In this study different water containing adducts, with MgCl 2 ÁnEtOHÁmH 2 O formula, were synthesized through melt quenching method. After characterization of support samples, the final catalysts were prepared by reaction of the samples with TiCl 4 and tested in slurry phase propylene polymerization. The prepared catalysts showed similar stereospecificities but different activities in polymerization experiments, so that, with increasing water amount from m = 0.0 to m = 0.4 wt%, the catalyst activity reached its maximum value of 4.62 kgPP/g Cat.h, and then by further water increase, from m = 0.4 to m = 1.0 wt%, the activity decreased. After optimizing water content, to reach the maximum efficiency of the catalytic system, optimization of the synthesis conditions was considered via response surface methodology. The studied operation conditions affecting the catalyst efficiency were volume ratio of TiCl 4 to toluene (V), initial TiCl 4 injection temperature (I) and TiCl 4 injection time (T). Results showed that catalytic performance is strongly dependent on its preparation conditions. Analysis of variance indicated that V and I are the most effecting parameters on the catalyst activity with F-value of 39.64, and 8.12, respectively. Indeed, it was found that TiCl 4 injection time had no enormous effect on the catalyst activity, but in combination with V, the injection time increment through the scrutinized range decreased the polymerization activity. The obtained model provided a promising tool for designing suitable catalysts for polypropylene production using MgCl 2 /TiCl 4 based Ziegler-Natta catalysts. Graphical Abstract The focus of the present study is to explore how the presence of water in the adduct synthesis step affects the final ZN catalyst performance in propylene polymerization. Besides water amount, effect of important catalyst synthesis parameters on the catalytic performance was studied as well through response surface methodology.

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