Synthesis of MCM-22 molecular sieve using piperidine as an organic template

For synthesizing MCM-22 molecular sieves with different silica-alumina ratio, the effects of ingredient SiO₂ to Al₂O₃ ratio, alkali concentration, and the amount of organic template and crystallization-supporting agent, on the molecular sieves were studied systematically. The obtained MCM-22 samples were characterized by X-ray diffraction, scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, X-ray photoelectron spectroscopy and N₂ adsorption-desorption. The results show that, MCM-22 molecular sieves with silica-alumina ratio of 25-500 could be successfully synthesized under this condition: using piperidine (PI) as the organic template and boric acid (BA) as the crystallization-supporting agent, n(OH^-)/n(SiO₂) of 0.03-0.20, n(PI)/n(SiO₂) > 0.03 and n(BA)/n(SiO₂) > 0.05. Moreover, the obtained molecular sieves using PI as the template have a smaller particle size and a larger specific surface area than those using hexamethyleneimine as the template.