About

Professor Scott M. Auerbach is a member of the CRUNCH Lab Team, focusing on research in computational materials science and energy. His work involves studying materials at the molecular level to understand and develop new energy-related technologies. The team includes graduate students and undergraduates working under his guidance, contributing to advancements in chemical and chemical engineering fields. His research aims to address key challenges in energy materials through computational approaches, fostering innovation in sustainable energy solutions.

Research topics

• Organic chemistry
• Chemistry
• Crystallography
• Physical chemistry
• Physics
• Optics
• Photochemistry
• Inorganic chemistry
• Medicinal chemistry
• Chemical engineering
• Computational chemistry
• Materials science

Selected publications

• Rapid Crystallization of Zeolites with Controllable Defects: Disentangling Fluoride Concentration and pH Using NH₄F

  Crystal Growth & Design · 2025-03-07 · 6 citations

  articleCorresponding

  Zeolite synthesis is typically conducted either under basic conditions or in neutral fluoride media using hydrofluoric acid (HF). While basic (OH–) conditions generally result in faster zeolite crystallization, they can also increase the likelihood of framework defects and crystal intergrowths. In contrast, synthesis in neutral fluoride media tends to produce fewer defects because fluoride balances positive charges from structure-directing agents. However, this method often requires significantly longer crystallization times and involves the handling of dangerous HF. In the present study, we pursue the best of both synthesis conditions, rapid syntheses with controllable defect concentrations, by disentangling of mineralizing agent and charge-balancing agent using ammonium fluoride (NH4F) as an alternative to HF. We have investigated the use of NH4F in the syntheses of siliceous and aluminum-containing zeolite A (LTA, small pore), ZSM-5 (MFI, medium pore), and siliceous Beta(*BEA, large pore). The crystallization times of all four zeolites decreased substantially with an increasing NH4F concentration. Crystallization times were reduced from 24 to 4 h (Si-LTA), 96 to 36 h (Al-LTA), 240 to 6 h (ZSM-5), and 24 to 3 h (Si-*BEA). Additionally, increasing the NH4F concentration in the synthesis mixtures decreases the defect densities of siliceous zeolites. Raman spectroscopy, along with 29Si MAS NMR, 19F MAS NMR, 13C MAS NMR, and fluorine elemental analysis of Si-LTA samples confirms that the reduction in charged defects (Si–O–) is due to the higher incorporation of F– within the double four-membered ring (D4R) present in the LTA samples. We show that the accelerated crystallization is due to the role of F– in enhancing the silica mineralization rate (formation of silicon hexafluoride species) and stabilizing D4Rs under basic conditions. Combining basic and fluoride-mediated synthesis could therefore be advantageous for faster zeolite production and improved control over structural properties for a wide variety of zeolite structures.

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• Removing Fluoride from Double Four-Membered Rings Yielding Defect-Free Zeolites under Mild Conditions Using Ozone

  Chemistry of Materials · 2024-01-08 · 7 citations

  articleOpen accessCorresponding

  We have investigated ozone treatment of as-made LTA zeolites under mild temperature conditions (175 °C) using experiments and periodic DFT as a method of energy savings and engineering defects such as silanol nests in comparison with conventional calcination at 550 °C. We have studied ozone treatment on LTA samples synthesized with 1,2-dimethyl-3-(4-methylbenzyl) imidazolium (denoted as “BULKY”) as the primary organic structure-directing agent (OSDA) and with various amounts of tetramethylammonium (TMA) as a secondary OSDA. Ozone treatment of LTA-BULKY at 175 °C was found to give defect-free, pristine LTA materials as determined by 29Si NMR, 13C NMR, Raman spectra, and DFT to assign the spectra. This represents a significant and unexpected finding: that fluoride ions can be completely removed from double four-membered rings (D4Rs) under such mild conditions. Ozone treatment of LTA-BULKY-TMA samples removed BULKY but left behind TMA/F, giving a new and more diverse structural landscape of Si environments in LTA. Ab initio MetaDynamics calculations provide pathways with relatively low barriers, explaining how fluoride ions can be removed from D4Rs, leaving behind defect-free LTA materials under mild conditions.

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• Improving the Perceived Utility Value of Teamwork and Collaboration among STEM Undergraduates

  International Journal of Science and Mathematics Education · 2024-05-28 · 4 citations

  article
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• Titrating Controlled Defects into Si-LTA Zeolite Crystals Using Multiple Organic Structure-Directing Agents

  Chemistry of Materials · 2022 · 17 citations

  • Materials science
  • Chemical engineering
  • Crystallography

  Controlling defects in zeolites is crucial for tuning their adsorption and catalytic properties. We have performed an integrated zeolite synthesis, spectroscopy, and density functional theory study to test the limit of F– as a charge-balancing agent that mitigates defects in siliceous zeolites. We focused on the synthesis of siliceous zeolite LTA at 150 °C with 1,2-dimethyl-3-(4-methylbenzyl) imidazolium as the primary organic structure-directing agent (OSDA) and tetramethyl ammonium (TMA) as the secondary OSDA. By varying the amount of TMA in the synthesis gel, positive charges were titrated into the resulting as-made Si-LTA. Surprisingly, we found that greater TMA concentration does not induce more F– to enter into the zeolite. 29Si solid-state MAS NMR, Raman spectroscopy, and density functional theory suggest that this system has surpassed its capacity for F– to balance OSDA charge, and additional positive charge is balanced by Si–O– framework defects. The number of defects in the as-made Si-LTA can be precisely titrated by the amount of TMA in the zeolite structures. For the Si-LTA synthesized without TMA, framework defects formed in the early stage of crystal growth were found to heal during later crystallization, leading to defect-free Si-LTA. However, for the Si-LTA synthesized with TMA, the defects formed in early stages do not heal. A DFT thermodynamic analysis explains that crowding of Si-LTA pores by TMA impedes defect healing; this prediction is corroborated by synthesis experiments at an elevated temperature (170 °C). These results indicate that F– can have a limited capacity to balance OSDA charge in zeolite synthesis, opening up a third route to zeolite synthesis intermediate between the fluoride and hydroxide routes.

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• Shape-Selectivity of Cyclopentenyl Cation Isomerization: Investigating Kinetic Control in Medium-Pore Zeolites

  The Journal of Physical Chemistry C · 2022-12-29 · 4 citations

  articleSenior authorCorresponding

  We performed periodic density functional theory (DFT) calculations to study the dynamics of alkyl substituents on cyclopentenyl cations in medium-pore acid zeolites, H-ZSM-5 and H-ZSM-22. Our study seeks to shed light on how zeolite shape selectivity can influence key reaction intermediates in the methanol-to-hydrocarbon process, which can lead to both value-added products and coke species. We considered the isomerization of 4-ethyl-4,5,5-trimethylcyclopentenyl cation (A), which has been shown by Hernandez et al. [ACS Catal.2021, 11, 12893–12914] to lead to IR spectra and alkyl substitution patterns that vary with zeolite pore structure, in contrast to DFT-predicted thermodynamics. Here, we investigate the role of kinetic control on zeolite shape-selectivity by computing exhaustive DFT dynamics of substituent rearrangement in medium-pore zeolites starting with cation A. We used the Rule Input Network Generator (RING) code to enumerate isomerization pathways from A to five product isomers that differ mainly in the presence or absence of an alkyl substituent on the central allylic carbon of the cyclopentenyl ring, yielding a reaction network with a total of 24 distinct species. We combined metadynamics and climbing-image nudged elastic band (CI-NEB) methods to compute the free-energy landscapes, including barriers for all species in H-ZSM-5 and H-ZSM-22 zeolites. Integrating kinetic equations for the reaction network in the two zeolites predicts that equilibrium product distributions are obtained after 103 s in H-ZSM-5, while 108–109 s is required for equilibration in H-ZSM-22, suggesting the clear possibility of kinetic control depending on zeolite structure.

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• How STEM Undergraduates Choose, Navigate, and Integrate Interdisciplinarity in College and Beyond

  The Journal of Higher Education · 2022-10-12 · 16 citations

  article

  Higher education has increasingly been called upon to develop interdisciplinary programs — particularly in STEM fields — that prepare students to address multi-faceted, real world problems. While the tensions between disciplinary cultures and interdisciplinary programs have been previously studied, relatively little is known about the experiences of students in interdisciplinary programs. In this grounded theory study, we interviewed 45 STEM students and alumnx from an interdisciplinary program at a public research institution to examine how individuals understand and integrate interdisciplinary perspectives into their academic pathways. Our findings demonstrate that participants moved through stages of interdisciplinarity regarding choice, navigation, and integration.

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• Shape-Selective Synthesis of Alkylcyclopentenyl Cations in Zeolites and Spectroscopic Distinction of Constitutional Isomers

  ACS Catalysis · 2021 · 29 citations

  • Chemistry
  • Photochemistry
  • Inorganic chemistry

  Alkylcyclopentenyl cations belong to the long-lived intermediates that make up the “hydrocarbon pool” during the catalytic conversion of methanol on zeolites, and recent works show that such cations contribute to olefin and aromatics formation. From liquid phase chemistry, two types of alkylcyclopentenyl cations are known and distinguished by the substituent at the central carbon (C-2) of the allylic system: a more stable type with a methyl group at the C-2 and a less stable type with hydrogen at the C-2. The following three linked objectives are pursued: (i) IR spectroscopic distinction of the different substitution patterns at the allylic system of alkylcyclopentenyl cations, (ii) the role of the zeolite framework in determining the substitution pattern, and (iii) identification of alkylcyclopentenyl cations from precursors relevant to methanol-to-olefins conversion. UV–vis and IR spectroscopy are applied in situ to characterize alkylcyclopentenyl cations produced by adsorption of a pentaalkylcyclopentadiene or by adsorption and thermally induced cyclization of 2,6-dimethyl-2,4,6-octatriene. Prior knowledge of electronic spectra is combined with DFT-computed and experimental IR spectra to establish the frequency of the C–H vibration of the C-2 hydrogen-substituted type, and a characteristic red shift of the asymmetric allylic stretching vibration (Δν ≈ −20 to −30 cm–1) after replacing hydrogen by methyl at the central carbon of the allylic system. Although DFT demonstrates that both types of ions fit into medium- and large-pore zeolites and that the C-2 methyl-substituted type is thermodynamically favored even in the pores of the considered zeolites, formation of alkylcyclopentenyl cations is found by UV–vis and IR spectra to be shape-selective. The bulkier C-2 methyl-substituted type is detected in large-pore zeolites (MOR, BEA) and in the intersections of medium-pore zeolites (MFI), whereas in channels of medium size (TON), the less bulky C-2 hydrogen-substituted type is exclusively formed. The type of ion formed and its overall size are dictated by the zeolite framework and are independent of the precursor; the same type of alkylcyclopentenyl cation as found through cyclization of dimethyloctatriene could be generated from ethene.

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• Identifying Order and Disorder in Double Four-Membered Rings via Raman Spectroscopy during Crystallization of LTA Zeolite

  Chemistry of Materials · 2021 · 18 citations

  • Chemistry
  • Crystallography
  • Optics

  Fluoride (F–) has been essential for the synthesis of low-defect siliceous zeolites. It has been hypothesized that F– balances the positive charges from organic structure-directing agents (OSDAs) and stabilizes key building units during zeolite crystallization such as the double four-membered ring (D4R). However, due to the lack of characterization techniques for investigating medium-range structures, including rings and cages formed during zeolite crystallization, the roles of F– in stabilizing building units and maintaining local charge balance during zeolite assembly are not yet fully understood. Here, the crystallization of siliceous Linde type A (LTA) zeolite in the presence of F– was investigated using Raman spectroscopy and periodic density functional theory (DFT) calculations. We have discovered that the F–-filled double four-membered ring (F–/D4R) and the empty D4R exhibit rather distinct Raman features. Both the F–/D4R and empty D4R are formed in the LTA zeolite synthesized in the presence of F– using 1,2-dimethyl-3-(4-methylbenzyl) imidazolium as the OSDA. Observed Raman bands of the F–/D4R and empty D4R, along with predictive DFT calculations on LTA supercells, reveal an ordered distribution of these two D4R units in the final as-made LTA zeolite. The discovery of these distinct Raman signatures of F–/D4R and empty D4R units opens an interesting new window for studying defects in the D4R during zeolite formation. In particular, we have observed variation in Raman intensities of F–/D4R and empty D4R bands during LTA crystallization; periodic DFT calculations indicate that the observed Raman behavior is consistent with empty D4R units containing one or two Si vacancies surrounded by Q3 Si—consistent also with solid-state nuclear magnetic resonance measurement. These defects appear to heal during further crystallization, leading to the formation of defect-free LTA zeolite crystals. Overall, our results provide deeper understanding on the roles of F– in charge balancing and stabilizing intact D4R units during zeolite formation.

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• Experimental and DFT Calculated IR Spectra of Guests in Zeolites: Acyclic Olefins and Host–Guest Interactions

  The Journal of Physical Chemistry C · 2020-04-23 · 19 citations

  articleSenior authorCorresponding

  We performed experimental and periodic density functional theory (DFT) IR spectroscopy to investigate the adsorption of acyclic olefins over both acidic and nonacidic zeolites. Two conjugated polyenes, 2,4-dimethyl-1,3-pentadiene (I) and 2,6-dimethyl-2,4,6-octatriene (II) were studied to probe organic intermediates that can be formed during methanol conversion and lead to deactivating species known collectively as “coke.” We computed vibrational spectra using zeolite-adsorbed and gas-phase models for both neutral and protonated forms of I and II and compared these DFT results to diffuse reflectance IR Fourier transform (DRIFT) spectra of zeolite−guest systems. Our experimental and computational results are precise enough to pinpoint the surprising fact that the gauche s-cis conformation of species I is the major conformer during adsorption over dealuminated zeolite β. Computed zeolite-adsorbed spectra of the protonated species I and II best represent the DRIFT spectra obtained after the adsorption of the olefins on HMOR at 20 °C, with computed bands at 1543 and 1562 cm–1 for molecules I+ and II+, respectively, attributed to the allylic stretching mode, ν(C=C–C+). These computed band frequencies are within 6 cm–1 of experimental data and confirm that the interaction between neutral acyclic olefins and acidic zeolites leads to protonation of the olefin. A comparison of computed spectra of the protonated species in the gas phase to those in the zeolite indicates that the electrostatic interaction between alkenyl and alkadienyl cations and negative zeolite framework does not significantly impact the position of the allylic stretching bands. These results highlight that computed spectroscopy and thermodynamics coupled with experimental spectra can be used to elucidate complex mixtures in zeolites, and certain spectral features of adsorbed olefins can be accurately modeled by gas-phase calculations.

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• Correction to “Modeling the Role of Excluded Volume in Zeolite Structure Direction”

  The Journal of Physical Chemistry Letters · 2019-09-30 · 3 citations

  erratum

  ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to "Modeling the Role of Excluded Volume in Zeolite Structure Direction"Cecilia BoresCecilia BoresMore by Cecilia Boreshttp://orcid.org/0000-0002-7359-1556, Scott M. Auerbach*Scott M. AuerbachMore by Scott M. Auerbachhttp://orcid.org/0000-0001-8598-3082, and Peter A. Monson*Peter A. MonsonMore by Peter A. Monsonhttp://orcid.org/0000-0002-7458-3443Cite this: J. Phys. Chem. Lett. 2019, 10, 20, 6089Publication Date (Web):September 30, 2019Publication History Published online30 September 2019Published inissue 17 October 2019https://pubs.acs.org/doi/10.1021/acs.jpclett.9b02767https://doi.org/10.1021/acs.jpclett.9b02767correctionACS PublicationsCopyright © 2019 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views485Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (493 KB) Get e-Alertsclose Get e-Alerts

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Recent grants

• Predictive Multi-Scale Modeling of Base Catalysis in Functionalized Zeolites

  NSF · $271k · 2006–2010

• UNS:Predictive Ab Initio Dynamics in Zeolite Biofuel Production Catalysts: Towards More Gas and Less Coke

  NSF · $330k · 2015–2020

• Predictive Multi-scale Modeling of Shape-Selective Adsorption and Reaction in Acid/Base Zeolite Biofuel Catalysts

  NSF · $300k · 2009–2013

Frequent coauthors

• Geoffrey A. Tompsett

  Worcester Polytechnic Institute

  22 shared

• Clare P. Grey

  University of Cambridge

  21 shared

• Karl D. Hammond

  University of Missouri

  18 shared

• Fulya Doğan

  Argonne National Laboratory

  17 shared

• Fabien Jousse

  Unilever (United Kingdom)

  16 shared

• W. Curtis Conner

  15 shared

• P. A. Monson

  University of Massachusetts Amherst

  14 shared

• Justin T. Fermann

  University of Massachusetts Amherst

  10 shared

Labs

• CRUNCH LabPI

Awards & honors

• NSF Postdoctoral Fellow, University of California, Santa Bar…