Green Chemistry Technologies and Solutions Paul Smith Manager

Green Chemistry Technologies and Solutions Paul Smith Manager - Green Chemistry Network www. chemsoc. org/gcn

Green Chemistry Technologies and Solutions • What is Green Chemistry? • How do we know what is Green? • A dip into the Clean/Green technology Pool with some examples.

What is Green Chemistry? Benign Disposal Recycle/Re-use Reduce Replace - Chemical usage Energy usage Hazardous materials, processes Inefficient processes Non-sustainable components

How do we know what is Green? Metrics in Green Chemistry “When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science” William Thompson, Lord Kelvin, (1891) “If you don’t keep score then you are only practising” “If you can measure it you can manage it”

Metrics in Green Chemistry How do we know what progress we are making? E - Factor Amount of waste/kg product: Factor Bulk Chemicals Product tonnage/a E 104 -106 Fine chemical Industry 102 -104 Pharmaceutical Industry 10 -103 <1 - 5 5 - >50 25 - >100 R. A. Sheldon, Chem & Ind, 1997, 12

Metrics in Green Chemistry Preparation of 2 -methoxypropane-1, 3 -diol from glycerol Assuming 100% yields, no reaction or work-up solvents and no reagent excesses 1 kg glycerol produces 1. 15 kg 2 -methyl ether and 12. 04 kg of waste!

Metrics in Green Chemistry

Catalysis Safer reactions and reagents. New Chemistry Renewable Feedstocks Alternative Solvents Process Intensification Membrane reactors Innovative Engineering

New Chemistry: Synthesis of 4 -ADPA Monsanto’s new route: rubber antidegradant 130, 000 M tonnes/annum Starting Material: Aniline Traditional Chemistry Organo-halogens used. Hazardous Solvent used. High Waste levels. Green Chemistry Safer. No Organo-halogens. Waste Minimised -74% less organic, 99% less water. Reusable catalyst employed. Reduced Cost. Product: 4 -ADPA

Catalysis Activity + selectivity, higher throughput with less waste, less energy Propeneamide is the first bulk chemical manufactured using an industrial biotransformation: The active enzyme is nitrile hydralase in whole cells of Rhodococcus rhodochrous, immobilised on poly(propeneamide) gel

Catalysis

Catalysis Zeolites as Alternatives to Classical Routes • Alumino-silicates • 3 D crystalline structure • Uniform pore size • Green applications in > Catalysis > Water treatment > Remediation > Odour control

Catalysis: Zeolites Shape selectivity allows only p-xylene to pass through

Solvent Replacement in Green Chemistry • Volatile organic solvents are the normal media for carrying out organic syntheses and extractions - usage £ 4, 000, 000 p. a. • Also used in products- paints, varnishes, cleaning agents, adhesives • VOC’s causing considerable environmental concern! (Global warming/Ozone Depletion)

Solvent Replacement in Green Chemistry Benzene • Excellent solvent but it is a Genotoxic human carcinogen • Limit in drinking water of 5 ppb(US EPA) • In 1990 Perrier water found to have 1220 ppb (cigarette smoke has 2000 times more benzene than this) - 160 million bottles withdrawn • EU limit in petrol 5% before 2000, now <1%

Solvent Replacement in Green Chemistry Halogenated Solvents Dichloromethane CH 2 Cl 2: • a suspected human carcinogen • widely used in synthesis and extractions • extraction of caffeine from coffee (<10 ppm residue) Perchoroethylene CCl 2: • a suspected human carcinogen • main use in dry cleaning(85% of all solvents) • also found in printing inks, typewriter correction fluid and shoe polish

Solvent Replacement in Green Chemistry Carbon Dioxide sc. CO 2 is inexpensive, non-flammable and non-toxic. Current applications include: • Decaffeination of coffee -replacing dichloromethane • Dry Cleaning -replacing perchloroethylene.

Membrane Technology Extractive Membrane Bioreactor Biomedium Detachment Dissolved Oxygen Nutrients Attachment B I O F I L M M E M B R A N E Wastewater Pollutants Andrew Livingston, Department of Chemical Engineering, Imperial College AND Membrane Extraction Technology Ltd

Membrane Technology Extractive Membrane Bioreactor New Stripper-Bio. Scrubber plant on site at Atofina Widnes (Three year roll-over contract started March 2000) Removals of benzene or toluene from 500 -1000 mg L-1 to less than 1 ppm from point source waste stream

Membrane Technology Biotransformations Raw Mixture After Centrifugation at 10, 000 g

Membrane Separations in Green Chemical Technology Biotransformations Membrane Bioreactor for Biotransformations Aqueous Phase Whole cells or enzymes as biocatalysts R R P P C Organic Phase R = Reactant P = Product Nonporous membrane

Membrane Technology Biotransformations Product Concentration (g L-1) Productivity Results Phase Separation Results Conventional Two -Phase Membrane Bioreactor for Biotransformations Time (min) Conventional Two Phase (Doig et al. , Biotech Bioeng, 1998) MBB

Renewable Feedstocks - Chemicals from Crops Nature. Works™ A new thermoplastic polymer family based on polylactic acid developed by Cargill Dow Derived from annually renewable resources like corn 20 to 50% fossil fuel reduction 144, 000 tpa plant built in Nebraska USA Potential market approaching 500, 000 metric tons per year.

Green Chemistry Technologies and Solutions Conclusions: Much still to do but Green Chemistry provides a focus for: • A pro-active approach to the increase in legislation (e. g. emissions, Green House Gases taxes, restricted chemicals list) • A competitive advantage: beneficial in reducing costs/risks and provide greater manufacturing flexibility • An improvement in public image