Reciclagem de poliolefinas por hidrocraqueamento

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

Although polyolefins can be recycled, they must be discarded after several uses. Polyolefin biodegradation is very slow, increasing the amount of plastic waste in the landfills. We have studied the recycling of PE (polyethylene) and PP (polypropylene) by hydrocracking. We have converted PE and PP into light hydrocarbons, which can be used as fuels after separation. We employed homogeneous and heterogeneous catalytic systems using decalin, tetralin and/or toluene as solvent. The gaseous products were analyzed by GC and GC/MS. The liquid fraction was filtered and analyzed by GC and GC/MS and the solid fraction was submitted to extraction with THF. The extract was analyzed by GC and GC/MS. The gaseous fractions had similar constitution for PE and PP; 85 -95% were C1 to C3 hydrocarbons and 5 -15% C4 and C5 hydrocarbons. For the homogeneous catalytic system, based on ferrocene, up to 100% of the polyolefins could be converted into gaseous products. When the system was optimized for liquid products, only 15% was converted into light hydrocarbons (C6-C12), and 25% was converted to heavy hydrocarbons (>C13). The use of more acid catalysts, ferric salts on alumina or Y zeolite, improved the conversion to liquids and the selectivity to light hydrocarbons. We obtained up to 75% of liquid hydrocarbons, 70% of which were light hydrocarbons. In the liquid fraction of the PE samples, we observed saturated hydrocarbons in up to 90% yield, while for the PP samples saturated, unsaturated and branched hydrocarbons were observed. Both polyolefins gave liquid hydrocarbons in good yield and selectivity, which may be used as fuels or as chemical feedstocks.

ASSUNTO(S)

plasticos

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