Catalytic co-pyrolysis of cellulose and waste polyoxymethylene to improve producing pyridines compounds over commercial HZSM-5 zeolites under ammonia atmosphere

Abstract

Polyoxymethylene resin, one of the five major engineering materials with excellent comprehensive performance, was widely used in the industry. Pyridines, a kind of important heterocyclic compounds, were widely used as substrates for synthesis pharmaceutical, agro-chemical and dye industries. In this study, N-containing chemicals could be produced from waste polyoxymethylene (POM) plastic and cellulose via catalytic pyrolysis over commercial zeolite under ammonia atmosphere. Zeolite acidity and pyrolysis temperature affected product distribution significantly. Suitable catalyst for pyridines production was HZSM-5 (Si/Al = 83.3), and lower temperature (500 °C) prefer to form pyridines, nitriles and pyrroles and higher temperature could increase pyridines selectivity while decreased its yield. In addition, significant synergetic effects have been observed when cellulose was added, which improved pyridines yield by 40.64 % to 11.32 C% at the mixing weight ratio of cellulose to POM of 5:1. The synergistic effect between cellulose and POM for enhancing pyridines production were that POM pyrolytic intermediate (HCHO) can be used not only as substrate to form pyridines but also as an alkylation reagent to produce alkylation substituted pyridines. Catalytic pyrolysis with ammonia process has been proved to be a promising method for producing N-containing chemicals from biomass and wasted oxygen-containing plastics.