Tom Gilbert Presentation Abstracts
- "Characterization of Catalyst Support Materials Synthesized by Successive Ionic Layer Deposition" Thomas I. Gilbert and Johannes Schwank. AIChE 2007 Annual Meeting. Salt Lake City, UT (November 2007).
Many catalytic systems show interesting metal-support interactions. However, the complexity of typical supported catalyst systems makes it difficult to isolate these effects. Successive Ionic Layer Deposition (SILD) enables the synthesis of model systems where well-defined monolayers and multilayers of active species can be deposited on high surface area supports. In this case, one of the key issues is conformal deposition, a synthesis feature difficult to achieve in conventional thin film model catalysts.
Successive Ionic Layer Deposition (SILD) is an aqueous technique to synthesize thin films on a substrate in a layer-by-layer fashion. In principle, monolayers of aqueous cations and anions are sequentially adsorbed on the substrate thereby forming SILD nanolayers. The parameter space of tunable variables available for SILD allows for significant control over the chemistry and morphology at the nanometer scale. This flexibility enables production of multicomponent thin films at mild conditions with simple hardware on planar and nonplanar surfaces.
In this paper the SILD of catalyst support materials such as ceria and zirconia was performed on substrates such as silicon wafers. The support materials were characterized using techniques such as Atomic Force Microscopy, Scanning Electron Microscopy, and X-ray Photoelectron Spectroscopy.
- "Successive Ionic Layer Deposition of Oxide Nanolayers" Thomas I Gilbert, Valeri P. Tolstoy, Johannes Schwank. 233rd American Chemical Society National Meeting. Chicago, IL (March 2007).
Successive ionic layer deposition (SILD) is an aqueous technique for synthesizing thin solid films on a support in a layer-by-layer fashion. In principle, monolayers of aqueous cations and anions are repeatedly adsorbed on the support to grow the SILD nanolayers. SILD offers the flexibility to systematically choose the composition of the deposited materials and thereby produce multicomponent or functionally graded nanolayers under mild conditions with simple hardware on planar and nonplanar surfaces. This flexibility makes SILD promising in applications such as biochemical or gas sensors, electrocatalysts, optoelectronic devices, and biocompatible or passivating coatings.
In this paper the SILD of oxide materials such as zirconium oxide was performed on supports such as silicon wafers and powders. The SILD nanolayers were characterized using techniques such as Atomic Force Microscopy, Scanning Electron Microscopy, and X-ray Photoelectron Spectroscopy. Properties of the nanolayers such as growth rate and microstructure were determined to be affected by the experimental SILD conditions such as solution pH, concentration, and residence time.
- "Ammonia Fiber Explosion (AFEX) for Pretreatment of Switchgrass" Hasan Alizadeh, Farzaneh Teymouri, Thomas I. Gilbert and Bruce E. Dale. 26th Symposium on Biotechnology for Fuels and Chemicals. Chattanooga, TN (May 2004).
Ammonia Fiber Explosion (AFEX) process has been used to treat switchgrass, a native prairie grass having potential for ethanol production. The AFEX process treats lignocellulosic biomass with high-pressure liquid ammonia and then explosively releases the pressure. The combined chemical effects (cellulose decrystallization and hemicelluloses prehydrolysis) and physical effect (increased accessible surface area) enhance the susceptibility of lignocellulosic biomass to enzymatic hydrolysis. Optimizing the process conditions and parameters greatly improves the efficiency of the pretreatment. Three different operational variables including: ammonia loading, moisture content of biomass and temperature were experimented with over different ranges to evaluate their effects on the AFEX treatment of switchgrass. The treated switchgrass samples were evaluated by enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) for the fermentable sugar content and eventual ethanol yield. All AFEX process variables studied affected the effectiveness of the treatment on switchgrass.
The optimal treatment conditions for switchgrass were found to be near 100°C-110°C; 1.25:1 kg of ammonia: kg of dry swtchgrass and 100% moisture content (dry weight basis [dwb]); at a residence time (holding at target temperature) of 5 minutes. The ethanol yield of the AFEX-treated sample was twice that of an untreated sample.