Design od a process for the one-pot bio-ethylene oxide production

DESIGN OF A PROCESS FOR THE ONE-POT BIO-ETHYLENE OXIDE PRODUCTION I. Rossettia, D. Ripamontia, A. Tripodia, F. Contea and G. Ramisb a Chemical Plants and Industrial Chemistry Group, Dip. Chimica, Università degli Studi di Milano, CNR-ISTM and INSTM Unit Milano-Università, via C. Golgi 19, 20133 Milan, Italy b Dip. Ing. Chimica, Civile ed Ambientale, Università degli Studi di Genova and INSTM Unit Genova, via all’Opera Pia 15A, 16145 Genoa, Italy The possibility to exploit renewable sources for the production of bulk chemicals is attractive and bio-ethanol has been recently proposed as platform to produce hydrogen via steam reforming and bio-ethylene by dehydration. Another C2 compound with huge industrial applications is ethylene oxide, which may be in principle obtained in two steps following the route bioethanol  bio-ethylene  bio-ethylene oxide. Recently, a one-pot synthesis has been proposed1,2 and the aim of this work is the design from the grass roots of a new production plant including the reactive and purification sections to exploit it industrially. Kinetic parameters for the reaction have been derived by regression of experimental literature data with a power law pseudo-homogeneous model and they were used for a preliminary sizing of the reactor. A shell&tube heat exchange reactor was implemented to control the exothermicity of the reaction, with simultaneous steam production and three catalyst layers (200, 500 and 2000 kg) with intercooling. 99.5% ethanol conversion and 84% selectivity to ethylene oxide were achieved, with ca. 100 kmol/h productivity, starting from the feedstock availability of a commercial bio-refinery. The product is first recovered with an absorption column (releasing most N2, CO, O2 and CO2 in gas phase, followed by a stripping column. A further distillation column separates crude ethylene oxide as distillate, while acetaldehyde, diethyl ether and minor impurities as bottom product. Further purification options for ethylene oxide and for the recovery of by-products were also compared. 1 - M.J. Lippits, B.E. Nieuwenhuys, Direct conversion of ethanol into ethylene oxide on copper and silver nanoparticles. Effect of addition of CeOx and Li2O, Catalysis Today, 154 (2010) 127 – 132 2 - M.J. Lippits, B.E. Nieuwenhuys, Direct conversion of ethanol into ethylene oxide on gold-based catalysts. Effect of CeOx and Li2O addition on the selectivity, Journal of Catalysis, 274 (2010) 142 – 149