Rapid Synthesis Of Beta Zeolite With High Yield And Its Alkylation Performance

Beta zeolite,with an intriguing three-dimensional architecture composed of intersecting 12-ring channels and excellent physic-chemical properties,is widely used in many industrial processes,including alkylation,hydroisomerization,hydrocracking,etc.However,the industrial production of this zeolite encountered problems of long crystallization time and high cost,the diffusion constraints also remain in the catalytic process.Aiming at these problems above,?-butyrolactone?GBL?and N-methyl-2-pyrrolidone?NMP?were introduced into the synthetic system to realize rapid synthesis of Beta zeolite with solid and hollow structure,respectively.The catalytic performance of the obtained zeolite Beta was tested by using liquid alkylation of benzene with isobutene as a probe reaction.Beta zeolite with highly crystallinity and high yields was synthesized with a simple one-pot hydrothermal method by introducing GBL in the synthesis,during which some parameters such as GBL/SiO₂,TEAOH/SiO₂,Na₂O/SiO_2,SiO₂/Al₂O₃ and H₂O/SiO₂molar ratios,as well as the crystallization temperature were optimized to realize fast synthesize of Beta zeolite.On the basis of the characterization from X-ray powder diffraction?XRD?,Scanning electron microscopy?SEM?,Thermal gravimetric analysis?TGA?,Fourier transform infrared spectroscopy?FT-IR?,and ¹³C liquid NMR,an acceleration nucleation formation mechanism of Beta zeolite was proposed and discussed.And the catalytic performance of the as-synthesized Beta catalyst?G-Beta?was also compared with that of commercial Beta zeolite using the liquid alkylation of benzene with isobutylene as a probe reaction,the results demonstrate that G-Beta showed a better performance.The hollow structured Beta zeolite was synthesized via interzeolite conversion of USY under the assistance of NMP,during which some parameters such as NMP/SiO₂,TEAOH/SiO₂,Na₂O/SiO_2,SiO₂/Al₂O₃ and H₂O/SiO₂ molar ratios,as well as the crystallization temperature were optimized to obtain pure and hollow Beta zeolite from the USY zeolite.On the basis of the characterization from XRD,SEM,Transmission electron microscope?TEM?,and ²⁹Si/²⁷Al magic angle spinning nuclear magnetic resonance(²⁹Si/²⁷Al MAS NMR),a formation mechanism of hollow Beta zeolite from USY was proposed and discussed.The catalytic performance of alkylation of benzene with isobutylene demonstrated that the obtained hollow Beta catalyst?HR-Beta?exhibited excellent catalytic performance against the solid Beta zeolite?HC-Beta?synthesized from amorphous silica/alumina.