ACT/SGER: Atomic Layer Deposition of Nitrides on Nano-Particles for Enhanced Energy Conversion to Combat Terrorism

William J. DeSisto, University of Maine, will apply atomic layer deposition reactions to passivate nanoparticles. These coated nanoparticles will be used in next-generation, high energy density, compact energy storage devices. Initial experiments will focus on coating nano-sized lithium-ion battery anodes with titanium nitride. Miniaturized batteries using these anodes will be fabricated and evaluated by industrial collaborators at Yardley/Lithion Technical Products.This award is supported jointly by the NSF Directorate for Mathematical and Physical Sciences and the Intelligence Community. The Approaches to Combat Terrorism Program supports new concepts in basic research and workforce development with the potential to contribute to national security. The coated nanoparticle technology may lead to smaller and more stable batteries that will be used in many specialty applications. Students will be engaged in the research in both academic and industrial settings

CAREER: A New Class of Modified Mesoporous Silica Membranes with Controlled Pore Size and Surface Functionalization Through Unique Synthetic Approaches

Artificial membranes made from sand-like materials known as silica are potentially more energy efficient than other separation processes such as distillation (change in phase from liquid to gas) because there is no phase change required to perform the separation. In addition, the opportunity exists for combining reaction and separation within a single unit using membrane reactors, thereby increasing yield on thermodynamically-limited reactions. However, the fabrication of high-quality silica membranes with pore size control and surface chemistry control remains challenging because of the inherent limits of existing synthetic approaches used to fabricate silica membranes. The researchers at the University of Maine have achieved promising preliminary results on pore size control and surface chemistry control using new synthetic approaches toward fabricating silica membranes. These techniques are based on highly controlled catalyzed surface chemistry reactions that are used to modify mesoporous silica membranes. The reactions are atomically controlled at the surface to provide a self-limited pore size reduction and the functionalization of the mesoporous matrix. In this CAREER plan, the university of Maine will use the new synthesis technique, known as catalyzed-atomic layer deposition, to prepare silica membranes with controlled pore sizes in the pore size range of 10-20 angstroms and create new hybrid organic/inorganic membranes. This will be achieved using both vapor phase deposition and supercritical fluid CO2 deposition techniques. This will provide a new class of silica materials that may find application in the separations of higher molecular weight compounds as well as a new class of hybrid organic/inorganic silica-based membranes for gas/vapor separations. The research will focus upon understanding chemical, microstructural, permeation, and separation properties of the new materials while quantitatively linking the synthesis procedure to material performance. The proposed synthesis techniques offer a level of atomic control during the materials preparation that is not known today. The applications for these membranes are diverse and include separations of heavy distillates in petroleum processing, separations of organic compounds from lighter gases, separators for lithium-ion batteries, and bio-separations. These new synthetic techniques are expected to spur application towards different classes of materials, including adsorbents or even different inorganic membranes. The proposed education activities will affect all chemical engineering undergraduates at the University of Maine and a significant number of high school students, including those in some of Maines poorest and most geographically remote communities

Sessile drops on nonhorizontal solid substrates

Experimental values of the maximum drop volume that can be sustained on an inclined solid surface are compared to the theoretical predictions by E. B. Dussan V. (J. Fluid Mech. 151, 1 (1985)). The agreement for both water and glycerol on Teflon substrates is within the measurement error. Thus, critical drop volumes can be predicted upon knowledge of the advancing and receding contact angles, the density and surface tension of the liquid, the gravitational acceleration, and the angle of inclination of the solid-all of which are system material properties or experimental conditions. Although the surface tension of glycerol is far less than that of water, it is held more firmly on the Teflon surface, showing that contact angle hysteresis has a key impact on when a drop will slide on the solid. The validity of the theoretical prediction can be exploited to accurately determine contact angle hysteresis for systems where the difference between the advancing and receding contact angles is small. © 1987

Fast Pyrolysis of Lignin Pretreated with Magnesium Formate and Magnesium Hydroxide

Kraft lignin (Indulin AT) pretreated with magnesium formate and magnesium hydroxide was fast-pyrolyzed in a continuously fed, bench-scale system. To avoid fouling issues typically associated with lignin pyrolysis, a simple laboratory test was used to determine suitable ranges of magnesium hydroxide and formic acid to lignin for feeding without plugging problems. Various feedstock formulations of lignin pretreated with magnesium hydroxide and formic acid were pyrolyzed. For comparison, calcium formate pretreated lignin was also tested. The organic oil yield ranged from 9% to 17% wt % on a lignin basis. Carbon yields in the oil ranged from 10% to 18% wt % on a lignin basis. Magnesium formate pretreatment increased oil yield and carbon yield in the oil up to 35% relative to the higher 1:1 g magnesium hydroxide/g lignin pretreatment. However, a lower magnesium hydroxide pretreatment (0.5:1 g magnesium hydroxide/g lignin) resulted in oil yields and carbon yields in the oils similar to the magnesium formate pretreatments. Magnesium formate pretreatment produced more oil but with a higher oxygen content than calcium formate under the same conditions. The GC-MS analysis of product oils indicated that phenols and aromatics were more prevalent in pyrolyzed magnesium-formate-pretreated lignin

Heuristics To Guide the Development of Sustainable, Biomass-Derived, Platform Chemical Derivatives

Hundreds of catalytic routes to upgrade biomass-derived platform chemicals have been proposed. In this study, we developed process selection and development heuristics for these catalytic transformations from techno-economic analysis of catalytically upgrading furfural (a potential platform chemical) to eight derivatives that vary in chemical functionality and process complexity. These heuristics included simple cost equations based on catalyst performance as well as process complexity to predict the minimum selling price of platform chemical derivatives. Additionally, design rules were developed to guide the development of catalytic technologies for upgrading platform chemicals. The conversion of platform chemicals to hydrocarbons must be avoided. For commercial relevance, attaining catalyst yield of 60% and weight hourly space velocity of at least on the order of 0.1 h^–1 are necessary. Precious metal catalysts, such as Pt, cannot be used if the desired platform chemical derivative is priced below 1.00 (US$/kg). Finally, it has been learned that the feasible plant size of platform chemical production is comparable to that of a lignocellulosic-based biofuel production

Chemical Shifts and Lifetimes for Nuclear Magnetic Resonance (NMR) Analysis of Biofuels

Determination of the molecular composition of biofuels is critical to process development. Because biofuels, such as pyrolysis oil, contain hundreds of compounds, quantitative determination of the mixtures is a formidable task and is often not necessary for routine development work. ¹³C and ¹H nuclear magnetic resonance (NMR) offer a reasonable trade-off between functional group identification and analytical measurement effort. However, accuracy depends upon selection of chemical-shift regions, baseline compensation, and correction for incomplete longitudinal relaxation effects. We propose chemical-shift assignments and <i>T</i>₁ correction factors based on ¹³C and ¹H NMR measurements of over 50 compounds that have been previously identified in pyrolysis oils and several plant natural products, especially terpenes. The results are intended to allow for a semiquantitative assessment of molecular composition of bio-oils on a time scale of 1−8 h to provide feedback for process development