Catalytic thermal decomposition of polyamides and polyurethanes mixed with acidic zeolites

• Published in: Journal of analytical and applied pyrolysis Vol. 97; pp. 189 - 197
• Main Authors: Bozi, János, Blazsó, Marianne
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2012
• Subjects: benzene; catalysts; Catalytic pyrolysis; isomers; naphthalene; Polyamide; polyamides; polyesters; Polyurethane; polyurethanes; pyrolysis; Pyrolysis-GC/MS; Y zeolite; zeolites; Polyamide; Pyrolysis-GC/MS; Y zeolite; Catalytic pyrolysis; Polyurethane
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2012.06.002

► Catalytic pyrolysis and conversion of polymers pyrolysate lead to different products. ► From 1:1 mixture of Y zeolite–polyamide dinitrile or dehydrated cyclic monomer form. ► Catalytic pyrolysis of MDI segments of PUR leads to aniline and p-toluidine. ► Excess of catalyst convert all the volatile pyrolysis products mainly to aromatics. The purpose of this work was to examine the pyrolysis products derived from zeolite–polyamide and zeolite–polyurethane mixtures prepared in different ratios in order to elucidate the chemical reactions taking place under pyrolysis of these polymers in the presence of acidic Y zeolites (ultra stabilized HY (HUSY) and NH4NaY). Therefore 5:1, 3:1, and 1:1 ratios of zeolite and nitrogen-containing polymer (polyamides and polyurethanes) mixtures were pyrolysed at 500°C in a micro-pyrolyser on-line coupled with GC/MS. The products and product distribution of zeolite–polymer mixtures indicate that the amount of catalysts significantly affects the pyrolysis product distribution. In case of zeolite–PA-6,6 1:1 mixtures hexanedinitrile is the main pyrolysis product indicating that the thermal decomposition of PA-6,6 via cis-elimination is enhanced. Main pyrolysis products of zeolite–PA-6 mixtures of 1:1 ratio are dihydro-azepine isomers that are the dehydrated derivatives of ɛ-caprolactam. Pyrolysis of 1:1 zeolite–PA-12 mixtures leads to the promoted formation of dehydrated cyclic monomer isomers (azacyclotrideca-dienes). For zeolite–PUR 1:1 mixtures it was concluded that MDI decomposition to N-containing aromatics is enhanced, while the polyester and polyether segments degrade to monomer type products and to aromatics. For all zeolite–polymer mixtures increasing ratio of catalysts leads to increased amount of aromatics (benzene and naphthalene compounds) and light unsaturated hydrocarbons, while the amount of main products of 1:1 mixtures decreases.