GREENER ZEOLITES - C&EN Global Enterprise (ACS Publications)

Sep 29, 2003 - New strategy recycles the organic template used to synthesize zeolites ... "In many cases, the creation of a novel zeolite structure re...
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NEWS OF THE WEEK BUSINESS

BIOTECH THAWS OUT Firms launch initial stock offerings in more favorable investment climate

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firms are capitalizing on the positive momentum that's returned to the market for biotechnology stocks. A dozen have announced plans this quarter to launch initial public stock offerings (IPOs), while nearly as many more hope to raise money through follow-on bids. The upturn, if it persists, may help rescue a sector where limited cash flow has precipitated major cutbacks and consolidation. The number of I P O announcements began to rise dramatically in late August. The shift was easy to see since biotech has

MATERIALS

been in an acute drought: The last IPO occurred back in the second quarter of 2002. And, whereas biotech IPOs raised less than $450 million in all of 2002, the 12 announced this quarter already target more than $850 million. After two years of declines, better stock market conditions, a run of regulatory approvals, strong clinical data, and better than anticipated earnings are driving a recovery in biotech stocks, says Andrew Barker, chairman of the venture-capital firm International Biotechnology Trust. As of last week, C&EN's biopharmaceutical stock index had climbed near-

SYNTHESIS

GREENER ZEOLITES New strategy recycles the organic template used to synthesize zeolites

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CIENTISTS HAVE FOUND A

way to eliminate a significant drawback in the synthesis of zeolites and like materials, making the process environmentally friendly more economical, and potentially more widely applicable than current syntheses. Zeolites—crystalline aluminosilicates used industrially as molecular sieves and catalysts—typically are made by allowing the porous, inorganic framework to assemble itself around organic molecules called structure-directing agents, or SDAs. The SDA determines the shape and size of the pores and actually occupies each pore as it is formed. The SDAs must then be burned off at high temperatures to yield a zeolite with the desired open porosity "In many cases, the creation of HTTP://WWW.CEN-ONLINE.ORG

a novel zeolite structure requires the preparation of complex and costly SDAs, but their destruction during zeolite synthesis is economically prohibitive," explains catalysis expert Avelino Cormaof the Polytechnic University of Valencia, in Spain. Furthermore, the burn-offof SDAs can be extremely detrimental to the zeolite itself and to its potential use in such applications as thin films and membranes. These hurdles have now been swept away by Caltech chemical engineering professor Mark E. Davis and colleagues Hyunjoo Lee and Stacey I. Zones. They have created SDAs that can be disassembled inside the zeolite's pores at relatively low temperatures, allowing the molecular fragments to be re-

ly 50% from a first-quarter plateau around 290 (1992 = 100). "Quite a few companies have matured to the point where they want to go public, and the capital markets are enticing," says G. Steven Burrill, CEO of the merchant bank Burrill & Co. But the bar has been raised, and an important common thread among those embarking on I P O s is "products in the clinic and/or marketplace," Burrill notes. "There's not a single platform [technology] company in the bunch." Therisingtide is lifting all boats, and already-public companies are finding investors interested in follow-on offerings as well. This month, nine firms announced plans to raise nearly $600 million, led by Neurocrine Biosciences' $200 million public offering, while private-equity investments are bringing in hundreds of millions more.-ANN THAYER

moved, recovered, and reassembled into the SDA [Nature, 425, 385(2003)1. Davis' team exploited this strategy to synthesize zeolites such as ZSM-5 using new SDAs that are subsequently cleaved into two fragments—either chemically or with light—for easy removal from the zeolite pores. In an accompanying commentary in Nature, Corma says the new procedure is "elegant" and promises the wider availability of novel zeolite structures.-RON DAGANI

C&EN

IN BRIEF: JOVIAN GRAVE

After its eight-year orbit of Jupiter, NASA's Galileo space probe ended its U-year mission on Sept 21 by plunging into the giant planet.

DISASSEMBLE In the new strategy for synthesizing zeolites, the structuredirecting agent (SDA) that serves to "template" the construction of the zeolite framework is cleaved inside the zeolite's pores. The fragments are then removed and recycled.

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