Chemical Processing - June 2008 - (Page 12)

IN PROCESS Waste CO2 edges toward feedstock role Catalyst development enables use of ﬂue gas to make cyclic carbonates LIKELY MOVES in the U.S. to limit greenhouse gas emissions (www.ChemicalProcessing.com/ articles/2008/038.html ), coupled with signiﬁcant eﬀorts already taking place elsewhere are making the question of how to deal with recovered carbon dioxide all the more pressing. Simply storing the gas, such as in salt domes and depleted coal seams, is a widely cited option but one that poses long-term safety and other challenges. So, ﬁnding ways to productively use the CO2 clearly makes sense. Researchers at the University of Newcastle, Newcastle upon Tyne, U.K., believe they’ve identiﬁed a role for the gas as a feedstock. Michael North, a professor of organic chemistry, and his team at the university have developed a method to convert waste CO2 into cyclic carbonates. ey note that substantial demand already exists for such carbonates in established applications, e.g., in solvents, paint strippers and biodegradable packaging, and that the materials also may serve as a feedstock for anti-knock agents for gasoline. e catalytic reaction of CO2 with an epoxide to form a cyclic carbonate is well known, note the researchers, but until now has required high purity CO2 as well high temperatures and pressures. ey have developed an “exceptionally active” catalyst, a dimetallic aluminum(salen) complex, that allows the reaction to use ﬂue gases and to take place at atmospheric pressure and ambient temperature. is dramatically reduces energy input, by obviating all the energy needed to purify, heat and compress the CO2, explains North. Economic Snapshot 55,000 54,500 54,000 $ Million 53,500 53,000 52,500 52,000 51,500 51,000 49,500 Apr 07 May 07 June 07 July 07 Aug 07 Sept 07 Oct 07 Nov 07 Dec 07 Jan 08 CO2 catalyst Figure 1. Michael North holds catalyst that enables cyclic carbonate production at atmospheric pressure and ambient temperature. Photo: University of Newcastle. Both shipments and capacity utilization rose modestly. Source: American Chemistry Council. Shipments (NAICS S325) Capacity utilization e process could consume a signiﬁcant amount of CO2, he believes. In the U.K. alone, “to satisfy the current market for cyclic carbonates, we estimate that our technology could use up to 18 million tonnes of waste CO2 per year, and a further 30 million tonnes if it is used as an anti-knocking agent,” says North. ( e cyclic carbonates can be converted into dimethyl carbonate, which Texaco has reported to be an excellent anti-knocking agent, he notes.) “At present we have only done the reaction on a gram scale… Preliminary results indicate that we can expect to remove at least 20% of the CO2 from a typical waste stream. We see no byproducts and, in particular, do not form polycarbonates. e cyclic carbonate we make is 100% pure,” he notes. “We have just secured two grants to optimize the process. What we aim to do is develop an 80.0 immobilized version of the catalyst 79.0 so that we can conduct a ﬂow reac78.0 tor and run the process continually rather than in batch mode. is 77.0 will allow us to address issues such 76.0 as catalyst lifetime and poisoning,” 75.0 North adds. 74.0 “I think the main remaining challenges are to immobilize the 73.0 catalyst and then simplify its struc72.0 ture as much as possible. Once this 71.0 is done and we have engineering Feb 08 Mar 08 data related to optimal ﬂow rates, etc., then we can look at scaling % JUNE 2008 CHEMICALPROCESSING.COM 12 http://www.ChemicalProcessing.com/articles/2008/038.html http://www.ChemicalProcessing.com/articles/2008/038.html http://CHEMICALPROCESSING.COM

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Chemical Processing - June 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Achieve Model Operations Bolster Your Condition Monitoring Toolbox Particle Analysis Makes Solid Progress Improve Batch Reactor Temperature Control Improve Your Job Security Plant InSites Process Puzzler Equipment & Services Product Spotlight/Classifieds Ad Index End Point

Chemical Processing - June 2008

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