Production Of Polyols Research Articles

Continuous Process of Fine Polyols Production in a Trickle-Bed Reactor

To produce polyols at small and medium scales via continuous processes, a three-phase system was applied to operate the catalytic hydrogenation of saccharides. A trickle-bed reactor (with a diameter of dR = 0.042 m and a height of Z = 0.800 m) with nickel (14.75%)/granulated activated carbon catalyst (2.38 mm < dp < 6.35 mm, where dp is the grain size) was used, in a range of 373−413 K and a hydrogen pressure of 1.22 MPa. The operational conditions, with a liquid-phase flow rate of 5.00−15.00 L/h and a gas-phase flow rate of 100.00−300.00 L/h, guaranteed a steady-state saccharide conversion, which was attained after 1 h of operation. Glucose conversions of 44% at 413 K were attained. In the saccharose processing, consecutive productions of monosaccharides and polyols led to yields of 24% for sorbitol and mannitol at 413 K. To describe the continuous process, a heterogeneous model with axial dispersion and considering the partial wetting of the catalyst was considered.

Glass-fiber disks provide suitable medium to study polyol production and gene expression in Eurotium rubrum

Eurotium species often dominate the fungal population in stored grain and are responsible for spoilage. In this study we tested the usefulness of glass fiber disks to aid the analysis of growth, polyol content and gene expression in E. rubrum in response to various water activities. Growth measurements based on ergosterol content and conidial production indicated that E. rubrum grew as well at 0.86 aw as 0.98 aw. The rate of growth was considerably reduced at 0.83 aw and 0.78 aw. In contrast, under our conditions, Aspergillus flavus and A. nidulans were able to grow only in the highest water activity (0.98 aw). Mannitol was the predominant polyol in all three fungal species grown at 0.98 aw. When E. rubrum was grown at 0.86 aw or lower, glycerol comprised greater than 90% of the total polyols. After a shift from 0.86 aw to 0.98 aw, mannitol levels in E. rubrum increased to 89% of the total polyols within 24 h. Of six genes whose expression was measured by quantitative real-time PCR, three were affected by water activity. Expression of putative hydrophobin and mannitol dehydrogenase genes was higher at 0.98 aw than at 0.86 aw. A putative triacylglycerol lipase gene was expressed at higher levels in 0.86 aw.. The results of this study indicate that the disk method is suitable to study the effects of water activity on growth, polyol biosynthesis and gene expression in E. rubrum. The results also indicate the potential competitiveness of E. rubrum over A. flavus and A. nidulans in low water environments associated with stored grain.

Gluconobacter oxydans NAD-dependent, D-fructose reducing, polyol dehydrogenases activity: screening, medium optimisation and application for enzymatic polyol production

Gluconobacter oxydans LMG 1489 was selected as the best strain for NAD(P)-dependent polyol dehydrogenase production. The highest enzyme activities were obtained when this strain was cultivated on a medium consisting of 30 g glycerol l(-1), 7.2 g peptone l(-1) and 1.8 g yeast extract l(-1). Two D-fructose reducing, NAD-dependent intracellular enzymes were present in the G. oxydans cell-free extract: sorbitol dehydrogenase, and mannitol dehydrogenase. Substrate reduction occurred optimally at a low pH (pH 6), while the optimum for substrate oxidation was situated at alkaline pHs (pH 9.5-10.5). The mannitol dehydrogenase was more thermostable than the sorbitol dehydrogenase. The cell-free extract could be used to produce D-mannitol and D-sorbitol enzymatically from D-fructose. Efficient coenzyme regeneration was accomplished by formate dehydrogenase-mediated oxidation of formate into CO2.

Optimization of erythritol and glycerol accumulation in conidia of Beauveria bassiana by solid-state fermentation, using response surface methodology

Entomopathogenic fungi are widely produced for use as mycoinsecticides. Therefore, improvement of the shelf life of fungal propagules under good and adverse conditions should be a pre-requisite of their production. In order to improve conidial physiology as well as mycoinsecticide efficiency, culture conditions may be varied. The Doehlert design was used to generate response surfaces with an estimation of the parameters of the quadratic model allowing the study of three different factors at a different number of levels. This experimental design was applied to optimize water activity (aw), pH, and fermentation time for Beauveria bassiana conidial production and accumulation of polyols in solid-state fermentation. Thus, it was possible to identify the region in the experimental range in which the optimum values of these parameters were simultaneously achieved. Maximal conidia production was achieved at pH 5-6 and aw=0.999. Under these conditions, polyol accumulation was 3 mg erythritol/g conidia and 29.6 mg glycerol/g conidia. However, maximal polyol accumulation was achieved at pH 4.5 and aw 0.950; erythritol production increased 33-fold and glycerol production 4.5-fold. Under these conditions conidia production was 1,000 times lower. The possibilities of increasing the quality of the biocontrol agent without neglecting yield are discussed.

Two‐Step Synthesis of Carbohydrates by Selective Aldol Reactions

AbstractFor Abstract see ChemInform Abstract in Full Text.

Construction of an intergeneric fusion from Schizosaccharomyces pombe and Lentinula edodes for xylan degradation and polyol production

A yeast-like fusant was successfully formed from protoplasts of Schizosaccharomyces pombe and Lentinula edodes. The new fusant could utilize 28 carbon sources, better than its parent yeast cell. Using glucose for the fusant, ethanol was produced as the major product and arabitol was a byproduct. Using xylose or glucose and xylose (1:5 (w/w)), arabitol and xylitol was produced as the major and minor products, respectively. Using xylan, the biomass increased rapidly to a plateau of 18.20–18.40 g l −1 at day 10. Xylose, xylitol and arabitol were produced with arabitol being the final and major product. The growth rates of single or co-substrate were in the descending order of glucose (0.28 h −1) > xylose–glucose (0.21 h −1) > xylose (0.15 h −1) > xylan (0.11 h −1). Agro-waste materials and arabinose were susceptible to degradation by the fusant. Extracellular xylanase, intracellular xylose reductase, xylitol dehydrogenase and arabitol dehydrogenase were predominant in the culture of the fusant. Overall, it will be preferable to introduce the ethanol or polyol production by the fusant.

Two-step synthesis of carbohydrates by selective aldol reactions.

Studies of carbohydrates have been hampered by the lack of chemical strategies for the expeditious construction and coupling of differentially protected monosaccharides. Here, a synthetic route based on aldol coupling of three aldehydes is presented for the de novo production of polyol differentiated hexoses in only two chemical steps. The dimerization of alpha-oxyaldehydes, catalyzed by l-proline, is then followed by a tandem Mukaiyama aldol addition-cyclization step catalyzed by a Lewis acid. Differentially protected glucose, allose, and mannose stereoisomers can each be selected, in high yield and stereochemical purity, simply by changing the solvent and Lewis acid used. The reaction sequence also efficiently produces (13)C-labeled analogs, as well as structural variants such as 2-amino- and 2-thio-substituted derivatives.

Characterization of glycerin-based polyols by capillary electrophoresis

Methods based on capillary electrophoresis (CE) have been developed to obtain the molar mass distribution (MMD) of glycerin-based polyols and details on the presence of mono- and difunctional byproducts in technical samples. Prior to the analyses the hydroxy end-groups of the trifunctional polyols were converted to chargeable and UV-active moieties with phthalic anhydride (PhAH) as the derivatization reagent. With a method of capillary zone electrophoresis (CZE) samples of glycerin-based polyols with average molar masses up to 6000 were separated according to their charge-to-size ratio. The separations were carried out with a buffer solution containing 50% (v/v) acetonitrile and 10 mM sodium tetraborate, and for detection UV absorption at 220 nm was measured. An approximately linear relation between the reciprocal of the effective mobilities and the degree of polymerisation of the glycerin-based polyols was found. Therefore, the proposed CZE system could be used to determine the degree of polymerisation and polydispersity of technical glycerin-based polyol samples. The effect of the presence of sodium dodecyl sulfate (SDS) in the buffer solution on the CE separation of linear polyethylene glycols (PEGs), polypropylene glycols (PPGs) and ethylene oxide–propylene oxide (EO–PO) copolymers with different molar masses was investigated. The interaction between the charged polymer derivatives and SDS ions in solution increased strongly with the degree of polymerisation and the amount PO in the chain of the polymeric compounds. This behaviour made it possible to invert the migration order of EO–PO containing polymers of different size. With a background electrolyte (BGE) composition of 10 mM SDS and 25% (v/v) acetonitrile in borate buffer mono- and difunctional byproducts were separated from the main glycerin-based polyols based on their number of end-groups. Accurate quantities for the mono- and difunctional impurities in technical glycerin-based polyol products were determined.

Kinetic evaluation of polyol production by three-phase catalytic hydrogenation of saccharides

Kinetic evaluations were accomplished in a discontinuous three-phase reactor for saccharose, glucose and fructose hydrogenations at 373, 393 and 413 K, and 24 atm. Selectivities attained values in the order of 99.05%. Langmuir-Hinshelwood models based on heterogeneous mechanisms were proposed and the optimization and kinetic quantification of the process were performed.

Rapid cold hardening process of insects and its ecologically adaptive significance *

Abstract In contrast to overwintering cold hardening, a rapid cold hardening process has recently been described in insects. This process can rapidly enhance cold tolerance of insects in several hours or even minutes. The characteristics of rapid cold hardening include inducing conditions, cold hardening effects, and fitness costs. Physiological and biochemical mechanisms of rapid cold hardening include rapid changes in the phospholipid composition and the increase in hemolymph osmolalities, polyols production, proline and cold-induced proteins. Moreover, there are different views about the ecologically adaptive significance of rapid cold hardening in insects. This paper reviews research results about rapid cold hardening of insects since 1987, focusing on forms of cold injury, strategies of cold tolerance, and definitions, characteristics, physiological and biochemical mechanisms and adaptive significance of rapid cold hardening.

Memory Based Local Learning: Application to Process Engineering Problems

Linear and nonlinear regression problems are very common in different fields of science and engineering. A number of different methods to provide accurate input/output relationship have been proposed in the literature. Lazy learning is a recently introduced nonparametric regression technique that employs a memory based local learning approach. Employment of (i) local weighted regression for parametric identification and (ii) PRESS statistic to assess a local model for structural identification, are the two unique features of Lazy learning. The method attempts to fit the training data in a region around the location of the query point by locally interpolating the relevant neighboring points based on distance measure. This is particularly useful when limited number of input/output pairs are available and an accurate prediction is required. Being a memory based technique, it does not require separate training, which greatly enhances the speed of implementation. Moreover the method is less susceptible to noise contamination. All these features are illustrated with one benchmark multivariate statistical example and three important chemical engineering examples comprising boiling point prediction of aliphatic hydrocarbons using quantitative structural property relations, system identification for a continuous stirred tank reactor in which an exothermal irreversible reaction between sodium thiosulfate and hydrogen peroxide occurs and a fermentation process for polyol production. The performance of the proposed method is compared with some of the state-of-art approaches.

Purification and properties of a NADPH-dependent erythrose reductase from the newly isolated Torula corallina.

Torula corallina (KCCM-10171) is a yeast strain that is currently used for the industrial production of erythritol and has the highest erythritol yield ever reported for an erythritol-producing microorganism. Production of erythritol in T. corallina is catalyzed by erythrose reductase, an enzyme that converts erythrose to erythritol using NADPH as a cofactor. In this study, NADPH-dependent erythrose reductase was purified to homogeneity from the newly isolated T. corallina. The relative molecular weight of the erythrose reductase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size exclusion chromatography was 35.4 and 71.0 kDa, respectively, indicating that the enzyme is dimeric. This enzyme catalyzed both erythrose reduction and erythritol oxidation; both enzyme activities required NADP(H). The pH and temperature optima for erythrose reduction and erythritol oxidation were 6.0, 40 degrees C and 8.0, 45 degrees C, respectively. The sequence of the first 10 amino acids of this enzyme was N-V-K-N-F-Y-Q-P-N-D. The affinity (K(m)( )()= 7.12 mM) of the enzyme for erythrose was comparable to that of other known erythrose reductases, and the specificity for erythrose was very high, resulting in no production of other polyols, which may explain the high erythritol yield observed in this strain.

Production of polyether polyols using caesium as catalyst

AbstractAn alternative catalyst to the traditional KOH was studied for preparation of polyols, having high molecular weight (about 6 000 g mol−1) and low unsaturation content. KOH catalyst is useful until the equivalent weight of the polyol reaches about 1 000 g mol−1, at which point an excess of allylic terminal unsaturation starts to develop. Polyols were synthesised using caesium and potassium hydroxide, at different temperatures and catalyst concentrations. Both the unsaturation content of the final polyol and the synthesis time decreased using caesium hydroxide instead of potassium hydroxide under the same synthesis conditions. The relationship to temperature and catalyst concentration was also studied. GPC analyses showed an additional small peak in the product, attributed to the allyl adduct, whose intensity was greater when potassium hydroxide was used as catalyst.© 2002 Society of Chemical Industry

Optimization of media by evolutionary algorithms for production of polyols.

Biotransformation of sucrose-based medium to polyols has been reported for the first time using osmophilic yeast, Hansenula anomala. A new, real coded evolutionary algorithm was developed for optimization of fermentation medium in parallel shake-flask experiments. By iteratively employing the nature-inspired techniques of selection, crossover, and mutation for a fixed number of generations, the algorithm obtains the optimal values of important process variables, namely, inoculum size and sugar, yeast extract, urea, and MgSO4 concentrations. Maximum polyols yield of 76.43% has been achieved. The method is useful for reducing the overall development time to obtain an efficient fermentation process.

Correlation between Urinary Excretion of Polyol Products and Type IV Collagen in Japanese Type 1 Diabetic Patients

Correlation between Urinary Excretion of Polyol Products and Type IV Collagen in Japanese Type 1 Diabetic Patients

O-Alkyl-Substituted Triphenyl Phosphines: Activity and Regioselectivity in Rhodium-Catalysed Propene Hydroformylation

Hydroformylation of propene is the most important hydroformylation process on the industrial scale. Typically, the aim has been the regioselective production of the linear product n-butanal. Recently, interest in selective formation of the branched aldehyde, isobutanal, has increased due to its use in the production of polyols, such as neopentyl glycol (2,2-dimethyl-1,3-propanediol). Study was made of the effect of o-alkyl-substituted triphenylphosphine ligands on the activity and regioselectivity in rhodium-catalysed propene hydroformylation. In addition, the effect of the process conditions on the activity and regioselectivity was investigated by varying the ligand-to-rhodium ratio (0–40), temperature (353–403 K), and deactivation for some of the ligands. The results suggest that o-alkyl-substituted triphenylphosphine ligands enhance the selectivity to isobutanal. However, the activity decreases at the same time. A correlation was found between the 31P-NMR shifts of the ligands and the regioselectivity and activity: as the shift decreases, the regioselectivity to isobutanal increases and the activity decreases. Changes in the process conditions had an effect similar to that in the reaction modified with triphenylphosphine.

Comparison of Activity and Selectivity of Weakly Basic Anion-Exchange Catalysts for the Aldolization of Butyraldehyde with Formaldehyde

Aldols are important intermediates in the production of polyols, which are raw material for lubricants, surface coatings, and synthetic resins. The activities and selectivities of gel-type and macroporous anion-exchange resin catalysts in the aldolization of butyraldehyde with formaldehyde in an aqueous environment were investigated at 60 °C. The experiments were carried out batchwise in a stirred glass reactor, and the reaction products were analyzed with high performance liquid chromatography. Two main products were observed, 2-ethyl-3-hydroxy-2-hydroxy-methylpropanal (trimethylolpropane aldol) and 2-ethylpropenal (ethylacrolein). The product ratio was strongly dependent on the catalyst. The selectivity with respect to trimethylolpropane aldol varied within the range 2.7−7.3 for the catalysts investigated. Systematic kinetic experiments were carried out at 50−70 °C with the gel-type resin catalyst displaying the highest aldol selectivity. A kinetic model based on molecular mechanisms was able to describe the product distribution.

Lyondell Flexes Its Muscles Outside The U.S.

Houston-based Lyondell Chemical has broken ground for a new 1,4- butanediol (BDO) plant at its site in Botiek, an industrial area of Rotterdam, in the Netherlands. The plant is one of two projects in varying stages of development in the Netherlands to supply customers in Asia, North America, and Europe. The ground-breaking festivities also are part of a concentrated effort by Lyondell to become better known in the European arena, putting its own stamp on a sweep of European operations that it got when it acquired Arco Chemical in 1998. The Arco purchase brought two sites in Rotterdam: the Botiek site and one in the nearby Maasvlakte region of reclaimed land at the mouth of the Rhine River. Lyondell also obtained major propylene oxide and polyols operations in Fos-sur-Mer, Marseille, on the Mediterranean coast of France; polyols production near Ghent in Belgium; technical and service centers in France and Rotterdam; and headquarters operations in Maidenhead, ...

Polyols production during single and mixed substrate fermentations in Debaryomyces hansenii

The kinetics of polyols production by Debaryomyces hansenii was studied both on single substrate and mixed substrate-containing media. From the single substrate experiments, polyols (xylitol and arabitol) and ethanol were produced from pentose sugars while ethanol was produced in significant amounts only from glucose-grown D. hansenii. The maximal xylitol volumetric productivity ( Q xylitol), 0.28 g l −1 h −1 was obtained from D-xylose, whereas the maximal arabitol volumetric productivity ( Q arabitol), 0.04 g l −1 h −1 was observed with arabinose. When D. hansenii was cultivated with mixed substrates, a simultaneous sugar consumption pattern occurred both for glucose/arabinose and xylose/arabinose mixtures. The addition of low amounts of xylose to an arabinose medium led to a fourfold increase in the arabitol volumetric productivity: 0.17 g l −1 h −1. Conversely, glucose addition had no effect on arabitol production. Xylitol was the main polyol produced for all tested cultivation conditions by D. hansenii. An enzymatic study of the first two xylose-catabolic enzymes in glucose and xylose-grown D. hansenii revealed that both enzymes were induced by D-xylose. Glucose caused total inhibition of xylitol dehydrogenase, whereas xylose reductase was only partially repressed.

Polyol production by culture of methanol-utilizing yeast

Four methanol-utilizing yeasts, Candida boidinii, Hansenula polymorpha, Hansenula ofunaensis, and Pichia pinus, produced polyols from corresponding sugars in a methanol medium. H. polymorpha produced larger amounts of xylitol than the other yeasts. Productivity was the highest at pH 8 when 5 g (dry)/ l cultured cells were incubated with 2.5 g/ l urea as the nitrogen source in a medium containing 1% (v/v) methanol and 1 g/ l MgSO 4·7H 2O. Under these conditions, 57 g/ l xylitol was obtained from 110 g/ l d-xylose after 3 d of cultivation. The largest amount of xylitol (58 g/ l; yield, 0.62 g/g) was produced from 125 g/ l, d-xylose and 5% (w/v) glycerol instead of methanol after 4 d of cultivation.