designing sustainable chemistry in a process intensified...

Office of Research and DevelopmentNational Risk Management Research Laboratory; Sustainable Technology Division July 28, 2010

Michael A. Gonzalez Ph.D.Director, Sustainable Chemistry Program

Designing SustainableChemistry in a Process Intensified Environment

Scope of Presentation

• Office of Research and Development• Sustainable Technology Division

– Areas of Concentration• Holistic Approach• Sustainable Chemistry

– Reaction / Synthesis– Reactor Modeling– Sustainability Metrics

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Mission of the United StatesEnvironmental Protection Agency

• “To safeguard and protect human healthand the environment”

• Office of Research and development• Yes, we have one

• 10 Laboratories and facilities across the nation• Offices in DC

Sustainable Technology DivisionNational Risk Management Research LaboratoryCincinnati, Ohio

• Life Cycle Assessment (LCA)• Life Cycle Impact Assessment• Decision Theory• Industrial Ecology• Chemistry• Chemical Engineering• Technology Development• Process Optimization

• Economic Theory• Policy• Legal Aspect• Hydrology• Ecology• Cost Engineering• Energy• Metrics and Indicators

3 www.epa.gov/ORD/NRMRL/std

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What is Sustainability?

Why Sustainable Chemistry?

• Can we apply a holistic/systems perspective/life cycle view towards chemical synthesis?

• Can we utilize technology to influence chemical synthesis?

• Can we utilize chemical synthesis to influence process design?

• Can we understand and quantify areas of opportunity within a chemical synthesis or process?

• Can we design sustainable chemical processes?

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Sustainable Chemistry

• Philosophy / Methodology• Chemical Synthesis• Reactor Design / Optimization• Reactor Modeling• Sustainability Metrics

– GREEnSCOPE

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Traditional Thinking

Chemistry Applied Chemistry

Bench-ScaleEngineering Pilot Plant

PlantScale

Multi-disciplinary Approach

Chemist

ChemicalEngineer

Conceptual-ization Chemistry Pilot Plant Plant

Scale

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Multi-Disciplined Approach

• Incorporate Chemistry and Chemical Engineering from the onset of research

• Not only improve the chemistry, but begin to envision the process design for the new reaction/technology

• Address the problems at the bench-scale not later in the development

• Experience the full range of benefits or potential

• Begin thinking of the big picture

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Process Intensification

• Ability to have a minimized physical and environmental footprint, while maintaining or increasing desired throughput

• Potential Benefits (some):– Reduced energy usage– Reduced solvent usage– Minimal by-product formation– Minimal separation steps– Increased worker safety– Increased feedstock utilization – Improved conversions and selectivities– Improved ease of product stream switching

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• The STT® is a 2-D reactor.

• Shear (mass transfer) and flow rate (residence time) are independently variable.

• Advantages include:– Improved reaction

control (yield, selectivity)

– Decreased reaction time (often 2-3 orders of magnitude)

– Scalability– Easier product

switching

STT® Reactor Basics

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STT® Cross-Section View

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• Thin-film flow is bounded between heat transfer surfaces

• Shear rate dependent on rotor speed and reactor dimensions (gap)

• Residence time dependent on reagent flow rate and reactor dimensions (length and gap)

• Minimized back-mixing

STT® Flow Characteristics

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• Liquid– Pumps (syringe, gear,

HPLC)• Gases

– Mass flow meters• Solid reagents

– dissolve and pump– melt and pump– suspend and pump

• suspension must be stable

• particle size must be compatible with rotor/stator gap

Schematic Representation of the Process

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*Reference bars are 18 inches long.

STT® Models – Working Volumes from 1.2 mL to 50 mL

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Experimental Setup

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Experimental Setup

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Innovator 200 STT® Reactor

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Mettler-Toledo MultiMax FTIR – High Pressure

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Currently:

• Batch production, High Temperatures, Long Rnx Time• Reaction solvent required, Excess Halide• Purification needed

Goals:• Continuous-flow process, Simple• Solvent-less• Minimize product purification

N

N

+ RXN

N

R

X-

Synthesis of Ionic Liquids

Alkylating Reagent (equiv.)

Product T(˚C)

Production Rate (g/min, kg/day)

Conversion (%)

ethyl chloride(1.19) 174

0.1, 0.1c0.5, 0.7c1.0, 1.4c

926638

ethyl bromide (1.20) 112

2.0, 2.93.5, 5.06.2, 8.9

9.6

>99937446

ethyl iodide (1.06) 83

5.0, 7.211.5, 16.620.0, 28.8

>99>9991

ethyl tosylate (1.25) 102

1.4, 2.02.8, 4.05.6, 8.1

>99>99>99

ethyl triflate (1.01) 73

2.8, 4.05.9, 8.5

12.4, 17.9

>99>99>99

Alkylating Reagent (equiv.)

Product T(˚C)

Production Rate (g/min, kg/day)

Conversion (%)

ethyl bromide (1.20) 112

2.0, 2.93.5, 5.06.2, 8.99.6, 13.8

>99937446

isopropyl bromide (1.07) 176 1.8, 2.6 76

t-butyl bromide (1.06) 106 2.0, 2.9 >99

benzyl bromide (1.05) 155

2.7, 3.95.4, 7.8

10.9,16.0

>99>99>99

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Synthesis of 1-butyl-3-methyl- imdiazolium bromide

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Synthesis of 1-butyl-3-methyl-imdiazolium bromide

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Magellan® Reactor Set-up

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Currently:

• Batch production – Low Conversion – Long RNX Time• Lewis Acid• Reaction solvent often required - usually to form an

azeoptrope• Purification needed

Goals:• Continuous-flow, faster process• Solvent-less, No Lewis Acid• Minimize product purification

H2NH

ON

H

+ + H2O

Synthesis of Imines (Schiff Bases)

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Reaction Modeling

• Goal is to better understand the STT® reactor• Model a spinning thin film in a plug flow motion• Predict reaction conditions• Correlate with experimental data• Faster process optimization• Design chemical synthesis in-silico

• Project to begin in August 2010

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Motivation

• Considerable research being performed in GCE, without a clear method to determine if the new research is improved over current in terms of greenness.

• There is a need for an evaluation methodology to determine and evaluate if the new technology is actually increasing the sustainability of a reaction/process.

• We can develop and use this methodology to influence research (lab-scale) which in turn influences process design.

• Can be viewed as a union of chemistry (What should we really be doing?) and engineering (How can it get involved in research at an earlier stage?).

• How do we know what we’re doing is better?• Is the research worth pursuing?

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Sustainability Metrics

• This portion allows the entire research program to be tied together.

• From bench to pilot-scale

• Measure of how effective the technology is, should be or where we need to be.

• Now we can measure how we are doing and how well we have done.

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GREEnSCOPE

Gauging ReactionEffectiveness for the ENvironmental Sustainability of Chemistries with a

multi-Objective Process Evaluator

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Basis of this Methodology

Efficiency(Reaction)

EnvironmentalEnergy

Economics

SustainableProcess

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Examples of Metrics

• Energy – reaction temperature, separations, recycle loops, pumps, heat integration

• Efficiency – atom economy, % conversion, % selectivity, by-product minimization

• Environment – solvent usage, fugitive emissions, heat dissipation

• Economics – material feeds, separation costs, capital, atom loss, by-product formation

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What information do we need?

Determine Information Needed

Products to measure StoichiometryReactor distribution Feed & product measures

Molecular weightsScale-up Flow, product destinationsEP (input/output) Chemical pricesConversion Feed measures (in & out)Atom economy Stoichiometry, MWsSelectivity Reactor distributionSeparation design Rel.volatility,Ht.vap.,TbpEnergy Flows, rxn temp., Cp, SepnEnvironmental impacts Impact database, flows,

Product destinations

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How are we Different?

• Our methodology is based on:

• Simplicity; ease of use and information needs• User defines level of desired information• Ability to be used for decision making• Understandable by a variety of audiences • Offers reproducibility• Each E is dependent on one another• The evaluation can be based on lab or plant-scale • Allows for a direct comparison – apples to oranges• Quantitative

• By incorporating WAR into the evaluator, we can identify and quantify potential environmental impacts (PEI).

• Development of an absolute scale, not relative or color coded. Others are limited by using a relative scale, no idea of level.

• Tradeoffs will exist.

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Why use Metrics?

• Identify reactions/processes to be investigated

• Determine levels needed to achieve

• Determine endpoint of a research project.

• What if scenario…

• Justification of research

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Summary

• In order for Sustainable Chemistry to progress and be successful, researchers must be forward thinking

• Must utilize a multi-disciplinary approach from the onset

• Use Green Chemistry and Engineering to improve the overall process

• Improvements to the entire process can be realized from improving the chemical reaction parameters

• Utilize sustainability metrics to quantify levels of improvements and observe areas of opportunity

• Metrics must be transparent, easily calculable, comparable between processes, logical and mathematically-based.

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Acknowledgements

• Dr. Raymond Smith, Dr. Douglas Young, Dr. Lee Vane• Dr. Gerardo Ruiz-Mercado (ORISE)• Dr. David Meyer• Dr. Jim Ciszewski• Mr. Tyler O’Dell – Lake Superior State University• Dr. Will K. Kowalchyk - Mettler-Toledo AutoChem, Inc.• Office of Research and Development

• Disclaimer:

–This research was performed under a Cooperative Research and Development Agreement (CRADA; # 0252-03) between Kreido Laboratories and the U.S. Environmental Protection Agency.

– It is understood the use of products in this research is not an endorsement by the U.S. Environmental Protection Agency.

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Principles of Green Chemistry

1. Prevention (Overall)2. Atom Economy3. Less Hazardous

Chemical Syntheses 4. Designing Safer

Chemicals5. Safer Solvents and

Auxiliaries6. Design for Energy

Efficiency

7. Use of Renewable Feedstocks

8. Reduce Derivatives9. Catalysis10. Design for Degradation11. Real-time Analysis for

Pollution Prevention12. Inherently Safer Chemistry

for Accident Prevention

Anastas, P.T., and Warner, J.C., Green Chemistry: Theory and Practice, 1998

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12 More Principles of Green Chemistry

1. Identify by-products; quantify if possible

2. Report conversions, selectivities and productivities

3. Establish a full mass balance for the process

4. Quantify catalyst and solvent losses

5. Investigate basic thermochemistry to identify exotherms (safety)

6. Anticipate other potential mass and energy transfer limitations

7. Consult a chemical or process engineer

8. Consider the effect of the overall process on choice of chemistry

9. Help develop and apply sustainable measures

10. Quantify and minimize use of utilities and other inputs

11. Recognize where operator safety and waste minimization may be incompatible

12. Monitor, report and minimize waster emitted to air, water and solids from experiments or process

Winterton, N., Green Chemistry, 2001, G73-G75

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12 Principles of Green Engineering

1. Inherent rather than circumstantial

2. Prevention instead of treatment

3. Design for separation4. Maximize mass,

energy, space, and time

5. Output-pulled versus input-pushed

6. Conserve complexity

7. Durability rather than immortality

8. Meet need, minimize excess

9. Minimize material diversity

10. Integrate local material and energy flows

11. Design for commercial “afterlife”

12. Renewable rather than depleting

Anastas, P.T. and Zimmerman, J.B., Environ. Sci. Technol. 37 (5), pp 94A-101A, 2003.

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The Sandestin Declaration of Green Engineering Principles

• Engineer processes and products holistically, use systems analysis, and integrate environmental impact assessment tools.

• Conserve and improve natural ecosystems while protecting human health and well-being.

• Use life-cycle thinking in all engineering activities• Ensure that all material and energy inputs and outputs are as

inherently safe and benign as possible. • Minimize depletion of natural resources.• Strive to prevent waste.• Develop and apply engineering solutions, being cognizant of

local geography, aspirations and cultures.• Create engineering solutions beyond current or dominant

technologies; improve, innovate, and invent (technologies) to achieve sustainability.

• Actively engage communities and stakeholders in the development of engineering solutions.

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Sustainable Chemistry

• Important: Must recognize the difference between “green” and “sustainable” chemistry

• Green Chemistry is focused on the design, manufacture, and the use of chemicals and chemical processes that have little or no pollution potential or environmental risk.

• Sustainable Chemistry not only includes the concepts of green chemistry, but also expands the definition to a larger system than just the reaction.

• Also considers the effect of processing, materials, energy, and economics.

• Now we can ask the following questions:– Which is more important?– Which is more desirable?– Can we have a sustainable process which is green?

Or more importantly:– Can a green process be sustainable?

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What Does the Chemist Bring?

• Synthesis expertise – i.e. catalysis• Reaction knowledge• Physical and chemical property information• Reaction trends• New reaction technologies• Solvent usage

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What Information Does the Chemical Engineer Need?

• Chemical engineer needs mass and energy inputs/outputs to analyze and to design scaled-up processes.

• Knowing the product distribution leaving the reactor system is critical.

• Obtaining data before maximum yield (i.e., at high selectivity) is very valuable. The cost of raw materials may be the most significant aspect of creating economic designs.

• For environmentally conscious process designs, reactor by-products have to be reacted or treated, or they will be released. Less feed into process means less by-products.

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What Information Does the Chemical Engineer Need?

• Is conversion relatively high? How large will scaled-up recycle loops be? Are separation costs for recycle loops large?

• The type and amount of energy and the process for generating it determine the potential impacts (of energy use). Thus, the temperature at which energy is needed is important.

• Is the chemist using a favorite solvent or the best (environmental) one? Can the reaction be done neat?

• How will mass transfer effects influence a scaled-up process?

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Now to be considered…

• Compressors, pumps

• Separations

• Storage

• Treatment

• Permits

• Transportation

• Heating

• Reactor Geometry

• Stirring

• Recycle loops

• Waste Streams

• Vent Gases

• Heat Integration

• To name a few

designing sustainable chemistry in a process intensified...

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