FAST PYROLYSIS OF PLASTIC WASTES

Preliminary results using an atmospheric-pressure fluidized-bed fast pyrolysis process have been obtained for the fast pyrolysis of commerical grades of polystyrene, poly(vinyl chloride), and polyethylene. On the basis of these tests, polyethylene was selected for detailed study because of the difficulty in regenerating the monomer in good yields and because of its abundance as a waste material—about 70% of all plastic waste. A test program was undertaken to attempt to produce higher value products from polyethylene, rather than monomer. This approach not only disposes of the waste but also offers the possibility of cost return. Both thermal and catalytic pyrolysis tests have been done in an atmospheric-pressure fluidized-bed reactor. Initial results suggest that catalytic pyrolysis can give promising yields of a liquid hydrocarbon product that could be refined to yield a transportation fuel. Product composition from the pyrolysis of polyethylene can be controlled over a wide range by a suitable combination of type of catalyst, temperature, and particle size. © 1990, American Chemical Society. All rights reserved.