Matching Items (23)

133581-Thumbnail Image.png

Synthesis and Characterization of Dual-Phase Membranes

Description

The combustion of fossil fuels accounts for over a third of total CO2 emissions in the United States. Carbon capture and storage technology is gaining influence as a method of

The combustion of fossil fuels accounts for over a third of total CO2 emissions in the United States. Carbon capture and storage technology is gaining influence as a method of reducing the release of greenhouse gas into the atmosphere. Mixed ionic-electronic conducting (MIEC) dual-phase membranes are in development for selective CO2 separation at high temperatures. The application of these membranes is limited by chemical instability in a CO2-rich atmosphere. Pr0.6Sr0.4Co0.2Fe0.8O3-δ (PSCF) was selected as a potential material for development into a dual-phase CO2 selective disk membrane because of its high oxygen permeation properties and preliminary CO2 stability measurements. Porous supports demonstrated highly repeatable synthesis with an average porosity of 36.9%, He permeance on the order of 10-6 mol·s-1·m-2·Pa-1, and pore diameter of 330 nm. Infiltration with a eutectic mixture of Li2CO3/Na2CO3/K2CO3 resulted in a 16.1% weight gain and reduction in He permeance to 10-9 mol·s-1·m-2·Pa-1. CO2 permeance measurements of the dual-phase membrane were inconclusive due to mechanical failure during heating. XRD, SEM imaging, and EDXS compositional analysis revealed significant strontium carbonate formation on the membranes surface after testing. More thorough CO2 permeance testing of dual-phase PSCF is recommended as the focus of future study.

Contributors

Agent

Created

Date Created
  • 2018-05

136987-Thumbnail Image.png

Model Membrane System to Determine Water Permeability of Linde Type A Zeolite

Description

In this research, construction of a model membrane system using Polyvinylidene Chloride-Co Acrylonitrile and Linde Type A zeolites is described. The systems aims to separate out flow through zeolite pores

In this research, construction of a model membrane system using Polyvinylidene Chloride-Co Acrylonitrile and Linde Type A zeolites is described. The systems aims to separate out flow through zeolite pores and flow through interfaces between zeolites and polymers through the use of pore filled and pore open zeolites. Permeation tests and salt rejection tests were performed, and the data analyzed to yield approximation of separated flow through zeolites and interfaces. This work concludes the more work is required to bring the model system into a functioning state. New polymer selections and new techniques to produce the membrane system are described for future work.

Contributors

Agent

Created

Date Created
  • 2014-05

137633-Thumbnail Image.png

Characterizing the Effects of Various Acids on Zeolites

Description

This project is part of a larger project involving making membranes for the separation of potable water from urine solutions for applications in space travel. This project deals specifically with

This project is part of a larger project involving making membranes for the separation of potable water from urine solutions for applications in space travel. This project deals specifically with testing LTA nanozeolites that will be used in the membrane under a variety of acidic conditions, specifically in solutions of sulfuric acid, chromium trioxide, and potassium phosphate of pHs ranging from .5 to 5, in order to investigate the effects of pH, acid type, and time. They were analyzed using SEM, FTIR, and XRD, in order to analyze how much the zeolite was degraded under the conditions of each solution. It was determined that, for high pH values (4-5), potassium phosphate had the strongest effect, as it degraded the zeolite to the point of destroying the crystal structure completely. Because of the solubility limit of potassium phosphate in water, it could not be analyzed at low pH, so only sulfuric acid and chromium trioxide were analyzed at low pH (.5-3). They both had severe effects, sulfuric acid being slightly more severe, with both of them completely dissolving the zeolite at pH values of 1 and lower. Decreasing pH increased degradation for all of the acids, with pH values above 2 for sulfuric acid and chromium trioxide showing only minor degradation, and pH 5 potassium phosphate showing only minor degradation.

Contributors

Agent

Created

Date Created
  • 2013-05

135609-Thumbnail Image.png

Fourier Transform Infrared Spectroscopy Study of Hexane Diffusion through Zeolitic Imidazolate Framework-68

Description

Zeolitic Imidazolate Frameworks (ZIFs) are a promising technology for the separation of gases. ZIFs represent a type of hybrid material that is a subset of metal organic frameworks while displaying

Zeolitic Imidazolate Frameworks (ZIFs) are a promising technology for the separation of gases. ZIFs represent a type of hybrid material that is a subset of metal organic frameworks while displaying zeolite properties. ZIFs have tunable pore metrics, high thermal stability, and large surface areas giving them advantages over traditional zeolites. The experiment sought to determine the flux of hexane vapor through ZIF-68 with Fourier Transform Infrared Spectroscopy (FTIR) mapping. FTIR mapping was used to obtain three spectra per crystal and the concentration gradient was analyzed to determine the flux. ZIF-68 was completely stable when loaded with hexane and exposed to the atmosphere. There was no hexane diffusion out of the crystal. As a result, ZIF-68 was heated to 50°C to increase diffusion and calculate the flux. ZIF-68 adhered to Knudsen Diffusion, and the flux was calculated to be 2.00*10-5 kg mol/s*m2. The small flux occurred because almost no concentration gradient was obtained through the crystal. It was hypothesized that the resistance in the crystal was substantially lower than the resistance at the boundary layer, which would have caused a small concentration gradient. Using film mass transfer theory, the resistance inside the crystal was found to be 1200 times lower than the resistance at the boundary layer confirming the hypothesis.

Contributors

Agent

Created

Date Created
  • 2016-05

136557-Thumbnail Image.png

Effect of Cellulose Templating on Nanostructured Lithium Lanthanum Zirconium Oxide (LLZO)

Description

Lithium-ion batteries are the predominant source of electrical energy storage for most portable electronics applications, including hybrid/electric vehicles, laptops, and cellular phones. However, these batteries pose safety concerns due to

Lithium-ion batteries are the predominant source of electrical energy storage for most portable electronics applications, including hybrid/electric vehicles, laptops, and cellular phones. However, these batteries pose safety concerns due to their flammability and tendency to violently ignite upon short circuiting or failing. Solid electrolytes are a current research development aimed at reducing the flammability and reactivity of lithium batteries. The compound Li7La3Zr2O12, or LLZO, exhibits satisfactory ionic conductivity in the cubic phase, which is normally synthesized via doping with Al. It has recently been discovered that synthesizing nanostructured LLZO can stabilize the cubic phase without the need for doping. Here nanostructured LLZO was formed using templating on various cellulosic fibers, including cotton fibers, printer paper, filter paper, and nanocellulose fibrils followed by calcination at 700-800 °C. The effect of templating material, calcination temperature, calcination time, and heating ramp rate on LLZO phase and morphology was thoroughly investigated. Templating was determined to be an effective method for controlling the LLZO size and morphology, and most templating experiments resulted in LLZO fibers or ligaments similar in size and morphology to the original template material. A systematic study on the various experimental parameters was performed, concluding that low calcination time and low ramp rate favored smaller ligament formation. Further, it was verified that cubic phase stabilization occurred for LLZO with ligaments of less than 1 micron on average without the use of doping. This research provides more information regarding the size dependence on cubic LLZO stabilization that has not been previously investigated in detail.

Contributors

Agent

Created

Date Created
  • 2015-05

136965-Thumbnail Image.png

Carbon Dioxide Separation by Ceramic-Carbonate Dual-Phase Membranes and Process Design for Membrane Reactor in IGCC Power Plant

Description

Currently, approximately 40% of the world’s electricity is generated from coal and coal power plants are one of the major sources of greenhouse gases accounting for a third of all

Currently, approximately 40% of the world’s electricity is generated from coal and coal power plants are one of the major sources of greenhouse gases accounting for a third of all CO2 emissions. The Integrated Gasification Combined Cycle (IGCC) has been shown to provide an increase in plant efficiency compared to traditional coal-based power generation processes resulting in a reduction of greenhouse gas emissions. The goal of this project was to analyze the performance of a new SNDC ceramic-carbonate dual-phase membrane for CO2 separation. The chemical formula for the SNDC-carbonate membrane was Sm0.075Nd0.075Ce0.85O1.925. This project also focused on the use of this membrane for pre-combustion CO2 capture coupled with a water gas shift (WGS) reaction for a 1000 MW power plant. The addition of this membrane to the traditional IGCC process provides a purer H2 stream for combustion in the gas turbine and results in lower operating costs and increased efficiencies for the plant. At 900 °C the CO2 flux and permeance of the SNDC-carbonate membrane were 0.65 mL/cm2•min and 1.0×10-7 mol/m2•s•Pa, respectively. Detailed in this report are the following: background regarding CO2 separation membranes and IGCC power plants, SNDC tubular membrane preparation and characterization, IGCC with membrane reactor plant design, process heat and mass balance, and plant cost estimations.

Contributors

Agent

Created

Date Created
  • 2014-05

137225-Thumbnail Image.png

Characterization of Carbon Molecular Sieve Membranes in the Separation of Propylene and Propane Gases

Description

A Carbon Molecular Sieve (CMS) membrane, in order to test separation of propylene and propane gases, was subjected to increases in feed pressure, varied propylene feed composition, and temperature changes

A Carbon Molecular Sieve (CMS) membrane, in order to test separation of propylene and propane gases, was subjected to increases in feed pressure, varied propylene feed composition, and temperature changes to determine how these factors affect permeance and selectivity. This membrane was prepared on a support made of α-alumina and γ-alumina supports. Feed pressure was increased between 30 and 100psi, and propylene and propane permeance decreased, as did the selectivity. Propylene feed composition increases resulted in an order of magnitude increase in propane permeance, but a decrease in propylene permeance, and a decrease in selectivity. Increases in temperature resulted in increases of propylene and propane permeance, but a decrease in selectivity.

Contributors

Agent

Created

Date Created
  • 2014-05

132403-Thumbnail Image.png

Safe Fire-resistant Electrolytes for Lithium-ion Batteries

Description

Lithium-ion batteries that employ an electrolyte consisting of LiFSI and TMP are shown to have better cycle performance than conventional carbonate electrolyte batteries at elevated temperatures. Additionally, an inorganic alumina

Lithium-ion batteries that employ an electrolyte consisting of LiFSI and TMP are shown to have better cycle performance than conventional carbonate electrolyte batteries at elevated temperatures. Additionally, an inorganic alumina or silica separator also improves cycling performance at high temperatures. Half-cells of Li metal and Li2TiO3 were constructed with LiFSI/TMP electrolyte and inorganic separators and cycled at increasing temperatures. Their cycle performance was compared to batteries with the same anode and cathode material that were prepared with conventional components. Half-cells using either the novel electrolyte or inorganic separators were able to continue cycling at temperatures up to 80 ℃, long after the conventionally prepared batteries had failed. A cell with a combination of the LiFSI/TMP electrolyte and silica separator still showed 75% capacity retention after 10 cycles at 85 ℃ as well.

Contributors

Agent

Created

Date Created
  • 2019-05

153013-Thumbnail Image.png

Modeling and analysis on pervaporation separation of composite zeolite membranes

Description

Pervaporation is a membrane separation technology that has had industrial application and which is the subject of ongoing research. Two major factors are important in judging the quality of a

Pervaporation is a membrane separation technology that has had industrial application and which is the subject of ongoing research. Two major factors are important in judging the quality of a membrane: selectivity and permeation flux. Although many types of materials can be used for the separation layer, zeolites will be the material considered in this thesis. A simple mathematical model has been developed to demonstrate the inter-relationships between relative permeation flux, reduced selectivity, and the relative resistance to mass transfer of the support to the zeolite layer. The model was applied to several membranes from our laboratory and to two examples from the literature. The model offers a useful way of conceptualizing membrane performance and facilitates the comparison of different membrane performances. The model predicts the effect of different supports on zeolite supported membrane performance.

Contributors

Agent

Created

Date Created
  • 2014

151601-Thumbnail Image.png

Continuous in-situ removal of butanol from clostridium acetobutylicum fermentations via expanded-bed adsorption

Description

The use of petroleum for liquid-transportation fuels has strained the environment and caused the global crude oil reserves to diminish. Therefore, there exists a need to replace petroleum as the

The use of petroleum for liquid-transportation fuels has strained the environment and caused the global crude oil reserves to diminish. Therefore, there exists a need to replace petroleum as the primary fuel derivative. Butanol is a four-carbon alcohol that can be used to effectively replace gasoline without changing the current automotive infrastructure. Additionally, butanol offers the same environmentally friendly effects as ethanol, but possess a 23% higher energy density. Clostridium acetobutylicum is an anaerobic bacterium that can ferment renewable biomass-derived sugars into butanol. However, this fermentation becomes limited by relatively low butanol concentrations (1.3% w/v), making this process uneconomical. To economically produce butanol, the in-situ product removal (ISPR) strategy is employed to the butanol fermentation. ISPR entails the removal of butanol as it is produced, effectively avoiding the toxicity limit and allowing for increased overall butanol production. This thesis explores the application of ISPR through integration of expanded-bed adsorption (EBA) with the C. acetobutylicum butanol fermentations. The goal is to enhance volumetric productivity and to develop a semi-continuous biofuel production process. The hydrophobic polymer resin adsorbent Dowex Optipore L-493 was characterized in cell-free studies to determine the impact of adsorbent mass and circulation rate on butanol loading capacity and removal rate. Additionally, the EBA column was optimized to use a superficial velocity of 9.5 cm/min and a resin fraction of 50 g/L. When EBA was applied to a fed-batch butanol fermentation performed under optimal operating conditions, a total of 25.5 g butanol was produced in 120 h, corresponding to an average yield on glucose of 18.6%. At this level, integration of EBA for in situ butanol recovered enabled the production of 33% more butanol than the control fermentation. These results are very promising for the production of butanol as a biofuel. Future work will entail the optimization of the fed-batch process for higher glucose utilization and development of a reliable butanol recovery system from the resin.

Contributors

Agent

Created

Date Created
  • 2013