Novel Process Windows E-Book

Volker Hessel

• Herausgeber: Wiley-VCH
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 445

Veröffentlichungsjahr: 2014

Beschreibung

This book introduces the concept of novel process windows, focusing on cost improvements, safety, energy and eco-efficiency throughout each step of the process.

The first part presents the new reactor and process-related technologies, introducing the potential and benefit analysis. The core of the book details scenarios for unusual parameter sets and the new holistic and systemic approach to processing, while the final part analyses the implications for green and cost-efficient processing.

With its practical approach, this is invaluable reading for those working in the pharmaceutical, fine chemicals, fuels and oils industries.

Leseprobe

Table of Contents

Cover

Related Titles

Title Page

Copyright

Dedication Page

Motivation – Who Should Read the Book!?

Acknowledgments

Abbreviations

Nomenclature

Chapter 1: From Green Chemistry to Green Engineering – Fostered by Novel Process Windows Explored in Micro-Process Engineering/Flow Chemistry

1.1 Prelude – Potential for Green Chemistry and Engineering

1.2 Green Chemistry

1.3 Green Engineering

1.4 Micro- and Milli-Process Technologies

1.5 Flow Chemistry

1.6 Two Missing Links – Cross-Related

References

Chapter 2: Novel Process Windows

2.1 Transport Intensification – The Potential of Reaction Engineering

2.2 Chemical Reactivity in Match or Mismatch to Intensified Engineering

2.3 Chemical Intensification through Harsh Conditions – Novel Process Windows

2.4 Flash Chemistry

2.5 Process-Design Intensification

References

Chapter 3: Chemical Intensification – Fundamentals

3.1 Length Scale

3.2 Time Scale

3.3 Length and Time Scale of Chemical Reactions

3.4 Temperature Intensification

3.5 Pressure Intensification

References

Chapter 4: Making Use of the “Forbidden” – Ex-Regime/High Safety Processing

4.1 Hazardous Reactants and Intermediates

4.2 Ex-Regime and Thermal Runaway Processing

References

Chapter 5: Exploring New Paths – New Chemical Transformations

5.1 Direct Syntheses via One Step

5.2 Direct Syntheses via Multicomponent Reactions

5.3 Multistep One-Flow Syntheses

5.4 Multistep Syntheses in One Microreactor/Chip

5.5 Multistep Syntheses in Coupled Microreactors/Chips

References

Chapter 6: Activate – High-T Processing

6.1 Tailored High-T Microreactor Design and Fabrication

6.2 Cryogenic to Ambient – Allowing Fast Reactions to be Fast

6.3 From Reflux to Superheated – Speeding-Up Reactions

6.4 Solvent-Scope Widening by Virtue of Pressurizing Existing High-T Reactions

6.5 New Temperature Field for Product and Material Control

6.6 Energy Activation Other than Temperature – Photo, Electrochemical, Plasma

References

Chapter 7: Press – High-p Processing

7.1 Tailored High-p Microreactor Design and Fabrication

7.2 High Pressure to Intensify Interfacial Transport in Gas–Liquid Reactions

7.3 Pressure as Direct Means – Activation Volume Effects and More

7.4 Pressure for Advanced Fluidic Studies – to be Used for Shaping Materials and More

References

Chapter 8: Collide and Slide – High-c and Tailored-Solvent Processing

8.1 Batch Process-Based Inspirations for High-c Flow Processes

8.2 Solvent-Free or Solvent-Less Operation – “Highest-c”

8.3 Supercritical Fluids to Combine the Former Separated – Mass Transfer Boost

References

Chapter 9: Doing More by Combining – Process Integration

9.1 Integration of Reaction and Cooling/Heating, Separation, or Other

9.2 Integration of Process Control and Sensing

9.3 Thermal Integration on a Process Level

9.4 Integration of Units on Racks, Backbones, Frames, Interfaces, or Similar Level

9.5 Fully Intensified/Flow Process Development

References

Chapter 10: Doing the Same with Less – Process Simplification

10.1 Omitting the Use of a Catalyst

10.2 Simplifying Separation

References

Chapter 11: Implications of NPW to Green and Cost Efficient Processing

11.1 Introduction

11.2 Knowledge-Based Design of Future Chemistry – Coupling the Implementation of NPW with Evaluation and Decision Support Tools

11.3 Evaluation Methods

11.4 Evaluation of the NPW Concept Impact on Sustainability

11.5 Future Environmental and Economic Sustainability Evaluation in the Context of Flow-Chemistry under NPW Conditions

References

Chapter 12: From Milligrams to Kilograms – Scale-Up in Modular Flow Reactors

12.1 Reactor Types

12.2 Scale-Up Parameters

12.3 Numbering-Up

12.4 Single-Channel Operation

12.5 Methodology for Continuous-Flow Process Development

12.6 Conclusions

References

Chapter 13: Evolution of Novel Process Windows

13.1 Multifaceted Novel Process Windows: Evolution

13.2 High-p,T Commercial Flow Chemistry Equipment

13.3 Funding Agency Initiatives

References

Chapter 14: Scientific Dissemination of Novel Process Windows

14.1 Literature Share for Chemical Intensification

14.2 Literature Share for Process-Design Intensification

References

Chapter 15: Outlook

15.1 Process Automation

15.2 Means of Activation Other than High-Temperature, High-Pressure, High-Concentration, and High-Solvent

References

Index

EULA

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Guide

Cover

Table of Contents

Chapter 1: From Green Chemistry to Green Engineering – Fostered by Novel Process Windows Explored in Micro-Process Engineering/Flow Chemistry

List of Illustrations

Figure 1.1

Figure 1.2

Figure 1.3

Figure 1.4

Figure 1.5

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.5

Figure 2.6

Figure 2.7

Figure 3.1

Figure 3.2

Figure 3.3

Figure 3.4

Figure 3.5

Figure 3.6

Figure 3.7

Figure 3.8

Scheme 3.1

Scheme 3.2

Figure 4.1

Scheme 4.1

Scheme 4.2

Scheme 4.3

Figure 4.2

Scheme 4.4

Scheme 4.5

Scheme 4.6

Scheme 4.7

Scheme 4.8

Scheme 4.9

Scheme 4.10

Scheme 4.11

Figure 4.3

Scheme 4.12

Figure 5.1

Scheme 5.1

Scheme 5.2

Scheme 5.3

Scheme 5.4

Scheme 5.5

Figure 5.2

Figure 5.3

Figure 5.4

Scheme 5.6

Scheme 5.7

Figure 5.5

Scheme 5.8

Scheme 5.9

Figure 5.6

Figure 5.7

Scheme 5.10

Scheme 5.11

Figure 5.8

Figure 5.9

Figure 5.10

Scheme 5.12

Figure 5.11

Scheme 5.13

Scheme 5.14

Scheme 5.15

Scheme 5.16

Figure 5.12

Figure 5.13

Figure 5.14

Figure 5.15

Scheme 5.17

Scheme 5.18

Figure 5.16

Figure 5.17

Figure 5.18

Figure 6.1

Figure 6.2

Figure 6.3

Figure 6.4

Figure 6.5

Figure 6.6

Scheme 6.1

Scheme 6.2

Scheme 6.3

Scheme 6.4

Scheme 6.5

Figure 6.7

Figure 6.8

Scheme 6.6

Scheme 6.7

Scheme 6.8

Figure 6.9

Figure 6.10

Scheme 6.9

Figure 6.11

Scheme 6.10

Figure 6.11

Figure 6.12

Scheme 6.12

Figure 6.13

Scheme 6.13

Scheme 6.14

Figure 6.14

Figure 6.15

Scheme 6.15

Scheme 6.16

Scheme 6.17

Figure 6.16

Figure 6.17

Figure 6.18

Figure 6.19

Figure 6.20

Scheme 6.18

Figure 6.21

Figure 7.1

Figure 7.2

Figure 7.3

Figure 7.4

Scheme 7.1

Figure 7.5

Scheme 7.2

Scheme 7.3

Figure 7.6

Figure 7.7

Figure 8.1

Scheme 8.1

Scheme 8.2

Scheme 8.3

Figure 8.2

Figure 8.3

Scheme 8.4

Figure 8.4

Figure 8.5

Figure 8.6

Scheme 8.5

Figure 8.7

Scheme 8.6

Scheme 8.7

Figure 8.8

Figure 8.9

Figure 8.10

Figure 8.11

Figure 8.12

Scheme 8.8

Figure 8.13

Figure 8.14

Figure 8.15

Scheme 8.9

Figure 8.16

Figure 9.1

Figure 9.2

Figure 9.3

Figure 9.4

Figure 9.5

Figure 9.6

Figure 9.7

Figure 9.8

Figure 9.9

Figure 9.10

Figure 9.11

Figure 9.12

Figure 9.13

Figure 9.14

Figure 10.1

Figure 10.2

Figure 10.3

Scheme 10.1

Scheme 10.2

Figure 11.1

Figure 11.2

Figure 11.3

Figure 11.4

Figure 11.5

Figure 11.6

Figure 11.7

Figure 11.8

Figure 11.9

Figure 11.10

Figure 11.11

Scheme 11.1

Scheme 11.2

Figure 11.12

Figure 11.13

Figure 11.14

Scheme 11.3

Figure 11.15

Figure 11.16

Figure 11.17

Figure 11.18

Figure 11.19

Figure 11.20

Figure 11.21

Figure 11.22

Scheme 11.4

Figure 11.5

Figure 11.23

Figure 11.24

Figure 11.25

Figure 11.26

Scheme 11.6

Scheme 11.7

Figure 11.27

Scheme 11.8

Figure 11.28

Figure 11.29

Figure 11.30

Figure 11.31

Figure 11.32

Scheme 11.9

Figure 11.33

Scheme 11.10

Figure 11.34

Scheme 11.11

Figure 11.35

Figure 11.36

Figure 11.37

Figure 11.38

Figure 12.1

Figure 12.2

Figure 12.3

Figure 12.4

Figure 12.5

Figure 12.6

Figure 12.7

Figure 12.8

Figure 12.9

Figure 12.10

Figure 12.11

Figure 12.12

Scheme 12.1

Figure 12.13

Figure 12.14

Figure 12.15

Figure 12.16

Figure 12.17

Figure 12.18

Scheme 12.2

Figure 12.19

Figure 12.20

Figure 12.21

Figure 12.22

Figure 12.23

Figure 12.24

Figure 12.25

Figure 12.26

Figure 13.2

Figure 13.1

Figure 13.3

Figure 13.4

Figure 13.5

Figure 14.1

Figure 14.2

Figure 14.3

Figure 14.4

Figure 14.5

Figure 14.6

Figure 14.7

Figure 15.1

Figure 15.2

Scheme 15.1

Scheme 15.2

Scheme 15.3

Figure 15.3

Figure 15.4

List of Tables

Table 1.1

Table 1.2

Table 3.1

Table 4.1

Table 6.1

Table 6.2

Table 8.1

Table 8.2

Table 8.3

Table 11.1

Table 11.2

Table 12.1

Table 13.1

Related Titles

Hessel, V., Renken, A., Schouten, J.C., Yoshida, J. (eds.)

Micro Process Engineering

A Comprehensive Handbook

2009

Print ISBN: 978-3-527-31550-5

(Also available in a variety of digitial formats)

Kashid, M.N., Renken, A., Kiwi-Minsker, L.

Microstructured Devices for Chemical Processing

2015

Print ISBN: 978-3-527-33128-4

(Also available in a variety of digitial formats)

Reniers, G.L., Sörensen, K., Vrancken, K. (eds.)

Management Principles of Sustainable Industrial Chemistry

Theories, Concepts and Industrial Examples for Achieving Sustainable Chemical Products and Processes from a Non-Technological Viewpoint

2013

Print ISBN: 978-3-527-33099-7

(Also available in a variety of digitial formats)

Sanchez Marcano, J.G., Tsotsis, T.T.

Catalytic Membranes and Membrane Reactors

Second Edition

2009

Print ISBN: 978-3-527-32362-3

(Also available in a variety of digitial formats)

Volker Hessel, Dana Kralisch, and Norbert Kockmann

Novel Process Windows

Innovative Gates to Intensified and Sustainable Chemical Processes

The Authors

Prof. Dr. Volker Hessel

Technische Universiteit Eindhoven

Den Dolech 2

5600 Eindhoven

Netherlands

Dr. Dana Kralisch

Friedrich Schiller University

Institut für Technische Chemie & Umweltchemie

Lessingstr. 12

07743 Jena

Germany

Prof. Dr. Norbert Kockmann

TU Dortmund

Fakultät Bio- und Chemieingenieurwesen

Emil-Figge-Str. 68

44227 Dortmund

Germany

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Print ISBN: 978-3-527-32858-1

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Windows Provide Panoramas

Novel ProcessWindows are a chance to explore new horizons for processing industry. Glass windows of churches initially were Romanic style, being small and protective, as long as constructional engineering was hampered by raw material manufacture, heat losses, and mechanical constraints.With improvements on the engineering side, they turned to the large, ornament-style gothic windows exposing the interior with sunlight giving rise to metaphysical illumination.

Motivation – Who Should Read the Book!?

This book may be approached by two kinds of readers

with background knowledge in microreactors and process intensification in general which want a further deeping in a central enabling function in for these areas

without such background knowledge and primary interest in flow processing, yet with interest in green chemistry and green engineering. The aim is to get to know the key enabling function of flow processing and to transfer that knowledge to advanced green batch processing and synthesis.

Novel Process Windows as defined in this book need microreactors to be performed in the best way. Yet, the general approach – in the same way as given for process intensification, as defined below – can provide learning also for other advanced chemical synthesis and processing, including with other advanced chemical apparatus.

For the second class of readers, a short summary is given below on microreactors, for the first class on process intensification and green processing. The references help to find more comprehensive information in case more deeper and widespread information is wanted. Both classes of readers may check the summaries they are familiar with as well, for consistency and completeness.

There are several books on micro process engineering, including those written or edited by the authors of this book. These books provide enabling the basic engineering enabling functions for flow chemical synthesis and processing such as the increased mass and heat transfer. Yet, knowing this without having considered the information here is like studying formula-1 racing cars, their construction principles and capabilities, however, to operate them still with normal tankstation fuel. In terms of such a picture, this means to run expensive, much advanced equipment under much reduced performance.

Microreactors as used under such boundary conditions still have many advantages as given below. Yet, they have one prime disadvantage (apart from blocking sensitivity) which is their short contact time as an intrinsic feature. Organic reactions as we know are typically processed on much longer times. One the one side, there is seconds scale, and on the other side, often hours and days scale – seemingly a misfit.

Indeed, it was prognosed from industrial microreactor experts that

only 20% of all organic reactions are suitable for flow

under such transfer-intensified operation (see citation [1] in Chapter 2).

Using the approach provided in this book gives a further enabling chemical-sided push so that the authors roughly estimate that

>70% of all organic reactions may become suitable for flow

that is, in a timescale which is appropriate to microreactors. The price for this is a demanding and laborious reinvention of chemistry beyond the green chemistry needs. This must honestly be stated.

Yet, there will be payback for this. The second process-sided push does allow – on an industrial scale – to truly benefit from such an advantage in application expansion.

For both reasons, not considering this book's knowledge does lead to an incomplete picture first of all in modern flow chemistry and micro processing engineering – yet finally also in green chemistry, green engineering, and process intensification. Thus, the authors believe to hopefully provide one more essential brick in the whole scenario of modern advanced and sustainable processing.

Reference

1. Roberge, D.M., Ducry, L., Bieler, N., Cretton, P., and Zimmermann, B. (2005)

Chem. Eng. Technol.

,

28

, 318–323.

Acknowledgments

Volker Hessel gratefully acknowledges funding provided by the Advanced European Research Council Grant “Novel Process Windows – Boosted Micro Process Technology” under grant agreement number 267443. He also acknowledges financial support from the Deutsche Bundesstiftung Umwelt. He likes to thank Tobias Illg for assistance with the preparation of Sections 3.1 and 3.2. Volker Hessel likes to thank IMM (Mainz, Germany) and Eindhoven University of Technology (The Netherlands) for offering the opportunities to work on the field of Novel Process Windows. This involves in particular Holger Loewe, Josef Heun, Patrick Loeb, Gunther Kolb, and Frank Hainel (all from IMM) and Jaap Schouten, Hans Niemantsverdriet, and Laurent Nelissen (all from TU Eindhoven).

Dana Kralisch gratefully acknowledges the support of Ina Sell in all aspects of Life Cycle Cost analyses.

Norbert Kockmann likes to acknowledge the help and support of Lonza colleagues, notably Dominique Roberge, for fruitful discussions on micro reactor development and application. He wants also to thank Christian Bramsiepe from TU Dortmund University, now INVITE GmbH in Leverkusen, for intensive discussions on modularization.

Abbreviations

AP

acidification potential

BOC

chemical protecting group,

tert

-butyloxycarbonyl

CED

cumulative energy demand

DMP

dimethoxypropane

EDL

electron diffusion layer

EHS

environment, health and safety

EP

ecotoxicity potential

GWP

global warming potential

HTP

human toxicity potential

LCA

life cycle assessment

LCC

life cycle costing

LCIA

life cycle impact assessment

LCI

life cycle inventory

LU

land use

NMP

n

-methylpyrrolidone

NP

eutrophication potential

NPV

net present value

ODP

(stratospheric) ozone depletion potential

POCP

(tropospheric) photochemical ozone creation potential

RA

risk assessment

RTD

residence time distribution

SLCA

simplified life cycle assessment

THF

tetrahydrofuran

1From Green Chemistry to Green Engineering – Fostered by Novel Process Windows Explored in Micro-Process Engineering/Flow Chemistry

1.1 Prelude – Potential for Green Chemistry and Engineering

Green Chemistry is since about 20 years an approach which is meanwhile quite established in chemical research and education [1]. Experts predict a fast-paced growth of the market for Green Chemistry-type processing, from $2.8 billion in 2011 to $98.5 billion in 2020 (Pike Research study [2]). Finally – yet probably not before the next 20 years – experts expect this to eliminate the need for Green Chemistry as an own approach, since it will be identical to the chemistry in the future. Anastas and Kirchhoff [3] bring this to the point in “Origins, Current Status, and Future Challenges of Green Chemistry” as follows.

The revolution of one day becomes the new orthodoxy of the next.

Green Engineering followed somewhat later and just recently came out the shadow of “its big brother.” The implementation of that idea in the chemical industry proceeds now steadily, yet for reasons of complexity of the chemical processes, unavoidably at a slow rate. Today, only 10% of the current process technologies employed on industrial scale can be considered environmentally benign. It is estimated that another 25% could be made so. That leaves room for exploring and discovering the residual 65% of industrial process technology and to render them sustainable [4].

That means that there is still a considerable need to improve the enabling technologies which render chemical synthesis and chemical processes green. Under the umbrella of process intensification, microreaction technology and flow chemistry are prime enablers on the reactor and process side (see later in this chapter for citations). They help to improve current Green Chemistry approaches and in addition even give opportunities to develop new Green Chemistry concepts, which are not possible with conventional equipment. On top of that, micro- and milli-continuous processing provides a more straightforward way to upscale new green ideas. Seeing the last paragraph and the achieved 10% penetration, this is obviously still an open issue.

In continuation of the above given aphorism, this book shall open a window from Green Chemistry to Green Engineering as follows.

The revolution in the chemical laboratory needs to stimulate and bridge to the sustainability evolution on the full-production scale. [5]

1.2 Green Chemistry

Driven by political as well as societal demands, sustainability aspects gain increasing importance in all areas of human beings. Chemical production of compounds, for example, textiles, construction, ingredients in food and cosmetics, packaging, pharmaceuticals, and so on, covers more or less all aspects of human needs. The resulting extensive impact on our environment and consumption of depletable resources distinctly demands for the most efficient use of raw materials and energy. Pollution has to be prevented or at least minimized at the source to avoid end-of-pipe treatments.

New concepts have to come off with significant benefits, for example, in yield, selectivity, heat management, waste reduction, to become an environmentally benign alternative to the state of the art. Also, the environmental burdens of any reaction component, auxiliaries, and energies, obtained during upstream processes, as well as all downstream processes involved have to be taken into account.

All this has stimulated an on-going and total rethinking how to change the elemental pathways of chemical synthesis design, which has become a large movement and created an own scientific filed and society known as Green Chemistry. While processes in the past were guided by economic, technical, and safety criteria, it is now becoming increasingly obvious and a to-do-must to have considered environmental criteria from the very beginning of the process development – which is the creative intuition of the organic chemist how to conceptually approach synthetic chemistry.

1.2.1 12 Principles in Green Chemistry

In one sentence, Green Chemistry was defined as follows [2].

Green chemistry is the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and application of chemical products.

In kind of tabellaric goal definition, Green Chemistry was defined as follows [1b, p. 30].

Prevention

Atom economy

Less hazardous chemical syntheses

Designing safer chemicals

Safer solvents and auxiliaries

Design for energy efficiency

Use of renewable feedstocks

Reduce derivatives

Catalysis

Design for degradation

Real-time analysis for pollution prevention

Inherently safer chemistry for accident prevention.

Essentially, one can reduce that to three major incentives which are to optimize the type of feedstock, its efficiency in conversion, and the safety while doing so (derived from own thoughts and [2]).

Feedstock

: A shift to renewable (non-petroleum) feedstocks

Efficiency

: (i) make maximal use of starting materials (reactants) and minimize waste; (ii) minimize solvent load; and (iii) minimize energy efficiency

Safety

: have maximal process safety and minimize toxicity (to human).

Ideally, supposed-to-be nongreen reagents just vanish from the chemical protocol by using a new chemical route such as given for GSK (Glaxo-Smith-Kline)'s green Friedel–Crafts alkylations [6]. Manifold applications have been demonstrated with respect to modern synthetic strategies, alternative solvents, renewable resources, catalysis, and environmental-friendly enzymatic catalysis in flow [1c-e, 7].

1.3 Green Engineering

1.3.1 10 Key Research Areas in Green Engineering

In 2005, the American Chemical Society (ACS) Green Chemistry Institute (GCI) and global pharmaceutical companies established the ACS GCI Pharmaceutical Round-table to motivate for integration of Green Chemistry and Engineering into the pharmaceutical industry [8]. This Roundtable developed a list of key research areas in green chemistry in 2007. In 2010, the Roundtable companies have identified a list of the key green engineering research areas that is intended to be the required companion of the first list. The companies involved were Boehringer Ingelheim Pharmaceuticals, Pfizer, Eli Lilly, GlaxoSmithKline, Dutch State Mines/De Staats Mijnen (DSM), Johnson & Johnson, AstraZeneca, and Merck (US).

Ten key green engineering research areas were ranked in relevance (see Table 1.1). The issues 6–10 match with what is understood under process-design intensification in this book – (6) life-cycle analysis, (7) integration of chemistry and engineering, (8) scale-up, (9) process energy intensity, and (10) mass and energy integration. The key areas 1–5 in Table 1.1 refer partly to chemical intensification.

Table 1.1 Ten prime green engineering research areas as identified by ACS GCI Pharmaceutical Round Table (reproduced with permission)

Rank

Main key areas

Sub-areas/aspects

1

Continuous processing

Primary, secondary, Semi-continuous, and so on

2

Bioprocesses

Biotechnology, fermentation, biocatalysis, GMOs

3

Separation and reaction technologies

Membranes, crystallizations, and so on

4

Solvent selection, recycle, and optimization

Property modeling, volume optimization, recycling technologies, in process recycle, regulatory aspects, and so on

5

Process intensification

Technology, process, hybrid systems, and so on

6

Integration of life cycle assessment (LCA)

Life cycle thinking, total cost assessment, carbon/eco-foot printing, social LCA, stream lines tools

7

Integration of chemistry and engineering

Business strategy, links with education, and so on

8

Scale-up aspects

Mass and energy transfer, kinetics, and others

9

Process energy intensity

Baseline for pharmaceuticals, estimation, energy optimization

10

Mass and energy integration

Process integration, process synthesis, combined heat and power, and so on

Adapted with permission from [8]. Copyright 2012 American Chemical Society.

1.3.2 12 Principles in Chemical Product Design

A product-design view is provided by the 12 Principles of Green Engineering which were proposed by Anastas and Zimmerman [9]. Sustainability is here approached in a hierarchical crossover between the molecular, product, process, and system levels.

Inherent rather than circumstantial

Designs of chemical processes shall be so much efficient and nonhazardous as possible. Example is a process to synthesize organic solvents from sugars, which has replaced many more hazardous solvents such as methylene chloride (Argonne National Laboratory). The very low energy input, high efficiency, elimination of large volumes of salt waste allows to reduce pollution and emissions.

Prevention instead of treatment

The production of waste shall be prevented rather than planning process including waste treatment.

Design for separation

The quest of energy and material efficiency is not only to be put on reaction but rather on separation and purification processes as well. Example is the use of supercritical CO2, nearcritical water, and CO2-expanded liquids, which in addition comprise nontoxic substitutes for conventional solvents.

Maximize efficiency

It shall be aimed at maximum efficiency in terms of mass, energy, space, and time. Example is a highly efficient family of catalysts to synthesize high-performance polymers from CO and CO2.

Output-pulled versus input-pushed

Outputs (“pull”) should be removed from the system, rather than adding more input stresses (“push”) to minimize the energy and material consumption.

Conserve complexity

Different from the system design issue given in (5), the product design shall be complex. Idea is that the products then can have longer reuse times through better recycling than given for less complex products.

Durability rather than immortality

Product design shall guarantee for the product lifetime, but no longer to avoid environmental problems. Example is cellulose acetate, which is used for the filters of cigarettes. Their decomposition after use took years in the past. This could be substantially improved by incorporation of weak organic acids in the material. These are released with rain water and degrade the cellulose acetate much quicker.

Meet need, minimize excess

The production amount should be set just to meet the needs and not to result in over-production that creates wastes and is costly.

Minimize material diversity

Recycling and reusing is much facilitated when fewer materials compose a product. Example is a “unibody” piece of aluminum laptop frame that considerably reduced the product's weight and allowed for easy recycling (Apple Inc).

Integrate material

and energy flows

The utilization of waste energy and material flows can be used to improve the efficiency of another part of the production process. Example is the use of CO2 to replace traditional blowing agents for the production of polystyrene foam sheets. The CO2 used came from existing commercial processes as a waste by-product or from natural sources (Dow Chemical Company).

Design for commercial “afterlife”

Selection of materials or components of a process, product, or system should head for reusability and keeping high value after fulfilling their initial product function.

Renewable rather than depleting

With a similar intention, renewable sources should be used for energy, materials, or reagents, wherever possible. Example is a water-based, catalytic process for producing gasoline, jet fuel, or diesel from biomass with little external energy consumption (Virent Energy Systems Inc).

1.4 Micro- and Milli-Process Technologies

Micro- and milli-process technologies refer to (chemical) processing with reactors and other equipment with open internals in the micro (<1 mm) or milli (a few millimeters) range [10–12]. These devices provide the following functions:

guide and structure flows;

predetermine mass and heat transfer in single and multiple phase;

define and reduce the volume;

carry functional coatings and elements such as catalyst layers or membranes.

1.4.1 Microreactors

Microreactors typically comprise one or (many) more microchannels, and may also encase chambers, column/fin arrays, foams, nets, and fibers, and so on [10–12]. It is for most of these microstructures characteristic that they are artificial and engineering-made, typically by means of precision engineering or microfabrication, as opposed to nano- or microsized reaction compartments mimicking nature's cells or other organizational units such as supramolecular assemblies (micelles, vesicles, etc.). In expansion of this fabrication-related definition, also formerly existing reactor concepts, for example, monoliths, foams, and mini fixed beds as well as even capillaries, are subsumed under the umbrella of the new technology.

Microreactors are defined as check card, thin sized reactors with small outer dimensions, not exceeding a few centimeters (see Figure 1.1) [13]. These are typically made by classical microfabrication techniques based on photolithography, thin-film coating, and etching steps so that the preferred materials are glass, silicon, and polymers. Characteristic internal dimensions are typically in the range of 50–1000 µm.

Figure 1.1Glass chip microreactor with mixer and elongated serpentine channel for reaction; from Chemtrix (a). Such chip reactors are embedded in a flow chemistry environment consisting of pumps, a microreactor holder with heating function and feed/collecting reservoirs, if needed, also a back-pressure valve for high-p experimentation; from Chemtrix (b).

(Reproduced with permission from Chemtrix).

1.4.2 Microstructured Reactors

Microstructured reactors have larger outer dimensions, especially concerning their length and width, while the internals are miniaturized (see Figure 1.2) [13]. These are typically made in stainless steel, but also in glass. For both, etching technologies can be used for microstructuring. Steel microstructured reactors are also accessible through precision engineering (micromilling, cutting, embossing, and more), laser machining, and micro-electro discharge machining (μEDM). Laboratory microstructured reactors are typically fist-size and below. Pilot- and production-scale reactors may be shoebox size or even approach extensions in the meter range.

Figure 1.2 Split-recombine micromixers have dedicated microchannel structures due to their mixing principle based on repeated flow splitting – caterpillar micromixer from ICT-IMM with smooth (“3D”) upwards and downwards sloping (left). Typically, such mixers are assembled as (screwed) two-plate structures.

(Reproduced with permission from ICT-IMM).

The same classification can be applied to milli-reactors and millistructured reactors, which are the dimensional extension of the devices given above. Such reactors that are designed for larger throughput and are less prone to failure, for example, by clogging, but certainly also with lower performance potential. Milli-process technologies often use commercial capillaries and tubes with millimeter internal measurements, sometimes being filled with foams or fibers as structured packings.

Microreactors and microstructured reactors (as well as their milli counterparts) are typically scaled-up by two means:

Numbering-up

: internally via parallel channels in plates and via parallel plates with channels (see

Figure 1.3

); externally via parallel devices;

Smart scale-out

: moderate increase in channel dimensions.

Figure 1.3 Flow production unit with internally numbered-up microreactor, at the right lower side of the plant; Plantrix system from Chemtrix.

(Reproduced with permission from Chemtrix).

The first concept has the charm of equaling-up the geometries and finally reaction conditions (mixing, hydrodynamics, heat transfer) from lab to production scale. It is especially applied towards gas-phase and multi-phase reactions. Gas-phase reactions benefit from comparatively easy means (diffuser/pressure barrier) for flow distribution. In case of multi-phase reactions, the maintenance of the flow pattern from lab- to production-scale is crucial; thus, the concept of smart scale-out will most often not be applicable. In case of liquid reactions, both the numbering-up and smart scale-out approaches are applied. Concerning the latter, Lonza Company has developed an extreme, but effective, version by making the whole flow development from lab to production scale within one reactor or even one channel passage and having that in three steps (lab, pilot, production) smartly increased [14]. The latter also reduces the fouling sensitivity.

1.5 Flow Chemistry

1.5.1 10 Key Research Areas in Flow Chemistry

Ten key research areas of synthetic flow chemistry were identified and provided a deeper understanding into current and future issues in the field [10]c. Comparing these flow essentials with the three intensification fields, as discussed in this book, shows that both views have overlapping contents (see Table 1.2). This clearly shows that issues on chemical intensification have a major role currently in the overall development.

Table 1.2 Ten key research areas in flow chemistry [10]c, which match with the three intensification fields, introduced in the next chapter

Issue

Key characteristics

Intensification field

1

Size matters – micro versus minifluidic (or mesofluidic) reactors

Transport

2

Residence time, flow rate, and reactor volume – key factors in flow chemistry

Transport

3

Flow, heat, and pressure – a crucial relationship

Transport

4

Flow and reactive intermediates – a classical application

Chemical

5

Flow and supported reagents

Chemical

6

Flow and supported catalysts – an ideal match

Chemical

7

Flow and multicomponent reactions

Chemical

8

Flow and photochemistry – new options

Chemical

9

Flow and multistep synthesis – mimicking nature

Process-design

10

Flow, scale up and industrial application – think big

Process-design

1.6 Two Missing Links – Cross-Related

There is a missing link between Green Chemistry and Green Engineering. Different approaches for green improvements of chemical syntheses pathways and process technologies have been followed by chemists and engineers during the last two decades, but often independently from each other. Whereas “Green Chemistry” approaches have been primarily apprehended as new chemical synthesis strategies [1] applying alternative solvents [2], chemistry based on renewable resources [3] or yield and selectivity improvements by catalysis [4], Green Engineering approaches have been put on a level with the design of novel equipment and new processing methods [5], using multifunctional reactors, new operating modes, or micro-process technology for process improvement and intensification [6]. Since environmental issues affect many disciplines, cross-disciplinary interaction is essential for success. Otherwise, undesired impacts are shifted from one domain to another, and well-intentioned green developments result in unexpected surprises. In the past, a lot of false decisions already emerged by concentrating only on the optimization of the chemical synthesis itself or by focusing on single principles of green process design, neglecting inconvenient aspects and missing broader implications.

One solution for this missing link was already been assigned to micro-process engineering and flow chemistry. Certainly, this is not the only solution and other solutions may be at hand as well. The citation and exploitation numbers show clearly that this is a prime concept (see Chapter 14).

Yet, there is a second missing link and this has been addressed already in the Motivation statement, placed directly before this first chapter. Microreactors as mostly used about 5 years ago had (and often still have) one prime disadvantage which is their short contact time given as an intrinsic feature. Organic reactions as we know are typically processed on much longer times. One the one side, there is seconds scale, on the other side often hours and days scale – seemingly a misfit.

In this context, this book aims to show how the novel equipment – micro-/flow reactors – allows to reach new operating modes – Novel Process Windows – which open novel opportunities in chemistry and overcome the above-mentioned dilemma (see Figure 1.4).

Figure 1.4Schematic representation of Novel Process Windows. A more detailed description is provided in the coming chapters.

(Hessel et al. [15]; reproduced with permission from Wiley-VCH).

Novel Process Windows can then result in a much improved sustainability footprint via a full-chain oriented and multifunctional process design. Such technology innovation is expected to improve the cost structure of chemical industry and has many other advantages concerning product flexibility, product quality, process development time, and more. It is thus important to point out that Novel Process Windows combines chemical and engineering perspectives.

The book is organized as given in Figure 1.5 which provides a hierarchic approach to implement green ideas on all development stages in chemical process development (from top to down in the said figure) and names also their evaluation method counterparts and the achieved process intensification result (from left to right).

Figure 1.5 Combined approach of Novel Process Windows process design and accompanying life cycle assessment (LCA) and life cycle costing (LCC).

(Kralisch et al. [15]; reproduced with permission from Wiley-VCH).

This results then in the following five-leveled hierarchy and interrelation of chapter packages and is the backbone of the book structure.

Chapters

1–3: Here, the industrial and society needs are translated into the knowledge-based design approaches for synthesis and processing (Chapter 1). Then, it is shown how this can be used for door-opening functions in chemistry in an entirely new way (Chapter 3). A theoretical assessment is done in Chapter 3 to have the foundation for the knowledge-based design.

Chapters

4–8: Here, the fundamental challenges and chances of the new door-opening concept are given to reach in praxis-intensified flow chemistry which relates to green metrics

Chapters

9, 10: On a higher-complexity (holistic) process level, it will be demonstrated how these process windows change the chemical plant as a whole. Herein, process chemistry, engineering, and chemistry will merge.

Chapters

11, 12: This ends in a demonstration that the technique is beneficial for society through sustainability benefits and mature for chemical industry.

Chapter

13: While the demonstration of the superiority of the concept of Novel Process Windows remains the task of the future, some first summary of 5-years achievement in terms of scientific dissemination and project exploitation is given here as a kind of concluding chapter and outlook.

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