Sustainable coke-resistant Ca-Al nano-sized catalyst for cogenerating of H2 and high value liquid fuels via pyrolysis catalytic steam reforming reaction of the polystyrene-phenol mixture

Abstract

The main challenge of pyrolysis-catalytic steam reforming to convert polystyrene wastes into high value products is the low selectivity and coke formation on the catalyst's surface. This work aims to design a highly catalytic active precious metal-free Ca-Al nanocatalyst, synthesized by impregnation and hydrothermal routes, for the conversion of polystyrene (PS) dissolved in phenol into H2 gas and liquid fuels via pyrolysis-catalytic steam reforming reaction using a well-designed setup reactor. The effect of physicochemical properties of the catalyst on the conversion mechanism. It was found that the catalyst with high γ-Al2O3 content (2Ca3Al) had an excellent overall performance due to its high surface area, sufficient holes uniformly distributed Ca and Al alloy, surface hydroxyl groups, and oxygen vacancies. The obtained phenol conversion and H2 yield of the 2Ca3Al nanocatalyst at 700 oC were 98.5% and 92.5%, respectively. The main detected compounds in the liquid product were tert-Butyl Hydroperoxide (TBH) and Dixanthogen. The relationship between the acidity of the catalyst's surface and the coke formation, which directly influences the performance and deactivation, was investigated. The results showed that the catalyst with higher acidity contents showed weaker resistance against coke formation. The as-prepared catalyst showed excellent performance and anti-coke formation, which would be applied for the simultaneous generation of hydrogen and valuable liquid fuels and the recycling of plastic wastes.