Beneficial role of SiO2 plugging in AlCl3 heterogenized plugged hexagonal templated silica (PHTS) for the isopropylation of m-cresol

An Overview of the Challenges and Progress of Synthesis, Characterization and Applications of Plugged SBA-15 Materials for Heterogeneous Catalysis

A new generation of SBA-15, plugged SBA-15, was initially synthesized in 2002 using extra silica precursors (Si/organic template molar ratios ≈ 80–140) in the gel mixture. The plugged SBA-15 materials possess short cylinders (length ≈ 20–100 nm), which are connected to neighbors by constricted entrances (windows) through the central axis. The gas adsorption–desorption isotherms of plugged SBA-15 materials present unique hysteresis loop Type H5 classification identified by IUPAC in 2015, which is related to certain pore structures containing open and plugged mesopores. The plugged SBA-15 has been used to support various types of catalysts, including metal complexes, metal nanocatalysts, and active metals by the incorporation in their framework demonstrating excellent (enantio)selectivity, stability against coke, and thermal stability. The plugged SBA-15 materials bear the other unique properties of the ship-in-the-bottle synthesis of, e.g., metal complexes that confine homogeneous catalysts, which is not possible by conventional SBA-15 due to leaching. In this mini-review, the challenges and progress of the synthesis in controlling the plugging and incorporation of metals and organic moiety in their framework, characterizing the short mesochannel dimensions (window and length sizes) by several advanced techniques and applying plugged SBA-15 materials in heterogeneous catalysis for challenging reactions, has been discussed.

A hierarchical ZSM-22/PHTS composite material and its hydro-isomerization performance in hydro-upgrading of gasoline

The ZSM-22/PHTS (ZP) composite material assembled from a ZSM-22 zeolite crystal displayed a mesoporous structure. The CoMo/ZPA120 catalyst presented a good balance between HDS activity (95.2%) and lower ΔRON (−1.1).

Improved synthesis and study of acidic properties of ‘plugs’-containing Al-SBA-15 materials

A novel ‘plugs’-containing Al-SBA-15 material (denoted as PAS) was directly synthesized through simultaneous introducing toluene and aluminum precursor into the reaction mixture of traditional SBA-15. Such material not only featured a unique two-step desorption isotherm as conventional plugged SBA-15 synthesized using excessive siliceous precursor, and higher pore wall thickness than that of other analogous materials, but also possessed weak and medium acidic sites, which implied the PAS would offer unusual advantages such as multifunctionality to process a large variety of feed-stocks in acid-involved reaction (e.g. polymerization of tetrahydrofuran) in industrial point of view. In addition, catalytic activity of the PAS was investigated by the tetrahydrofuran (THF) polymerization reaction in the presence of acetic anhydride and compared with Al-doped MCM-41 prepared via conventional direct hydrothermal synthesis. The PAS exhibited good performance on polymerization of THF. Such result could be related to the large pore size and moderate acidic sites.