Photocolorimetric determination of zirconium microcontent in the products of linear alpha-olefins production

Abstract

Analytical control of the technological process of linear alpha-olefins (LAO) production using a zirconium carboxylate based catalyst according to α-SABLIN technology calls for determination of the residual zirconium in the solvent when washing equipment, in the reaction products and wastewater, the purity of which is strictly regulated. Features of photocolorimetric determination of zirconium impurities with different complexing agents are considered and sensitivity of the determination with iron, aluminum, nickel and chromium present is estimated by comparing the values of the «sensitivity index» (by E. Sendel) and «specific absorption» (by Z. Marchenko). The reaction of complex formation with arsenazo III in 9 – 10 M HCl is used for determination of zirconium in the LAO production related products. The resulting colored complex exhibits the maximum light absorption at a wavelength of 670 nm. The measured content ranges from 0.100 to 100 mg/kg, 103-fold amounts of Ni2+, Fe3+, Al3+ and 400-fold amounts of Cr3+ do not interfere with the determination. The method of additives is used to eliminate the interfering effect of the acidity of the medium. It is shown that the developed technique provides a satisfactory level of the reproducibility and correctness of the results for analytical control of LAO production.