Pyrolysis behaviors of model compounds with representative oxygen-containing functional groups in carbonaceous feedstock over calcium

Abstract

Compounds with different functional groups and bridged bonds have been extensively used as model compounds of carbonaceous feedstock to investigate the mechanism of catalytic pyrolysis. Aiming to understand the structure evolution mechanism of different oxygen-containing functional groups and weak-covalent bonds during catalytic pyrolysis of carbonaceous feedstocks over calcium, polyacrylic acid, polyvinyl alcohol, polyethylene terephthalate, and polymethyl methacrylate were used as model compounds. The structural characteristics, reactivity, and pyrolysis products of model compounds with and without calcium addition were investigated by using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and in-situ pyrolysis vacuum ultraviolet photoionization time-of-flight mass spectrometry (in-situ Py-VUV-PIMS). The results show that calcium can form calcium complexes with the carboxyl or alcoholic hydroxyl structures in the long aliphatic carbon chain, but it has no obvious effect on the structure and reactivity of the ester groups in different compounds. The pyrolysis products analysis showed that the chemical structure and decomposition pathway of the model compounds containing carboxyl or alcoholic hydroxyl groups changed significantly after calcium addition, and a large number of carbonyl compounds appeared in the pyrolysis products. This result provides a theoretical basis for understanding the mechanism of calcium-catalyzed carbonaceous feedstock pyrolysis.