Hierarchical Nanospherical ZSM-5 Nanosheets with Uniform Al Distribution for Alkylation of Benzene with Ethanol

As the catalytic performances typically depend on various factors, especially the distribution of Al species in the zeolite framework, in this contribution, hierarchical nanospherical ZSM-5 zeolites have been successfully synthesized using uniform aluminosilicate (AS) nanobeads containing silica and alumina species as a starting material to improve the Al dispersion in the framework. The synthesized zeolites were characterized by means of XRD, TEM, SEM, EDS, N-2 physisorption, Al-27 MAS NMR, and NH3-TPD. This example demonstrates that the use of AS nanobeads can effectively control the uniform Al distribution. Subsequently, the synthesized materials were tested for their catalytic activity in the alkylation of benzene with ethanol to ethylbenzene. Interestingly, the designed ZSM-5 nanospheres prepared by using AS nanobeads clearly exhibit an improvement of the catalytic performance in terms of benzene conversion and ethylbenzene selectivity compared with the conventional ZSM-5 and the ZSM-5 nanospheres prepared by using a typical synthesis method. The reason for the improved benzene conversion (60%) and ethylbenzene selectivity (62%) on Hie-SZSM-5-AS relates to the generated mesoporous structure as well as a homogeneous distribution of Al frameworks directed by AS nanobeads. The synthesis approach reported herein illustrates an efficient way to control Al species as well as Al distribution in the zeolite framework, eventually enhancing the catalytic performance in acid catalyzed reaction, such as in the case of benzene alkylation with ethanol.