Document Type : Original research
Authors
Instituto de Química, Universidade Federal do Rio Grande do Sul
Abstract
The determination of Ti+4 in Ziegler–Natta catalysts is highly relevant for industrial plants that use Ziegler–Natta (ZN) catalysts based on TiCl4 as a source of titanium. The catalyst preparation step requires analytical monitoring during the dilution process for the morphological effect according to the relationship between the Ti+3 and Ti+4 concentrations in the polymerization process, which in turn depend on a variety of intended grades for different market applications. Spectrophotometry in the visible region was evaluated as a potential analytical technique for the quantification of Ti+4 in ZN catalysts. The present study proposes the use of an easily accessible, reliable and low-cost validated instrumental method for Ti+4 determination. Therefore, the technical details regarding sample preparation, instrumental analytical parameters and performance characteristics of the method were descriptively addressed. The quantitative evaluation of performance parameters (namely, specificity, linearity, detection and quantification limits, precision, accuracy and robustness) demonstrated successful results compared with the theoretical values of the studied reference sample. The precision of the method by visible spectrophotometry was estimated at 0.4% for the relative error, and the accuracy presented within an IC of 95% for the LOC ± 1.7 mmolTi/L for the average concentration of 339.5 mmolTi L-1 in reference to the Tyzor ® TnBT sample with a theoretical concentration of 337 mmol L-1 study solution from this work. The method was shown to be a supporting tool for quantitative Ti+4 species determination in the control of industrial processes.
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