Allyl Alcohol Selectivity Research Articles

Glycerol Conversion into Allyl Alcohol Using a Coke‐tolerant ZnAl2O4‐β Zeolite Catalyst: Effect of Structural, Textural, and Acidic Properties on Catalytic Stability

AbstractCatalysts with different ZnAl2O4 contents impregnated in beta zeolite were synthesized and their catalytic activity in glycerol dehydration to allyl alcohol was investigated. The materials were characterized by XRD, XRF, FTIR, DRIFTS‐ pyridine, NH3‐TPD, and N2 physisorption. In addition, the surface electrostatic potential maps were generated by a molecular mechanics approach. The XRD patterns indicated a high dispersion of the ZnAl2O4, evidenced by the absence of reflections in the diffractograms, except for the sample containing the highest spinel content. The FTIR spectra indicated the presence of zinc aluminate spinel in the zeolite matrix. The DRIFTS‐pyridine and NH3‐TPD analyses indicated that the incorporation of ZnAl2O4 modifies the acidic properties of the zeolite concerning the number, type, and distribution of acid sites. The N2 physisorption tests showed the maintenance of the micro and mesoporous properties of H‐BEA after modification, despite the reduction of the specific area and pore volume values. The samples impregnated with the ZnAl2O4 phase showed larger mesopores sizes, which may favor its catalytic performance. The catalytic tests indicated the allyl alcohol production for the impregnated materials, which the best results were obtained by the sample containing 2 % of ZnAl2O4, with 90.65 % glycerol conversion and 37 % allyl alcohol selectivity due to appropriate tuning of the acidic and textural properties, as well as the presence of basic sites evidenced by CO2‐TPD analysis and electrostatic potential maps. The presence of acid‐base sites is essential to conduct hydrogen transfer, according to the proposed mechanism, generating allyl alcohol. Finally, the results with a longer reaction period showed greater stability for the sample impregnated with low spinel content, whose coke deposition was smaller, which may be related to the larger size of secondary mesopores.

Allyl alcohol production by gas phase conversion reactions of glycerol over bifunctional hierarchical zeolite-supported bi- and tri-metallic catalysts

The gas-phase conversion of glycerol into allyl alcohol over Fe–Mo and Cs–Fe–Mo/HZSM-5 (with SiO2/Al2O3 = 30 and 1500) zeolite catalysts in a packed-bed continuous flow reactor has been reported for the first time. To the best of our knowledge, the Cs–Fe–Mo/HZSM-5 catalyst appears to be most promising for gas-phase conversion of glycerol into allyl alcohol. The structure and catalytic performance for the glycerol conversion over bi- and tri-metallic-promoted zeolite catalysts were studied. The synthesized catalysts were characterized by ICP–AES, ICP–MS, N2 physisorption, SEM, STEM–EDX, XRD, NH3–TPD, CO2–TPD, XPS, TGA and pyridine-DRIFT techniques, which showed that differences in catalysts activity and product distribution are influenced by metal loading, changes of acid-base, and porosity. The most stable allyl alcohol selectivity achieved was 46.1 mol.% at 98.1 mol.% glycerol conversion over the 5wt.%Cs–2.5wt.%Fe–2.5wt.%Mo/HZSM-5 (SiO2/Al2O3 = 1500) catalyst achieved with 10 wt% glycerol feed at 350 °C reaction temperature after 26 h time-on-stream. The superior performance of the synthesized catalyst was attributed to the presence of the basic sites, high mesopore volume and mesopore surface area, balance between acidic-basic sites, synergetic interaction between metal species and ZSM-5 zeolite support. The reaction pathway mechanisms of glycerol to value-added allyl alcohol via the direct glycerol dehydration and hydrogen transfer mechanism over basic sites are proposed.

Correction to: CeO2 promoting allyl alcohol synthesis from glycerol direct conversion over MoFe/CeO2 oxide catalysts: morphology and particle sizes dependent

MoFe-N, MoFe/c–CeO2, MoFe/p1–CeO2, and MoFe/p2–CeO2 (where N, c, and p stand for non-supported, nanocube, and nanoparticle) oxide catalysts were designed for gas-glycerol direct catalytic conversion into allyl alcohol. The catalysts also were characterized by XRD, TEM, BET, H2-TPR, and NH3-TPD. Mo–Fe oxides were highly dispersed on the surface of c-CeO2 and p-CeO2 supports, different with the MoFe-N consist of crystalline Fe2(MoO4)3 and Fe2O3 crystalline phase. The support effect and special natural property of CeO2 significantly improve the allyl alcohol selectivity from gas-glycerol over MoFe/CeO2. The p-CeO2 with low particle sizes and crystalline degree was superior to high-crystalline nanocube c-CeO2 to promote its interaction with the MoFe oxide active components, and improve the surface acid site concentration and reducibility of MoFe/CeO2 as well as catalytic activity and stability for allyl alcohol synthesis from gas-glycerol without any extra hydrogen donors. Over the MoFe/p2–CeO2, the glycerol conversion reached 97.1%, and the selectivity of allyl alcohol, enthanal, propanoic acid, and acrylic acid were 23.3%, 8.6%, 12.6%, and 7.8%, respectively, yielding allyl alcohol of 22.6%.

Replication of SMSI via ALD: TiO2 Overcoats Increase Pt-Catalyzed Acrolein Hydrogenation Selectivity

The effects of sub-nanometer atomic layer deposition films of titania and alumina are compared for the acrolein hydrogenation selectivity of Pt/SrTiO3 catalysts. The titania-overcoated catalyst is similar to strong metal-support interaction catalysts formed by high temperature reduction, with a thin titania film on top of the supported Pt nanoparticles and an increase in allyl alcohol selectivity, neither of which are observed for the alumina-overcoated catalyst.

Structure Sensitivity of Acrolein Hydrogenation by Platinum Nanoparticles on BaxSr1−xTiO3 Nanocuboids

AbstractThe structure sensitivity of Pt nanoparticles (PtN) for gas‐phase acrolein (AC) hydrogenation was probed for PtN on BaxSr1−xTiO3 nanocuboid supports with (0 0 1) facets in a combined theoretical and experimental study. The in situ selectivity for allyl alcohol increased with the increase of the Sr concentration in the support, which corresponds to modifications in the stable Winterbottom shape and lattice strain of the Pt nanoparticles as a result of the interfacial energy between Pt and the BaxSr1−xTiO3 supports. “Local model” nanofacets of the Pt surface, edge, and corner morphologies were developed as compact representations of adsorption and reaction sites. DFT was used as the primary modeling tool for the equilibrium adsorption states. We argue that adsorption on edge sites is critically important for the overall allyl alcohol selectivity of PtN catalysts. A simple model was developed to represent PtN strain effects caused by its interaction with the substrate. Bader topological atom, spherical volume averaging charge, and modified bond valence sum analyses were used to understand the bonding structure. Density of states analysis was performed for the structures of PtN, adsorbed AC, and intermediate products to examine adsorbate–particle interactions. The simulated hydrogenation of AC on PtN nanofacets was compared to the in situ hydrogenation of AC by PtN on BaxSr1−xTiO3 to examine the effects of facet, edge, and corner sites on the overall selectivity.

Bifunctional Hierarchical Zeolite‐Supported Silver Catalysts for the Conversion of Glycerol to Allyl Alcohol

AbstractThe establishment of suitable processes for the conversion of glycerol into allyl alcohol is hindered by the fast deactivation of solid acids in the dehydration of the substrate to acrolein and by the requirement of hydrogen donors to enhance the selectivity of the subsequent reduction step. In this work, silver nanoparticles deposited onto a hierarchical ZSM‐5 zeolite are proved to be an effective bifunctional catalyst to conduct the two reactions in the gas phase and in the presence of hydrogen by using a continuous fixed‐bed reactor. The acidic function was accomplished by using a ZSM‐5 zeolite modified by facile alkaline and acid treatments, which decreased the amount of Lewis acid centers while preserving the amount of Brønsted acid centers, and introduced an auxiliary network of intracrystalline mesopores, thus boosting the selectivity to acrolein (62 %) and the resistance to coking. Upon screening of various metals supported on the aluminosilicate, silver was identified as a superior hydrogenation catalyst, enabling a relatively high activity with >50 % allyl alcohol selectivity. Tuning of the metal loading, temperature, pressure, and contact time led to 15 % yield of allyl alcohol, thus approaching the state‐of‐the‐art transfer hydrogenation systems, and stable behavior for 100 h on stream. Our results highlight the advantage of conducting the two transformations over a bifunctional material rather than over two separate single‐function solids.

Synthetic Niobium Oxyhydroxide as a Bifunctional Catalyst for Production of Ethers and Allyl Alcohol from Waste Glycerol

A synthetic niobia was modified by treatment with hydrogen peroxide to be used as a catalyst for converting glycerol into petrochemical compounds. The catalytic properties of niobium oxyhydroxide were obtained by generating acidic and oxygenated groups (peroxo groups) on the solid surface. Compounds like ethers and allyl alcohol were obtained. A very active H2O2-modified catalyst showed high activity for the oxidation and dehydration of 91% of glycerol conversion using H2O2 and 46% of allyl alcohol selectivity in volatile phase. The product was analyzed by gas chromatography-mass spectrometry (GC-MS), thermogravimetry-mass spectrometry (TGA-MS) and nuclear magnetic ressonance (NMR). These results strongly suggest that the reactions involve acid and oxidizing species generated after the reaction of niobium with H2O2. 1H and 13C multidimensional NMR spectroscopy confirmed the results obtained with GC-MS and showed the production of several compounds after niobia treatment.

Role of Cu, Ni and Co metals in the acidic and redox properties of Mo catalysts supported on Al2O3 spheres for glycerol conversion

Promoters play an important role in the acidity and redox properties of Mo oxide catalysts supported on alumina spheres, and the catalytic performance reveals a potential effect between Cu and Mo oxides reduced partially, which improves the allyl alcohol selectivity.

Zeolite-supported iron catalysts for allyl alcohol synthesis from glycerol

Under most reaction conditions studied, acrolein is reported as the primary product in the conversion of glycerol over zeolites. In such processes, acrolein forms at relatively high yields, with negligible allyl alcohol selectivity. In this contribution, we report the development of ZSM5-supported iron catalysts, modified by rubidium deposition, as stable materials for production of allyl alcohol from glycerol. Our results demonstrate a reduced rate of formation of acrolein over modified catalysts. Both unmodified and modified catalysts were analysed by inductively coupled plasma optical emission spectrometry, nitrogen adsorption, scanning electron microscope, X-ray diffraction, ammonia temperature programmed desorption, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. These techniques revealed that differences in product distribution and catalyst performance are due to the combined effects of iron loading, catalyst acidity and changes in the porosity of the catalyst.

Enhancing allyl alcohol selectivity in the catalytic conversion of glycerol; influence of product distribution on the subsequent epoxidation step

AbstractConversion of glycerol to allyl alcohol in a flow reactor and subsequent conversion to glycidol in a batch reactor are discussed in this paper. To increase reaction selectivity in the glycerol to allyl alcohol reaction, the catalyst was modified with alkali metal salts. The treatment of the catalyst (Fe/Al2O3) with potassium, caesium and rubidium salts enhanced the allyl alcohol yield when a 35 wt% glycerol solution was used as feed. Furthermore, the addition of organic reductants or hydrogen to the glycerol feed increased the allyl alcohol yield. Optimisation of allyl alcohol selectivity was achieved by a combination of alkali metal cation modifiers and the addition of reductants. The influence of acid, base and redox properties on selectivity is presented, focusing on the effect of these properties on product distribution. The effect of by‐products from the conversion of glycerol to allyl alcohol on the epoxidation reaction was examined to identify the ideal reaction conditions for maximising the glycidol yield. Epoxidation of allyl alcohol by 30 wt% hydrogen peroxide was conducted in a batch reactor at 333K using titanium silicate‐1 catalyst. Conversion of allyl alcohol was high for all conditions; however, hydrolysis of glycidol to glycerol reduces selectivity. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.

The effect of catalyst modification on the conversion of glycerol to allyl alcohol

Conversion of glycerol to allyl alcohol was carried out over an iron on alumina catalyst. With the aim of enhancing selectivity towards the desired product and to reduce acrolein formation (a detrimental impurity in the subsequent epoxidation of allyl alcohol) the supported iron catalyst was modified using alkali metals. It was found that lithium, sodium, potassium, rubidium and caesium deposition on the catalyst surface increased allyl alcohol yield and reduced the rate of catalyst deactivation. Coincidently, acrolein selectivity decreased by up to 75% following treatment with the alkali salt.Changes in the product distribution were determined to be associated with altering the acid/base properties of the catalyst, as confirmed by isopropanol dehydration/dehydrogenation, ammonia and carbon dioxide temperature programmed desorption. The treatment was also found to influence the physical properties of the catalyst surface. A correlation between acid to basic site concentration and allyl alcohol selectivity was established. A reduction in the former value results in an enhancement in the rate of allyl alcohol formation. A reaction mechanism was developed based on the effect of iron and alkali metals catalysing the conversion of glycerol into allyl alcohol. The proposed catalyst modification technique is a straightforward method, readily applicable at a larger scale due to the simplicity of the alkali inclusion and its striking influence on the reaction selectivity.

Catalyst-free Gas-phase Epoxidation of Alkenes

Abstract Butadiene, styrene, cyclohexene, allyl acetate, methyl methacrylate, and allyl alcohol were epoxidized in a gas-phase reaction in the absence of a catalyst. The applied oxidizing agent is ozone. With exception of allyl alcohol (selectivity to glycidol: 58%), the selectivity to the corresponding epoxide ranged from 88 to 97%. For acrylonitrile, there was no measureable conversion.

Approaches for the Isolation ofArabidopsisadh1Regulatory Mutants Using Allyl Alcohol Selection

Allyl alcohol, a suicide substrate for the alcohol dehydrogenase enzyme (EC.1.1.1.1), has been frequently used as a negative selection method for the isolation of alcohol dehydrogenase mutants in plants, animals and microorganisms. This approach led to the isolation of mutants that mapped to the ADH gene itself. We attempted to use allyl alcohol selection for the isolation of adh1 regulatory mutants in Arabidopsis. First we selected at plantlet level on ADH1–GUS transgenic plants. This enabled us to use GUS staining to discriminate between structural and regulatory mutants. Allyl alcohol selection of 50000 EMS-treated seeds did not yield any potential mutants. Secondly we selected EMS and γ-ray-treated seeds of a transgenic line transformed with an additional copy of the ADH1 gene including its own promoter. Fifteen allyl alcohol-resistant plants were selected from the mutagenized seed. Genetic analysis of three putative mutants (adr8, adr10, and adr15) indicated that the ADH1-null phenotype was due to monogenic trans-recessive mutations. But treatment with the demethylating agent 5-azacytidine and analysis of methylation levels of the ADH1 gene indicated that these mutant candidates have increased levels of methylation in the promoter and coding region of ADH1. These results suggest that the allyl alcohol resistance of adr8, adr10, and adr15 is due to silencing of ADH1 rather than to a mutation of a regulatory locus.

Effect of MgCl2 in Vapor-Phase Hydrogen Transfer Reaction between Acrolein and 2-Propanol over MgO Catalyst Systems

Abstract Vapor-phase hydrogen transfer reaction between acrolein and 2-propanol over MgO catalyst systems has investigated. We found that, particularly at early reaction time, both the high activity and remarkable increase of allyl alcohol selectivity were achieved by the addition of a small amount of MgCl2 on MgO catalyst.

Isolation and characterization of a mutant defective in the production of methanol dehydrogenase from a new restricted facultative methanol-oxidizing bacterium.

A new restricted facultative methanol-oxidizing bacterium Methylobacillus sp. strain SK1 (DSM 8269) was subjected to insertion mutagenesis studies with the transposon Tn5 to generate mutants deficient in the production of methanol dehydrogenase (MDH). The transposon was conjugally transferred into the methylotroph by using the triparental mating procedure. The mutants induced by Tn5 were selected directly from a plate containing succinate by using the allyl alcohol selection procedure. The transposition of Tn5 to the bacterium showed a moderate transposition frequency (10(-5) - 10(-6)). Southern hybridization analysis confirmed that the transposon Tn5 was inserted into the chromosomal DNA of the mutants. In addition, the mutants had no RNA transcripts produced from the mdh gene, as judged by Northern blot analysis. The mutants could neither grow on methanol nor produce MDH protein, as determined by Western blot analysis with anti-MDH antibody. These results suggest that Tn5 mutagenesis maybe a useful tool for the molecular analysis of a facultative methanol-oxidizing bacterium.

Hydrogenation of substituted acrolein over alumina supported ruthenium catalysts

The gas phase hydrogenation of acrolein, 2-methyl-2-propenal, 2-butenal and 3-methyl-2-butenal was studied on Ru/Al2O3 and RuM/Al2O3 catalysts (M=Sn, Fe, Zn, Ge, Sb). The specific activity increases when the second element is added to the parent Ru/Al2O3 catalyst. This was ascribed to the activation of the C=O bond by Mδ+ species. Tin is the only additive which promotes the allyl alcohol selectivity. When methyl groups are tagged on the C=C bond the selectivity to the unsaturated alcohol increased sharply due to the steric hindrance against the adsorption of the substrate via the C=C double bond.

Coenzyme-dependent alcohol dehydrogenases in Candida guilliermondii Y4

Candida guilliermondii Y4 is capable of synthesizing two different alcohol dehydrogenases. ADH1 is constitutive on different carbon sources under shaking or settling conditions and its activity is prominent on gel electrophoresis. ADH2 is only synthesized under shaking condition. Two types of mutants were isolated using an allyl alcohol selection technique. ADH1-deficient mutants had 2.7% ADH activity of the wild type, while ADH2-deficient mutants had an ADH activity as high as that of the wild-type ADH activity. The alcohol dehydrogenases of the mutants differ from those of the wild type in their relative oxidation rates of alcohols. ADH1 appears to possess a functional role mainly in the production of ethanol from acetaldehyde, while ADH2 functions mainly in the oxidation of ethanol to acetaldehyde. However, both enzymes seem to be capable of carrying out the reverse reactions, since mutants lacking either of them still grew satisfactorily on different carbon sources. Key words: Candida guilliermondii, alcohol dehydrogenase, ADH1-deficient mutant, ADH2-deficient mutant.

Genetic and molecular characterization of an Adh-1 null mutant in tomato

Treatment of tomato seeds with ethyl methanesulphonate (EMS) followed by allyl alcohol selection of M2 seeds has led to the identification of one plant (B15-1) heterozygous for an alcohol dehydrogenase (Adh) null mutation. Genetic analysis and expression studies indicated that the mutation corresponded to the structural gene of the Adh-1 locus on chromosome 4. Homozygous Adh-1 null mutants lacked ADH-1 activity in both pollen and seeds. Using an antiserum directed against ADH from Arabidopsis thaliana, which cross-reacts with ADH-1 and ADH-2 proteins from tomato, no ADH-1 protein was detected in seeds of the null mutant. Northern blot analysis showed that Adh-1 mRNA was synthesized at wild-type levels in immature seeds of the null mutant, but dropped to 25% in mature seeds. Expression of the Adh-2 gene on chromosome 6 was unaffected. The potential use of the Adh-1 null mutant in selecting rare transposon insertion mutations in a cross with "mutable" Adh-1+ tomato lines is discussed.

Isolation and biochemical analysis of ethyl methanesulfonate-induced alcohol dehydrogenase null mutants of arabidopsis thaliana (L.) Heynh.

Several mutants have been isolated at the Arabidopsis thaliana (L.) Heynh. alcohol dehydrogenase (ADH) gene locus using allyl alcohol selection on ethyl methanesulfonate (EMS)-mutagenized seeds. Eleven mutants were isolated in the ADH1-A electrophoretic allele, and 21 in the ADH1-S allele. These null mutants are characterized by the absence of measurable ADH activity and genetic data showed that the mutations were confined to the ADH1 gene locus of Arabidopsis. Eleven mutants in the ADH1-A background were further characterized at the protein and mRNA level. These experiments revealed striking differences in the ADH protein and mRNA content. Some of the mutants did not synthesize any mRNA or ADH-like protein, whereas some of them had a nearly normal level of ADH protein and mRNA. Others had a very low level of both protein and mRNA. ADH null mutants differed physiologically from the wild type by their higher sensitivity to anaerobic treatment in plants and significantly reduced resistance to acetaldehyde in suspension cultures.

Allyl Alcohol Selection for Lower Alcohol Dehydrogenase Activity in Nicotiana plumbaginifolia Cultured Cells

One cell strain with stable tolerance to allyl alcohol (AA(r)) was selected from 6 x 10(8) suspension cultured Nicotiana plumbaginifolia Viviani cells. The selected strain contained one-half the alcohol dehydrogenase (ADH) activity of the wild type (NP) due to the loss of two of three bands of ADH activity seen on starch gels following electrophoresis of wild-type cell extracts. Anaerobic conditions, simulated by not shaking the suspension cultures, increased the ADH specific activity to more than 3-fold the initial level in both strains but did not change the number of activity bands or the relative levels of activity. The cell strain with decreased ADH activity lost viability more rapidly than the wild type under the anaerobic conditions. The AA(r) cells were 10 times more tolerant to ethanol than the NP cells and were also somewhat more tolerant to acetaldehyde and antimycin A. The substrate specificities of the ADH enzymes from both strains were very similar. Further selection of AA(r) cells with allyl alcohol produced strains with even lower ADH activity and selection under anaerobic conditions produced strains with increased ADH activity. Genetic studies indicate that the N. plumbaginifolia ADH activity bands arise from subunits produced by two nonallelic genes. This is the first example of the use of allyl alcohol to select for decreased ADH using cultured plant cells.