(334aa) Tuning Catalysts for Efficient Chemical and Energy Transformation

The activity of platinum group metals have placed majority of these catalysts far above other types of metal catalysts, turnover frequencies have typically landed them on top of the volcano curves of most chemical reactions. However, its biggest attraction is also the reason for its lack of practicality; two of the biggest problems involving platinum group metals include lack of selectivity control, and susceptibility to poison¹. Hydrodeoxygenation (HDO) is a key chemistry in pushing forward more bio-derived feedstocks in the industry, succinic acid -through HDO- has been highlighted as a potential alternative to maleic anhydride for the production of 1,4-butanediol, gamma-butyrolactone and tetrahydrofuran. However, upgrading these carboxylic acids proves problematic over the preferred catalysts (noble metals) because of a lack of selectivity control. These active catalysts facilitate a multitude of undesired reactions such as hydrogenolysis, decarbonylation, decarboxylation, and methanation, which all lead to a slew of low-value products². It is widely reported that the addition of oxophilic “promoter metals,” such as Sn can be used to tune the selectivity of noble metals during the HDO of carboxylic acids³; however, their mechanism of action is poorly understood. Another common problem in both upgrading and extracting energy (fuel cells) from carboxylic acids is formation of carbon monoxide, which has a tendency to inhibit reaction rates. A new approach has been brought to the forefront in modern catalyst operation, dynamic catalysis. This involves the use of an external stimuli in order to oscillate between energy state⁴; these different states will manipulate the rate determining steps (rds) in a reaction mechanism, bouncing between different rds’s has the potential operate at rates magnitudes higher than operating under a static condition. In this poster, we use two separate approaches for solving the practical limitations of platinum group metals.

First, we use propionic acid HDO as a model system for tackling selectivity control over supported Pt catalysts. While succinic acid HDO might be more practical to an industrial setting, a simpler molecule is ideal for a fundamental study as it captures all the essential chemistries expected without a product stream being overcrowded. We will dissect HDO activity over monometallic Pt using experimental and computational techniques, providing macroscopic insight on reaction pathways and major inhibitors to HDO selectivity. This shall play a crucial role in understanding how the addition of an oxophilic promoter, Sn, can intrinsically tune the catalytic activity towards higher yields of HDO products.

Second, we explore the effect of dynamic catalysis on carboxylic acid oxidation using electric fields. Formic acid oxidation will be used as a model reaction for the production of carbon dioxide, this is common reaction in fuel cells. Oscillating in between different applied potentials will allow us to observe this concept experimentally and the degree to which a rate increase can be achieved using a potentiodynamic approach while also overcoming the hurdle of product inhibition.

Research Interests

Oxygenated compounds have become a major corner stone in today’s industrial landscape, finding itself on the forefront of energy storage as well as chemical production. The expansion of modern catalysis is tantamount to efficiently carry out these chemical processes in order to meet social demands. As there are many aspects of a chemical process that can be approved upon, there are also many approaches one can take to solve current problems, and in some instances, a combination of approaches. Bimetallic catalysts have demonstrated it’s resistance to product inhibition though the production of oxygenated products over typical undesirable ones that can be formed over highly active catalysts³: undesired compounds include carbon monoxide, carbon dioxide and alkanes/alkenes. Dynamic catalysis has recently been brought to the forefront as a means of increasing catalytic turn over frequencies by switching between catalytic energy states, theoretical and experimental work has exhibited reaction rates orders of magnitude higher during dynamic operation versus static operation^4-5. It has also been reported through a theoretical investigation, that dynamic catalysis also has the capability of tuning the selectivity of pathways by making alterations to the amplitude and frequency of the stimuli promoting the dynamic operation⁶. My research interests include leveraging the favorable properties of bimetallic catalysts along with the vast potential of dynamic catalysis to tune the selectivity while increasing the rates of reactions involving heavily oxygenated compounds. There have been past studies that unknowingly demonstrated this idea to be plausible in an experimental setting^7-8, however without approaching the concept with the specific purpose of uncovering it’s mystery, there will be gaps in the overall understanding that will dampen it’s journey to real world applications. These research interests can find a place within many different industrial sectors such as energy extraction, biomass upgrading and pharmaceuticals; a refined solution to a commonly encountered problem.

References

1. Gurbuz, E.; Bond, J. Q.; Dumesic, J. A; Román-Leshkov, Y. 261-288. Elsevier, 2013.
2. Lugo-José, Y. K.; Monnier, J. R.; Williams, T. C. Appl. Catal. A: General 469, 410-418. 2014.
3. Vardon, D. R., Beckham, G. T., et al. ACS Catal. 7, 9. 2017.
4. M. Alexander, A.; Omar A., A.; Paul, D., Principles of Dynamic Heterogeneous Catalysis: Surface Resonance and Turnover Frequency Response. 2019.
5. Gopeesingh, Joshua; Ardagh, Matthew; Shetty, Manish; Burke, Sean; Dauenhauer, Paul; Abdelrahman, Omar (2020): Resonance-Promoted Formic Acid Oxidation via Dynamic Electrocatalytic Modulation. ChemRxiv. Preprint.
6. Ardagh, M. A.; Shetty, M.; Kuznetsov, A.; Zhang, Q.; Christopher, P.; Vlachos, D.; Abdelrahman, O.; Dauenhauer, P. J., Chem. Sci. 2020.
7. Adžić, R. R.; Popov, K. I.; Pamić, M. A., Electrochim. Acta 1978, 23 (11), 1191-1196.
8. Juan Victor Perales-Rondón; Adolfo Ferre-Vilaplana; Juan M. Feliu; Enrique Herrero. Journal of the American Chemical Society. 2014.