Theoretical–Experimental Study of the Action of Trace Amounts of Formaldehyde, Propionaldehyde, and Butyraldehyde as Inhibitors of the Ziegler–Natta Catalyst and the Synthesis of an Ethylene–Propylene Copolymer

Abstract

The copolymer synthesis process can be affected by failures in the production process or by contaminating compounds such as ketones, thiols, and gases, among others. These impurities act as an inhibiting agent of the Ziegler–Natta (ZN) catalyst affecting its productivity and disturbing the polymerization reaction. In this work, the effect of formaldehyde, propionaldehyde, and butyraldehyde on the ZN catalyst and the way in which it affects the final properties of the ethylene-propylene copolymer is presented by analyzing 30 samples with different concentrations of the mentioned aldehydes along with three control samples. It was determined that the presence of formaldehyde 26 ppm, propionaldehyde 65.2 ppm, and butyraldehyde 181.2 ppm considerably affect the productivity levels of the ZN catalyst; this effect increases as the concentration of aldehydes is higher in the process; likewise, these impurities affect the properties of the final product, such as the fluidity index (MFI), thermogravimetric analysis (TGA), bending, tension, and impact, which leads to a polymer with low-quality standards and less resistance to breakage. The computational analysis showed that the complexes formed by formaldehyde, propionaldehyde, and butyraldehyde with the active center of the catalyst are more stable than those obtained by the ethylene-Ti and propylene-Ti complexes, presenting values of −40.5, −47.22, −47.5, −5.2 and −1.3 kcal mol−1 respectively.

Furan as Impurity in Green Ethylene and Its Effects on the Productivity of Random Ethylene–Propylene Copolymer Synthesis and Its Thermal and Mechanical Properties

“…This result is because furan acted as an inhibitor of the reaction since it reacted with the active center of titanium, preventing the propylene from polymerizing in the vibrant center of titanium. It should be noted that the inhibitory behavior of impurities on the productivity of the Ziegler–Natta catalyst has been previously reported [ 1 , 3 , 12 , 35 , 36 , 37 , 38 , 39 , 40 ], showing that the presence of impurities such as H 2 S, oxygenated compounds, and thiol, among others, affects the efficiency in the production of polypropylene on an industrial scale.…”

Dimethylformamide Impurities as Propylene Polymerization Inhibitor

“…In this section, we present the results of simulating the binding of the inhibitor to the active TiCl 3 /Mg 8 Cl 16 center, as illustrated in Figure 7 a. The choice of this model is based on previous calculations that suggest that the coordination of TiCl 4 with the (104) plane is quite weak or even unstable, whereas the coordination of TiCl 4 with the (110) plane is energetically favored [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ].…”

“…Its presence can decrease the catalytic activity and affect the selectivity and quality of the polymers obtained [ 8 , 9 ]. To better understand the poisoning of ZN catalysts during polypropylene synthesis, it is necessary to use theoretical and experimental tools [ 10 , 11 , 12 ]. The density functional theory (DFT) has established itself as an indispensable tool in investigating the inhibition of ZN catalysts.…”

Development of an online optical prototype for the simultaneous analysis of defects or gels in industrially synthesized polypropylene films. Part 1: Comparison with ASTM D 3351–93 methods

“…Within these figures, the significant contribution of PP in the form of films stands out, which, thanks to its exceptional mechanical resistance, superior quality, optical clarity, and flexibility, has become a reliable option for packaging, printing, and lamination applications. The demand for PP in the form of films is projected to exceed 25 million tons in 2023 [7] . PP films are manufactured using extrusion machines composed of a worm screw, five heating zones, a feeding drum, and rollers, as illustrated in Fig.…”