| Popis: |
Over the last seven years Shell has developed a novel, economically attractive, and environmentally benign process for the production of methyl methacrylate (MMA). The process is based on the highly efficient Palladium-catalysed methoxycarbonylation of propyne (methyl-acetylene or MA) under mild, non-corrosive reaction conditions (temperature ca. 50°C, CO pressure ca. 10 bar) according to the equation: MeOH + CO + HC ≡ C − Me(MA) H2C = C(Me) − C(O)OMe(MMA) The activity (> 20000 mol-MMA/mol-Pd.h) and selectivity (> 99%mol) of the homogeneous Pd catalyst are very high making a once-through process with minimal waste possible. The MA feedstock for the process, together with propadiene (PD), is separated from a steam-cracker C3 stream by extractive distillation with DMF. Subsequently, PD is removed from this MA + PD/DMF mixture and isomerized over a heterogeneous K2O/Al2O3 catalyst to yield additional MA. Crude MMA obtained from the methoxycarbonylation of MA can easily be purified by a ‘topping and tailing’ procedure to yield MMA of very high purity (> 99.99 w%). This article describes some of the R&D work carried out at the ‘Koninklijke/Shell-Laboratorium, Amsterdam’ which has enabled the design of a plant, based on this novel technology. |
Plný text