Experimental and techno-economic investigation of industrial para-xylene plant revamping to produce meta-xylene

Abstract

In this research, the feasibility study of revamping of simulated moving bed for paraxylene separation in ELUXYL process to produce meta-xylene using industrial Ba-faujasite exchanged adsorbent by changing operating condition (temperature and pressure) were examined experimentally and theoretically. Two different mixed-xylene feed cases (with and without presence of para-xylene) were considered. Different sets of temperature and pressure were evaluated with the help of equilibrium and dynamic experiments to obtain optimum operating condition in a favor of separation of meta-xylene. Results confirm that in the presence of para-xylene in a feed, selectivity of the adsorbent could not change towards meta-xylene. But, in the absence of para in some pressure and temperature meta-xylene was more selective than ortho and ethylbenzene. Finally, by the means of statistical experimental design method the results of all experiments were compered and an optimum temperature and pressure were found. Breakthrough experiment in optimum condition showed MX/OX and MX/EB selectivity as 1.83 and 1.15, respectively. Furthermore, the design and simulation of the real industrial SMB plant was performed in Aspen Chromatography and HYSYS software to evaluate the real performance of MX separation. Simulation results showed the final purification in SMB plant can be reached to 83.91%. At the end, for the aim of promoting purity by considering extra distillation towers the purity of meta-xylene was achieved by 96%. The economical investigation showed that by considering 700$/ton for feed supplied, the process can be satisfactory from economical point of view.

Modeling of Liquid-Phase Oxidation of Para-xylene at a Low Oxygen Partial Pressure

“…The amount of a certain component at the inlet of the reactor is equal to the sum of the amount in the reaction and the amount at the outlet of the reactor For the oxygen component in the gas phase, the difference between the inlet and outlet of the reactor equals the amount transferred from the gas phase to the liquid phase. Equation 2illustrates the mass balance of oxygen gas (2) where N i | δ=0 represents the mass transfer flux of oxygen components at the two-phase interface calculated from the subsequent liquid film equation.…”

“…As one of the most important aromatic compounds, terephthalic acid (TPA) has been widely used in organic synthesis, particularly in the polyester industry. − Commercially, the majority of TPA is produced by the air oxidation of para -xylene (PX) in acetic acid at temperatures ranging from 150 to 210 °C, which is catalyzed by cobalt and manganese salts and promoted by bromine. , Currently, there are two popular oxidation processes: one is represented by Mitsubishi processes (MPCs), and the other is represented by BP Amoco processes. , It has been shown that the reaction is not effective when the oxygen concentration is higher. − Both Cao et al and Digruov et al proposed that the oxidation reaction of PX is of the zero order with respect to the oxygen concentration when the partial pressure of oxygen is above 20 kPa at 80–130 °C and 1 atm. Gai further proposed that this reaction is still a zero-order reaction with respect to the oxygen concentration when the partial pressure of oxygen is higher than 200 kPa at 216 °C under 2.47 MPa.…”