Metal ion effect on pore enlargement in solid acid catalyst and CO2 decomposition

Metal substituted aluminophosphate are synthesized by incorporation of divalent metals ions such as Ni2+ and Mn2+ using simple novel method. Tetrapropylammoniumbromide is used as a template for the synthesis of M–AlPO4 molecular sieves. The synthesized catalysts are systematically characterized by using physicochemical method. Textural evaluation shows that the materials possessed an enlarged pores, especially Ni–AlPO4 has a formation of double pores with the diameter of about 2.7 and 13.8 nm. Similarly Mn–AlPO4 creates pore in diameter of 9.9 nm. The binding of TPA+ ion with negative charge of the M–AlPO4 is the major reason for pore enlargement. Thus the synthesized materials are applied for the carbon dioxide decomposition. The influence of various parameters such as temperature, catalyst dosage, flow rate and time on stream was examined. It is observed that Ni–AlPO4 produces 96% oxygen selectivity and Mn–AlPO4 produces 82% oxygen selectivity. This is due to the carbon deposition inside the pores. These results are revealed that the Ni–AlPO4 is suitable for CO2 decomposition.