About

Sheima Khatib is an Associate Professor in the Department of Chemical Engineering at Virginia Tech. Her research areas include the design and implementation of sustainable catalytic processes, structure-activity relations in heterogeneous catalysis, and reactor engineering with a focus on membrane reactors. She has contributed to advancing understanding in methane dehydroaromatization and the development of catalytic materials, with numerous publications in these fields. She holds a Ph.D. from the Institute of Catalysis and Petrochemistry (Spanish National Research Council) and the Autonomous University of Madrid, along with a master's and bachelor's degree in chemical engineering from the University of Malaga, Spain. Her work emphasizes catalytic process optimization and the development of materials for industrial applications. She has received multiple awards for her teaching and research excellence, including the NSF CAREER Award and the Jerry S. Rawls Outstanding Undergraduate Educator Award.

Research topics

• Organic chemistry
• Chemical engineering
• Chemistry
• Inorganic chemistry
• Nanotechnology
• Materials science
• Engineering
• Physical chemistry

Selected publications

• Evolution, Speciation, and Distribution of Mo Oxides in MFI-Type Zeolites

  The Journal of Physical Chemistry C · 2025-03-10 · 2 citations

  article

  Mo oxide-impregnated H-ZSM-5, the most extensively studied catalyst for methane dehydroaromatization (MDA), is typically prepared by impregnating Mo precursors into H-ZSM-5 zeolite through physical mixing or incipient wetness impregnation. To understand the transformation of Mo oxide/(H−)ZSM-5 during catalyst preparation and the anchoring stages of MDA, we employ density functional theory (DFT) calculations to investigate changes in the electronic structure, composition, and location of Mo oxide in H-ZSM-5. Using the climbing image nudged elastic band (CI-NEB) method, we explore the anchoring and formation processes of various MoOx motifs within H-ZSM-5 and provide mechanistic insights into the interconversion between these structural motifs. We also develop a statistical model informed by the kinetics of Mo oxide anchoring and formation, predicting the distribution of Mo oxide catalyst precursors as a function of the synthesis method, zeolite acidity, and Mo loading. Additionally, by employing temperature-programmed calcination under oxidative conditions, we monitor the transformation of Mo oxides by measuring the water released during anchoring. These experimental results are correlated with the modeling predictions, providing insights into the molecular processes during catalyst preparation and how we can rationally control the design of Mo oxides in MFI-type zeolites.

  PublisherDOI

• Harnessing Metal-Carbon Interactions to Obtain Enhanced Yield in Aromatics and Improved Coking Resistance in Methane Aromatization

  2024-06-12

  reportOpen access1st authorCorresponding

  1 1) What are the major goals of the project?The project targets direct methane dehydroaromatization (MDA) which converts methane to hydrogen and aromatics in one step.The major goals of the project are the following:Aim 1: Establish multifunctional Mo-X/zeolite with maximized Mo-X interactions inside the zeolite channels.Aim 2: Investigate the effect of the activation conditions on the evolution of the Mo-X interactions and on the structure of the activated surface species.Aim 3: Establish fundamental structure-activity relationships during the catalyst life cycle (activation-reaction-deactivation-regeneration). 2) What was accomplished under these goals?Bimetallic Mo-X/ZSM-5 (X=Fe,Co, Ni) catalysts with high X loadings

  PublisherDOI

• Recommendations for improving rigor and reproducibility in site specific characterization

  Journal of Catalysis · 2024-03-18 · 18 citations

  articleOpen access
  PublisherOA PDFDOI

• Sonochemically Prepared Ni-Based Perovskites as Active and Stable Catalysts for Production of CO<i>_x</i>-Free Hydrogen and Structured Carbon

  ACS Catalysis · 2023-03-13 · 12 citations

  articleSenior authorCorresponding

  A sonochemical method is employed to synthesize LaNiO3 perovskites as catalysts for methane decomposition to produce clean COx-free hydrogen and structured carbon. The catalytic activities of perovskites prepared under various sonochemical conditions (different power densities and exposure times) are contrasted with those of LaNiO3 prepared by a conventional sol–gel method. The results show that a sonochemically prepared catalyst presents a methane conversion of up to 60% after 16 h of reaction, while the conventional sol–gel LaNiO3 catalyst deactivates quickly, reaching 1% methane conversion after 30 min of reaction. Structural characterization of the as-prepared materials indicates that under certain sonochemical conditions (low-intensity sonication for 8 h) it is possible to obtain NiO inclusions in the LaNiO3 perovskite structure, which are not present when employing the conventional synthesis technique. Upon activation of these materials under reducing conditions, it is found that the presence of the sonochemically formed NiO inclusions facilitates exsolution of the reduced Ni species to the surface of the catalyst particles, improving the catalyst activity in methane decomposition. The sonochemically synthesized catalysts, which exhibit coexistence of LaNiO3 phase and NiO inclusions, also seem to exhibit autocatalytic properties as they steer the methane decomposition reaction toward formation of non-encapsulating carbon nanotubes, which not only enhance catalyst stability but also increase the catalyst activity over long reaction times.

  PublisherDOI

• Elucidating the role of Fe-Mo interactions in the metal oxide precursors for Fe promoted Mo/ZSM-5 catalysts in non-oxidative methane dehydroaromatization

  Chemical Engineering Journal · 2023 · 18 citations

  Senior authorCorresponding
  • Chemistry
  • Inorganic chemistry
  • Chemical engineering
  PublisherOA PDFDOI

• Understanding the Control of Speciation of Molybdenum Oxides in MFI-Type Zeolites

  Chemistry of Materials · 2023-11-21 · 4 citations

  articleOpen accessSenior authorCorresponding

  Metal oxide-impregnated zeolites are employed in a wide variety of catalytic reactions, including methane dehydroaromatization (MDA). The most studied catalysts for MDA are Mo carbides supported on H-ZSM-5, formed through the carburization of Mo-oxide-loaded H-ZSM-5. A complete structural understanding of these materials has not yet been achieved, limiting the potential for rational catalyst design for improved performance. We hereby pursue experimental and theoretical investigations of these catalyst precursors to uncover rational design principles. We employ temperature-programmed oxidation and extended X-ray absorption fine-structure experiments, density functional theory calculations, and QuantEXAFS analysis to unveil Mo-oxide speciation in H-ZSM-5. We demonstrate that Mo-oxides exist within these systems as a combination of various motifs, and the relative abundance of these species is controlled through tailored preparation methods. The synergies exploited in this work may be leveraged in other related catalysts. The conclusions drawn are applicable to other relevant applications of zeolite-supported metal oxides.

  PublisherOA PDFDOI

• Effect of Si/Al ratio of ZSM-5 support on structure and activity of Mo species in methane dehydroaromatization

  Fuel · 2020 · 72 citations

  Senior authorCorresponding
  • Chemistry
  • Inorganic chemistry
  • Chemical engineering
  PublisherOA PDFDOI

• A critical literature review of the advances in methane dehydroaromatization over multifunctional metal-promoted zeolite catalysts

  Applied Catalysis A General · 2020 · 94 citations

  Senior authorCorresponding
  • Chemistry
  • Nanotechnology
  • Chemical engineering
  PublisherOA PDFDOI

• Increasing the catalytic stability by optimizing the formation of zeolite-supported Mo carbide species ex situ for methane dehydroaromatization

  Journal of Catalysis · 2019-06-26 · 41 citations

  articleOpen accessSenior authorCorresponding
  PublisherOA PDFDOI

• Bimetallic Mo-Co/ZSM-5 and Mo-Ni/ZSM-5 catalysts for methane dehydroaromatization: A study of the effect of pretreatment and metal loadings on the catalytic behavior

  Applied Catalysis A General · 2019-10-22 · 88 citations

  articleOpen accessSenior authorCorresponding
  PublisherOA PDFDOI

Frequent coauthors

• S. Ted Oyama

  Aoyama Gakuin University

  12 shared

• Miguel Á. Bañares

  7 shared

• Simon R. Bare

  Stanford Synchrotron Radiation Lightsource

  7 shared

• Apoorva Sridhar

  Texas Tech University

  7 shared

• Mustafizur Rahman

  7 shared

• J.M. Guil

  Instituto de Química Física Blas Cabrera

  6 shared

• E. Lomba

  6 shared

• M. A. Garcı̀a

  Instituto de Cerámica y Vidrio

  5 shared

Awards & honors

• Jerry S. Rawls Outstanding Undergraduate Educator Award, 202…
• Texas Tech University Teaching Academy Inductee, 2022
• Whitacre Research Award, Texas Tech University-Whitacre Coll…
• National Science Foundation, CAREER Award, 2019
• Apple Polishing award from Texas Tech’s Mortar Board, 2021