Renewable chemicals

Dauenhauer's focus on renewable chemicals produced from glucose has targeted both drop-in replacement chemicals and new chemicals with novel characteristics. In 2012, he discovered a high yield pathway to synthesize p-xylene from glucose; this molecule is the key ingredient in polyethylene terephthalate plastic.^[7] This process technology utilized a new class of weak acid zeolites that permits the manufacture of biorenewable polyester.^[8]

In 2015, Dauenhauer and his team developed a new class of surfactants, detergents, and soaps that are derived from biomass (furans from sugars and fatty acids from triglycerides), oleo-furan sulfonates (OFS).^[9] These molecules were shown to have high hard water stability (>1000 ppm Ca++) and are being commercialized by Sironix Renewables, Inc.^[10]

In 2016, Dauenhauer and Abdelrahman developed the acid-catalyzed dehydra-decyclization mechanism that simultaneously opens cyclic ether rings and dehydrates to synthesize diene products.^[11] This technology was subsequently used to optimize the catalytic production of isoprene, the key chemical in the production of car tires. Subsequent research identified pathways to similarly convert biomass-derived tetrahydrofuran to butadiene and 2-methyl-tetrahydrofuran to piperylene.^[12]

Key publications include:

• C.L. Williams, C.C. Chang, P. Do, N. Nikbin, S. Caratzoulas, D.G. Vlachos, R.F. Lobo, W. Fan, P.J. Dauenhauer "Cycloaddition of Biomass-Derived Furans for Catalytic Production of Renewable p-Xylene", ACS Catalysis, 2, 6, 935–939, (2012).^[13]
• Dae Sung Park, Kristeen E. Joseph, Maura Koehle, Christoph Krumm, Limin Ren, Jonathan N. Damen, Meera H. Shete, Han Seung Lee, Xiaobing Zuo, Byeongdu Lee, Wei Fan, Dionisios G. Vlachos, Raul F. Lobo, Michael Tsapatsis, Paul Dauenhauer "Tunable Oleo-Furan Surfactants by Acylation of Renewable Furans", ACS Central Science, 2(11), 820–824, (2016).^[14]
• Omar A. Abdelrahman, Dae Sung Park, Katherine P Vinter, Charles S. Spanjers, Limin Ren, Hong Je Cho, Kechun Zhang, Wei Fan, Michael Tsapatsis, Paul J. Dauenhauer "Renewable Isoprene by Sequential Hydrogenation of Itaconic Acid and Dehydra-Decyclization of 3-Methyl-Tetrahydrofuran", ACS Catalysis, 7(2), 1428–1431, (2016).^[15]

Cellulose Pyrolysis

Dauenhauer's study of cellulose in 2008 led to the discovery of an intermediate liquid state of short-chain cellulose oligomers of sub-second duration at temperatures around 500 deg C.^[16] He further outlined the challenges in understanding high temperature cellulose chemistry by publishing his "Top Ten Challenges" of biomass pyrolysis in 2012,^[17] one of which was based on his discovery of the mechanism of aerosol formation through liquid intermediate cellulose.^[18]

Dauenhauer further developed a new reactor technique called 'PHASR' (Pulse-Heated Analysis of Solid Reactions) which led to the first isothermal kinetics of cellulose conversion and product formation.^[19] This technique permitted a molecular analysis of cellulose activation and the discovery that cellulose has a unique reaction transition at 467 deg C.^[20] The high temperature kinetic transition was attributed to the catalytic role of chain-to-chain cellulose hydroxyl groups in stabilizing the chain fragmentation of inter-monomer bonds.^[21]

Key publications include:

• Vineet Maliekkal, Saurabh Maduskar, Derek J. Saxon, Mohammadreza Nasiri, Theresa M. Reineke, Matthew Neurock, Paul Dauenhauer "Activation of Cellulose via Cooperative Hydroxyl-Catalyzed Transglycosylation of Glycosidic Bonds", ACS Catalysis, 9(3), 1943–1955, (2019).^[22]
• Andrew R. Teixeira, Kyle G. Mooney, Jacob S. Kruger, C. Luke Williams, Wieslaw J. Suszynski, Lanny D. Schmidt, David P. Schmidt, and Paul J. Dauenhauer "Aerosol generation by reactive boiling ejection of molten cellulose", Energy & Environmental Science, 4, 4306–4321, (2011).^[23]

Catalytic Resonance Theory

Catalytic resonance theory was proposed by Dauenhauer based on the Sabatier principle of catalysis developed by French chemist Paul Sabatier. Optimal catalyst performance is depicted as a 'volcano' peak using a descriptor of the chemical reaction defining different catalytic materials. Experimental evidence of the Sabatier principle was first demonstrated by Balandin in 1960.^[24][25] In his initial discovery of the behavior of oscillating chemical reactions on metal surfaces, Dauenhauer showed that steady state reaction rates could achieve chemical reaction speeds as much as 1000 times greater than previously achievable rates, even with optimized catalytic systems.^[26] This work broke down surface chemical reactions into its component parts and associated natural frequencies, which could be matched to resonate with the catalytic surface frequencies.^[27]

Follow-up work on catalytic resonance theory by Dauenhauer and his team broadened to understand the relationship between surface chemistry with its linear scaling relationships and the surface binding energy oscillation waveform.^[28] He introduced the concept of superVolcanoes as a superposition of all possible Sabatier volcanoes for varying linear scaling parameters, before further connecting the behavior of oscillating catalytic surfaces to molecular machines and pumps.

Key publications include:

• A. Ardagh, O. Abdelrahman, P.J. Dauenhauer "Principles of Dynamic Heterogeneous Catalysis: Surface Resonance and Turnover Frequency Response", ACS Catalysis, 9(8), 6929–6937, (2019).^[29]
• A. Ardagh, T. Birol, Q. Zhang, O. Abdelrahman, P.J. Dauenhauer "Catalytic Resonance Theory: superVolcanoes, catalytic molecular pumps, and oscillatory steady state", Catalysis Science & Technology, 9, 5058–5076, (2019).^[30]
• M.A. Ardagh, M. Shetty, A. Kuznetsov, Q. Zhang, P. Christopher, D.G. Vlachos, O.A. Abdelrahman, P.J. Dauenhauer, "Catalytic Resonance Theory: Parallel Reaction Pathway Control", Chemical Science, 2020.^[31]