Designing Sustainable Chemistry in a Process Intensified Environment. Michael A. Gonzalez Ph.D. Director, Sustainable Chemistry Program

Transcription

1 Designing Sustainable Chemistry in a Process Intensified Environment Michael A. Gonzalez Ph.D. Director, Sustainable Chemistry Program Office of Research and Development National Risk Management Research Laboratory; Sustainable Technology Division July 28, 2010

2 Scope of Presentation Office of Research and Development Sustainable Technology Division Areas of Concentration Holistic Approach Sustainable Chemistry Reaction / Synthesis Reactor Modeling Sustainability Metrics 1

3 Mission of the United States Environmental Protection Agency To safeguard and protect human health and the environment Office of Research and development Yes, we have one 10 Laboratories and facilities across the nation Offices in DC 2

4 Sustainable Technology Division National Risk Management Research Laboratory Cincinnati, 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

5 4 What is Sustainability?

6 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? 5

7 Sustainable Chemistry Philosophy / Methodology Chemical Synthesis Reactor Design / Optimization Reactor Modeling Sustainability Metrics GREEnSCOPE 6

8 7

9 Traditional Thinking Chemistry Applied Chemistry Bench-Scale Engineering Pilot Plant Plant Scale Multi-disciplinary Approach Chemist Conceptualization Chemistry Pilot Plant Plant Scale Chemical Engineer 8

10 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 9 Begin thinking of the big picture

11 10

12 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 11

13 STT Reactor Basics 12 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

14 13 STT Cross-Section View

15 STT Flow Characteristics 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 14

16 Schematic Representation of the Process 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 15

17 STT Models Working Volumes from 1.2 ml to 50 ml *Reference bars are 18 inches long. 16

18 17 Experimental Setup

19 18 Experimental Setup

20 19 Innovator 200 STT Reactor

21 20 Mettler-Toledo MultiMax FTIR High Pressure

22 Synthesis of Ionic Liquids N N + RX N N R X - Currently: Batch production, High Temperatures, Long Rnx Time Reaction solvent required, Excess Halide Purification needed 21 Goals: Continuous-flow process, Simple Solvent-less Minimize product purification

23 Alkylating Reagent (equiv.) Product T ( C) Production Rate (g/min, kg/day) Conversion (%) ethyl chloride (1.19) , 0.1c 0.5, 0.7c 1.0, 1.4c ethyl bromide (1.20) , , , > ethyl iodide (1.06) , , , 28.8 >99 >99 91 ethyl tosylate (1.25) , , , 8.1 >99 >99 >99 ethyl triflate (1.01) , , , 17.9 >99 >99 >99

24 Alkylating Reagent (equiv.) Product T ( C) Production Rate (g/min, kg/day) Conversion (%) ethyl bromide (1.20) , , , , 13.8 > isopropyl bromide (1.07) , t-butyl bromide (1.06) , 2.9 >99 benzyl bromide (1.05) , , ,16.0 >99 >99 >99

25 24 Synthesis of 1-butyl-3-methyl- imdiazolium bromide

26 25

27 26 Synthesis of 1-butyl-3-methyl-imdiazolium bromide

28 27 Magellan Reactor Set-up

29 28 Magellan Reactor Set-up

30 29 Magellan Reactor Set-up

31 30 Magellan Reactor Set-up

32 Synthesis of Imines (Schiff Bases) H 2 N O H Currently: H N + + H 2 O Batch production Low Conversion Long RNX Time Lewis Acid Reaction solvent often required - usually to form an azeoptrope Purification needed 31 Goals: Continuous-flow, faster process Solvent-less, No Lewis Acid Minimize product purification

33 32 Synthesis of Imines (Schiff Bases)

34 33 Synthesis of Imines (Schiff Bases)

35 34

36 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

37 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? 36

38 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. 37

39 GREEnSCOPE Gauging Reaction Effectiveness for the ENvironmental Sustainability of Chemistries with a multi-objective Process Evaluator 38

40 Basis of this Methodology Sustainable Process Efficiency (Reaction) Economics Energy Environmental 39

41 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 40

42 What information do we need? Determine Information Needed Products to measure Reactor distribution Scale-up EP (input/output) Conversion Atom economy Selectivity Separation design Energy Environmental impacts Stoichiometry Feed & product measures Molecular weights Flow, product destinations Chemical prices Feed measures (in & out) Stoichiometry, MWs Reactor distribution Rel.volatility,Ht.vap.,T bp Flows, rxn temp., C p, Sepn Impact database, flows, Product destinations 41

43 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. 42

44 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 43

45 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. 44

46 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: 45 This research was performed under a Cooperative Research and Development Agreement (CRADA; # ) 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.

47 46

48 Principles of Green Chemistry 1. Prevention (Overall) 2. Atom Economy 3. Less Hazardous Chemical Syntheses 4. Designing Safer Chemicals 5. Safer Solvents and Auxiliaries 6. Design for Energy Efficiency 7. Use of Renewable Feedstocks 8. Reduce Derivatives 9. Catalysis 10. Design for Degradation 11. Real-time Analysis for Pollution Prevention 12. Inherently Safer Chemistry for Accident Prevention 47 Anastas, P.T., and Warner, J.C., Green Chemistry: Theory and Practice, 1998

49 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 48 Winterton, N., Green Chemistry, 2001, G73-G75

50 12 Principles of Green Engineering 1. Inherent rather than circumstantial 2. Prevention instead of treatment 3. Design for separation 4. 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 49 Anastas, P.T. and Zimmerman, J.B., Environ. Sci. Technol. 37 (5), pp 94A-101A, 2003.

51 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. 50

52 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? 51

53 What Does the Chemist Bring? Synthesis expertise i.e. catalysis Reaction knowledge Physical and chemical property information Reaction trends New reaction technologies Solvent usage 52

54 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 byproducts. 53

55 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? 54

56 Now to be considered Compressors, pumps Separations Storage Treatment Permits Transportation Reactor Geometry Stirring Recycle loops Waste Streams Vent Gases Heat Integration 55 Heating To name a few