Triboelectric effects of a pneumatically injected silica catalyst support on polyethylene fluidized bed wall fouling

Abstract

In commercial ethylene gas-phase polymerization, small loads of catalyst particles periodically fed into the reactor. This necessitates studying their contribution on the fluidized bed reactor electrification and sheeting. Prior to testing catalysts utilized in commercial processes, this work focused to investigate the role of a typical amorphous silica catalyst support used in ethylene polymerization on the polyethylene fluidized bed electrification and wall fouling. A 5-m in length and 0.00475-m inner diameter stainless-steel pneumatic conveying line was used to convey 0.1 and 1 g of silica (representing 100 and 1000 ppmw) at various fluidization times of 0, 15 and 30 min into a 1-kg bed of polyethylene fluidized in a 0.1 m diameter stainless-steel atmospheric column. Overall, a reduction was observed in the wall fouling. This was attributed to the silica's negative charge upon entering the bed, silica/polyethylene particle number ratio, and silica's capability to induce negative charge within the bed.