This project will investigate and develop a new one-step processing approach, to synthesize and attain high loading of nanoparticle catalyst assemblies at internal surfaces of macroscopic samples of mesoporous supports, with control over nanoparticle and pore shapes, and nanocatalyst-support distance. This will be accomplished by exploiting a unique combination of surfactant aggregate self-assembly, templating, spatial immobilization, and catalyst/support precursor chemistry.
Highway
Many key reactions relevant to automobiles, diesel powered ships and other modes of transportation, such as the conversion of hydrocarbons to CO2, or Nox to N2 rely on expensive noble metals, or their alloys, as catalysts (e.g., Pt, Pd, Rh). The limited reserves of these metals, increasing regulations for reduction of pollution, and fuel cell applications are producing pressure on these industries to discover improved and more efficient catalysts. Precisely engineered nanostructured materials, with high surface area and large number of controllable sites that serve as active catalytic regions offer new opportunities for significantly enhancing catalytic activity and selectivity and decreasing the usage of expensive noble metals, increasing efficiency and decreasing pollution simultaneously. The increased catalytic activity of nanoparticles is typically attributed to high surface to volume ratios, as well as to the nanoscale dimension of particles, and is sensitive to particle size, shape and preparation methods. It is vital to be able to distribute the nanosized catalyst throughout a microporous support in order to be able to access all of the catalyst particles and their surfaces. This remains a significant challenge.
This project will investigate and develop a new one-step processing approach, to synthesize and attain high loading of nanoparticle catalyst assemblies at internal surfaces of mesoporous supports, with control over nanoparticle and pore shapes, and nanocatalyst-support distance. This will be accomplished by exploiting a unique combination of surfactant aggregate self-assembly, templating, spatial immobilization, and catalyst/support precursor chemistry. The method proposed will pave the way for scalable production of noble-metal nanocatalysts with tailored spacing and interaction with mesoporous oxide or carbon supports in bulk or thin film form, all in a single processing step. This will reduce the cost of production while enabling unprecedented molecular control of catalytic and mechanical properties in bulk samples
The success of our research will lead to a new class of cost-effective processing methodologies for producing bulk quantities of high-efficiency nanocatalyst-support composites with unprecedented molecular-level control over catalytic properties. In the short one-year time frame, we expect to be able to demonstrate the production of one catalyst and two support materials with high surface area and a well dispersed distribution of catalytic particles within the porous support. Increased reaction rates and selectivity as well as the suppression of deleterious side-reactions will be demonstrated with this optimized catalyst. This general strategy is applicable, and will eventually be leveraged for creating polymer/nanoparticle composite materials with unique functionalities.
The research will be conducted at the University of Rhode Island with significant interaction and input from scientists at Honda. We will combine the unique talents of materials engineers, colloid scientists and catalyst/reaction chemists to address the challenges of this proposal in the areas of materials synthesis/scale-up, template organization and tailoring, and catalysis/reaction engineering. The specific tasks and expected time lines for the cross-functional team are outlined below.
We will develop (and if necessary, synthesize) surfactants, image surfactant aggregate structures using our expertise in Freeze Fracture Direct Imaging (FFDI), cryogenic transmission electron microscopy (cryo-TEM) and Small Angle Neutron Scattering (SANS) and light scattering measurements. The SANS experiments will be carried out at the National Center for Neutron Research in Gaithersburg, MD, where a beam line is available for academic use. The AB group has used this beam line extensively. The morphological evolution of catalyst and support will be examined in real time, and the relationship to surfactant architecture and composition will be determined. Ms. Sarkar, a graduate student in the PIs group will be responsible for this part of the project. Ms. Sarkar has extensive experience in cryoimaging already, and has initiated work in the area of nanoparticle support composite materials. Ms. Jacinta Dos Santos, an undergraduate working in the PI’s group has experience with light scattering and sample preparation. She will work on complementary aspects of this project.
The molecular templates will be extracted by calcinations or solvent treatments, and provide detailed characterization of the shape, size, morphology, anchoring chemistry, and coverage of nanoparticles on the porous supports using a variety of electron and light spectroscopies, SEM, conventional and high-resolution TEM, BET, temperature-desorption mass spectroscopy and porosimetry. Scale-up strategies will also be developed. We will select a few reactions as prototypes, and conduct detailed testing and characterization of catalysts. Reaction testing will be conducted in a micro-reactor system with on-line analytical instrumentation. Catalyst performance will be compared against benchmark catalysts that will be provided by a leading catalyst manufacturer. Reference experiments will be carried out on planar surfaces to understand the key kinetic and chemical parameters governing the synthesis and assembly processes. Mr. Ashish Jha will be responsible for this part of the work.
The PI has regular group meetings once/week with all the students, where they discuss progress and roadblocks. Potential solutions to the roadblocks are identified in these joint brainstorming sessions.
The research proposed here is cross-disciplinary, between chemical engineering, chemistry and materials. The graduate and undergraduate students working on this project will therefore get exposure to several fields, as well as experience in using advanced analytical tools.
The PI will be offering a Graduate/Senior Undergraduate course in nanoscience and nanotechnology in Spring 2006. In this course, students will be exposed to various new facets of this exciting new field. The work proposed here will be directly integrated into a few lectures and demonstrations in this class, since it is a relevant example of how nanoscale materials are prepared and characterized.
0-3 months
+ Examine morphology of zirconium propoxide and titanium butoxide gels (roles of concentration, temperature and aqueous phase content)
+ Examine morphology of gel containing Pt precursor
3-9 months
+ Establish and optimize conditions for morphology, pore and particle size control of Pt/zirconia and Pt/titania composites
6-12 months
+ Examine catalytic activity and thermal stability of composites and provide feedback to synthesis process
$144,120.50
Ms. Jacinta Dos Santos is a senior in Chemical Engineering who works in my group. She will be conducting research on this project during Spring 2006 as well as the summer.
Ms. Jayashri Sarkar is a graduate student in my group. She will be working on this project through the calendar year.
Mr. Ashish Jha, a graduate student in my group will work on this project through the calendar year (supported by the Honda grant)
The work proposed here follows up on work done under a previous URITC grant ‘Nanostructured materials for Advanced Transportation Applications’. Under that grant we initiated work in the nanoparticle/support composite materials area. A brief summary is outlined below.
There are two key areas where catalysts play a very significant role in the transportation industry – catalytic converters in cars and development of fuel cells. The three major car exhaust pollutants are carbon monoxide, hydrocarbons or volatile organic compounds (VOCs) - produced mostly from unburned fuel that evaporates, and nitrogen oxides (NO and NO2, together called NOx) - contributing to smog and acid rain, and also causes irritation to human mucus membranes. The goal for the catalytic converter is to pass the exhaust gases over the catalyst that is dispersed within a porous ceramic support. Platinum, rhodium and palladium as well as binary alloys are the primary catalyst materials used. The limited reserves of these metals (Pt, Pd, Rh), increasing regulations for reduction of pollution, and fuel cell applications are producing pressure on the automobile industry to discover improved and more efficient catalysts. Precisely engineered nanostructured materials, with high surface area and large number of controllable sites that serve as active catalytic regions offer new opportunities for significantly enhancing catalytic activity and selectivity and decreasing the usage of expensive noble metals. This project focuses on efficiently and cost-effectively producing porous support/catalyst structures using a single-step synthesis technique.
As an offshoot of this project, in collaboration with Prof. Shukla, we have also processed carbon nanotube/polyester composite materials and are currently looking at increasing the efficiency of the dispersions as well as analyzing the dynamic mechanical properties of these materials.
The work done under this project also provided some of the preliminary results in the silica/gold composite formation for the successful proposal to Honda.
All technology that can be potentially commercialized will be protected by filing for patents, and followed up with licensing to interested commercial parties.
The area of nanoscience and nanotechnology has exploded over the past few years. The Rhode Island Department of Transportation is a state agency that will directly benefit from this research. If the project proves successful, and the technology is commercialized, the benefits will be more far reaching. Clearly, Honda is interested in this work, and we will discuss technology licensing with them as the project results emerge.
Nanostructured materials