(6jt) Catalyst Studies on the Conversion of Biobased Intermediates to Biobased Products

“Catalyst Studies on the Conversion of Biobased Intermediates to Biobased Products”

Under the supervision of Dr. Dennis J. Miller, Department of Chemical Engineering and Materials Science, Michigan State University

Research Interests:

Catalytic reactions and chemicals separations are of quite high industrial significance among chemical engineering researches and the principle for the production of a wide variety of chemicals in the market. My work at Michigan State University has been focused on optimizing the conversion of bio-based raw materials and selectivities of desired products through catalytic reactions. I have been able to work on several projects in this area such as the production of acrylate esters from 2-acetoxy propanoate esters (APA esters) and n-butanol from ethanol. In both projects, I improved the selectivity of desired products to up to 80%. Through this work, I have been able to hone my experimental skills and develop a foundation of conceptual knowledge in the areas of reactions, process and reactor design, catalyst characterization, and kinetic and thermodynamic modeling. Perhaps the most rewarding part of my graduate school experience was learning the “ins and outs” of scientific research through practice. The objectives I met in both projects revealed new questions that I am interested in pursuing as a faculty member.

My research on the production of acrylate esters [1] was conducted in a fixed bed reactor at atmospheric pressure and the temperature of 500-600 ^OC. In this reaction, acrylates are formed by the elimination of acetic acid group of the APA ester molecules. While multiple contact materials were tested, best results were obtained using non-porous silica support with low surface acidity/basicity. It is suspected that porous materials can trap the reactants and provide the contact time required for their decomposition to smaller compounds. Furthermore, our studies showed the dramatic effect of using carbon dioxide as the carrier gas instead of nitrogen on acrylate yield. This was due to the occurrence of the Boudouard reaction (CO₂ + C ↔ 2CO), which in the presence of excess CO₂ facilitated the removal of carbon deposits from the surface of the contact material, therefore enhancing the available sites for the reactant to produce the desired product.

In the second research project, I investigated the continuous condensed phase conversion of ethanol to n-butanol. The first stage involved reproducing results previously obtained using nickel supported lanthanum- alumina catalyst in a batch reactor [2] with a packed bed reactor. Next, several bimetallic catalysts were characterized and tested to optimize the performance of the reaction. These characterizations and experiments entailed several analytical techniques such as spectroscopy and chromatography, and material surface analyses including microscopies, surface area measurements, and molecules adsorption/ desorption techniques. Our studies showed the beneficial effect of hydrogen uptake of the catalyst on ethanol conversion, suggesting that the first step of the reaction, the dehydrogenation of ethanol to acetaldehyde, is the rate limiting step for the catalysts with low hydrogen adsorption capability. Moreover, addition of copper to the nickel catalyst improved n-butanol selectivity while decreasing the C₆+ alcohols selectivity, therefore increasing the n-butanol purity in the outlet stream while maintaining the same C₄+ selectivity. Another catalyst variation, cobalt-nickel bimetallic catalyst, showed superior activity compared to the nickel catalyst despite lower selectivity to higher alcohols. Finally, the economic viability of n-butanol production process with the same mechanism was analyzed using experimental data, kinetic and thermodynamic modeling, and process simulations. The results indicated that the n-butanol selling price of $1.33-$1.58 provides a return on investment of 25% for different cases of ethanol conversion and alcohols selectivities. This price is reasonably competitive with current n-butanol market price.

Upon continuing my research, I aim to continue improving the efficiency of n-butanol formation in the Guerbet reaction. The Guerbet mechanism consists of three main reactions: ethanol dehydrogenation to acetaldehyde, aldol condensation of acetaldehyde to crotonaldehyde and finally, crotonaldehyde hydrogenation to n-butanol. Several studies report a selectivity of >97% for the production of acetaldehyde from ethanol with an ethanol conversion of >37% [3–5]. However, little work has been performed on distinctly improving the last two steps of the Guerbet mechanism. Optimizing these stages will provide a sustainable process to produce bio-derived n-butanol with high selectivities. Several discussions have approved the need for an acid-base supported catalyst for the second step, and a metallic catalyst for the third step [6,7]. Our initial screenings on the aldol condensation reaction show that while acetaldehyde is significantly more active compared to ethanol, the selectivity to crotonaldehyde is within the same range as the n-butanol selectivity from ethanol in the successive Guerbet reaction using a multi-functional catalyst. This suggest that the crotonaldehyde production could be the limiting step of the Guerbet mechanism regarding the selectivity to desired products. I aim to improve the total selectivity of n-butanol from ethanol by optimizing the catalyst required for the aldol condensation reaction, experimental analyses on the n-butanol selectivity of the last step of the Guerbet reaction, and detailed kinetic modeling of the reaction tree.

Teaching Interests:

Throughout my academic and professional careers, I have continuously tried to improve my leadership and mentoring skills by learning from multiple resources and collaborating in numerous activities. For instance, I pursued and acquired certification through the Engineering Research Mentor Training program developed by the National Research Mentor Network (NRMN). In this program, I participated in a series of workshops that involved multiple aspects of mentor-mentee relationship such as aligning expectations, maintaining effective communication, and addressing equity and inclusion. I have tried to develop these concepts during the time that I have had as a research mentor for training undergraduate research assistants in our group’s laboratory. I also had the opportunity to contribute to the business development of an innovative technology as a venture fellow. During this experience, I was a part of STEM-MBA student team that investigated the market, developed financial analysis and created a business model to assess the viability of bringing the idea into the market. Recently, I have been able to participate in the A2H2 health hackathon team project to develop an innovative idea regarding the transition into independence for individuals with disabilities. All these experiences along with other groupwork activities that I have had in recent years have helped me grow a confident personality in leading projects and coordinating group works.

Aside from my mentoring capabilities, I have developed an evolving passion in teaching throughout my career. I served as a teaching assistant (TA) for the sophomore-level Materials and Energy Balances, junior-level Modeling and Analysis of Transport Phenomena, and junior-level Pascal Programming courses at Michigan State University and Sharif University of Technology. In this role, my responsibilities included (but were not limited to) leading recitations, designing exam questions, grading assignments and exams, and holding office hours. To further improve my teaching capabilities, I took a course on pedagogical concepts and instructional design. The class served to further familiarize me with effective pedagogical practices, including collaborative learning and using technology in the classroom. I am currently in the process of completing the requirements for the certification in college teaching program. Moreover, my research deals directly with principles normally taught in Material and Energy Balances, Chemical Engineering Kinetics and Thermodynamics, Transport Phenomena, Unit Operations, Separation Sciences, and Chemical Engineering Design. Therefore, I am confident in my ability to teach these courses. However, I am also interested in teaching several other areas such as Computational Courses, Data Analysis, Process Control, Fluid Mechanics, and Physical Chemistry.

References

[1] I. Nezam, L. Peereboom, D.J. Miller, Enhanced Acrylate Production from 2-Acetoxypropanoic Acid Esters, Org. Process Res. Dev. 21 (2017). doi:10.1021/acs.oprd.7b00047.

[2] T.L. Jordison, C.T. Lira, D.J. Miller, Condensed-Phase Ethanol Conversion to Higher Alcohols, Ind. Eng. Chem. Res. 54 (2015) 10991–11000. doi:10.1021/acs.iecr.5b02409.

[3] W.-D. Lu, Q.-N. Wang, L. He, W.-C. Li, F. Schüth, A.-H. Lu, Copper Supported on Hybrid C@SiO ₂ Hollow Submicron Spheres as Active Ethanol Dehydrogenation Catalyst, ChemNanoMat. 4 (2018) 505–509. doi:10.1002/cnma.201800021.

[4] P. Zhang, Q.N. Wang, X. Yang, D. Wang, W.C. Li, Y. Zheng, M. Chen, A.H. Lu, A Highly Porous Carbon Support Rich in Graphitic-N Stabilizes Copper Nanocatalysts for Efficient Ethanol Dehydrogenation, ChemCatChem. 9 (2017) 505–510. doi:10.1002/cctc.201601373.

[5] M. V. Morales, E. Asedegbega-Nieto, B. Bachiller-Baeza, A. Guerrero-Ruiz, Bioethanol dehydrogenation over copper supported on functionalized graphene materials and a high surface area graphite, Carbon N. Y. 102 (2016) 426–436. doi:10.1016/j.carbon.2016.02.089.

[6] D. Gabriëls, W.Y. Hernández, B. Sels, P. Van Der Voort, A. Verberckmoes, Review of catalytic systems and thermodynamics for the Guerbet condensation reaction and challenges for biomass valorization, Catal. Sci. Technol. 5 (2015) 3876–3902. doi:10.1039/C5CY00359H.

[7] X. Wu, G. Fang, Y. Tong, D. Jiang, Z. Liang, W. Leng, L. Liu, P. Tu, H. Wang, J. Ni, X. Li, Catalytic Upgrading of Ethanol to n-Butanol: Progress in Catalyst Development, ChemSusChem. 11 (2018) 71–85. doi:10.1002/cssc.201701590.