Synthesis and characterization of chromium-based heterogeneous catalystscontaining tridentate ligands for the production of ۱-hexene

Alpha olefins play a crucial role in petrochemical production. In this study, we developed two typesof catalysts, both homogeneous and heterogeneous, using chromium and tridentate SNS ligands. Ourinvestigation focused on examining the selectivity and activity of these catalysts in ethylenetrimerization and ۱-hexane production. For the heterogeneous catalysts, we stabilized the TridentateCr-SNS-D SNS and Cr-SNS-B SNS catalysts on SBA-۱۵ and Ti-SBA-۱۵ ordered mesoporous silicasubstrates. To evaluate the catalytic activity in ethylene trimerization, we introduced non-silicainorganic oxide (TiO۲) to modify SBA-۱۵. Comparing the activity of the Cr-SNS-D@SBA-۱۵catalyst with Cr-SNS-D@Ti-SBA-۱۵, we observed a ۱.۵-fold increase in catalytic activity whenusing the modified substrate with titanium. This increase can be attributed to the decrease in thenumber of hydroxyl groups on the surface due to modification with titanium and empty orbitals oftitanium.. Moreover, the use of the titanium-modified substrate not only boosted activity but alsoeliminated by-products such as polyethylene. Under the reaction conditions, the Cr-SNS-D@Ti-SBA-۱۵ and SNS-D@SBA-۱۵ heterogeneous catalysts yielded ۳۵۱۱۵ and ۱۹۳۹۴ g۱-C۶/gCr.h,respectively, as the product of ethylene trimerization and ۹۹.۷% selectivity was achieved.

کلیدواژه ها:

Ethylene trimerization ، ۱-Hexene ، Heterogeneous catalyst ، Ordered mesoporous silicaSBA-۱۵ ، Titanium dioxide ، Chromium