Chemical Processing - March 2008 - (Page 31) size of many organic molecules. “Recently, we’ve found that when zeolites absorb certain molecules in the pores, that makes the zeolite crystals swell.” This shrinks the pore size, dramatically raising selectivity. “We think it’s a big find,” he says. “If you look at branched C6s, a molecule that only goes through the defects — such as 2,2-dimethylbutane [C6H14] — is too large to go through the zeolites at significant rate.” However, by adding 1% to 2% of hexane to the gas, “we see the flux decrease through the defects by one to two orders of magnitude for some membranes.” A lower cost option However, some see costs remaining prohibitive for membranes made from pure inorganics and metallics. “They have good performance, but they cost about 500 to 1,000 more times per square meter [than polymerics],” says Koros, who also is editor-in-chief of the Journal of Membrane Science. “The problem [potential end-users say] is: ‘They have high performance, but if it’s so expensive, I can’t do that.’” He suggests the solution is obvious: “Get production that’s less expensive. But you can’t do that if there’s no demand.” The potential demand certainly exists. Commercial plants would require thousands of square meters, notes Tsapatis, who’s currently collaborating with Pall Corp. as well as Koros. But Tsapatsis asks, “Who’s going to make those thousands of square meters? And how?” Those are the primary obstacles now, he believes. Techniques used in the laboratory don’t suit largescale production, he notes. Mixed-matrix membranes, which combine zeolites with polymers, promise to address both production and cost issues, hopes Koros. He and his colleagues focus on hollow-fiber membranes. This should allow using the production technology for hollow-fiber membranes, he believes. “Hollow fibers are spun like textile fibers. The same spinning machines could www.chemicalprocessing.com http://www.buschusa.com http://www.buschusa.com http://www.chemicalprocessing.com
Table of Contents Feed for the Digital Edition of Chemical Processing - March 2008 Chemical Processing - March 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Distillation is Bubbling Feel Secure About Vulnerability Assessments The Door Opens For Membranes Achieve Effective Heat Exchanger Control Epoxy Maker Finds the Right Glue for Its Business Process Puzzler Plant InSites Equipment & Services Product Spotlight/Classifieds Ad Index End Point Chemical Processing - March 2008 Chemical Processing - March 2008 - Chemical Processing - March 2008 (Page Cover1) Chemical Processing - March 2008 - Chemical Processing - March 2008 (Page Cover2) Chemical Processing - March 2008 - Chemical Processing - March 2008 (Page 3) Chemical Processing - March 2008 - Chemical Processing - March 2008 (Page 4) Chemical Processing - March 2008 - Contents (Page 5) Chemical Processing - March 2008 - Contents (Page 6) Chemical Processing - March 2008 - From the Editor (Page 7) Chemical Processing - March 2008 - From the Editor (Page 8) Chemical Processing - March 2008 - ChemicalProcessing.com (Page 9) Chemical Processing - March 2008 - ChemicalProcessing.com (Page 10) Chemical Processing - March 2008 - Field Notes (Page 11) Chemical Processing - March 2008 - Field Notes (Page 12) Chemical Processing - March 2008 - In Process (Page 13) Chemical Processing - March 2008 - In Process (Page 14) Chemical Processing - March 2008 - In Process (Page 15) Chemical Processing - March 2008 - In Process (Page 16) Chemical Processing - March 2008 - Energy Saver (Page 17) Chemical Processing - March 2008 - Energy Saver (Page 18) Chemical Processing - March 2008 - Compliance Advisor (Page 19) Chemical Processing - March 2008 - Distillation is Bubbling (Page 20) Chemical Processing - March 2008 - Distillation is Bubbling (Page 21) Chemical Processing - March 2008 - Distillation is Bubbling (Page 22) Chemical Processing - March 2008 - Distillation is Bubbling (Page 23) Chemical Processing - March 2008 - Distillation is Bubbling (Page 24) Chemical Processing - March 2008 - Distillation is Bubbling (Page 25) Chemical Processing - March 2008 - Feel Secure About Vulnerability Assessments (Page 26) Chemical Processing - March 2008 - Feel Secure About Vulnerability Assessments (Page 27) Chemical Processing - March 2008 - Feel Secure About Vulnerability Assessments (Page 28) Chemical Processing - March 2008 - The Door Opens For Membranes (Page 29) Chemical Processing - March 2008 - The Door Opens For Membranes (Page 30) Chemical Processing - March 2008 - The Door Opens For Membranes (Page 31) Chemical Processing - March 2008 - The Door Opens For Membranes (Page 32) Chemical Processing - March 2008 - The Door Opens For Membranes (Page 33) Chemical Processing - March 2008 - Achieve Effective Heat Exchanger Control (Page 34) Chemical Processing - March 2008 - Achieve Effective Heat Exchanger Control (Page 35) Chemical Processing - March 2008 - Achieve Effective Heat Exchanger Control (Page 36) Chemical Processing - March 2008 - Achieve Effective Heat Exchanger Control (Page 37) Chemical Processing - March 2008 - Achieve Effective Heat Exchanger Control (Page 38) Chemical Processing - March 2008 - Epoxy Maker Finds the Right Glue for Its Business (Page 39) Chemical Processing - March 2008 - Epoxy Maker Finds the Right Glue for Its Business (Page 40) Chemical Processing - March 2008 - Process Puzzler (Page 41) Chemical Processing - March 2008 - Process Puzzler (Page 42) Chemical Processing - March 2008 - Plant InSites (Page 43) Chemical Processing - March 2008 - Equipment & Services (Page 44) Chemical Processing - March 2008 - Equipment & Services (Page 45) Chemical Processing - March 2008 - Product Spotlight/Classifieds (Page 46) Chemical Processing - March 2008 - Product Spotlight/Classifieds (Page 47) Chemical Processing - March 2008 - Product Spotlight/Classifieds (Page 48) Chemical Processing - March 2008 - Ad Index (Page 49) Chemical Processing - March 2008 - End Point (Page 50) Chemical Processing - March 2008 - End Point (Page Cover4) Chemical Processing - March 2008 - End Point (Page Cover4)
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