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This report details the preliminary design and economic analysis of a paraxylene production plant that uses glucose as the raw material in the form of a hydrolysate obtained from an ethanol plant. The process of taking glucose and converting it to paraxylene happens through three main chemical reactions. The first is the conversion of glucose to hydroxymethylfurfural (HMF), the second is the hydrogenolysis of hydroxymethylfurfural to produce dimethylfuran (DMF) and the last is the reaction of dimethylfuran with ethylene gas to produce paraxyelene. In this report the overall process is broken down in two sections, the first is the production and purification of DMF and second is the production and purification of paraxylene. The first step in the production of DMF is the glucose to HMF conversion, which occurs in a continuously stirred, biphasic reactor with a selectivity of 75%. HMF is then concentrated in a butanol solution and fed into a trickle bed reactor where it reacts with hydrogen to produce DMF and water, DMF has selectivity of 70%. DMF is then purified in a separation train comprised by three distillation columns and one liquid-liquid extraction column. DMF is then fed to a fixed bed reactor where it reacts with ethylene to produce paraxylene using hexane as a solvent, the selectivity of DMF is 98%. Finally, paraxylene is purified in a separation train comprised by a decanter and two distillation columns. The process uses about 140,000 lbs/hr of hydrolysate feed and produces about 13,000 lbs/hr of paraxylene at a 99.9% purity. In this report it is assumed that the market price of paraxylene is $1.00 per pound, at that price the process presented is not profitable at a return on investment of -88%. The total capital investment required for this project is close to $47 million. The main expense of the process is its utilities in energy intensive separation units; the steam requirement of a single distillation column is alone 37% of the cost of paraxylene.
Date Posted: 04 May 2015