Montmorillonite is a clay mineral which when exchanged with hydroxyaluminum oligomers produces a pillared clay mineral. On calcination at 500(DEGREES)C the pillars are fixed, and a microporous structure having good thermal stability and high surface area (about 350 m('2)/g) is generated. The pillared interlayered clay (PILC) has a two dimensional pore network with a slit width of about 8.5 (ANGSTROM). By incorporating a (de)hydrogenation function such as Pt on the PILC, a bifunctional catalyst capable of catalyzing hydroisomerization of n-paraffins is obtained. Hydroisomerization of C(,5) to C(,7) n-paraffins on a Pt-Re/PILC catalyst was studied using an isothermal fixed bed reactor operated at 1 atmosphere pressure. The rate data fit a model based on bifunc- tional catalysis. The acid catalyzed isomerization of carbenium ions appears to be the rate controlling step. Single branched isomers are the dominant products. Poisoning experiments, using dimethyl sulfide to deactivate the metal sites and pyridine as a poison for the acid sites, support the bifunctional mechanism model. A temperature programmed reduction of PILC shows that during high temperature reduction almost all the iron in the clay lattice is reduced from Fe('+3) to Fe('+2). This was confirmed by Mossbauer spectroscopy. The presence of Pt and Re accelerates the reduction of iron as evidenced by temperature programmed reduction. When the iron in the lattice is reduced, the resulting increase in the negative charge of the clay lattice is balanced by H('+) ions on the surface which increase the Br(SLASHCIRC)nsted acidity. Infrared spectroscopy of adsorbed pyridine shows that reducing the PILC increases the Br(SLASHCIRC)nsted acidity. Temperature programmed desorption of butyl- amines showed that the acidity of PILC is comparable to silica-alumina cracking catalysis, in both amount and activity. It is evident from scanning and transmission electron microscopy that almost all the platinum is in the form of particles in the range of 100 (ANGSTROM) to 200 (ANGSTROM). The Re is finely dispersed in small clusters containing at most a few atoms and is evenly distributed. There is no significant alloy formation.

Structural, kinetic and catalytic effects relevant to the combustion and gasification of coal-derived chars were investigated. A Texas lignite, an anthracite and two bituminous coals, Pittsburgh #8 and Illinois #6, were pyrolyzed in a nitrogen atmosphere to prepare chars. Optical microscopy, mercury porosimetry and gas adsorption techniques using nitrogen, CO(,2) and CO, were employed for pore structure characterization. The micropores present in the lignite char were accessible to all adsorbents. However, a substantial fraction of the pore space in other chars was inaccessible to nitrogen at 77(DEGREES)K. The lignite char also exhibited the fastest rates of gaseous diffusion, followed in order of decreasing diffusivities by the Illinois #6, Pittsburgh #8 and anthracite chars. The changes in reactivities and pore structures of chars were measured experimentally during their reaction with oxygen (400-550(DEGREES)C) and CO(,2) (800-1000(DEGREES)C). For a particular char-gas system, the normalized rate-conversion pattern was invariant with respect to temperature and gaseous concentration. In the case of lignite and Pittsburgh #8 chars, the rate-conversion pattern was similar during reaction with oxygen and CO(,2). Adsorption experiments on partially reacted chars indicated that the micropores in the lignite char were accessible to both reactants. The micropores in the Illinois #6 char were, however, not accessible during its reaction with oxygen. The evolution of pore structure during reaction was modeled by using a probabilistic approach which accounts for overlapping pores with different shapes and sizes. A priori predictions of pore structure evolution are obtainable from the structural measurements on unreacted char. The model predictions were validated using the experimental data reported in literature and the data obtained in this work. The kinetics of gasification of the lignite and the Pittsburgh #8 chars was studied using a Langmuir-Hinshelwood type kinetic expression to correlate the experimental data. CO was found to inhibit the reaction substantially. The effect of a potassium carbonate catalyst on the reaction of these two chars was also investigated. A marked change in the reactivity-conversion pattern was observed when the catalyst impregnated char samples were reacted with oxygen and CO(,2). Substantial increases in reaction rates were observed, and the enhancement was approximately proportional to the catalyst loading.

The transport of methanol and formaldehyde in obligate RMP-cycle methylotrophs Methylomonas L3 and strain T15 was studied by using radioactive tracers in anaerobic whole cell suspensions. The corrected accumulation ratios were found to be about 24 to 30 for methanol and about 40 to 75 (respectively) for formaldehyde in Methylomonas L3, depending upon the experimental conditions. In both strains, the transport profiles of methanol and formaldehyde always showed oscillatory efflux and reuptake phases. This was hypothesized to be an effect of the energy limitation imposed by the anaerobic assay conditions coupled with the high permeabilities of the transport substrates. The transport of methanol in M. L3 was not inhibited by protonophores, but was partially inhibited by 10mM arsenate and very strongly inhibited by dicyclohexyl carbodiimide (DCCD). Direct ATP profile monitoring, paralleling the methanol transport experiments, using the highly sensitive luciferase/luciferin assay, showed that ATP was consumed for the transport of methanol. Further, the ATP profiles showed oscillations, in parallel to the oscillations in the methanol profile, indicating that the oscillations in the energy content were responsible for the oscillatory uptake profiles, in support of our hypothesis. In contrast, the formaldehyde transport in M. L3 was inhibited partially by DCCD, and more strongly by protonophores. Thus, perhaps the proton-motive force ((DELTA)pmf) was more closely coupled to the transport of formaldehyde in M. L3, although both ATP and (DELTA)pmf could be used for transport. Similar results were obtained for formaldehyde transport in strain T15, with ca. 40% inhibition being caused by both FCCP and DCCD. Thiol reagents, particularly HgCl(,2) inhibited the transport of both methanol and formaldehyde in M. L3, implying the presence of essential cysteine residues in the transport associated proteins. The formaldehyde transport in M. L3 was also inhibited by diethyl pyrocarbonate (DEPC), indicating an essential histidine residue also. Overall, the results mean that both formaldehyde and methanol M. L3, and at least formaldehyde in strain T15 are transported by (similar) active transport mechanisms.

Various anionic surfactant-oil-brine systems were studied to understand the transition between liquid crystal and microemulsion phases produced by changes in composition. This work involved equilibrium phase behavior studies and included optical microscopy and measurements of electrical conductivity, density, viscosity, and interfacial tension. These studies provide information important in designing slugs for oil recovery processes and should be useful in understanding certain detergency processes. The effects of alcohol on surfactant-alcohol-brine systems were determined in the composition range pertinent to oil recovery. A general relationship was found between apparent viscosity and phase behavior for lamellar liquid crystals of high water content (>85%) and low viscosity and their dispersions which were prominent in these systems. A simple model was developed to explain the transition from lamellar to isotropic phases with increasing salinity in anionic surfactant systems, and with increasing temperature in nonionic surfactant systems. Basically, a decrease in tension at surfaces of plate-like particles allows more particles with smaller diameters to be formed with a resulting increase in the entropy of dispersion. The effect of added oil in several systems, including petroleum sulfonate, pure sulfonate (Texas-1), and salt-tolerant ethoxylated, propoxylated sulfate was studied. A general pattern of behavior was found at and above optimum salinity, where oil first caused transformation of liquid crystal to a water-continuous isotropic phase, then gradual inversion of this phase. At low salinities behavior was similar but without the inversion. Just below optimum, the transition was more complex with two three-phase regions found in the petroleum sulfonate and Texas-1 systems and a four-phase region in the salt-tolerant system. Lamellar liquid crystals in equilibrium with excess oil were discovered at equal water-to-oil ratios and low salinities on equilibrating petroleum sulfonates with longer chain hydrocarbons. These liquid crystals have low viscosities and exhibit low interfacial tensions with oil (about 0.02 dyne/cm) despite their minimal oil solubilization. Finally, phase behavior of alcohol-free Aerosol-OT-oil-brine systems were studied. The results with n-dodecane were plotted on a series of ternary diagrams for different salinities. Brine was found to be a satisfactory pseudocomponent in substantial portions of the diagrams for salinities well below and above optimum.

The HSE (Hard Sphere Expansion) theory calculates the thermodynamic properties of a mixture by separating its properties into contributions from molecular repulsion, which are calculated directly from a hard sphere mixture equation of state, and other contributions from various types of intermolecular attraction, which are obtained by corresponding states from known values of similar contributions in a pure reference fluid. Shape factors are used to establish conformality between individual constituents and the reference fluid. This theoretically based approach represents composition dependence better than the empirical mixing rules used in the traditional mixture equations of state. By applying the first and second order variational principles, a procedure is developed to determine the optimal repulsion contribution and rigid core dimensions. The procedure requires an equation of state capable of predicting accurate second derivatives for the reference fluid. A 32 constant modified Benedict-Webb-Rubin (MBWR) equation with exceptional accuracy is used for this purpose. Engineering equations of state are permissible for constituents other than the reference. The new development allows an accurate analytical approach to be applicable to the differentiation of the mixture Helmholtz free energy property with respect to component moles involved in the phase equilibrium calculations. The importance of the reference fluid selected for phase equilibrium calculations is discussed. The reference fluids used are the three hydrocarbons: methane, ethane, and propane. For mixtures containing polar fluids, such as carbon dioxide or hydrogen sulfide, the total attraction contribution may be evaluated entirely from the attraction in a pure nonpolar reference fluid by means of shape factors. An alternate method is to evaluate separate symmetrical and asymmetrical attraction terms, in which the multipole expansion is used to account for the polar contributions. Both approaches are discussed and compared. The HSE theory are applied to gaseous and liquid phases of binary hydrocarbon mixtures containing high concentrations of hydrogen sulfide or carbon dioxide. Calculations of densities and the vapor-liquid composition ratios (K-values) are presented. Good agreement with experimental data is achieved over a wide range of pressure and temperature. The computational procedure is detailed in this work.

Highly filled polymer composites, such as polymer concrete (PC), suffer from setting stresses generated during the cure of the resin binder, when polymerization shrinkage is hindered by the close packing of filler and aggregate particles. Setting stresses impair significantly the strength of the cured composite. Current zero-shrinkage and expanding polymer concrete formulations achieve these properties with a sacrifice in strength. In this investigation, a novel system was developed for producing zero-shrinkage and expanding polymer concrete composites with concomitant enhancement in strength. This was achieved by dispersing small amounts of the hydrated mineral montmorillonite (MMT) into the resin and was found effective with three different resin binders (polyester, epoxies, and acrylics). Most resins require less than 2% MMT to produce zero-shrinkage systems with flexural strengths and splitting tensile strengths 30% and 16% greater than conventional PC; higher MMT contents create PC systems which expand upon curing or generate positive hydrostatic pressure during constant-volume cure. We have examined here the complex physicochemical interactions between the polymerizing resin and the dehydrating mineral, which give rise to the observed cure-expansion and strength enhancement. This required extensive experimental work, including strength measurements, X-ray diffractometry, differential scanning calorimetry, thermomechanical analysis, scanning electron microscopy, X-ray spectroscopy, and gas chromatography/mass spectrometry data. Based on the results of these measurements we propose a mineral-resin interaction mechanism that involves the migration of organic species from the curing resin into the MMT crystal structure; these organic molecules replace some of the ordered hydration water, released by the mineral at the temperatures generated by the exothermic polymerization reaction. The MMT-resin bonding takes place through the molecules of silane coupling agents, thus contributing to the strength enhancement of the composite. The observed expansion at cures above 100(DEGREES)C is due to the release of highly disordered water, which remains distributed in the pores and internal structure of MMT, rather than forming a discrete gas phase.

Videomicroscopy was used to study nonequilibrium phenomena in various systems containing oil, water, and surfactant. This novel technique included the use of a vertical configuration microscope to allow easy observation of intermediate phase formation, interfacial instabilities, and spontaneous emulsification. In most systems, diffusion path analysis was utilized to explain the observed events. A petroleum sulfonate system typical of those used in surfactant flooding of oil reservoirs was examined to determine salinity effects on nonequilibrium phenomena. Microemulsions and/or brine phases formed as intermediate layers at all salinities. Diffusion paths calculated for a model system match the experimental results with regard to the number and rate of formation of the intermediate phases. Contacting experiments were also performed between an oil phase containing oleic acid and caustic brine solutions of varying salinity and pH. In these experiments, which are pertinent to enhanced oil recovery by alkaline flooding, interfacial turbulence and liquid crystal formation were commonplace. Spontaneous emulsification of water in the oil was observed at conditions where the surfactant was oil-soluble. Oil-in-water emulsions formed spontaneously at conditions where the surfactant was hydrophilic. For application to low-temperature detergency, hydrocarbons were contacted with aqueous solutions of pure ethoxylated alcohol surfactants. Enhanced solubilization of oil was seen at temperatures above the cloud point of the nonionic surfactant solutions due to the presence of surfactant-rich phases. In addition, intermediate liquid crystal and microemulsion layers typically formed near the phase inversion temperature, while conversion of oil into a water-in-oil microemulsion occurred at higher temperatures. Comparison of a pure ethoxylated alcohol system was also made to formulations having the same cloud point but containing a different ethoxylated alcohol and a lipophilic additive. Differences in nonequilibrium behavior were observed upon contacting with hydrocarbons due to partitioning of additive into the oleic phase. Finally, contacting experiments were compared to calculated diffusion paths for a well-characterized oil-water-alcohol system. One of the more interesting observations was the formation of an interface across a three-phase region. This phenomenon, which has not previously been reported for liquid systems, also occurred at certain conditions in the experiments using surfactants.

A technique utilizing radioisotopic tracers to probe the branching of carbon flow in chemostatic cultures of methylotrophic bacteria has been developed to obtain in situ and in vivo measurements of key intracellular reaction rates. Employing this method, it is possible to determine the effects of bioreactor conditions on the cellular regulation of carbon flow in RuMP-type methylotrophs. Growth rate, substrate composition, biomass yield and fermentation mode all influence the extent of branching of carbon flow through assimilation, decarboxylation/carboxylation, and linear or cyclic oxidation reactions in Methylomonas L3. A complementary analysis of the steady-state, in vitro specific activities (IVSA) for key assimilatory and dissimilatory methylotrophic enzymes from numerous batch and continuous cultures reveals that there is no simple correlation between enzyme activity and the corresponding reaction rate. The evidence implicates two well-known regulatory mechanisms in the expression of these enzyme levels: catabolite repression and induction. The generality of these findings was suggested by the demonstration of similar results in a novel RuMP-type methylotroph (strain T15), which was isolated on the basis of high linear oxidation IVSA and characterized. Linear oxidation was predominant, and highest cyclic oxidation rates usually corresponded to lowest biomass yields in both organisms, demonstrating poor coupling between energy generation and energy utilization. Two ramifications for process bioenergetics were explored. First, the cyclic oxidation path may only function in the immediate disposal of CH$\sb 2{\rm O}$, which can rapidly build to toxic levels under certain kinetically-imposed circumstances. Second, compiled data show that variations in biomass yield are due to variable carbon assimilation/oxidation kinetics rather than changes in macromolecular composition. The problem of CH$\sb 2$O toxicity becomes further compounded if this inhibitory and regulatory substrate is actively transported. Accumulation ratios ( ($\sp{14}{\rm CH}\sb 2$O) $\sb{\rm i}$/ ($\sp{14}$CH$\sb 2$O) $\sb{\rm o}$) were measured in aerobic batch cultures (30-fold) and in anaerobic, CH$\sb 3$OH-energized, whole cell suspensions (10-fold) of strain T15. Transport is energy-dependent and associated with the protonmotive force ($\Delta$pmF), as demonstrated by its inhibition with classical ionophores that collapse either or both of its components ($\Delta$pH and $\Delta\Psi$), and correlation with external pH.

Highly crystalline silicoaluminophosphate-5 (SAPO-5) was prepared according to a Union Carbide patent. This solid material was characterized by a number of physical techniques and used as a catalyst for several alkylaromatic interconversion reactions. Information about the reaction mechanisms and the active sites was provided by kinetic studies involving tracer molecules labeled with $\sp{13}$C and D isotopes. The bulk composition of SAPO-5 was shown by neutron activation and atomic adsorption to be (Si$\sb{0.10}$Al$\sb{0.56}$P$\sb{0.34})$O$\sb2.$ A fresh calcined sample had a BET surface area of 235 ${\rm m}\sp2\over{\rm g}$. X-ray analysis indicated that the structure of the catalyst was not affected by coking/regeneration cycles. The catalyst contained 1.3 $\sp{\*}\ 10\sp{14}$ ${\rm H\ atoms}\over{\rm cm\sp2}$ that could be readily exchanged. Xylene isomerization was the primary reaction used to test the activity of SAPO-5 in a CSTR. While the three xylene isomers were the principle products observed in the temperature range 300-400$\sp\circ$C, some disproportionation products were also observed. Xylene isomerization followed first order kinetics with observed activation energies for xylene interconversion in the range of 21-24 ${\rm kcal}\over{\rm mole}$. The disproportionation reactions follow reversible second order kinetics with an observed activation energy of 8.5 ${\rm kcal}\over{\rm mole}$. The xylene isomerization reactions are primarily intramolecular. More than 90% of the m-xylene formed initially from mixtures of o-xylene and o-xylene labeled with $\sp{13}$C in the methyl groups was either completely unlabeled or labeled. However, at higher conversion where disproportionation becomes significant, intermolecular scrambling increases. While aryl hydrogens are extremely labile under these conditions, the hydrogens in the methyl groups are relatively inert. Even at short contact times, the ring hydrogens of mixtures of perdeuterated and unlabeled o-xylene exchanged to statistical equilibrium, whereas the methyl groups remained either fully labeled or unlabeled. It was shown, however, that during isomerization one H (or D) atom was exchanged on the average in the migrating methyl group. The activities of other acidic oxide catalyst (amorphous silica-alumina, ZSM-5, and AlPO-5) were compared with SAPO-5. It was concluded that all exhibit similar types of catalytic behavior with the rates varying over several orders of magnitude and ZSM-5 being the most active. (Abstract shortened with permission of author.)

The creep of polymer concrete (PC) systems based on unsaturated polyester/styrene and versamid-cured epoxy resins was investigated using PC systems with different resin and aggregate contents, as well as the unfilled resins respectively. In both polyester and epoxy PC systems data was obtained at different temperatures, stresses, and resin contents. Data reduction made it possible to describe the creep compliance (J) of PC systems as a product of separable functions of time (t), temperature (T), stress ($\sigma$) and resin volume fraction (v): J(t,T,$\sigma$,v) = J$\sb{\rm r}$ (exp (-$\Delta$H$\sb{\rm T}$/RT) exp (K$\sb{\sigma}\sigma$) exp (K$\sb{\rm v}$v) t)$\sp{\rm m}$. The activation energy of the creep compliance is independent of temperature (Arrhenius behavior), decreases with increasing stress, and increases with resin content, indicating that creep behavior of the aggregate-filled PC systems is governed by the polymer matrix. Use of this master curve enables prediction of the long-term creep compliance of different PC systems through a range of temperatures, stresses and resin contents from limited data on a single system over short time periods (ca. 10 hours). Introduction of chopped glass fiber in the polyester PC systems (in addition to aggregate and filler) enhanced their short-term flexural strength as well as their creep resistance. It also extended the stable creep domain to stress-to-strength ratios of 0.8. The creep data obtained with fiber-reinforced PC systems at different levels of the governing variables (temperature, stress, resin content) were also reduced to a master curve using the triple-superposition scheme. Treatment of the glass fibers with silane coupling agent and dispersion of the mineral montomorrilonite (MMT) into the resin produced further enhancement in both the short-term flexural strength as well as the long-term creep resistance of fiber-reinforced PC systems. Morphological studies of the fracture surface of the PC systems indicated either adhesive failure (disbonding of the aggregate or the fiber from the resin matrix) or cohesive failure (aggregate or fiber rupture). The mode of failure depends on the size of aggregate, type of binding polymer, treatment of glass fiber and use of special additives. (Abstract shortened with permission of author.)