Study on the Preparation and Application of H 3 PW 12 O 40 and Zr Co‐Modified SBA‐12 Molecular Sieve Catalyst in Nitration Reaction

ABSTRACT SBA‐12 zeolites synthesized using Polyoxyethylene(10) stearyl ether(Brij76) as a templating agent exhibit broad applicability, characterized by high thermal and mechanical stability. It plays a significant role, particularly in catalysis or in the nitration reaction for synthesizing acetanilide. The SBA‐12 molecular sieve catalyst has a three‐dimensional hexagonal structure with a P63/mmc space group and a specific surface area typically above 1000 m 2 /g, which facilitates multidirectional diffusion of reactant molecules, allowing them to access active sites more easily. This makes it an ideal catalyst. However, unmodified SBA‐12 molecular sieve exhibits weak acidity, necessitating modification. This study employed the hydrothermal synthesis method using Brij76 as a templating agent to prepare SBA‐12, Zr‐SBA‐12 zeolites, and Zr‐SBA‐12 loaded with phosphotungstic acid (PTA). The synthesized samples were subjected to XRD analysis, FT‐IR analysis, scanning electron microscopy (SEM) testing, Mapping, EDS analysis, TEM testing, BET testing, TPD analysis, and TG analysis. Additionally, the catalytic efficiency of the modified molecular sieve catalysts in nitration reactions was investigated. The results indicate that loading with metal Zr can effectively increase the number of surface‐active sites on the molecular sieve. However, excessive loading of Zr may partially disrupt the pore structure of the molecular sieve and reduce its orderliness. When the loading amount of H 3 PW 12 O 40 is 35%, and that of Zr is 0.05, the synthesized catalyst Z35‐0.05Zr‐SBA‐12, under reaction conditions of 12 h and 90°C, achieves an acetanilide conversion rate of 91.7% and a selectivity toward p‐nitroacetanilide of 85.8% in the nitration reaction.