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- Creators: Barrett, The Honors College
- Creators: School of Sustainability
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Project 1 Abstract: Ethylene Oxychlorination
The current two-step process for the industrial process of vinyl chloride production involves CuCl2 catalyzed ethylene oxychlorination to ethylene dichloride followed by thermal cracking of the latter to vinyl chloride. To date, no industrial application of a one-step process is available. To close this gap, this work evaluates a wide range of self-prepared supported CeO2 and EuOCl catalysts for one-step production of vinyl chloride from ethylene in a fixed-bed reactor at 623 773 K and 1 bar using feed ratios of C2H4:HCl:O2:Ar:He = 3:3 6:1.5 6:3:82 89.5. Among all studied systems, CeO2/ZrO2 and CeO2/Zeolite MS show the highest activity but suffer from severe combustion of ethylene, forming COx, while 20 wt.% EuOCl/γ-Al2O3 leads to the best vinyl chloride selectivity of 87% at 15.6% C2H4 conversion with complete suppression of CO2 formation and only 4% selectivity to CO conversion for over 100 h on stream. Characterization by XRD and EDX mapping reveals that much of the Eu is present in non-active phases such as Al2Eu or EuAl4, indicating that alternative synthesis methods could be employed to better utilize the metal. A linear relationship between conversion and metal loading is found for this catalyst, indicating that always part of the used Eu is available as EuOCl, while the rest forms inactive europium aluminate species. Zeolite-supported EuOCl slightly outperforms EuOCl/γ Al2O3 in terms of total yield, but is prone to significant coking and is unstable. Even though a lot of Eu seems locked in inactive species on EuOCl/γ Al2O3, these results indicate possible savings of nearly 16,000 USD per kg of catalyst compared to a bulk EuOCl catalyst. These very promising findings constitute a crucial step for process intensification of polyvinyl chloride production and exploring the potential of supported EuOCl catalysts in industrially-relevant reactions.
Project 2 Abstract: Alkyne Semihydrogenation
Despite strongly suffering from poor noble metal utilization and a highly toxic selectivity modifier (Pb), the archetypal catalyst applied for the three-phase alkyne semihydrogenation, the Pb-doped Pd/CaCO3 (Lindlar catalyst), is still being utilized at industrial level. Inspired by the very recent strategies involving the modification of Pd with p-block elements (i.e., S), this work extrapolates the concept by preparing crystalline metal phosphides with controlled stoichiometry. To develop an affordable and environmentally-friendly alternative to traditional hydrogenation catalysts, nickel, a metal belonging to the same group as Pd and capable of splitting molecular hydrogen has been selected. Herein, a simple two-step synthesis procedure involving nontoxic precursors was used to synthesize bulk nickel phosphides with different stoichiometries (Ni2P, Ni5P4, and Ni12P5) by controlling the P:Ni ratios. To uncover structural and surface features, this catalyst family is characterized with an array of methods including X-ray diffraction (XRD), 31P magic-angle nuclear magnetic resonance (MAS-NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Bulk-sensitive techniques prove the successful preparation of pure phases while XPS analysis unravels the facile passivation occurring at the NixPy surface that persists even after reductive treatment. To assess the characteristic surface fingerprints of these materials, Ar sputtering was carried out at different penetration depths, reveling the presence of Ni+ and P-species. Continuous-flow three-phase hydrogenations of short-chain acetylenic compounds display that the oxidized layer covering the surface is reduced under reaction conditions, as evidenced by the induction period before reaching the steady state performance. To assess the impact of the phosphidation treatment on catalytic performance, the catalysts were benchmarked against a commercial Ni/SiO2-Al2O3 sample. While Ni/SiO2-Al2O3 presents very low selectivity to the alkene (the selectivity is about 10% at full conversion) attributed to the well-known tendency of naked nickel nanoparticles to form hydrides, the performance of nickel phosphides is highly selective and independent of P:Ni ratio. In line with previous findings on PdxS, kinetic tests indicate the occurrence of a dual-site mechanism where the alkyne and hydrogen do not compete for the same site.
This work is the subject of a publication of which I am a co-author, as cited below.
D. Albani; K. Karajovic; B. Tata; Q. Li; S. Mitchell; N. López; J. Pérez-Ramírez. Ensemble Design in Nickel Phosphide Catalysts for Alkyne Semi-Hydrogenation. ChemCatChem 2019. doi.org/10.1002/cctc.201801430
The summer after my Junior year, I studied abroad in Denmark and was given the opportunity to create my own research topic. My interest in Sustainability has always revolved around food, so I started thinking about ways that I could incorporate this interest with the geographical backdrop of Århus, Denmark. Food is a medium for so many uniquely human creations: celebrations, art, connection, and taste. Food is also a big driver of climate change, as the meat and agriculture industries account for more than half of all greenhouse gas emissions. However, I wanted to research more than food. I wanted to incorporate balance; a balance of local and global food systems, a balance of individual and community relationships, and a balance of science and art. I wanted to show how food is a driving force in achieving global sustainability and resilience.
After much contemplation, I began researching the connections between local food and community wellbeing in the city. I interviewed farm-to-table chefs, local farmers, farmer’s market vendors, street food vendors, and consumers on their relationships with food. The topic itself was flexible and open-ended enough so that each interviewee could relate it to their lives in a unique way. I loved the research so much that I decided to continue interviewing stakeholders in the Phoenix metropolitan area. Through the continuation of my research in Arizona, I was able to include a comparative element that offered a better perspective on the matter. I found that the history of the country itself has a significant influence on people’s mindsets and actions surrounding food and the environment. The common theme I heard from all interviewees, however, was their confidence in the power of food to unite people to one another and to the natural world.
I chose to create this illustrated book because my research experience was a whole and inseparable experience; it could never be fully expressed in words. I wanted my project to be an intellectual and visual map of my journey, inspiring the reader to go on a journey of their own. Therefore, I partnered with an undergraduate art student at Arizona State University, Sofia Reyes, to help create my vision. I shared my experiences, photos, and stories with her so that she could create the beautiful watercolor paintings that make the book so visually appealing and accessible to all demographics. The images act as a way of engaging all of our human senses, initiating a stronger connection to the material presented.
Creating this project was my favorite experience as an undergraduate, and I feel fortunate to be able to tell the stories of those intimately tied to the local food system. I am in the process of entering my book in various competitions including Writer’s Digest, Reader’s Favorites, The Food Sustainability Media Award, and The Indie Book Awards. I am also going on to publish the book through a small publishing company.
As technology has evolved over time and the U.S. population increases each year, this thesis focuses on the ways in which food production has shifted from the original farm to table to industrialized, processed food systems. Through a rationalization perspective, this research looks to the history and repercussions of industrial agriculture as it has shifted over time. The term over-industrialization is used to operationalize the state of our current production methods. These methods focus extensively on the least expensive and most rapid methods to produce large yields of food products and pay no mind to ethics, respect of culture, land, or quality of products. Today, there is a shroud the corporations have placed over food production to ensure a “what we can’t see doesn’t affect us” belief system. In this way, the thesis provides insight on past, current, and future methods of manufacturing. I conclude that although plausible alternatives are present, continued research and substantial producer and consumer changes must be our main priority.
A brief history of the Mediterranean diet and its geographical origins as a meeting point for cultures will guide understanding of the construction of this specific dietary pattern. The nutrients and foods typical of the Mediterranean diet will be outlined as well as their health benefits, allowing for a deeper analysis of the ways in which the Mediterranean diet is associated with reducing the risk of certain chronic diseases. The lifestyle choices and physical activity practiced adjacently to the diet will establish the positive synergistic effects of conviviality and moderate exercise on general human health. Contemporary movements in the Mediterranean region, like Slow Foods, aim to preserve traditional dietary and lifestyle choices. In comparison, the U.S. food system seems to be most shaped by the influences of globalization and industrialization. Economic and health-cost perspectives as well as the role of modern-day media in diet trends, body image, and food marketing will establish and deepen the complexities of food choices and health disparities in Western societies. The diagnosis of the Mediterranean Diet in the U.S. as a solution to poor general population health will be challenged and holistic perspectives on eating will provide an exploratory lens for understanding health and food choice as a modern-day consumer.