Higher-alcohols biorefinery

The concept of a biorefinery for higher-alcohol production is to integrate ethanol and methanol formation via fermentation and biomass gasification, respectively, with, conversion of these simple alcohol intermediates into higher alcohols via the Guerbet reaction. 1-Butanol results from the selfcondensation of ethanol in this multistep reaction occurring on a single catalytic bed. Combining methanol with ethanol gives a mixture of propanol, isobutanol, and 2-methyl-1-butanol. All of these higher alcohols are usefulas solvents, chemical intermediates, and fuel additives and, consequently, have higher market values than the simple alcohol intermediates. Several new catalysts for the condensation of ethanol and alcohol mixtures to higher alcohols were designed and tested under a variety of conditions. Reactions of methanol ethanol mixtures gave as high as 100% conversion of the ethanol to form high yields of isobutanol with smaller amounts of 1-propanol, the amounts in the mixture depending on the starting mixture. The most successful catalysts are multifunctional with basic and hydrogen transfer components.     

Correlation between surface and bulk structures of alcohol-water mixtures

Adsorption isotherms of binary aqueous solutions of methanol, ethanol, 1-propanol, 2-propanol, tert-butanol, and 1-butanol are demonstrated, being calculated by using the Gibbs adsorption equation with experimental data of surface tension and vapor pressure found in the literature. For all of the alcohol-water mixtures, the maximum value in the adsorption isotherm, namely, the maximum surface excess is about that expected for the formation of a monolayer. Furthermore, the composition of the mixture for the maximum surface excess coincides with that corresponding to the minimum in the excess partial molar volume of the solutes. These results indicate that the hydrophobic hydration in bulk induces the surface excess of the alcohols and after a monolayer is formed, the hydrophobic hydration itself is no longer retained.     

Electrosteric Stabilization of Al(2)O(3), ZrO(2), and 3Y-ZrO(2) Suspensions: Effect of Dissociation and Type of Polyelectrolyte

The mechanisms of eight anionic polyelectrolytes stabilizing colloidal sized alpha-Al(2)O(3), pure ZrO(2), and Y(2)O(3)-doped ZrO(2) particles in aqueous solution are discussed. The polyelectrolytes studied were the Na(+) and NH(4)(+) salts of polyacrylic acid and polymethacrylic acid having different molecular weights. The particle-dispersant interactions were studied by measuring adsorption isotherms, particle size, thickness of adsorbed layer, and zeta potentials by elektrokinetic sonic analysis at different powder volume fractions (straight phi=0.01-0.3), pH, and electrolyte (KCl) content. The dissociation of the polyelectrolytes was studied by potentiometric titrations. The dissociation constant of the polymethacrylates was found to be 0.6 pH unit higher than that for the polyacrylates. High-affinity adsorption isotherms were observed over the pH range when the polyelectrolytes were fully ionized. The results show good correlation between adsorption isotherms and zeta potential data in systems of dispersed, dilute alumina particles. When particles and polymers were of equal charge (the same sign of charge) the polymer shell was thicker. At higher volume fractions (straight phi=0.3), and when alumina particles/added ammonium polyelectrolyte were of equal charge, a maximum in the absolute value of zeta potential resulted. Due to adsorption all the anionic polyelectrolytes studied provided electrosteric stabilization of the alpha-Al(2)O(3), and Y(2)O(3)-doped ZrO(2) suspensions by enhancing the zeta potential to 40 mV or over and by shifting the isoelectric point to lower pH, the low-molecular-weight polyelectrolytes decreasing the isoelectric point more than the polyelectrolytes having higher molecular weight. The polyelectrolytes studied failed to stabilize pure monoclinic ZrO(2) particles. Due to the shortness of the chain of polyelectrolytes studied, no bridging was observed between oppositely charged polyelectrolyte/alumina particles. Copyright 2000 Academic Press.     

1-丁基-3-甲基咪唑六氟磷酸盐+水+醇体系的相行为

在298.15 K, 常压下研究了1-丁基-3-甲基咪唑六氟磷酸盐([bmim][PF₆])+水+甲醇、[bmim][PF₆]+水+乙醇、[bmim][PF₆]+水+2-丙醇、[bmim][PF₆]+水+1-丙醇三元体系的相行为. 结果表明, 对于含甲醇、乙醇和2-丙醇的体系, 醇在水+醇溶液中摩尔分数分别为0.55-1.00、0.40-0.75 和0.35-0.50 时, 醇的水溶液与[bmim][PF₆]可以互溶. 而水+1-丙醇体系没有此类现象. 这说明, 这类三元系的相行为不但取决于醇分子的大小, 而且取决于其结构.     

Thermodynamic analysis of surface formation of {1,4-dioxane + 1-alkanol} mixtures

Surface tensions (sigma) for {1,4-dioxane + methanol, ethanol, or 1-propanol} at the temperature 298.15 K and normal atmospheric pressure have been determined as a function of mole fractions. The experimental results have been analyzed using the ideal and Langmuir models and in the light of the well-documented bulk properties of these systems, which reflect hydrogen bonding between the alcohol and 1,4-dioxane molecules. For {1,4-dioxane + ethanol} surface tensions were also measured at other temperatures between 288.15 and 308.15 K, and these data were used to calculate the surface entropy and enthalpy per unit area.     

Excess Volume of Ternary Water + Diacetone Alcohol + 2-Propanol as a Function of Pressure,Temperature and Composition

Abstract

The excess volume V^E of the ternary water + diacetone alcohol (or DAA) + 2-propanol and of the three binaries water + DAA, water + 2-propanol and DAA + 2-propanol was evaluated from experimental density data (2772 values) as a function of the pressure P (between 0.1 MPa and 65 MPa), the temperature T (303.15K, 323.15K and 343.15K) and the composition. Various representative models are discussed. It is possible to account for the values of the density with an average absolute deviation of about 0.06% in the experimental P-T domain.     

Solubility of Anthracene in Binary Alcohol + Butyl Acetate Solvent Mixtures at 298.2 K

Abstract

Experimental solubilities are reported for anthracene dissolved in six binary alcohol + butyl acetate solvent mixtures at 25° C. The alcohol cosolvents studied were 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and 3-methyl-1-butanol. Results of these measurements are used to test a mathematical representation based upon the combined Nearly Ideal Binary Solvent (NIBS)/Redlich-Kister equation. For the six systems studied, the Combined NIBS/Redlich-Kister equation was found to mathematically describe the experimental data, with overall average absolute deviations between measured and calculated values being approximately\pm 0.6%.     

Solubility of Anthracene in Binary Alcohol + 1-chlorobutane Solvent Mixtures at 298.2 K

Abstract

Experimental solubilities are reported for anthracene dissolved in six binary alcohol + 1-chlorobutane solvent mixtures at 25°C. The alcohol cosolvents studied were 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and 3-methyl-1-butanol. Results of these measurements are used to test a mathematical representation based upon the combined Nearly Ideal Binary Solvent (NIBS)/Redlich-Kister equation. For the six systems studied, the Combined NIBS/Redlich-Kister equation was found to mathematically describe the experimental data, with overall average absolute deviations between measured and calculated values being approximately\pm 0.4%.     

Electrokinetics of concentrated suspensions of spherical colloidal particles with surface conductance, arbitrary zeta potential, and double-layer thickness in static electric fields

In this paper the electrophoretic mobility and the electrical conductivity of concentrated suspensions of spherical colloidal particles have been numerically studied under arbitrary conditions including zeta potential, particle volume fraction, double-layer thickness (overlapping of double layers is allowed), surface conductance by a dynamic Stern layer model (DSL), and ionic properties of the solution. We present an extensive set of numerical data of both the electrophoretic mobility and the electrical conductivity versus zeta potential and particle volume fraction, for different electrolyte concentrations. The treatment is based on the use of a cell model to account for hydrodynamic and electrical interactions between particles. Other theoretical approaches have also been considered for comparison. Furthermore, the study includes the possibility of adsorption and lateral motion of ions in the inner region of the double layers (DSL model), according to the theory developed by C. S. Mangelsdorf and L. R. White (J. Chem. Soc. Faraday Trans.86, 2859 (1990)). The results show that the correct limiting cases of low zeta potentials and thin double layers for dilute suspensions are fulfilled by our conductivity formula. Moreover, the presence of a DSL causes very important changes, even dramatic, on the values of both the electrophoretic mobility and the electrical conductivity for a great range of volume fractions and zeta potentials, specially when double layers of adjacent cells overlap, in comparison with the standard case (no Stern layer present). It can be concluded that in general the presence of a dynamic Stern layer causes the electrophoretic mobility to decrease and the electrical conductivity to increase in comparison with the standard case for every volume fraction, zeta potential, and double-layer thickness.     

Kinetics of small molecule adsorption studied using precision ellipsometry

On the basis of a miniature polarisation modulator, a precision ellipsometry system has been made, enabling real-time measurement of subnanometre thin layers on reflecting substrates. This system monitored the kinetics of adsorption and desorption of propanol, or ethanol, or methanol on oxidised Si substrates. While adsorption of propanol and ethanol increased the thickness, adsorption of methanol showed surprising kinetics: the thickness first increased, then decreased. To explain this, a model of substitutional (or competitive) adsorption has been used, where the target molecule is adsorbed only when it substitutes another one leaving an adsorption site. The model fits the experimental data quantitatively and can predict processes involving several components on solid surfaces. Precision ellipsometry demonstrated its high analytical potential in investigation of surfaces at molecular level.     

Solubility of Trans-Stilbene in Binary Alcohol + 1-Propanol Solvent Mixtures at 298.2 K

Abstract

Experimental solubilities are reported for trans-stilbene dissolved in six binary alcohol + 1-propanol solvent mixtures at 25°C. The alcohol cosolvents studied were 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol and 3-methyl-1-butanol. Results of these measurements are used to test two mathematical representations based upon the combined Nearly Ideal Binary Solvent (NIBS)/Redlich-Kister and Modified Wilson equations. For the six systems studied, the Combined NIBS/Redlich-Kister equation was found to provide the better mathematical representation of the experimental data, with overall average absolute deviations between measured and calculated values being approximately ±0.4%. Slightly larger deviations were noted in the case of the Modified Wilson equation.     

Conformation of poly(methacrylic acid) in alcohol–water mixtures. II. Methanol,ethanol, n-propanol,and 1,2-ethanediol

The intrinsic viscosity of poly(methacrylic acid) has been studied in mixtures of 0.002N HCI and a series of aliphatic alcohols. The behavior found previously with ethanol is shown to apply in the case of admixture with methanol, n-propanol, and 1,2-ethanediol. The intrinsic viscosity first drops to a minimum and then increases sharply to a maximum. With ethanol and n-propanol the maximum is followed by another minimum and maximum. With methanol and 1,2-ethanediol this effect is absent or much smaller. Methanol and 1,2-ethanediol are equivalent, molecule for molecule, in their influence on the intrinsic viscosity. With ethanol and n-propanol there are in addition one and two shoulders, respectively, in the passage from the first minimum to the first maximum. Good correlation of the data is obtained if alcohol concentration is plotted as the mole fraction of carbon atoms per OH group (in the alcohol). The first maximum in particular was shown to correspond to the point where the number of water molecules per alcohol in the solvent mixture equals the number of C atoms per hydroxyl in the alcohol. The shoulders and first minima were found to correspond to other simple ratios. This behavior reflects changes in alcohol–water structure. The maximum in the case of ethanol was found to be the most pronounced and ethanol seems to possess optimal properties from this point of view.     

Adsorption dynamics of gases and vapors on the nanoporous metal organic framework material Ni2(4,4'-bipyridine)3(NO3)4: guest modification of host sorption behavior

This study combines measurements of the thermodynamics and kinetics of guest sorption with powder X-ray diffraction measurements of the nanoporous metal organic framework adsorbent (host) at different adsorptive (guest) loadings. The adsorption characteristics of nitrogen, argon, carbon dioxide, nitrous oxide and ethanol and methanol vapors on Ni2(4,4'-bipyridine)3(NO3)4 were studied over a range of temperatures as a function of pressure. Isotherm steps were observed for both carbon dioxide and nitrous oxide adsorption at approximately 10-20% of the total pore volume and at approximately 70% of total pore volume for methanol adsorption. The adsorption kinetics obey a linear driving force (LDF) mass transfer model for adsorption at low surface coverage. At high surface coverage, both methanol and ethanol adsorption follow a combined barrier resistance/diffusion model. The rates of adsorption in the region of both the carbon dioxide and methanol isotherm steps were significantly slower than those observed either before or after the step. X-ray diffraction studies at various methanol loadings showed that the host structure disordered initially but underwent a structural change in the region of the isotherm step. These isotherm steps are ascribed to discrete structural changes in the host adsorbent that are induced by adsorption on different sites. Isotherm steps were not observed for ethanol adsorption, which followed a Langmuir isotherm. Previous X-ray crystallography studies have shown that all the sites are equivalent for ethanol adsorption on Ni2(4,4'-bipyridine)3(NO3)4, with the host structure undergoing a scissoring motion and the space group remaining unchanged during adsorption. The activation energies and preexponential factors for methanol and ethanol adsorption were calculated for each pressure increment at which the linear driving force model was obeyed. There was a good correlation between activation energy and ln(preexponential factor), indicating a compensation effect. The results are discussed in terms of reversible adsorbate/adsorbent (guest/host) structural changes and interactions and the adsorption mechanism. The paper contains the first evidence of specific interactions between guests and functional groups leading to structural change in flexible porous coordination polymer frameworks.     

Alcohols and wide-bore capillaries in nonaqueous capillary electrophoresis.

The feasibility of using C1-C5 alcohols as electrolyte solutions in nonaqueous capillary zone electrophoresis was investigated. The separation of basic narcotic analgesics and acidic diuretics was modified by changing the alcohol in an electrolyte solution containing alcohol-acetonitrile-acetic acid (50:49:1, v/v) and 20 mM ammonium acetate while other experimental conditions were kept constant. The alcohols studied were methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 1-pentanol. The results indicate that even longer-chain alcohols can be used in nonaqueous capillary zone electrophoresis and, because of the lower currents they allow, they are especially advantageous in wider capillaries. Basic analytes were separated in 200 microm and 320 microm ID capillaries with 1-butanol-acetonitrile-acetic acid (50:49:1, v/v) containing 20 mM ammonium acetate as electrolyte solution. Problems related to the use of wide-bore capillaries are discussed.     

Surface tension and density of mixtures of 1,3-dioxolane+alkanols at 298.15 K: analysis under the extended Langmuir model

Surface tensions (sigma) for [1,3-dioxolane+methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 1-pentanol] and excess molar volumes (v(E)) for [1,3-dioxolane+methanol, ethanol, 1-propanol, 2-propanol, and 2-butanol] at the temperature 298.15 K and normal atmospheric pressure have been determined as a function of mole fractions. The magnitude of these experimental quantities is discussed in terms of the nature and type of intermolecular interactions in binary mixtures. In order to analyze the surface tension behavior, the extended Langmuir (EL) model was used and the results obtained for the systems containing 1,3-dioxolane were compared with those of other formerly published series: [1,4-dioxane+alkanes] and [1,4-dioxane+alcohols].     

Excess enthalpies of binary solvent mixtures of N-methylacetamide with aliphatic alcohols

The molar excess enthalpies H _m ^E of binary solvent mixtures of N-methylacetamide with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and t-butanol have been measured with a flow microcalorimeter at 40°C. The excess enthalpies are negative for methanol and positive for the other alcohols over the whole composition range, except for t-butanol which exhibits a sigmoid curve with a deep minimum at low mole fractions of the amide. The values for the primary alcohols increase in the order methanol < ethanol < 1-propanol < 1-butanol. The partial molar excess enthalpies have also been evaluated. Intermolecular interactions in these mixtures are discussed through comparison of the results with those for the corresponding binary mixtures of N,N-dimethylacetamide.     

Thermochemical investigations of hydrogen-bonded solutions. Part 11. Expressions for predicting anthracene solubilities in alcohol+alkoxyalcohol mixtures based on mobile order theory

Experimental solubilities are reported for anthracene dissolved in eight binary mixtures containing 2-ethoxyethanol with 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol, 3-methyl-1-butanol and 1-octanol, and also in binary 1-pentanol+2-methoxyethanol and 2-methyl-1-propanol+2-propoxyethanol solvent systems at 25°C. Results of these measurements, combined with previously reported anthracene solubility data in 22 different alcohol +2-alkoxyethanol (2-methoxyethanol, 2-propoxyethanol and 2-butoxyethanol) solvent mixtures, are used to test the limitations and applications of expressions derived from Mobile Order theory. The first predictive expression assumes only formation of homogeneous self-associated hydrogen-bonded species, whereas the second equation includes additional terms to account for heterogeneous complex formation between the dissolved alcohol and 2-alkoxyethanol solvent molecules. Both equations predict the observed anthracene solubilities to within an average absolute deviation of about 3%.     

Excess Molar Volumes and Excess Partial Molar Volumes of Triethylene Glycol Monoethyl Ether–n-Alcohol Mixtures at 25°C

We have measured excess molar volumes V^E _m of binary mixtures of triethylene glycol monoethyl ether with methanol, ethanol, 1-propanol, 1-pentanol, and 1-hexanol over the full range of compositions at 25°C. The measurements were carried out with a continuous-dilution dilatometer. The excess molar volumes V^E _m are negative over the entire range of composition for the systems triethylene glycol monoethyl ether + methanol, + ethanol, and + 1-propanol and positive for the remaining systems, triethylene glycol monoethyl ether + 1-pentanol, and + 1-hexanol. The excess V^E _m increases in the positive direction with increasing chain length of the n-alcohol. The measured excess volumes have been compared to our previous published data with an effort to assess the effects of replacing methyl by ethyl groups and of inserting oxyethylene groups. The results have been used to estimate the excess partial molar volumes V^E _m,i of the components. The behavior of V^E _m and V^E _m,i with composition and the number of carbon atoms in the alcohol molecule is discussed.     

Adsorption of gases and vapors on nanoporous Ni2(4,4'-Bipyridine)3(NO3)4 metal-organic framework materials templated with methanol and ethanol: structural effects in adsorption kinetics

Desolvation of Ni(2)(4,4'-bipyridine)(3)(NO(3))(4).2CH(3)OH and Ni(2)(4,4'-bipyridine)(3)(NO(3))(4).2C(2)H(5)OH give flexible metal-organic porous structures M and E, respectively, which have the same stoichiometry, but subtly different structures. This study combines measurements of the thermodynamics and kinetics of carbon dioxide, methanol, and ethanol sorption on adsorbents M and E over a range of temperatures with adsorbent structural characterization at different adsorbate (guest) loadings. The adsorption kinetics for methanol and ethanol adsorption on porous structure E obey a linear driving force (LDF) mass transfer model for adsorption at low surface coverage. The corresponding adsorption kinetics for porous structure M follow a double exponential (DE) model, which is consistent with two different barriers for diffusion through the windows and along the pores in the structure. The former is a high-energy barrier due to the opening of the windows in the structure, required to allow adsorption to occur, while the latter is a lower-energy barrier for diffusion in the pore cavities. X-ray diffraction studies at various methanol and ethanol loadings showed that the host porous structures E and M underwent different scissoring motions, leading to an increase in unit cell volume with the space group remaining unchanged during adsorption. The results are discussed in terms of reversible adsorbate/adsorbent (host/guest) structural changes and the adsorption mechanism involving hydrogen-bonding interactions with specific surface sites for methanol and ethanol adsorption in relation to pore size and extent of filling. This paper contains the first evidence for individual kinetic barriers to diffusion through windows and pore cavities in flexible porous coordination polymer frameworks.     

Heats of immersion of titanium dioxide pigments in alcohol—water mixtures

The heats of immersion of partially dried anatase and rutile pigments in mixtures of water with methanol, ethanol, and n-propanol were measured by a differential calorimetric method. The anatase heats of immersion could best be explained by assuming preferential adsorption of the alcohols, the effect being greatest for n-propanol The rutile pigment, however, appeared to adsorb water preferentially in methanol—water and ethanol—water mixtures over the whole concentration range. In propanol—water mixtures the rutile pigment preferentially adsorbed water below an alcohol mol fraction of 0.25, and preferentially adsorbed propanol at mol fractions of alcohol greater than 0.25. The differences in behaviour between the two pigments may be explained qualitatively from the point of view of their surface morphology.