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In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In Alumni Files

Type of Resource

DigitalDocument

Rights Statement

In President's Report

Type of Resource

DigitalDocument

In President's Report

Abstract

2006-2016: A decade in review

Type of Resource

DigitalDocument

In President's Report

Type of Resource

DigitalDocument

In President's Report

Type of Resource

DigitalDocument

In President's Report

Type of Resource

DigitalDocument

In President's Report

Type of Resource

DigitalDocument

In President's Report

Type of Resource

DigitalDocument

In President's Report

Type of Resource

DigitalDocument

In Steinmetz Symposium

Abstract

Aerogels are nanoporous materials that are comprised of 95 - 99% air. They have unique properties, such as being insulating materials, as well as having a high specific area and porosity. Silica aerogels can be used to make windows due to their translucent nature. In the aerogel lab at Union College, various projects have been conducted to characterize these properties and learn more about aerogels. One of these projects includes producing colored aerogels through the use of different colored dyes, which has been successful. These can then be used in producing windows with a stained glass effect. My work builds on those experiments by investigating the ability to produce aerogels that experience photochromic effects, which means the color of the aerogel would change based on exposure to different light intensities. This could be useful in a real-world application as no shades would be needed since the window would act as its own shade, darkening when the sunlight is over a certain intensity. Initial experiments focused on the use of photochromic dyes. Due to the high temperature and pressure required for processing that the aerogel must undergo, that approach has not been successful: the resulting materials were not translucent aerogels. Another approach under investigation is to use salts in an ion-exchange method to produce a photochromic effect. Using silver nitrate (AgNO3) in the precursor solution for the aerogel resulted in gels that showed no photochromic properties. The current approach is to synthesize silver chloride (AgCl) nanoparticles to use in the aerogel solution and characterize the results. This presentation will focus on the approaches and results taken to obtain photochromic aerogels.

Type of Resource

VideoObject

Rights Statement

In Steinmetz Symposium

Abstract

Over one billion automobiles are in use around the world, the majority of which employ internal combustion engines. Catalytic converters are used to convert the toxic compounds found in car exhaust -- carbon monoxide, nitrogen oxides (NOx) and hydrocarbons -- to less harmful gases. The typical catalytic converter employs, as three-way catalysts, expensive raw materials such as platinum, palladium and/or rhodium. Aerogel materials have high surface area and thermal stability, properties that make them attractive for catalysis applications. Aerogels made with transition metal oxides (TMOs) are candidates to replace platinum in the catalytic converter. Chromium oxide (chromia) materials have demonstrated catalytic activity in other applications due to favorable redox chemistry, stability and selectivity. In this work, sol-gel synthesis techniques, using a 1:5 mole ratio of chromium(III) to aluminum, are adapted to a patented rapid supercritical extraction (RSCE) method to fabricate chromia-alumina catalytic aerogels. Physical characterization via several methods, including XRD and SEM, is performed on the chromia-alumina aerogels as prepared and following heat treatment. Catalytic performance of these promising materials is evaluated using an in-house-constructed testbed in which the aerogel materials are exposed to simulated automotive exhaust under temperature conditions that approximate those experienced in a catalytic converter. Initial tests demonstrate that chromia-alumina aerogels act as three-way catalysts.

Type of Resource

VideoObject

Rights Statement

In Steinmetz Symposium

Abstract

Aerogels have high porosity and specific surface area, as well as the ability to maintain textural stability at high temperatures, making them good heterogeneous catalysts. Catalytic performance can be enhanced by adding metal salts in the synthesis process. One application of great interest of catalytic aerogels is found in their potential to replace the environmentally unfriendly three-way-catalysts (TWCs) employed in automobile catalytic converters. Characterization can provide information about aerogels' microstructure (availability of catalyst sites), which can reveal ways to optimize catalytic efficiency. Alumina aerogels were synthesized by two different methods and with varying amounts of copper using the patented Union College rapid supercritical extraction (RCSE) method. These aerogels were then characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Copper(0) microrods and microparticles were identified, as well as microcrystals containing copper and chlorine (the latter from the alumina aerogel precursor). The catalytic activity of aerogels prepared with different copper loading was assessed using the Union Catalytic Aerogel Testbed (UCAT).

Type of Resource

VideoObject

Rights Statement

In Steinmetz Symposium

Abstract

Aerogels possess physical properties that make them appealing for applications in catalysis. They have a low density as well as high surface area and porosity. Alumina-based aerogels also have high thermal stability. Most catalytic converters currently in use in automobiles employ precious metals such as platinum, palladium, and rhodium as 'three-way' catalysts to oxidize carbon monoxide (CO) and unburned hydrocarbons (HCs) and reduce nitrogen oxides (NOx). These precious metals are expensive due to their low abundance in the earth's crust. Aerogels containing more abundant catalytic metals such as copper or nickel could be a less expensive alternative to the modern solution. In prior work, copper-, nickel-, and cobalt-containing silica and alumina aerogels have demonstrated three-way catalytic ability. These mixed-metal catalytic materials are readily fabricated from metal salts using an epoxide-assisted sol-gel synthetic approach with subsequent processing via a patented rapid supercritical extraction (RSCE) method to yield aerogels. Although the aerogels are predominantly amorphous, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and powder X-ray diffraction (XRD) analyses of the catalytic aerogels demonstrate convincingly that the materials have transition-metal-containing microcrystalline components. In order to develop a fundamental understanding of catalytic aerogel materials, it is necessary to identify the forms that are present at the elevated temperatures employed in catalytic converters. In this presentation, a comparison of powder XRD patterns of mixed-metal RSCE aerogels is made. Differences observed in the XRD patterns and SEM images for these materials as-prepared, following calcination (up to 800 ËšC), and at temperature (up to 800 ËšC) provide convincing evidence of the chemical and structural changes that have occurred. Through the use of powder x-ray diffraction (XRD) with thermal control, the microcrystalline components that are present at elevated temperatures can be identified.

Type of Resource

VideoObject

Rights Statement

In Steinmetz Symposium

Abstract

Silica aerogels are unique nanoporous materials that can be used in a variety of applications. Silica aerogels are attractive for window applications as they are monolithic, thermally insulating, and extremely lightweight. They also can be made transparent or translucent. Aerogels can be made using a variety of methods; in this work, a rapid supercritical extraction method (RSCE) is employed. Although typically translucent, silica aerogels can have dyes incorporated within them to create aerogels of a variety of colors. We are investigating the usage of dyed monolithic silica aerogels in window applications to improve aesthetic effects. However, the high temperatures and pressures required for the RSCE process can lead to dye degradation. In this presentation, we demonstrate how to incorporate Rhodamine 6B, Rhodamine B, and Fluorescein into monolithic silica aerogels. Rhodamine B experiences thermal degradation during monolithic aerogel synthesis. Adjusting processing parameters, including temperature and pressure, can minimize thermal degradation while ensuring the structural integrity of the aerogel. Ultraviolet radiation can also lead to dye degradation, which would be problematic for aerogels in a window application. Future work will focus on spectroscopic characterization of the dyed aerogel monoliths.

Type of Resource

DigitalDocument

Rights Statement