Selectivities in Post-Synthetic Modification of Borosilicate Zeolites

Non‐oxidative Coupling of Methane to Ethylene Using Mo2C/[B]ZSM‐5

“…The 2% Mo/[Al]ZSM-5 showed two IR bands assigned to OH stretching vibrations:t he band at 3743 cm À1 attributedt ot erminal silanol groups, [34] and the band at 3610 cm À1 is typical for the acidic bridging OH of SiÀOHÀAl. [17] For the [B]ZSM-5, the OH vibration signal from silanol groups is slightly red-shifted to 3735 cm À1 ,a nd the OH vibration band from SiÀOH···B is observeda t3 724 cm À1 and 3709 cm À1 .I nazeolite framework, the boron atom is coplanar with three oxygens due to its small atomic diameter,a nd the distance to the fourth oxygen is too long to form strong bond. [34] Therefore the acidity of the bridging OH in [B]ZSM-5 is much weaker than that of [Al]ZSM-5.…”

“…Unlike dealumination in aluminosilicate zeolite, boron can be removed from the framework even under mild conditions (e.g. stirring in water at room temperature), an in the presence of high temperatures and water vapor this process is accelerated . The amount of framework B can be estimated on the basis of the size of the unit cell because unit cell dimensions are linearly correlated with the boron content in the unit cell .…”

“…Diffused reflectance FT‐IR experiments were carried out to compare the role of [B]ZSM‐5 to that of the [Al]ZSM‐5 (Figure ). The 2 % Mo/[Al]ZSM‐5 showed two IR bands assigned to OH stretching vibrations: the band at 3743 cm −1 attributed to terminal silanol groups, and the band at 3610 cm −1 is typical for the acidic bridging OH of Si−OH−Al . For the [B]ZSM‐5, the OH vibration signal from silanol groups is slightly red‐shifted to 3735 cm −1 , and the OH vibration band from Si−OH⋅⋅⋅B is observed at 3724 cm −1 and 3709 cm −1 .…”

“…stirring in water at room temperature), an in the presence of high temperatures and water vapor this process is accelerated. [17] The amount of framework Bc an be estimated on the basis of the size of the unit cell because unit cell dimensions are linearly correlated with the boron content in the unit cell. [18,19] According to the published correlation, [19] the as-made zeolite B-MFI sample contained about 2.5 boron atoms per unit cell, this number decreased to 1.7 after calcination and decreasedf urthert o1p er unit cell after carburization.…”

A Facile and Green Method for the Synthesis of SFE Borosilicate Zeolite and Its Heteroatom‐Substituted Analogues with Promising Catalytic Performances

“…To overcome such drawbacks, on one hand, significant efforts have been made to synthesize zeolitic materials in green routes: a) using commercialized low‐cost OSDA (economic); b) crystallizing in faster ways (energy saving); c) employing small amounts of OSDA and water (safe, economic, and environmentally friendly) . On the other hand, considerable efforts have also been devoted to introducing tri‐ or tetravalent metal atoms (Al, Ga, Fe, Ti, V, and Sn) into the B‐ or Ge‐rich framework structures by direct‐ or post‐synthesis, which would endow these zeolitic materials with excellent stability and acidic or oxidative properties . The progresses in these two aspects will undoubtedly facilitate the application of zeolitic materials, especially in industrial catalysis.…”