Effect of Acid Treatment of Montmorillonite on “Support-Activator” Performance to Support Metallocene for Propylene Polymerization Catalyst

Abstract

This work is focused on montmorillonite (MMT)‐based “support‐activators” (S‐As) for the metallocene‐catalyzed propylene polymerization. This catalyst was previously industrialized; however, for further technological advances, the activation mechanism is investigated. The chemical and morphological requirements of the S‐A are surveyed using both commercially available raw clay minerals (non‐acid‐treated) and acid‐treated clay minerals. The S‐A possessing strong‐acid sites (pKa < −8.2) gives a highly active catalyst. Acid treatment of MMT induces morphological changes as well as the formation of strong acid sites. Based on pore size distribution analysis and atomic force microscopy observations, it is concluded that the strong acid sites are located in the small pores around the edge of the clay mineral (not in the interlayer), where the structure is disordered by the acid treatment.

Tailoring Hexagonal Gibbsite Single Crystal Nanoplatelets for Ethylene Polymerization and Nanocomposite Formation on MAO‐Free Heterogeneous Bis(imino)pyridine Iron(II) Catalyst

“…Kotohiro et al synthesized new (imido)vanadium(V) complexes for MAO‐free ethylene polymerization . Recently, Tayano et al succeeded to use acid treated montmorillonite as support and activator for propylene polymerization catalysts . Owing to the cation exchange, curling was observed at the edges of the acidified layered silicates but nanocomposite formation via clay exfoliation was not mentioned.…”

α‐Iminocarboxamide‐Ni Complex Immobilized on Acid‐Treated Montmorillonite as Catalyst for Ethylene Polymerization

“…These results suggested that the acid treatment of the montmorillonite has a crucial impact on inducing the catalytic activity. Tayano et al reported that the acid treatment of montmorillonite increased the amount of the acid sites having p k a < –8.2, and these substantial acid sites effectively promoted the activation of zirconocenes as a catalyst for the propylene polymerization . It was likely that the strong acid sites on the montmorillonite formed by the acid treatment reacted with the alkylaluminum compound and formed surface Lewis acidic sites to promote the formation of “real” active species from the α‐ICA‐Ni complex.…”

Remarkable Promotion Effect of Sulfation over the SiO2‐Supported Vanadium‐Oxide‐Based Catalysts for UHMWPE

“…This also inspired us to find another way to further improve the activity of this catalyst. As a matter of fact, enhanced acidity could be approached by numerous ways, such as the metal oxides mixtures or even direct acid treatment . While introducing solid superacids consisting of sulfated metal oxides is more preferred, as these compounds are endowed with fairly high acidity, which could be maintained even under temperature higher than 500 °C, and the green nature and low corrosion also make them very attractive .…”

“…As a matter of fact, enhanced acidity could be approached by numerous ways, such as the metal oxides mixtures or even direct acid treatment. [23][24][25] While introducing solid superacids consisting of sulfated metal oxides is more preferred, as these compounds are endowed with fairly high acidity, which could be maintained even under temperature higher than 500 °C, and the green nature and low corrosion also make them very attractive. [26] The catalytic applications in alkylation, isomerization, esterification, and reduction of NO are extensively studied, and the enhancement effect in vanadium-oxide-based catalysts for methanol oxidation are widely reported.…”