Ethylene oxychlorination process using a CuCl2 catalyst is widely used to manufacture Poly Vinyl Chloride (PVC). The high exothermicity of this process makes temperature control difﬁcult. The failure of proper temperature control leads to the volatilisation of the catalyst active material. Hence, it is a necessity to understand the activity of the catalyst during the reaction so as to control the process.
This work exemplifies the use of a novel combination of Multivariate curve resolution (MCR) technique to solve and understand ethylene oxychlorination UV-vis spectroscopy. The focus of the project was to use this chemometric combination to develop a multivariate UV-vis resolution kinetics approach (MURKA). The approach successfully differentiated the states of different CuCl2 catalysts and their contributions during ethylene oxychlorination. MURKA allows one to evaluate the performance and stability of the catalyst during oxychlorination by using UV-vis spectroscopy data.
The approach was applied to UV-vis reaction data sets of un-promoted, Li-, K-, Cs-, Na-, Rb-, Mg-, Ca-, La- and Ce-promoted CuCl2 catalyst on γ-Al2O3 support. The calculated contributions from the catalyst species gave better insights into the different promoters promotion capacity. Also, the contributions described the inﬂuences on catalyst reducibility during the oxychlorination reaction. The results described caesium and potassium promoters to be better than other tested promoters, as it decreased the volatilisation of copper. The inﬂuence of 0.4 mole ratio (molR) of potassium promoted catalyst was the major among all other molR of potassium during ethylene oxychlorination. Hence, a kinetic model was set up to obtain kinetic parameters for the contributions of 0.4molR of potassium promoted catalyst at the various reaction temperature using MURKA.
The kinetic rates modelled using MURKA for ethylene and oxygen were validated and found to be similar to the rates calculated from the mass spectrometer. Also, the potassium promoted catalysts exhibited a faster rate for oxygen as temperature increased. The validation experiments proved capacity of MURKA to identify and differentiate CuO and CuCl2 from Cu2OCl2 during the chlorination reaction step.
A catalyst activity perspicacity was achieved by just applying MURKA on oxychlorination UV-vis reaction data set. This novel combination proved to be a straightforward in situ technique to study ethylene oxychlorination reaction as it transpired inside the reactor.