Influence of Pore-enlarging Methods on the Alkylation Performance of Nano-Hierarchical Porous β Zeolite Catalyst

The alkylation reaction of C4 hydrocarbons with FCC gasoline represents an effective approach for the production of high-octane clean gasoline. The development of environmentally friendly solid acid catalysts is a key focus in petrochemical research. Nano-hierarchical porous β zeolite has shown remarkable potential in enhancing catalyst activity, improving reactant diffusion capabilities, and extending catalyst lifespan within academic research on catalysis. Nonetheless, the synthesis of nanometer hierarchical porous β zeolite is fraught with challenges. Low crystallinity often occurs during the preparation, resulting in an imperfect zeolite framework that may compromise its catalytic performance. Unstable process conditions further complicate the reproducibility of synthesis, making it difficult to obtain consistent results. Additionally, the easy formation of impurity peaks in the synthesized product indicates the presence of unwanted by-products, which can interfere with the desired properties of the zeolite. Therefore, how to prepare nano-hierarchical porous β zeolites with large mesoporous sizes and high thermal stability has become a hot topic in this issue. To address these challenges, this study employs the desilication method, physical pore enlargement method, and chemical pore enlargement method to synthesize nano-gradient pore β molecular sieves. A systematic assessment has conducted to evaluate the performance of the catalyst in alkylating reactions under specific conditions: 90 °C temperature, 2 MPa pressure, 10 hydrogen/oil volume ratio, and an airspeed of 2 h−1. Furthermore, the physicochemical properties of the samples were comprehensively characterized using techniques including low-temperature nitrogen adsorption-desorption measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The results indicate that the desilication method can destroy the crystal forms, the physical pore enlargement method cannot improve the catalytic performance of the catalyst, the β zeolite treated by chemical pore enlargement method formed the characteristic peaks of β zeolite in the XRD, with well crystal form, high consistency in particle size, significantly improved pore-expanding effect, and excellent alkylation performance. Therefore chemical pore enlargement method is more suitable for preparing the nano-hierarchical porous β zeolites.