Silica-alumina catalysts polyolefins

The poor selectivity of the thermal decomposition of polyolefins has promoted the development of catalytic cracking. Catalytic cracking lowers the pyrolysis process temperature and lowers the boiling temperature range of the resultant liquid products. The use of molecular sieves and amorphous silica-alumina catalysts for the cracking of waste polymers into a range of hydrocarbons has been widely studied (see Chapters 3-5, 7, 8). 

C. Vasile, P. Onu, V. Barboiu, M. Sabliovschi, G. Moroi, Catalytic decomposition of polyolefins. II. Considerations about the composition and the structure of reaction products and the reaction mechanism on silica-alumina cracking catalyst. Acta Polym. 36, 543 (1985). 

V. Dufaud and J.-M. Basset, Catalytic hydrogenolysis at low temperature and pressure of polyethylene and polypropylene to diesels or lower alkanes by silica-alumina a step toward polyolefin degradation by the microscopic reverse of Ziegler-Natta polymerization, Angew. Chem. Int.Ed., (1998) 37(6) 806-810. I. Nakamura and K. Fujimoto, Development of new disposable catalyst for waste plastics treatment for high quality transportation fuel. Catalysis Today, 27,175-179 (1996)... 

Various kinds of Zeolites are engaged in the catalytic cracking of hydrocarbon feedstocks, such as ZSM-5, Beta, Y, in addition to other known acid solids such as silica-alumina, alumina and clays. Various combinations of these catalysts such as SAHAyZSM-5 and MCM-41/ZSM-5 have been also employed for the recycling of polyolefins [30]. 

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