Acid properties of silica-alumina catalysts and catalytic degradation of polyethylene

Abstract

A relationship between the acid strengths and amounts of silica-alumina catalysts and the compositions of products formed by the catalytic degradation of polyethylene at 673 K was studied. The acid strengths and amounts were varied with SiO{sub 2}/Al{sub 2}O{sub 3} weight ratio in the catalysts. Although the resulting products and amounts were varied with SiO{sub 2}/Al{sub 2}O{sub 3} weight ratio in the catalysts. Although the resulting products consisted of gases, oils, and wax, the fraction of gases increased, and, inversely, the fraction of oils decreased, as the acid amounts over the catalysts increased. The fraction of aromatics in the oils was enhanced, however, as the acid amounts over the catalysis increased, which was discussed in terms of the acid types: Broensted and Lewis acids generated on silica-aluminas. Since some inorganic compounds such as MgO, ZnO, TiO{sub 2}, and carbon are incorporated into plastics, the catalytic activities and selectivities of these additives for polyethylene degradation were also discussed.