Chemistry and Chemical Engineering

Project Summary

This senior design project proposes an innovative process for the production of acetylene gas (C2H2) by utilizing carbon dioxide (CO2), water (H2O), and calcium carbide (CaC2) through a sequence of reactors and separators. A key advancement of this process is repurposing carbon dioxide emissions from flue gas, aligning with sustainability and carbon capture initiatives. The method involves the electrochemical reduction of carbon dioxide in a high-temperature molten salt reactor with calcium oxide (CaO) to produce CaC2 and oxygen (O2). The CaC2 is subsequently hydrolyzed in a continuous stirred-tank reactor (CSTR) to generate acetylene gas and calcium hydroxide (Ca(OH)2), followed by purification steps to ensure the production of high-purity C2H2. The CO2 required for this reaction is sourced from coal-fired power plant flue gas located in Tatum, Texas, which typically contains 8-10% CO2 by volume. A separation technique using monoethanolamine (MEA) absorption is selected as the optimal method for carbon dioxide capture. This process assumes a 66% carbon capture efficiency and 70% acetylene conversion, leading to an estimated production rate of 1,400 kmol/hr of acetylene and an annual output of approximately 308,000 metric tons. Concurrently, the system captures 4,300 kmol/hr of carbon dioxide, translating to 1.5 million metric tons annually. Acetylene is a well-established industrial commodity valued at $3.7 billion in 2023, with a projected compound annual growth rate of 5.4%, expected to surpass $5 billion by 2030. It is extensively utilized in welding and cutting operations, chemical synthesis, portable lighting, and steel manufacturing. Additionally, valuable byproducts such as oxygen, calcium hydroxide, and calcium oxide hold significance in industries including wastewater treatment, pharmaceuticals, and plastic production. Process modeling and simulation are conducted using Aspen Plus, incorporating black-box representations for critical reaction steps due to the challenges associated with simulating solid-phase reactions such as CaC₂ hydrolysis. Sensitivity analyses are performed to assess reaction conditions, separation efficiencies, and overall economic viability. The process leverages a sustainable feedstock approach by utilizing waste CO₂, thereby reducing greenhouse gas emissions and supporting circular carbon economy principles. This project highlights the feasibility of a scalable and environmentally sustainable acetylene production process, providing an alternative to conventional fossil fuel-based methods while meeting industrial demands for high-purity acetylene gas. This plant is expected to be extremely profitable, with a projected net profit of $127,000,000 per year.

Project Objective

The objective of this project is to design a sustainable and economically viable process for producing high-purity acetylene gas (C₂H₂) using waste carbon dioxide (CO₂), water, and calcium oxide (CaO). By repurposing CO₂ from coal-fired power plant flue gas, the process reduces emissions through electrochemical conversion, hydrolysis, and separation. This approach offers a carbon-negative alternative to conventional acetylene production while meeting industrial demand and ensuring profitability.

Manufacturing Design Methods

The acetylene production process was modeled using Aspen Plus, with black-box representations for key units like the molten salt reactor and CSTR due to solid-phase reaction complexities. Standard equipment was sized based on process conditions, fluid properties, and heuristics from Appendix G. Design assumptions included 66% CO₂ capture and 70% acetylene conversion. Capital and manufacturing costs were estimated using Turton’s method, adjusted for 2025 using CEPCI values. This approach ensures a sustainable, cost-effective, and scalable process.

Specification

The acetylene production process uses flue gas containing 8–10% CO₂ from a coal-fired power plant in Tatum, Texas. CO₂ is captured using monoethanolamine (MEA) at 38–50 °C and 2.24 atm, with a 66% capture efficiency. In the molten salt reactor operating at 550 °C, CO₂ reacts with CaO to form CaC₂, which then undergoes hydrolysis in a CSTR to produce acetylene and Ca(OH)₂. Calcium oxide is regenerated from Ca(OH)₂ at temperatures above 512 °C. The process achieves 70% acetylene conversion, producing 1,400 kmol/hr (308,000 metric tons/year) of acetylene and capturing 4,300 kmol/hr of CO₂. Key equipment includes heat exchangers, pumps, compressors, heaters, and distillation columns, all designed based on Aspen Plus simulations and standard design heuristics.

Analysis

The final report presents a well-designed and innovative process for sustainable acetylene production by converting CO₂ emissions from flue gas into valuable products. Using Aspen Plus simulation and black-box modeling for complex reactions, the team effectively outlines process design, equipment sizing, and economic analysis. The plant demonstrates strong financial viability, breaking even in three years with a 52.1% IRR when capturing CO₂. The report also emphasizes environmental compliance, safety, and efficient resource recycling. While some assumptions, such as high recycling efficiencies and manual electrode replacement, may limit scalability, the overall design is both technically sound and economically promising.

Acknowledgement

We would like to sincerely thank Dr. Jonathan E. Whitlow for his guidance, support, and expertise throughout our senior design project. His insight and encouragement were instrumental in helping us develop a process that is both innovative and practical. We are grateful for his time, mentorship, and dedication to our success.

Project Summary

Hydrazine, a commonly used rocket propellant and known carcinogen, poses toxicity at levels lower than detectable by odor. Current sensors are limited by irreversible chemical reactions, undesirable response times, and thresholds above advised safety recommendations. Carbazolopyridinophane is a reusable chemical sensor capable of detecting hydrazine at a threshold of 100 ppb. However, there remains a need for a reusable chemical sensor with a detection threshold to fit current safety recommendations of 10 ppb. This work aims to synthesize a monobridged carbazolopyridinophane sensor capable of detection within the recommended range, fulfilling the targets of a real-time, reusable sensor at low concentrations. Initial steps include a Hardwig-Buchwald reaction to synthesize the carbazole structure, followed by an Åkermark cyclization. Previous works noted difficulties isolating the target compound from starting materials after the cyclization. This was remedied with the use of prep plates, where eluting the plates three times created enough separation to isolate the target intermediate at high purity.

Project Summary

Ethylene is a key component in the production of plastics, solvents, and other industrial materials. Traditionally, it is produced through steam cracking, a high-emission process that relies on fossil fuels. This project proposes a more sustainable method by producing ethylene from bioethanol via catalytic dehydration. The process utilizes BASF’s CircleStar catalyst, which offers improved selectivity and operates at lower temperatures compared to conventional catalysts. The plant is located in South Dakota to leverage access to bioethanol and affordable industrial land. It produces 37,000 kilograms of ethylene per hour. The plant design prioritizes efficiency, scalability, and sustainability, with operations tailored to minimize energy consumption and environmental impact.

Project Objective

The objective of this project is to design a process that efficiently converts bioethanol into high-purity ethylene using catalytic dehydration. The system incorporates BASF’s CircleStar catalyst, which enables high selectivity and lower-temperature operation compared to conventional catalysts.

Manufacturing Design Methods

The process starts by separating ethanol from water through distillation. The ethanol stream is then compressed, heated, and sent through two reactors containing the CircleStar catalyst, which helps convert ethanol to ethylene efficiently. After the reaction, the stream is cooled and goes through multiple flash separators and compressors to purify the ethylene. Each step is designed to improve efficiency, reduce waste, and save energy.

Specification

The plant is designed for continuous operation, running 24 hours a day for 350 days per year. It is engineered to maintain consistent temperature and pressure conditions across all unit operations.

Project Summary

Tetrahydrofurfuryl Alcohol (THFA) is an environmentally friendly and water-miscible solvent used in manufacturing advanced electronics, vinyl resins, dyes for leather, rubber, and nylon. Furfural, THFA's parent compound, is derived from any lignocellulosic waste biomass such as corn stover, oats, and sugarcane. The biomass is processed and separated into furfural by a series of distillation columns. Furfural then undergoes a double hydrogenation reaction inside a packed-bed reactor, yielding THFA. Catalysts such as Pd, Pt, and Ru are excellent for hydrogenation reactions but come with extreme costs and problematic by-products. In recent years, transition metals such as Nickel, Copper, and Cobalt have been investigated for potential use in furfural hydrogenation. This process focuses on a novel NiCu-Al catalyst that boasts complete furfural conversion and 99% THFA yield with high selectivity.

Project Objective

To develop a sustainable and economically viable process for producing 99% purity Tetrahydrofurfuryl Alcohol using agricultural waste biomass and cost-effective catalysts.

Manufacturing Design Methods

Our design incorporates a multi-step process of taking biomass waste and converting it first into furfural, and then hydrogenating it into THFA before purifying it to 99%.

Project Summary

Polyurethane (PU) is an organic polymer joined by repeating carbamate (urethane) groups with a wide range of technological and daily applications, as it can be used as either rigid or flexible plastic. It is the 6th most used polymer in the world, with 18 million tons produced per year. Some uses consist of the insulation of refrigerators and freezers, building insulation, and cushioning for furniture and mattresses. It can also be used for bonding materials like wood, concrete, and metal. Polyurethane foams are classified into three types: conventional, viscoelastic, and high resilience. Most commonly, viscoelastic foam is used to produce mattresses and pillows. This project will recycle old mattresses, specifically the polyurethane component, to be used for future use. Most mattresses are thrown away into landfills, and this process would reduce the amount of mattresses that are disposed of. While recycling mattresses is not inherently a unique idea, utilizing such a specific process is unique. To encourage people to turn in their mattresses a buy back system will be implemented. This system will measure the weight of the mattress, and based on the total weight of the foam will give the individual who turned it in $0.30 per pound. Most mattresses vary between 50 to 150 pounds, depending on the type, so on average people will get $30 per mattress turned in. There will be various sites around the Austin area to decrease the amount of driving time people will have to drive, and to encourage people to turn in their mattresses by making it more convenient. An alternative option to the buy back system would be a reward or discount system. This involves the company who purchases our product of polyols to give us coupons for our recyclers. This way people will get a discount on their next mattress, and it encourages people to turn their old mattresses in while they’re in the market for a new one. The first few years of production will keep the $0.30 per pound buy back system, until the company is settled enough and comfortable in its own operation to negotiate with our customers to try and get alternative rewards to those who turn in their mattresses.

Project Summary

This project addresses the challenge of waste accumulation and resource scarcity on the Moon by developing a closed-loop waste-to-resource conversion system. The process transforms astronaut waste and feces into valuable products such as methane and oxygen, essential for sustaining life and enabling long-term lunar habitation. Using thermochemical and electrochemical techniques, the system supports NASA's goals for in-situ resource utilization and off-world sustainability.

Project Objective

The objective is to engineer a process capable of thermochemically converting astronaut-generated waste into methane and oxygen on the Moon. This system should minimize waste storage needs, reduce Earth resupply missions, and support a closed-loop, resource-efficient habitat.

Manufacturing Design Methods

The system integrates gasification, electrolysis, and Sabatier reactions. Aspen Plus was used to simulate the full process. Equipment was selected and scaled using chemical engineering design correlations and cost estimation tools.

Analysis

Sensitivity analysis was performed on different waste-to-feces input ratios (from 1:1 to 1:20) to determine the flexibility and performance of the process. Economic analysis revealed a net profit of $116 billion/year.

Acknowledgement

Special thanks to Dr. A. Meier at NASA Kennedy Space Center and Dr. MT Reza with the BioFCM research group for insight and collaboration.