Dual catalytic system using industrial solid waste and zeolite for enhanced aromatic hydrocarbon conversion from...

The present study developed a dual-catalyst system combining typical industrial solid waste (i.e. red mud, coal fly ash, blast furnace slag, red gypsum and anode slag) and zeolite in synergistically promoting the catalytic fast pyrolysis (CFP) of waste bamboo biomass for aromatics production. The results demonstrated that industrial solid wastes significantly enhanced deoxygenation and decreased the oxygenated compound content by 2.60 % to 26.26 % compared to non-catalytic pyrolysis. Notably, red gypsum exhibited the most pronounced effect, increasing the content of aromatic precursors, such as hydrocarbons, by 21.82 %. In the dual-catalyst system, the red gypsum/HBeta (H-form Beta zeolite) combination (1:1 ratio) attained a total aromatics relative content of 43.58 % at 550°C, representing a 30.79 % improvement over single HBeta. Moreover, the contents of monocyclic aromatic hydrocarbons (MAHs) and benzene-toluene-xylenes (BTX) increased by 37.27 % and 49.29 %, respectively. The improved aromatics content was primarily attributed to the abundant reactive oxides and hierarchical pore structure within the dual-catalyst CFP (DC-CFP). In the DC-CFP, the mesopores of the industrial solid waste promote the diffusion of macromolecules produced by pyrolysis, while lattice oxygen transfer from Fe₂O₃ (28.29 %) in red gypsum facilitates the cleavage of the C-O, C=O and C-C bond to yield small-molecule precursors. These intermediates then undergo aromatization driven by the acidic sites of the microporous HBeta zeolite, synergistically enhancing aromatics content and offering a novel approach for utilizing industrial solid waste resources and biomass energy.