Formation Of Higher Alcohols Research Articles

The mechanism of higher alcohol formation on ZrO2-based catalyst from syngas

A chain growth scheme for the synthesis of alcohols from carbon monoxide and hydrogen is proposed based on the chemical enrichment method on ZrO2-based catalyst. Methanol addition has no obvious effect on the STY of C2+ alcohols, indicating that COH→CCOH is a slow initial growth step. Addition of ethanol and propanols can enhance the STY of isobutanol, especially n-propanol, revealing that n-propanol is largely the precursor of isobutanol. Results of large alcohols addition further reveal the relationship between small alcohols and large alcohols of formation. Also, addition of aldehydes has a similar effect on the formation of higher alcohols, indicating that alcohols exist in the form of aldehydes before desorption. Anisole are introduced into syngas for confirmation of predicted intermediates and the result indicates that formyl species is participated both in the formation of methanol and higher alcohols. Reaction temperature has a significant effect on the chain growth of alcohols synthesis. Under low temperature, chain growth occurs with CO insertion and alcohols are linear products. Isobutanol appears and becomes the main product during C2+ alcohols undergo an aldo-condensation reaction at high temperature.

Metabolic Control of Higher Alcohols Producing by <i>Saccharomyces cerevisia</i> in Mulberry Wine Brewing

Aiming at the problem that higher alcohols has too high level in mulberry wine, the factors which have impact on the production of higher alcohols during alcoholic fermentation in mulberry wine was studied, including pH, fermentation temperature, inoculation, SO2, the amount of nitrogen. The results showed that: higher alcohols formation was significantly reduced when increase inoculation or lower the pH and fermentation temperature. Added nitrogen lead to the increasing formation of higher alcohols. With the increased levels of SO2, higher alcohols formation increased in a certain range. The higher alcohols formation was inhibited when the SO2content up to 200.00mg/L.

Effect of immobilized polygalacturonase fromMucor circinelloidesITCC-6025 on wine fermentation

Pectinases are among the most widely distributed enzymes in bacteria, fungi, and plants. Almost all the commercial preparations of pectinases are produced from fungal sources. Mucor circinelloides ITCC-6025 produced polygalacturonase when grown in Riviere's medium containing pectin (methyl ester) as the sole source of carbon. Immobilization of purified polygalacturonase was done on silica gel with 86% efficiency. The enzyme took 60 Min to bind maximally on the support. The immobilized enzyme showed maximum activity at a temperature of 45°C (4.57 U/mg) and pH 5.4. The immobilized enzyme was reused for four cycles as it retained almost 55% of its activity. The immobilized enzyme treatment increased the formation of higher alcohols and phenolics during the course of wine formation from apple and plum juices, whereas there was a decrease in the amount of carbohydrates. The enzyme treatment also resulted in clarification of wine; there was an increase in transmittance at 650 nm (201.78% in the case of apple wine and 223.4% in the case of plum wine) as compared to the control (untreated wine).

ChemInform Abstract: Alcohol Synthesis from Syngas Over Nickel Catalysts: Effect of Copper and Lithium Addition.

Abstract Carbon monoxide hydrogenation at 5 MPa was investigated on silica-supported Ni, Ni-Cu, Ni-Li and Ni-Cu-Li catalysts, with special focus on C 2+ OH formation. Copper addition does not result in formation of higher alcohols while lithium does. Over Ni-Cu-Li/SiO 2 , selectivities towards alcohols as high as 85% are observed and higher alcohols such as ethanol and propanol were effectively produced. Addition of copper to nickel results in a remarkable stabilization of the catalytic activity while lithium promotion increases aging of the catalyst significantly. Infrared spectroscopy of adsorbed carbon monoxide shows that copper addition inhibits subcarbonyl formation (Ni(CO) x , x = 2 or 3) and increases the relative abundance of linear species. When lithium promoter is added to Ni/SiO 2 , some is deposited on the silica support whilst the remaining decorates the metal particles. Subcarbonyl species are stabilized by lithium addition. The spectra obtained over Ni-Cu-Li/SiO 2 are practically composed of only two bands, subcarbonyl and linear. By comparing catalytic pattern and infrared data it is concluded that the presence of subcarbonyl species is related to catalyst aging and that active sites for C 2+ OH formation are, either isolated nickel atoms associated with Li + , or linked to subcarbonyl formation.

Characterization and reactivity of nanoscale La(Co,Cu)O 3 perovskite catalyst precursors for CO hydrogenation

The characterization of La(Co,Cu)O 3 perovskites has been performed by several techniques including XRD, BET, H 2-TPR, O 2-TPO, TPRS, and the solids tested as catalysts for the hydrogenation of CO. The reducibility of the perovskites is strongly affected by the preparation route, calcination temperature, catalyst morphology, and the amount of remnant alkali. Compared with the citrate-derived perovskite, LaCoO 3 sample prepared by mechano-synthesis has various distinct Co 3+ ions in perovskite lattice, which are reduced at different temperatures. Under typical conditions, the reduction of cobalt ions occurs in two consecutive steps: Co 3+/Co 2+ and Co 2+/Co 0, while the intra-lattice copper ions are directly reduced from Cu 2+ to Cu 0. The reducibility of cobalt ions is promoted by the presence of metallic copper, which is formed at a lower reduction temperature. The re-oxidation of the reduced lanthanum cobaltite perovskite could regenerate the original structure, whereas that of the reduced Co–Cu-based samples is less reversible under the same experimental conditions. The cobalt atom in the reduced perovskites plays an important role in the dissociation of CO, but the presence of a neighboring copper along with remnant sodium ions on the catalyst surface has remarkably affected the reactivity of cobalt for CO hydrogenation. The addition of copper into the perovskite framework leads to a change in the product distribution of CO hydrogenation and a decrease in reaction temperature. An increased copper content leads to a substantial decline in the rate of methanation and an increase in the formation of higher alcohols. A close proximity between cobalt and copper sites on the Na +-modified catalyst surface of the reduced nanocrystalline Co–Cu-based perovskites plays a crucial role in the synthesis of higher alcohols from syngas.

Potassium and nickel doped β-Mo2C catalysts for mixed alcohols synthesis via syngas

Potassium and nickel doped β-Mo2C catalysts were prepared and their performances of CO hydrogenation were investigated. The main products over β-Mo2C catalyst were hydrocarbons, and only few alcohols were obtained. The potassium promoter resulted in remarkable selectivity shift from hydrocarbons to alcohols over β-Mo2C. Moreover, it was found that the potassium promoter enhanced the ability of chain propagation of β-Mo2C catalyst and resulted in a higher selectivity to C2+OH. When doped by potassium and nickel, β-Mo2C catalyst showed high activity and selectivity for mixed alcohols synthesis, the Ni promoter further enhanced the whole chain propagation to produce alcohols especially for the step of C1OH–C2OH. From the XPS analysis, it had been proved that the formation of higher alcohols might be attributable to the presence of MoIV species, whereas the formation of hydrocarbons was closely associated with the presence of MoII species on the surface of the catalysts.

Addition of amino acids to grape juice of the Merlot variety: Effect on amino acid uptake and aroma generation during alcoholic fermentation

The effects of adding selected amino acids (phenylalanine, alanine, aspartic acid and threonine) to grape juice on the generation of aroma compounds and on amino acid uptake were studied. The fermentation kinetics varied according to the quantities of amino acids added. The fermentations finished more quickly in supplemented juices and their alcoholic content was significantly higher than in the control ( p < 0.05). Amino acids were consumed mainly in the first quarter of fermentation. Higher alcohol formation took place at the same time as ethanol formation: with more amino acids present in the medium, more phenyl ethanol ( p = 0.01) and benzyl alcohol were formed while isoamyl alcohol production decreased. The contents of isoamyl and phenylethyl acetates, ethyl hexanoate and ethyl octanoate, as well as most fatty acids increased during the fermentation, reaching a maximum for 10% of ethanol; with higher alcoholic contents, their concentrations decreased.

Effects of CO2 on the formation of flavour volatiles during fermentation with immobilised brewer's yeast.

Immobilised-cell fermentors offer great benefits compared to traditional free-cell systems. However, a major problem is unbalanced flavour production when these fermentors are used for the production of alcoholic beverages. One of the keys to obtaining better control over flavour formation may be the concentration of dissolved CO2, which has inhibitory effects on yeast growth and metabolism. This article demonstrates that the presence of immobilisation matrices facilitates the removal of CO2 from the liquid medium, which results in a low level of dissolved CO2 during fermentation. Moreover, the formation of volatile higher alcohols and esters was greatly enhanced in the immobilised-cell system when compared to the free cell system. By sparging a CO2 flow (45 ml/min) into the immobilised-cell system, cell growth was reduced by 10-30% during the active fermentation stage, while the fermentation rate was unaffected. The uptake of branched-chain amino acids was reduced by 8-22%, and the formation of higher alcohols and esters was reduced on average by 15% and 18%, respectively. The results of this study suggest that mismatched flavour profiles with immobilised-cell systems can be adjusted by controlling the level of dissolved CO2 during fermentation with immobilised yeast.

Influence of must nitrogen composition on wine and spirit quality and relation with aromatic composition and defects - A review

&lt;p style="text-align: justify;"&gt;The development of wine-growing practices (reducing of nitrogen supply, grass cover) in order to improve the production control and environment protection lead to nitrogen deficiencies in must. Many fermentation problems appeared : stuck and sluggish fermentation, aromatic deviation. In opposite, it was underscored that must with high nitrogen content could lead to wine containing potentially dangerous molecules for human health, like amine and ethyl carbamate.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;Many studies related the nitrogen fertilisation and grass cover effects on vine and must composition, but just a few works were done about their consequences on wine and spirit quality.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;The quantitative aspects of alcoholic fermentation are now well know as the yeast nitrogen requirements (140 à 160 mg/l N). But yeast has also qualitative requirement (amino acids, vitamins, fatty acids), in relation with the medium (t°, O&lt;sub&gt;2&lt;/sub&gt;, turbidity).&lt;/p&gt;&lt;p style="text-align: justify;"&gt;In case of nutrient lack, even slight, yeast produce volatile acidity, H&lt;sub&gt;2&lt;/sub&gt;S and many sulphur compounds (origin of aromatic defects), and fermentation rate is slowed, sometime stopped. The yeast strains play an important role because of genetic differences and specific nutrient requirements. On the other hand, the possibility of enhancing wine aroma appears with the control of the nitrogen content of must which induce mainly ester and higher alcohols formation. Furthermore, it must keep in mind that large amount of must nitrogen (&amp;gt; 1,000 mg/l) could also lead to problems with wine composition.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;Sensory analyses show correlations between must nitrogen content and soil management with wine quality. It seems that must with medium nitrogen give the better wines.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;The aim of this study was to resume the actual experimental knowledge on this subject.&lt;/p&gt;

Concomitant extracellular accumulation of alpha-keto acids and higher alcohols by Zygosaccharomyces rouxii

Alpha-keto acids are key intermediates in the formation of higher alcohols, important flavor components in soy sauce, and produced by the salt-tolerant yeast Zygosaccharomyces rouxii. Unlike most of the higher alcohols, the alpha-keto acids are usually not extracellularly accumulated by Z. rouxii when it is cultivated with ammonium as the sole nitrogen source. To facilitate extracellular accumulation of the alpha-keto acids from aspartate-derived amino acid metabolism, the amino acids valine, leucine, threonine and methionine were exogenously supplied during batch and A-star cultivations of (routants of) Z. rouxii. It was shown that all alpha-keto acids from the aspartate-derived amino acid metabolism, except alpha-ketobutyrate, could be extracellularly accumulated. In addition, it appeared from the concomitant extracellular accumulation of alpha-keto acids and higher alcohols that in Z. rouxii, valine, leucine and methionine were converted via Ehrlich pathways similar to those in Saccharomyces cerevisiae. Unlike these amino acids, threonine was converted via both the Ehrlich and amino acid biosynthetic pathways in Z. rouxii.

Concomitant Extracellular Accumulation of Alpha-Keto Acids and Higher Alcohols by Zygosaccharomyces rouxii

Alpha-keto acids are key intermediates in the formation of higher alcohols, important flavor components in soy sauce, and produced by the salt-tolerant yeast Zygosaccharomyces rouxii. Unlike most of the higher alcohols, the alpha-keto acids are usually not extracellularly accumulated by Z. rouxii when it is cultivated with ammonium as the sole nitrogen source. To facilitate extracellular accumulation of the alpha-keto acids from aspartate-derived amino acid metabolism, the amino acids valine, leucine, threonine and methionine were exogenously supplied during batch and A-star cultivations of (routants of) Z. rouxii. It was shown that all alpha-keto acids from the aspartate-derived amino acid metabolism, except alpha-ketobutyrate, could be extracellularly accumulated. In addition, it appeared from the concomitant extracellular accumulation of alpha-keto acids and higher alcohols that in Z. rouxii, valine, leucine and methionine were converted via Ehrlich pathways similar to those in Saccharomyces cerevisiae. Unlike these amino acids, threonine was converted via both the Ehrlich and amino acid biosynthetic pathways in Z. rouxii.

Studium úlohy kvasničného kmene při vzniku vyšších aromatických senzoricky aktivních alkoholů v závislosti na podmínkách kvašení.

Moderní analytické metody umožnily autorům podrobně studovat změny obsahu vyšších aromatických alkoholů během kvašení v&nbsp;laboratorních podmínkách v&nbsp;závislosti na rozdílných podmínkách kvašení. V&nbsp;úvodní stručné rešerši jsou shrnuty současné poznatky týkající se chemismu vzniku vyšších aromatických alkoholů, jejich senzorických vlastností a vlivu technologických podmínek na jejich obsah v&nbsp;pivě. Pro vlastní zkoušky byly vybrány dva rozdílné provozní kmeny, avšak shodného genetického původu. Experimentálně bylo ověřeno, že kromě teploty kvašení má na tvorbu vyšších aromatických alkoholů vliv i použitý provozní kvasničný kmen. Získané výsledky nasvědčují tomu, že se i velmi geneticky příbuzné kvasničné kmeny mohou lišit v&nbsp;produkci vyšších aromatických alkoholů. I když se hodnoty obsahu tyrosolu a tryptofolu v&nbsp;pivě pohybovaly hluboko pod uváděnými prahovými hodnotami, nelze jejich vliv na senzorický profil piva, s&nbsp;ohledem na možný synergický efekt s&nbsp;ostatními senzoricky aktivními látkami, zanedbat. Hodnoty obsahu 2-fenylethanolu se naproti tomu řádově blížily jeho předpokládané prahové hodnotě vnímání.

Sake: Production and flavor

Sake, its history in Japan, the unique brewing process, and microbes concerned with the characteristics of flavor are described. The main flavor components derived mainly from the fermentation process are higher alcohols, isoamyl acetate, ethyl caproate, and phenethyl acetate. These are the compounds which give an accent to the flavor of sake. The esters are formed mainly by yeast during mash fermentation. Isoamyl acetate is produced by the reaction of acetyl CoA with isoamyl alcohol catalyzed by alcohol acetyl transferase. The enzyme, bound to the yeast cell membrane, is unstable to heat and unsaturated fatty acids. The ester formation is regulated by the amount of isoamyl alcohol produced. Acyl CoA alcohol acyl transferease catalyzes the formation of ethyl caproate from caproyl CoA and ethanol. In this reaction, the amount of caproyl CoA supplied is important. The mechanism of higher alcohol formation, including the biosynthetic pathway of amino acids and its feedback regulation, is discussed. Finally, breeding and the practical use of sake yeast with high productivity of higher concentrations of higher alcohols and esters are described.

Alcohol synthesis with [formula omitted] catalysts in a slurry reactor

A laboratory stirred autoclave reactor has been developed to operate at temperatures up to 375°C and pressures of at least 170 atma. The performance of a commercial “high pressure” methanol synthesis catalyst, the so-called “zinc chromite” catalyst, has been characterized over a range of temperature from 300 to 375°C, pressures from 68 to 174 atma, H 2 CO ratios from 0.5 to 2.0 and space velocities from 1500 to 10000 sL/kg(catalyst)-hr. Towards the lower end of the temperature range, methanol was the only significant product. At the highest temperatures, the methanol synthesis reaction was close to equilibrium. There were significant quantities of methane, dimethyl ether and olefins in the product at these temperatures. Formation of higher alcohols was insignificant, although small amounts of isobutanol were formed at the highest temperatures and pressures, with 10 mole percent CO 2 in the feed gas.

The synthesis of alcohols using Cu/ZnO/A12O3 + (Ce or Mn) catalysts

CU/ZnO/A12O3 catalysts modified by compounds of manganese or cerium were prepared by coprecipitation or by impregnation and were tested for the synthesis of alcohol mixtures from synthesis gas at pressures of up to 70 bar. They were also examined by XPS both before and after the reaction. With both the impregnated and the coprecipitated catalysts, manganese increased the selectivity to higher alcohols (mainly isobutanol). However, in the case of cerium, the location of the cerium ions appeared to determine the selectivity; it shifted towards alkanes and C02 when cerium was present at the surface of the catalyst (probably as Ce02), but to isobutanol when the cerium ions were present in the bulk. Changes were found in the selectivities of the catalyst doped with cerium with time on stream and these could be explained by a segregation of the cerium ions to the surface. Some of the mechanistic steps in the formation of higher alcohols as proposed in the literature were confirmed.

Alcohol synthesis from syngas over nickel catalysts: Effect of copper and lithium addition

Carbon monoxide hydrogenation at 5 MPa was investigated on silica-supported Ni, Ni-Cu, Ni-Li and Ni-Cu-Li catalysts, with special focus on C 2+OH formation. Copper addition does not result in formation of higher alcohols while lithium does. Over Ni-Cu-Li/SiO 2, selectivities towards alcohols as high as 85% are observed and higher alcohols such as ethanol and propanol were effectively produced. Addition of copper to nickel results in a remarkable stabilization of the catalytic activity while lithium promotion increases aging of the catalyst significantly. Infrared spectroscopy of adsorbed carbon monoxide shows that copper addition inhibits subcarbonyl formation (Ni(CO) x , x = 2 or 3) and increases the relative abundance of linear species. When lithium promoter is added to Ni/SiO 2, some is deposited on the silica support whilst the remaining decorates the metal particles. Subcarbonyl species are stabilized by lithium addition. The spectra obtained over Ni-Cu-Li/SiO 2 are practically composed of only two bands, subcarbonyl and linear. By comparing catalytic pattern and infrared data it is concluded that the presence of subcarbonyl species is related to catalyst aging and that active sites for C 2+OH formation are, either isolated nickel atoms associated with Li +, or linked to subcarbonyl formation.

Étude du Mécanisme de La Réaction D'Hydrocondensation D'Oxydes de Carbone

AbstractIn this work, a reaction mechanism for oxides hydrocondensation of carbon monoxide on nickel‐molybdenum catalyst is proposed. The formation of higher alcohols may occur by a CO insertion into a growing carbon‐carbon chain whereas methanol may be formed from CO via formyl or formate species.Hydrocarbon formation may result from superficial “CHx” species hydrogenation.

Relation between preparation, porosity and selectivity of CuO-ZnO-MeO x catalysts in the synthesis of alcohol mixtures

Some relations between the preparation of modified CuO-ZnO catalysts, their structural properties and their catalytic performance in the hydrogenation of carbon monoxide have been demonstrated. The different activities in the formation of higher alcohols have been attributed to an influence of the porosity on chain growth. The coupling or insertion of C1 intermediates seems to be favoured by an increasing surface coverage with C1 intermediates due to a transport limitation of methanol production. The pore size distribution of the catalysts has been varied by different calcination, thermal ageing, CuO/ZnO ratios, the method of promoting with Al2O3 and pelleting.

Molybdenum Catalysts for Synthesis of Mixed Alcohols from Synthesis Gas.

Highly active Mo catalysts for synthesis of mixed alcohols from synthesis gas were prepared using SiO2 as a carrier. KCl promoted the selectivity to alcohols but reduced CO conversions, in particular, to hydrocarbons. High specific activity of 420g (kg-catalyst)-1bh-1 was attained at 5.0MPa, 573K, and W/F=1.4g-catalystbhbmol-1. The alcohol formation was found to require two kinds of Mo species, metallic Mo and MoO2, after reduction with flowing H2. The presence of K prevented the complete reduction of Mo to metal, resulting in increased production of alcohols. Marked increase in alcohol yield with time on stream indicated that active species for alcohol synthesis were formed during the CO hydrogenation. From the study of the effect of pretreatment of Mo catalysts with CO, CO-H2, and butane-H2, and Mo 3d XPS, it has been concluded that the formation of CO-reduction induced defects on MoO2, MoO2-x, during the CO hydrogenation reaction, is the cause of the increase in the alcohol synthesis rate. On the other hand, the hydrocarbon synthesis appeared to be solely based on metallic Mo. From the study of addition of probe molecules to CO-H2, it has been clarified that the higher alcohol formation from CO-H2 proceeded by way of the same intermediate as the alkene hydrocarbonylation. A dual-site mechanism for the alcohol formation over SiO2-supported Mo has been proposed: CO dissociates on metallic Mo to form surface carbide, followed by hydrogenation of carbene and/or methyl species. While addition of methylene unit to surface alkyl species and following hydrogenolysis and/or dehydrogenation of alkyls to give hydrocarbons also occur on metallic Mo, CO insertion leading to alcohols is catalyzed by MoO2-x species. It has been found that K is effective in retarding hydrogenolysis of alkyls, improving the selectivity to alcohols. The mechanism can account for the difference in selectivities to branched products between hydrocarbons and alcohols.

Ruthenium catalyzed hydroformylation reactions using in situ generation of synthesis gas from aqueous methyl formate

Aqueous methyl formate can be used as a source of carbon monoxide and hydrogen via catalysis with Ru 3(CO) 12+ tricyclohexylphosphine in the hydroformylation of cycloalkenes and linear alkenes. Hydrogenation of the alkene is a competing reaction. The best results regarding formation of higher alcohols are obtained with lower alkenes. In some cases, the addition of Pd(acac) 2 is able to modulate the selectivity with respect to the alcohols. The hydroformylation reaction involves [HRu 3(CO) 11] -.