Conversion of polyethylene terephthalate plastic waste and phenol steam reforming to hydrogen and valuable liquid fuel: Synthesis effect of Ni–Co/ZrO₂ nanostructured catalysts

Ni–Co/ZrO₂ (NCZ) nano-structure catalysts prepared by the hydrothermal method (NCZ-hyd) and conventional impregnation (NCZ-imp) method. The comparative catalytic activity and coke resistance for each prepared catalyst were examined in steam reforming of phenol and polyethylene terephthalate (PET) plastic waste. The Physico-chemical catalysts properties were characterized by N₂-adsorption, XRD, FTIR, TEM, SEM, EDX, H2-TPR, CO2-TPD, and TGA. The effects of preparation methods of NCZ nano-structure catalyst on the catalytic performances in PET-phenol steam reforming were investigated. The NCZ-hyd nanostructure catalyst exposed more outstanding catalytic activity and more excellent coke resistance in comparison with the NCZ-imp. The experimental findings exhibited that catalyst synthesized by hydrothermal method were uniform with the size of 8.8 nm, while NCZ particles prepared by conventional impregnation method were un-uniform, unshaped, and agglomerated, and the size distribution of its particles was from 25 to 50 nm. PET-Phenol conversion and hydrogen yield of 56.5% and 52.5% for the NCZ-imp while 67.6% and 64.8% for the NCZ-hyd catalyst were achieved, respectively. The kinetic study of steam reforming of PET-phenol was also implemented. The activation energy was found to be 69.03 J/mol for NCZ-imp while 107.3 J/mol for the NCZ-hyd nanostructured catalysts. The PET-phenol steam reforming produced valuable liquid products such as benzene, 2-methyl phenol, and dibenzofuran which is one of the crucial keys to solving the waste plastic recycling problem.