Selective formation and mechanistic pathways of carbonyl compounds from cellulose catalytic pyrolysis over nanometal oxides

Analytical pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) was used to investigate the catalytic fast pyrolysis of cellulose. The catalysts investigated in this study included rutile TiO 2 , anatase TiO 2 , Fe 2 O 3 , ZrO 2 , CeO 2 , CuO, CaO, and NiO. These catalysts exhibited distinct effects on the distribution of cellulose pyrolysis products. Among the tested catalysts, rutile TiO 2 was the most effective in suppressing carbohydrate-derived products, reducing their relative content to 65.1%, and in promoting carbonyl compounds, increasing their relative content to 30.11%. The relative contents of 2(5H)-furanone, furfural (FF), 5-hydroxymethylfurfural (5-HMF), and 2-hydroxy-3-methyl-2-cyclopenten-1-one increased most markedly. ZrO 2 caused only minor changes in the distribution of primary cellulose pyrolysis products, whereas CeO 2 induced the most extensive transformation, leading to the identification of 21 new compounds in the catalytic pyrolysis products. Moreover, NiO selectively promoted hydroxyacetaldehyde formation, whereas the other seven metal oxides suppressed it, with Fe 2 O 3 showing the strongest inhibitory effect. These findings provided a scientific basis for producing carbonyl-rich bio-oil through facile catalytic pyrolysis.