Selective production of pyrroles via catalytic fast pyrolysis of cellulose under ammonia atmosphere at low temperature

Abstract

In this study, cellulose was selectively converted into pyrroles via catalytic fast pyrolysis under ammonia atmosphere over the γ-Al2O3 catalyst. Both in situ and ex situ lab-scale fast pyrolysis sets were designed and used for investigation, and more pyrroles were produced via in situ CFP process. In addition, the effects of catalyst, reaction temperature and catalyst-to-cellulose ratio on the product distribution were investigated systematically. All these factors played important roles in the production of pyrroles. Under the optimized in situ CFP condition, at 400°C and catalyst-to-cellulose ratio at 2, the carbon yield of N-containing chemicals from cellulose under ammonia atmosphere reached 9.7%. The selectivity of pyrroles in N-containing chemicals was 89.5%. The possible conversion pathway from cellulose to pyrroles was also proposed, that is, cellulose was firstly converted into anhydrosugars through thermal decomposition, then anhydrosugars underwent dehydration and rearrangement reactions to form furans. Thereafter, the furans were transformed into pyrroles by reacting with ammonia.