PDF Publication Title:
Text from PDF Page: 049
168 E.J. Beckman / J. of Supercritical Fluids 28 (2004) 121–191 Table 1 Production and E-factors for various industry segments [315] CO2 in green chemistry, it would seem that the obvi- ous choice would be bulk chemicals and petrochem- icals. On the other hand, because fine chemicals are typically produced in batch mode in small volumes, the cost of high-pressure equipment for these indus- tries may not be as much of an impediment as it would be for their commodity cousins. Finally, as we note in a later section, the education of scientists and engineers in the use of CO2 as a solvent has a value of its own, and as such the publication of papers on reactions that fall into this chapter has done much to ‘demystify’ CO2. Hence, these papers have significant educational/outreach value. 4.1. Enzymatic chemistry At first glance, enzyme/CO2 mixtures appear as ideal reaction systems for the performance of green chemistry. Enzymes are naturally derived catalysts that are highly selective, while CO2 is a naturally abun- dant, benign solvent. However, research into enzy- matic reactions in CO2 has dropped precipitously since the mid-1990s and no commercialization of such pro- cesses is currently anticipated. The reasons for this are straightforward and scientifically based, deriving from the substantial research performed in this area during the 1990s. Enzymes are naturally derived catalysts, proteins whose primary, secondary and tertiary structure has evolved to create a catalyst that is highly selective and very active under a set of narrowly defined conditions. Enzymes themselves are green catalysts, and their means of production (fermentation) is also typically a green process. In nature, enzymes perform their catalytic function in water, yet Klibanov (and others) showed that enzymes would function adequately (not as well as in water) in organic media provided that a small amount of water remains bound to the enzyme [232]. Further, while lipases (and other analogous enzymes) naturally perform hydrolysis reactions in an aqueous environment, these same enzymes were shown to perform esterification in an organic environ- ment. Because enzymes do not dissolve in the organic solvents under consideration, enzymatic chemistry in organic solvents is governed by heterogeneous reac- tion kinetics. This, however, is not a drawback, as catalyst recovery is easier than for a homogeneous system. Given this background, enzymatic reactions Industry segment Oil refining Bulk chemicals Fine chemicals Pharmaceuticals Production (tons/annum) 106 –108 104 –106 102–104 10–103 E-factor (mass waste/mass product) ≈0.1 <1–5 5–50 25–>100 3.12. Industrial activity: CO2 and polymers in microelectronics manufacture It was recently announced that Air Products and Chemicals had agreed to purchase equipment from SC Fluids for use in photoresist development using carbon dioxide [230]. SC Fluids is also working with ATMI (chemical supplier to the microelectronics industry) and IBM on photoresist development using CO2. Ash- land Specialty Chemicals has formed an alliance with Dainippon Screen and Kobe Steel to develop technol- ogy for microelectronics processing using CO2 [230]. In addition to using CO2 to strip material from wafer surfaces, industry has applied carbon dioxide process- ing to create porous materials that will function as a low dielectric substrate or film [231]. 4. Other reactions in CO2 Researchers in both academia and industry (al- though most of the publications come from academic laboratories) have conducted a large number of reac- tions in carbon dioxide, demonstrating the feasibility for use of CO2 in a broad range of applications. Again, the question we must pose is ‘is this green chemistry’? And further, what is the impact of this work on the greater chemical industry? If we examine the ‘E-factors’, or mass of waste per mass of product for various industries, we find chemicals and pharmaceuticals produce waste at a rate several orders of magnitude higher than that for bulk chemicals or petrochemicals (see Table 1). However, if we examine the impact of each industry (related to the E-factor times the production rate), we see that the commodity segments still exercise the greater impact. Hence, if one had to choose which industry seg- ments upon which to focus research efforts in use ofPDF Image | Supercritical and near-critical CO2 in green chemical synthesis and processing
PDF Search Title:
Supercritical and near-critical CO2 in green chemical synthesis and processingOriginal File Name Searched:
sos.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |