@article { author = {Fu, Ting and Cheng, Ruihua and He, Xuelian and Liu, Zhen and Tian, Zhou and Liu, Boping}, title = {How can pH value during catalyst preparation affect the performance of vanadium-modified (SiO2/MgO/ MgCl2)•TiClx Ziegler-Natta polyethylene catalysts}, journal = {Polyolefins Journal}, volume = {5}, number = {1}, pages = {31-45}, year = {2018}, publisher = {Iran Polymer and Petrochemical Institute}, issn = {2322-2212}, eissn = {2345-6868}, doi = {10.22063/poj.2017.1492}, abstract = {Vanadium-modified (SiO2/MgO/MgCl2)•TiClx Ziegler-Natta catalysts were prepared through co-impregnation of water-soluble magnesium and vanadium salts under different pH values. Several key factors such as pH value of co-impregnation solution during catalyst preparation, catalyst performances including catalytic activity, ethylene/1-hexene copolymerization and hydrogen response were investigated. It is found that the components, structures and performance of the catalysts are obviously affected by changing the pH value (pH=5, 7 and 9) of co-impregnation solution. An appropriate pH value (pH=7) can maximize catalytic activity and hydrogen response, while lower pH value (pH=5) is beneficial to the 1-hexene incorporation. The GPC results show that the polymers obtained have high average molecular weight.}, keywords = {Ziegler-Natta catalysts,polyethylene,polymerization kinetics}, url = {http://poj.ippi.ac.ir/article_1492.html}, eprint = {http://poj.ippi.ac.ir/article_1492_3410ff58c56c8a8091034af80db9260f.pdf} }