface composition. Surface Hf may produce a significant background in the Raman spectra that increases for higher Hf compositions; the extent of the background depends upon both calcination temperature and Hf composition.

Catalytic conversion of alcohols: Role of sodium in altering the alkene products obtained with alumina catalysts

In order to study the catalytic conversion of alcohols to alkenes, catalysts were prepared by impregnating Degussa aluminum oxide C with aqueous NaNO/sub 3/ and then drying and calcining the catalysts. The alcohols studied were 2-butanol and 2-octanol; but since a serious secondary isomerization effect present when 2-butanol is converted is eliminated when a mixture of the two alcohols is converted, the mixture was used for this study. The results indicated that two types of dehydration sites must occur on the alumina catalyst. One type designated A is more active for dehydration, and their selectivity from 1-butene and cis-2-butene in about equal amounts with only a small fraction of trans-2-butene. The other type of sites, B sites, form isomers in nearly equal amounts.

Catalytic conversion of alcohols: XXI. Comparison of aluminum and molybdenum oxide catalysts

Molybdena, as a very selective dehydration catalyst, resembles alumina. Neither catalyst causes isomerization of the initial gas-phase alkene dehydration products. This was confirmed by adding a similar alkene to an alcohol reactant. However, molybdena produced products from some alcohol reactants that even required methyl migrations. For example, dehydration of 4,4-dimethyl-2-pentanol with molybdena produced primarily β-elimination products, whereas the isomeric 2,2-di-methyl-3-pentanol produced only about 10% β-elimination with the remaining dehydration products requiring isomerization by methyl migration. On the basis of alkene distributions from cyclic and acyclic alcohols, molybdena catalyzes dehydration by an E-1-like mechanism in contrast to the concerted mechanism for alumina.

Catalytic conversion of alcohols. Selectivity of neodymium oxides

Catalytic conversion of alcohols. Selectivity of neodymium oxides

Catalytic conversion of alcohols: XVIII. Comparison of cis-trans isomerization of 2-methylcyclohexanol isomers and the corresponding methyl ethers

Methoxymethylcyclohexane did not undergo cis-trans isomerization over three oxide catalysts under conditions where the corresponding alcohol undergoes isomerization to the cis-trans equilibrium composition. The ether underwent elimination to form an alkene to about the same extent as the corresponding alcohol. The ketone formed from the alcohol but not from the ether.

Catalytic conversion of alcohols. Origin of anti-Saytzeff dehydration

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic conversion of alcohols. Origin of anti-Saytzeff dehydrationBurtron H. DavisCite this: J. Org. Chem. 1982, 47, 5, 900–902Publication Date (Print):February 1, 1982Publication History Published online1 May 2002Published inissue 1 February 1982https://doi.org/10.1021/jo00344a034RIGHTS & PERMISSIONSArticle Views254Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (428 KB) Get e-Alerts Get e-Alerts

On the role of shape selectivity in the catalytic conversion of alcohols and simple hydrocarbons molecules on zeolite ZSM-5

On the role of shape selectivity in the catalytic conversion of alcohols and simple hydrocarbons molecules on zeolite ZSM-5

Catalytic conversion of alcohols. Part 16.—Attempt to correlate the ESCA oxygen 1s binding energy with the selectivity

Neither the dehydration nor the terminal alkene selectivity for the conversion of secondary and tertiary alcohols over more than twenty metal oxide catalysts was related to the oxygen 1s binding energy of the catalyst. Even the attempt to correlate the selectivity to the oxygen 1s binding energy within a smaller group of metal oxide catalysts, Group IIIA or IVB, was not successful.

Catalytic conversion of alcohols. 15. Alkene selectivity from the conversion of 2-octanol over hafnium-zirconium mixed oxide catalysts

Catalysts containing 0-100% zirconia/hafnia were prepared by coprecipitation of the hydroxides and calcination at 600/sup 0/C. No surface enrichment occurred because the hydroxides have similar solubilities and the oxides similar free energies. The selectivity of these catalysts for 2-octanol dehydration to 1-octene was identical to that of hafnia, approx. 30% up to approx. 75 mole % zirconia content; it changed abruptly to that of pure zirconia, 90% at higher zirconia contents.