Associate Professor, Director of UTC Institute for Advanced Systems Engineering
Ph.D., Aristotle University of Thessalonik i(2006), Greece
Postdoc, Massachusetts Institute of Technology (2009), Cambridge, MA USA
- Chemical-Looping Combustion and Reforming (NSF-sponsored)
- Biomass Catalytic Pyrolysis (UConn/CCAT-sponsored)
- Fischer-Tropsch Synthesis (ACS-PRF-sponsored)
- Biomass Gasification Tar Upgrading (NSF-sponsored)
- Advance Process Systems Engineering for Aerospace Application (UTC-sponsored)
- Refinery Simulation (W.R. Grace & Co.-sponsored)
- Simulation and Optimization of Energy Systems
Chair: Applied Chemical Technology Subdivision (ACTS) of the Industrial & Engineering Chemistry Division (I&EC) of the American Chemical Society (ACS) 2011
Member: Editorial Advisory Board, The Open Catalysis Journal.
Member: Editorial Board of the Journal of Energy and Chemical Engineering
Member: Review Editor for the Frontiers in Energy Research Journal.
Reviewer: NSF GRFP Fellowship Program 2014
Reviewer: DoE Graduate Fellowship Program 2012
Reviewer: National Defense Science & Engineering Graduate Fellowship Program 2013.
Member: Sigma Xi, The Scientific Society – MIT Chapter – (2009-present)
Member: AIChE (2006-present)
Member: ACS (2007-present)
Member: Technical Chamber of Greece (2001-present)
Member: Hellenic Chemical Engineering Society (2001-present)
Current Research Group
|Post Doctoral Associate||Ph.D. Students||Masters Students||Undergraduate Students|
|Xiaodong Yan||Kyle Such
- Collaboration with Aspen Technology Inc. in developing and implementing refined electrolyte-thermodynamic models in the Aspen simulation code.
- Scale-up of bench-scale data of W.R. Grace & Co. to industrial FCC process selectivity.
- Dynamic optimization, sensitivity analysis and model predictive control of the Boeing 787-10 cabin air compressor designed by United Technologies Corporation.
- Ph.D. Thesis applications: revamp of pilot FCC riser of CPERI (Thessaloniki, Greece); design and implementation of novel FCC model-based control structure.
Work with Underrepresented Groups:
- Strong record of undergraduate students’ participation in research, including one first place, two second place awards in the AIChE Undergraduate Student Competitions and supervision of undergraduate participations in ACS and AIChE student symposia.
- Member of the NSF Joule Fellows program (2011-2013) (high school teachers participating in research); mentor of Donna Aranibar (2012-2013) (research intro to high school student).
- Speaker for climate change teach-in in E.O. Smith High-School, Storrs, Connecticut.
George Bollas is performing research related to the design, modeling and optimization of processes that address the growing energy crisis, such as those of conventional/coal/biomass refineries and hydrogen production plants. Emerging technologies (e.g., carbon-free hydrogen production, biomass conversion to liquid fuels, hybrid/integrated hydrogen-carbon technologies, chemical looping combustion and reforming, etc.) show much promise in addressing tomorrow’s energy demand and the environmental issues associated. Besides the conceptual modern processes being proposed, traditional refinery operations are driven to extremes because of the use of heavier feedstocks and modern catalysts. Simulation can be used as a valuable tool for the design, analysis and optimization of these processes. Existing steady-state and dynamic simulation programs, thermodynamic and electrostatic theories need to be redefined for application to the new challenging processes being proposed. George Bollas’ research focuses on processes related to the production of alternative environmentally friendly energy carriers. His research approach integrates experimentation and model-assisted experimental design, process scaling and control. His current research portfolio includes model-based comparisons of processes for chemical-looping combustion with an emphasis on the scale-up of existing pilot plants to power plant capacities; experimental and theoretical studies of biomass pyrolysis, gasification, and catalyst deactivation during biomass catalytic processing; identification of unit-independent catalyst selectivity rankings by modeling bench-scale fixed and fluidized bed reactors and pilot risers for fluid catalytic cracking, development of bifunctional catalysts for Fischer-Tropsch structured (micro-) reactors, and zeolite catalysts for the upgrading of biomass gasification tar.
Research Interest: Simulation and Design of Chemical-Looping Combustion and Reforming Processes
Chemical looping combustion (CLC) or chemical looping reforming (CLR) are novel processes for heat and power production with inherent carbon dioxide capture. One very important advantage of the chemical looping system is that the gas from the reduction reactor consists of almost pure carbon dioxide and steam. Isolation of the fuel from air minimizes the number of chemical reactions and side products in the reduction reactor. Employing oxygen without nitrogen eliminates the primary source for the formation of nitrogen oxide, producing a flue gas composed primarily of carbon dioxide and steam; other trace pollutants depend on the fuel selected. Research focuses on studying appropriate materials (size, selectivity, hydrodynamic properties) and conceptual reactor designs that would take full advantage of their properties. Issues that need to be addressed include the selection of low cost oxidation catalysts, development of alternative process schemes, integration of the CLR process with a Fisher-Tropsch reactor, and the optimization of the conceptual process design.
Research Interest: Enhancing Deoxygenation and Reducing Catalyst Deactivation in Biomass Catalytic Pyrolysis
The objective of this work is to explore the role of catalytic additives and co-feeding of biomass with hydrogen-rich hydrocarbons on unleashing the potential of biofuel technologies. The origins of catalyst deactivation during biomass catalytic pyrolysis are explored as a function of the catalytic coke formation. The overall aim is to enhance understanding of the parallel contributions of catalytic and feedstock enhancements to lignocellulosic biomass pyrolysis. The main hypothesis explored is that bifunctional catalysts and co-pyrolysis with hydrogen-rich hydrocarbons can significantly improve the selectivity of biomass pyrolysis towards aromatic hydrocarbons, while reducing undesirable coke formation. The key ideas are to investigate the effect of CH4 co-feeding on lignocellulose pyrolysis selectivity, and to interpret laboratory measurements into theoretical insights of the contribution of coke formation to catalyst deactivation.
Research Interest: Advanced Coal-Biomass-to-Liquid (CBTL) Systems Configurations and Efficiency Analysis: Systems Optimization with Emphasis on Incorporation of Advanced Fuel Cells
We are investigating carbon dioxide (CO2) management technologies. Elements of this include evaluation and recommendation for future testing of carbon capture, sequestration and reuse technologies. This project focuses on optimizing process flowsheets for conversion of coal and biomass mixtures to liquid hydrocarbons and energy with in-situ CO2 capture. Implementation of fuel cells for improving carbon capture efficiency and gas fuel utilization is explored by developing flowsheets with FCs for power generation. Alternative process flowsheets are developed and evaluated in terms of efficiency and CO2 separation capability and optimized for the intermediate temperatures and pressures required. This poly-generation study will include a sensitivity analysis to identify the accuracy of the proposed process efficiency estimate as a function of model parameters, assumptions and process constraints.
Research Interest: Refinery Operations
Design of more efficient/selective catalysts for the current refinery processes (e.g., fluid catalytic cracking and hydrocracking) and the use of heavier feedstocks are expected to change considerably the established principles in design and modeling of these processes. Fundamental models that deal explicitly with the selective behavior of the catalyst and the reaction mechanisms of heavier hydrocarbons under cracking conditions are, thus, highly desirable as a short-term solution to the forthcoming energy crisis. Kinetic models and catalytic deactivation pathways can be combined for the detailed simulation of catalytic processes. Understanding the particular effects of inter-particle and intra-particle diffusion and the reaction kinetics on the surface zeolite and active matrices can lead to better catalyst formulations and improved product selectivity. Modeling of laboratory catalyst testing reactors and their scaling-up to translate the results to catalyst selectivity in commercial reactors can improve the efficiency of catalyst testing procedures and thus help the overall effort in getting more out of crude.
Research Interest: Turning Tars into Energy: Zeolites with Hierarchical Pore Structure for Cat Cracking of Tars
This project aims at conversion of waste tars compounds into valuable gases using one step catalytic process. The importance of this research is driven by three significant factors: (a) the detrimental effect of tars in downstream gasification processes, (b) the carcinogenic nature of tars (multi-ring aromatic hydrocarbons), which makes their disposal impossible and (c) the potential to increase the efficiency of the overall biomass gasification process by transforming byproducts to valuable products. The key objective in this research is to test the hypothesis that zeolite-based materials with hierarchical pore network architecture will eliminate the diffusion limitations of the heavy multi-ring aromatic compounds hydrocarbons present in tars and will accommodate their cracking. Moreover, they will provide the open framework structure for the incorporation of transition metals, which will enhance the reforming reactions of the produced lighter hydrocarbons to synthesis gas.
Research Interest: Fischer-Tropsch Synthesis in Structured Reactors
Fischer-Tropsch synthesis can contribute significantly to the production of liquid fuels, reducing our dependency on foreign oil. Energy independence and security, and reduced environmental impact (depending on the raw source of syngas and other carbon capture technologies) are some of the merits of making Fischer-Tropsch a more efficient and less centralized process. Fischer-Tropsch Synthesis combined with biomass gasification technologies can also result in renewable, sustainable and environmentally friendly process life-cycles. Unleashing the potential of biomass gasification technologies for fuel production, through Fischer-Tropsch Synthesis, requires scalable and more efficient Fischer-Tropsch technologies and catalysts. Among the many challenges in Fischer-Tropsch catalysis, process intensification for scalable processes and selectivity to gasoline-range products are of interest.
Research Interest: Processing of Waste CO2 to Solid Carbon and Liquid Fuels
This project focuses on exploring novel options for CO2 utilization through processes that involve dry reforming of light hydrocarbons. The proposed work focuses on the conversion of CO2 to liquid fuels and solid carbon. The former serves the purpose of improving the overall process economics for CO2 sequestration, while the latter serves as an optimal option for concentrating and storing CO2. This project addresses the major challenges of energy production, energy storage, and CO2 utilization as an integrated problem. The overall goal of this project is to explore a novel process of indirect conversion of CO2 to carbon nanofibers, validated theoretically and experimentally. The process options considered are relevant to CO2 captured via chemical-looping combustion, which is delivered at atmospheric conditions, in contrast to the high-pressure CO2 storage technologies.
Research Interest: Systems Approach on Advanced Utilization and Exploration of Dynamic Models of Thermal Fluids Applications
This project will develop and explore novel system representations (steady state and dynamic models) of thermal fluid systems (TFS) in equation-oriented environments. These models, developed to study and optimize cabin temperature control in aerospace applications, shall be embeddable in program architectures that allow system dynamic optimization, sensitivity and uncertainty analysis, fault detection and optimal control. The main focus of this project is on systems under uncertainty, disturbances and degradation, under conventional and optimal control, with the objective to explore system reliability and optimality, guide experiments for the identification of failures, explore the impact of degradation and methods for failure prognosis and understand the effect of system size on system stability. These constrained problems, cast as dynamic sensitivity analysis and optimization programs, will use well-established and novel UTC TFS as paradigms for dynamic analysis. Transformative components of this project include: a) novel methods for system dynamic optimization, taking into account transient sensitivities; b) system-level dynamic sensitivity analysis in virtual process environments; c) optimal design of experiments that reveal controllability issues and employ fault detection strategies; and d) evaluation of the value proposition of model predictive control for TFS. This project is sponsored by the UTC Institute for Advanced Systems Engineering (http://www.utc-iase.uconn.
|2009||Research Associate, Rive Technology Inc., Cambridge, MA, USA|
|2006 – 2009||Postdoctoral Research Associate, Massachusetts Institute of Technology, Department of Chemical Engineering, Cambridge MA, USA|
|2004 – 2006||Cooperative Research Member, Automation Department, Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, Greece|
|2001 – 2006||Doctoral Research Assistant, CPERI, Thessaloniki, Greece|
|1999 – 1999||Pre-graduate Scholarship, Aristotle University of Thessaloniki, Greece|
Awards & Honors
|2013||ACS Petroleum Research Found Doctoral New Investigator Award 2013|
|2011||NSF CAREER Award|
|2011||Elected Chair for the Applied Chemical Technology Subdivision (ACTS) of the American Chemical Society (ACS)|
- Zhou Z, Han L, Nordness O, Bollas GM. Continuous regime of chemical looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) reactivity of CuO oxygen carriers. Appl. Catal. B Environ. 2015;166-167:132-44.
- Fischer A, Du S, Valla JA, Bollas GM. The effect of temperature, heating rate, and ZSM-5 catalyst on the product selectivity of the fast pyrolysis of Spent Coffee Grounds, RSC Adv. 2015; 5, 29252–61.
- Du S, Sun Y, Gamliel DP, Valla JA, Bollas GM. Catalytic pyrolysis of miscanthus × giganteus in a spouted bed reactor. Bioresour Technol.2014;169:188-97.
- Zhou Z, Han L, Bollas GM. Kinetics of NiO reduction by H2 and Ni oxidation at conditions relevant to chemical-looping combustion and reforming. Int J Hydrogen Energy. 2014;39: 8535-56.
- Han L, Zhou Z, Bollas GM. Heterogeneous Modeling of Chemical-Looping Combustion. Part 2: Particle Model. Chem Eng Sci. 2014;113:116-28.
- Zhou Z, Han L, Bollas GM. Overview of Chemical-Looping Reduction in Fixed Bed and Fluidized Bed Reactors Focused on Oxygen Carrier Utilization and Reactor Efficiency. Aerosol Air Qual Res. 2014;14:559-71.
- Noshadi I, Kanjilal B, Du S, Bollas GM, Suib SL, Provatas A, Liu F, Parnas RS. Catalyzed production of biodiesel and bio-chemicals from brown grease using Ionic Liquid functionalized ordered mesoporous polymer. Appl Energy.2014;129:112-22.
- Zhou Z, Han L, Bollas GM. Model-based Analysis of Bench-Scale Fixed-Bed Units for Chemical-Looping Combustion. Chem Eng J. 2013;233:331-48.
- Han L, Zhou Z, Bollas GM. Heterogeneous Modeling of Chemical-Looping Combustion. Part 1: Reactor Model. Chem Eng Sci. 2013;18:233-49.
- Du S, Valla JA, Bollas GM. Characteristics and Origin of Char and Coke from Fast and Slow, Catalytic and Thermal Pyrolysis of Biomass and Relevant Model Compounds. Green Chem. 2013;15(11):3214-29.