A sandwich framework effect on the conversion of cylindrical pore into slit pore and its catalytic application

Abstract

CO₂ is the most prevalent greenhouse gas that traps heat and raises the global temperature. To stabilize or reduce concentrations of this greenhouse gas, it is mandatory to decompose CO₂. So we have synthesized AlPO₄ and ZnO₄-AlPO₄ catalysts using tetrapropylammonium hydroxide (TPAOH) as a template. The synthesized catalysts are systematically characterized by physicochemical methods. XRD analysis proved that AlPO₄ has a tetrahedral framework. But the ZnO₄-AlPO₄ has two separate frameworks, such as a novel ZnO₄ and AlPO₄, in which the ZnO₄ framework is sandwiched between the AlPO₄ frameworks. As of now, such kind of sandwich framework has not yet been reported. Textural evaluation shows that there is a formation of two types of pores, namely cylindrical (AlPO₄) and slit-shaped pore (ZnO₄-AlPO₄). The conversion of cylindrical pores into slit pores in ZnO₄-AlPO₄ may be due to the formation of a ZnO₄ sandwiched framework in AlPO₄. It is confirmed by the BET analysis. The acidity and thermal stability of the materials are confirmed by the TPD and TGA analyses. The acidity of AlPO₄ (0.44 mmol/g) may be due to the deposition of Al³⁺ in the pores and surface of the material. The HR-TEM analysis proved the morphology of the synthesized materials. The synthesized materials are applied for CO₂ decomposition. The maximum conversion is reached above 95% and oxygen selectivity is above 55% in both catalysts.