Gasification of Polyethylene over Solid Catalysts (Part 1)

Selective recoveries of useful gaseous hydrocarbons from polyethylene were attempted over various zeolites and silica-alumina at 420∼580°C by the use of a batchwise reactor. The rates of degradations of polyethylene over these catalysts were promoted 2 to 7 times faster than that of the thermal degradation.The order in degree of total formation of hydrocarbons of 1∼4 carbon atoms (gasification) at 480°C was silica-alumina, CaX, NaX, and NaY>CaA>NaA>thermal. In the thermal degradation and catalytic degradations over A-type zeolites, hydrocarbons of 2 and 3 carbon atoms were mainly produced. In catalytic degradations over others, hydrocarbons of 3 and 4 carbon atoms were main products and isobutane was formed. Over CaX and silica-alumina the amount of isobutane was in the same order or more of hydrocarbons of 3 carbon atoms (C3) and other C4 hydrocarbons were about 1/4 of isobutane. Over NaX and NaY isobutane was about 1/3 of other C4 hydrocarbons.Further, dependences of the gasification and product composition on reaction time and temperatue were revealed in detail.