A novel method for Controlling silica-gel porosity used as support in Phillips Cr/silica catalyst

The porosity of Phillips Cr/silica catalysts plays a major role in determining the molecular weight (MW) and molecular weight distribution obtained during ethylene polymerization. Silica gels have different physical properties such as surface area, pore volume, radius of curvature, or average pore diameter. These properties have important role on final production (PE) features. It could be noted, pore volume determines the fragility of the catalyst, which governs the degree of fragmentation during polymerization, and the fragment size. Many methods have been introduced to controlling porosity of silica gels such as using different solvents in the drying stage of hydrogel, dry silica gel pressing and compacting under varying pressures up to 70,000 psig and alkaline aging. In this study we investigated effect of acid concentration on porosity at gelation stage in sol-gel route. Our results shows that pH of used acid in the gelation stage can be considered as important factor in the porosity controlling

کلیدواژه ها:

Porosity ، Silica gel ، Pore volume ، Sol-gel process ، Acid concentration ، Cr/silica catalysts ،