The two main projects currently ongoing in our lab involve: (1) the study of interactions between large petroleum-relevant molecules and modified oxide surfaces, and (2) the preparation and investigation of surface-supported hybrid materials for gas absorption and reactivity. Funding for (1) is from the an American Chemical Society Petroleum Research Fund grant (#50385-UNI5), while funding for (2) is from a Research Corporation Cottrell College Science Award (#20043) and a recent National Science Foundation CAREER Award (DMR#1255326). Additional financial support is provided by the University of San Diego and the Henry Luce Foundation's Clare Boothe Luce Program.

(1) The study of petroleum relevant molecules: One current problem in the desulfurization of petroleum is the persistence of certain stable, aromatic, heteroatom-containing refractory compounds which are not removed in the hydrodesulfurization (HDS) processing steps. This leads to sulfur in petroleum which when burned can result in acid rain formation, and is also problematic in downstream petroleum processing steps. At the same time, sulfur emission standards are becoming increasingly tight, so new removal methods are required. Adsorptive, rather than catalytic, removal methods have shown promise as a solution to this problem. In order to shed light on this problem and propose possible solutions, we are studying the fundamental interactions between organosulfur species in petroleum and modified surfaces including titania-supported metal clusters. Progress to date includes the study of four structurally analogous molecules which shed light on the nature of the interaction with metal oxide surfaces, as well as a study of the interaction of dibenzothiophene with supported Ag clusters. For more information plese see related publications in the publications tab above.

(2) Investigation of supported hybrid materials: We are currently investigating supported thin films of metal organic frameworks with the goal of examining the adsorption, desorption, and reaction of energy-relevant molecules over such films using temperature programmed reaction spectroscopy (TPRS) and X-ray photoelectron spectroscopy (XPS). TPRS and XPS are two techniques capable of providing detailed information on the binding and reactivity of molecules at surfaces. However, very few studies to date investigate MOF films in vacuum using fundamental surface science techniques in highly controlled environments. Many basic questions regarding binding sites, relative desorption energies, and reactivity remain in this exciting and emerging field which we are well-equipped to answer. We are currently examining nanoparticle ZIF-8 films for CO2 adsorption and reactivity.

See our apparatus below for current capabilities. The Department also holds additional materials characterization instrumentation including XRD and DSC/TGA, and we have access to a brand new SEM/EDX system in the Biology department.

A picture of our vacuum chamber is below. 

 

Click on the captions for more information about the various capabilities, also listed below.

chamber
X-ray source

X-ray Source:

A dual anode Mg/Al X-ray source capable of producing photoelectrons characterstic of a given surface element and its chemical state.

Analyzer

Electron Analyzer:

A double-pass cylindrical mirror analyzer capable of detecting the energy of photoelectrons escaping from the sample upon illumination with the source.

organic doser

Organic Doser:

A solid material doser designed for dosing large, low vapor pressure organics and organometallic precursors onto surfaces in vacuum.

manipulator

Sample Manipulator:

A manipulator capable of x,y,z translation, and rotation, as well as cooling to 90 K with liquid nitrogen, and heating to 1000 K.

mass spectrometer

Mass Spectrometer:

A quadrupole mass spectrometer with a 300 amu range capable of monitoring the desorption of various molecules from a surface as a function of time and surface temperature.

metal doser

Evaporative Metal Doser:

A filament-style evaporative metal doser capable of depositing metal onto a surface in vacuum.