PORTALE DELLA DIDATTICA

Ricerca CERCA
  KEYWORD

Area Engineering

A cavitational reactor concept for catalytic oxidation of P-XYLENE (pX) to produce high-purity Terephtalic Acid (TPA)

Reference persons SAMIR BENSAID

External reference persons GIULIANO CAVAGLIA'

Thesis type MODELLISTICA

Description Terephthalic acid (TPA), with current annual world capacity of exceeding 70 million metric tons, is a commercially important chemical used primarily in the manufacture of polyesters and PET (poly-ethylene-terephtalate). A rotating cavitational reactor, in which the continuous liquid phase, containing dissolved p-xylene (pX) and the catalyst(Co/Mn/Br), is subjected to cavitation and receives the injection of O2 rich oxidant gas phase just before cavitational region, is expected to produce high-purity TPA with less than 10 ppm 4-carboxybenzaldehyde (4-CBA) in the solid TPA product. In sharp contrast, the solid TPA product obtained from a conventional stirred reactor similar to the configuration used in the conventional Mid-Century (MC) process contains nearly 1000 ppm 4-CBA even though the reactor is operated at similar pressure and temperature (15 bar and 200 °C). The dramatic improvement in TPA product quality during cavitational reactor operation is attributed to two main factors: the strong abatment of interphase gas-liquid mass transfer resistances that facilitates more complete oxidation of the pX and the intermediate oxidation products to TPA, and perfect plug flow that enhances the oxidation rates.
Kinetic studies of pX oxidation to TPA already performed in a well-stirred 50 mL reactor confirm that the intermediate oxidation steps are controlled by mass transfer resistances even at the highest rotational speed used. This thesis, through theoretical calcultion, aims to show that the time constants for O2 diffusion in liquid phase under cavitation are one to two orders of magnitude lower than the kinetic rate Constant, confirming complete O2 penetration and saturation of liquid phase and confirming that with cavitational reactor pX oxidation step is controlled by chemical kinetic, and to evaluate impurities level.
Once achieved this goal, the new TPA process scheme with heat/mass balances shall be developed and compared “gate-to-gate” through economical analysis with conventional MC process so to make an assessment of expected capital investment cost as well as operating cost expected saving.

See also  thesis proposal.pdf 


Deadline 15/02/2019      PROPONI LA TUA CANDIDATURA




© Politecnico di Torino
Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY
Contatti