Synthesis and Properties of Lanthanide Incorporated Mesoporous Molecular Sieves

✍ Scribed by A.S. Araujo; M. Jaroniec

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 84 KB
• Volume: 218
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1999.6437

✦ Synopsis

Nanostructured lanthanum and cerium incorporated MCM-41 molecular sieves were synthesized via a hydrothermal method using cethyltrimethylammonium bromide as template and trimethylammonim hydroxide as mineralizer. Characterization of these materials by X-ray diffraction and nitrogen adsorption indicates that the resulting materials possess an MCM-41-like mesoporous structure. Atomic absorption and infrared spectroscopy studies revealed the presence of La and Ce in these materials. Their BET surface areas were ca. 590 and 700 m 2 /g for La-and CeMCM-41, respectively, whereas the average mesopore diameters were in the range between 3.0 and 3.5 nm. Total acidity determined by n-butylamine adsorption showed that the samples possess from weak to strong acid sites, the strengths of which are much higher for CeMCM-41 than for LaMCM-41. Adsorption energy distributions evaluated from low pressure adsorption isotherms indicate that the amount of surface hydroxyls is also higher for the cerium containing materials.