tailieunhanh - Synthesis, Characterization, and Catalytic Properties of a Microporous/Mesoporous Material, MMM-1

A microporous+mesoporous material composed of MCM-41 and MFI was produced by a two-step synthetic process. The solid, called 99MMM-1,:: was characterized by X-ray di4raction (XRD), N2 physisorption, and transmission electron microscopy (TEM). | Journal of Solid State Chemistry 167 363-369 2002 doi Synthesis Characterization and Catalytic Properties of a Microporous Mesoporous Material MMM-1 Raja H. P. R. Poladi and Christopher C. Landry1 Department of Chemistry Cook Physical Science Building University of Vermont Burlington Vermont 05405 Received October 19 2001 in revised form February 11 2002 accepted Febumry 15 0002 uublished online Apri1 17 0022 DEDICATED TO PROFESSOR GALEN STUCKY ON THE OCCASION OF HIS 61th birthday A microporous-mesoporous material composed of MCM-41 and MFI was produced by a two-step synthetic process. The solid called MMM-1 was characterized by X-ray diffraction XRD N2 physisorption and transmission electron microscopy TEM . At early stages of crystallization at 170 C MCM-41 was formed exclusively while at heating times longer than 96 h MFI was formed. At intermediate times MMM-1 was formed with varying amounts of MFI depending on the crystallization time. XRD revealed that the material could be severely oriented by sample preparation which was consistent with an unusual ribbon-like morphology observed in TEM. This morphology was not seen for either pure MCM-41 or MFI. The N2 physisorption isotherm for MMM-1 showed two distinct regions of capillary condensation with H2 hysteresis. Synthesis and subsequent use of Al-MMM-1 in the isomerization of w-xylene and comparison to Al-MCM-41 and Al-MFI showed that although the latter material had a higher total conversion Al-MMM-1 had a higher selectivity for -xylene. Al-MMM-1 had a much higher selectivity and conversion than Al-MCM-41 which makes it promising for use in future catalytic applications. 2002 Elsevier Science USA Key Words microporous mesoporous MFI MCM-41 MMM-1. INTRODUCTION Zeolites are widely used as cation exchangers adsorbente and catalysts 1 . Their unique activity and use in a growing variety Iff appiicahons has caeed ht in the devetop-ment of novel zeolitic materials with varying pore dimensions .

• Báo cáo khoa học
• Silicate polymerized
• Solid State Chemistry
• Mesoporous Material
• Transmission electron microscopy
• Molecular Sieves
• Micromeritics Instrument