Research Projects

Current Research Topics:

 

Heterogeneous Catalysis

Syngas Conversion to Higher Alcohols

Hydrodeoxygenation of Biomass-Derived Oxygenates

Zeolite Catalyzed Phenol Alkylation

Supported Copper Oxide Catalysts for Oxidation and Coupling Reactions

Palladium Catalyzed Semi-Hydrogenation of Alkynes to Produce Olefins

 

Supported Molecular Catalysis

Supported M-Salen Complex Catalysts for Enantioselective Reactions

Design of Supported Catalysts for Enantioselective Reactions in Flow Reactors

Design of Acid-Base Bifunctional Catalysts on Silica and Polymer Supports

 

Separations

Supported Amine Materials for CO2 Capture from Flue Gas

Supported Amine Materials for CO2 Capture from Ultra-Dilute Gases such as Ambient Air

Dynamics of CO2 Adsorption on Supported Amine Materials

Amine-Modified Mesoporous Silica Membranes

Zeolite Modification for Incorporation in Mixed-Matrix Membranes

Metal-Organic Framework Materials as Membranes and Adsorbents

 

Reactive Separations

Alkane Dehydrogentation in Catalytic Zeolite Membrane Reactors

Separation and Reaction of Trace Air Pollutants

 

Selected Research Descriptions:

 

Catalytic Chemistry for Fine Chemical and Pharmaceutical Synthesis

Immobilized metal complexes have the potential to combine the best attributes of both homogeneous (highly active and selective) and heterogeneous (easy separation from the reaction media) catalysts. Despite this possibility, there have been few large scale industrial applications of immobilized molecular catalysts where catalyst recovery is desired. Due to the fact that the field lies at the historical interface of homogeneous and heterogeneous catalysis, the science of catalysis by immobilized organometallics has not become highly developed, as there have been few long term, detailed investigations of specific catalytic systems. To this end we have established a collaborative GT-NYU Program on Supported Molecular Catalysis to undertake a thorough, multi-faceted investigation into these important catalytic systems. In this Department of Energy sponsored program, we are working in conjunction with the Weck Group in chemistry at NYU, the Sherrill Group in Chemistry and Biochemistry at Georgia Tech, and the Jang Group in Materials Science and Engineering at Georgia Tech. The focus of our investigations has centered on the understanding the structural factors that influence the activity and selectivity of Co-Salen catalysts for kinetic resolution of epoxides by ring-opening with various nucelophiles. These catalysts are interesting targets for catalyst immobilization studies, because they generally operate by a coopertaive cataltic mechanism, whereby two salen complexes must cooperate to effectively enhance the rate of reaction and thus the organization of two complexes can be facilitated by smart immobilization strategies. From this supported salen platform, other cooperative and standard catalytic reactions are being studied on polymeric supports, and cooperative acid-base systems based on organic modified porous oxides are also being evaluated.

 

Conversion of Synthesis Gas to Oxygenates over Supported MoS2 Catalysts

In a collaboration with the Dow Chemical Company, we are working on the design and understanding of supported catalysts for the conversion of syngas to higher alcohols, with a specific focus on producing alcohol distributions shifted away from methanol production. Several new catalysts based on K/MoS2 compositions on oxide and carbon supports have been developed, and reaction pathways leading to enhanced higher alcohol selectivity are being explored.

 

Catalytic Dehydrogenation of Alkanes to Alkenes in Membrane Reactors

In a collaboration with the Dow Chemical Company, we have launched a new project exploring zeolite-based membrane reactors for alkane dehydrogenations. This is a collaboration with the Sholl and Nair groups.

 

Catalytic Conversion of Biomass and Utilization of Chemicals Derived from Biomass

Working with the Institute of Paper Science and Technology (IPST) at Georgia Tech, we are studying the conversion of woody biomass as a feedstock for chemicals and energy. Biomass, and especially woody biomass, represents a vast, under-utilized, domestic, renewable feedstock for the production of chemicals and fuels. Working with Professor, Pradeep Agrawal , we have embarked on a program investigating the depolymerizationof lignin and its conversion to chemicals and fuels. Our past studies have also investigated solublization of sugars from lignicelulosic biomass via catalytic hydrolysis.

 

CO2 Capture from Dilute Gas Streams (Flue Gas, Natural Gas, etc.)

There is growing political pressure world-wide to cut down on CO2 emissions in an attempt to slow the rate of global warming. Much of the CO2 emitted comes from gas or coal-fired power plants. The huge scale on which CO2 is produced at these sites and the fact that the gases are emitted at single point sources (as opposed to at millions of points spread across the country as in the case of automobiles) makes these streams potentially viable targets for CO2 capture strategies. A common, traditional CO2 capture strategy is to use aqueous solutions of amines for the absorptive separation of CO2 from natural gas, for example. After absorption, the amines are regenerated by CO2 removal induced by a temperature swing. However, the vast amount of energy to heat an aqueous solution in a temperature swing process and the corrosion of process equipment associated with aqueous bases make this technology quite expensive for flue gas applications. An alternative that has attracted attention in recent years is adsorptive separation using amine-functionalized oxides or polymers in a fluidized bed or other configuration. Our group has extensive experience in the design and characterization of oxide-supported amine materials for CO2 capture. We balance fundamental studies on the impact of adsorbent structure on separation performance with applied studies evaluating practical aspects of the use of amine adsorbent materials. Our group invented class 3 aminosilica materials, which are based on the in-situ polymerization of amine-containing monomer on/in a porous support, and described these materials in 2008 (paper 57 in publication list). We have also written a comprehensive review of adsorbent materials for CO2 capture from flue gas (paper 73) and another on oxide-supported amine materials for acid gas separations (paper 110). We were the first group to report the oxidative stability of supported amine adsorbents in 2010 (paper 93), and the first to identify materials based on primary 3-aminopropyl groups as highly stable to oxidation (paper 105). Currently, we are leading a multi-faceted effort to implement oxide-supported amine adsorbents in a new scalable contactor, based on a rapid-temperature swing adsorption (RTSA) process invented by Koros (paper). This program, launched in 2011, is supported by DOE-NETL and involves 4 other PIs ( Realff , Koros , Kawajiri , Sholl ) and 3 partner companies.

 

CO2 Capture from Ultra-Dilute Gas Streams - Ambient Air

Implementation of CO2 capture from large point sources such as power plants on a large scale is a first step towards combatting CO2-induced climate change. However, this approach can only address about 1/3-1/2 of CO2 emissions. Roughly 1/3 of CO2 emissions are associated with mobile sources such as planes, cars, trucks, ships, etc. One approach to address these emissions is to extract CO2 directly from the atmosphere. Since 2008, we have worked with a start-up company, Global Thermostat, to design and implement supported amine adsorbents for CO2 capture from ambient air and other ultra-dilute gas streams. In 2009 we described the use of supported amine adsorbents for extraction of CO2 from ambient air at the Fall AIChE Annual Meeting. In 2011, we wrote the first review of modern research on CO2 capture from air, and published the first examples of class 1 and class amine adsorbents for CO2 capture from air. In 2012, we demonstrated that primary amines are better suited for CO2 capture from air than secondary or tertiary amines (paper 123).

In addition to capturing CO2 for sequestration purposes (implemented alongside CO2 capture from point sources, not instead of point source capture), “air capture” shows promise as a way to generate CO2 in remote locations for beneficial use, such as greenhosue or algae-biofuel production, for food service, or for EOR.

 

Synthesis, Characterization and Application of Porous Materials

Silicas: The Jones group is widely involved in the engineering of porous silica for applications in catalysis and separations, as described above. Silica is our support of choice for catalyst immobilization as its particle size, porosity and surface chemistry can be easily manipulated to produce well-defined, desired structures. Furthermore, silica is environmentally benign, inexpensive and chemically inert in most media, making it an ideal support material. In many cases, well-defined hexagonal or cubic mesoporous silicas such as MCM-41, MCM-48 or SBA-15 are synthesized and utilized as model hosts for catalytic and adsorption applications.

Zeolites: We are also working in the area of zeolite synthesis and surface modifications. The Jones group has the capacity to prepare virtually any known molecular sieve. Working with Professors Bill Koros and Sankar Nair , we are working on the synthesis, functionalization and optimization of surface-modified zeolites for mixed-membrane applications. We also characterizing zeolite catalysts for acid-catalyzed phenol conversions relevant to biomass upgrading into chemicals and fuels.

MOFs: We are exploring MOFs for separation applications, in collaboration with the Sholl , Nair , Walton and Koros groups. We have described some of the first hybrid MOFs, made from mixed linkers (paper ) and are exploring mixed matrix (MOF-polymer) and polycrystalline MOF film membranes for gas separations and pervaporation. We have also modified MOFs with amine sites for CO2 capture from air (paper 118). This paper, published in parallel with independent work by others, is the first description of CO2 capture from air with MOFs.