Multifunctional heteroatom zeolites: construction and applications

Synthesis and Catalytic Applications of Advanced Sn- and Zr-Zeolites Materials

The incorporation of isolated Sn (IV) and Zr (IV) ions into silica frameworks is attracting widespread attention, which exhibits remarkable catalytic performance (conversion, selectivity, and stability) in a broad range of reactions, especially in the field of biomass catalytic conversion. As a representative example, the conversion route of carbohydrates into valuable platform and commodity chemicals such as lactic acid and alkyl lactates, has already been established. The zeotype materials also possess water-tolerant ability and are capable to be served as promising heterogeneous catalysts for aqueous reactions. Therefore, dozens of Sn- and Zr-containing silica materials with various channel systems have been prepared successfully in the past decades, containing 8 membered rings (MR) small pore CHA zeolite, 10-MR medium pore zeolites (FER, MCM-56, MEL, MFI, MWW), 12-MR large pore zeolites (Beta, BEC, FAU, MOR, MSE, MTW), and 14-MR extra-large pore UTL zeolite. This review about Sn- and Zr-containing metallosilicate materials focuses on their synthesis strategy, catalytic applications for diverse reactions, and the effect of zeolite characteristics on their catalytic performances.

Study of Electric and Magnetic Properties of Iron-Modified MFI Zeolite Prepared by a Mechanochemical Method

Zeolites are materials of undeniable importance for science and technology. Since the properties of zeolites can be tuned after the inclusion of additional chemical species into the zeolitic framework, it is necessary to study the nature of zeolites after modification with transition metals to understand the new properties that were obtained, and with this information, novel applications can be proposed. This paper reports a solvent-free approach for the rapid synthesis of zeolites modified with iron and/or iron oxide particles. The samples were characterized, and their electrical and magnetic properties were investigated.

Preparation of new microporous europium silicate molecular sieve by selective leaching of alkali metal cations from europium silicate Eu-AV-9

Acid treatment of crystalline silicates is a facile method of creating pores for the preparation of crystalline silica-based microporous materials, but its success depends on the acid treatment conditions and both the composition and crystallinity of the starting silicates. Here, europium silicate Eu-AV-9 containing Na⁺, K⁺, and Eu³⁺ ions was treated with acetic acid for 1 d or 14 d to synthesize microporous silicate with high Eu loading by the selective leaching of K⁺ and Na⁺ from the silicate. The acid-treated Eu-AV-9 had both crystallinity and microporosity capable of adsorbing CO₂, while the adsorption of Ar was very low. In addition, the values of both micropore volume and BET area of acid-treated samples increased when the time of acid treatment was increased. This result was attributed to the formation of structural defects caused by eliminating Eu in Eu-AV-9 over time of acid treatment.

Sn-Beta Catalyzed Transformations of Sugars—Advances in Catalyst and Applications

Beta zeolite modified with Sn in the framework (Sn-Beta) was synthesized and introduced as a heterogeneous catalyst for Baeyer–Villiger oxidations about twenty years ago. Since then, both syntheses strategies, characterization and understanding as well as applications with the material have developed significantly. Remarkably, Sn-Beta zeolite has been discovered to exhibit unprecedented high catalytic efficiency for the transformation of glucose to fructose (i.e., aldoses to ketoses) and lactic acid derivatives in both aqueous and alcoholic media, which has inspired an extensive interest to develop more facile and scalable syntheses routes and applications for sugars transformations. This review survey the progress made on both syntheses approaches of Sn-Beta and applications of the material within catalyzed transformations of sugar, including bottom-up and top-down syntheses and catalyzed isomerization, dehydration, and fragmentation of sugars.