Recent Progresses in Titanosilicates

Abstract

Titanosilicates, with tetrahedrally coordinated Ti 4＋ ions in highly crystalline zeolite frameworks, are a class of unique heterogeneous catalysts useful for the liquid-phase selective oxidation reactions. The great success of green Ti-zeolites/H 2 O 2 reaction system has aroused considerable scientific and industrial interests. The catalytic properties of titanosilicates relay on zeolite topologies, crystal morphology, the content and micro-environment of tetrahedral Ti 4＋ ions. The ever-growing needs for the oxidation catalysts in processing bulky molecules in petrochemical and fine chemical industries have set off a new tide of developing novel titanosilicates with significantly improved catalytic performance than traditional ones. This mini review summarizes recent progresses in developing the titanosilicates with novel topology, morphology as well as chemically modified micro-environment.

Relation of Selective Oxidation Catalytic Performance to Microenvironment of TiIV Active Site Based on Isotopic Labeling

“…Heteroatom-containing zeolites with well-defined isolated active sites in framework exhibit unrivalled catalytic properties in numerous important reactions. − The most attractive example is the titanosilicates that are capable of serving as highly active and selective oxidation catalysts with H 2 O 2 oxidant under mild conditions. , In particular, the epoxidation of alkenes and the ammoximation of ketones, producing value-added bulk chemicals of epoxides and oximes, respectively, are of great industrial interests. However, no specific titanosilicate is the all-round one for universal reactions with different purposes, because the catalytic performances are closely related to framework topology, tetrahedrally coordinated Ti active sites, pore aperture, and crystal morphology-dependent diffusion as well as hydrophilic/hydrophobic natures.…”

Au supported defect free TS-1 for enhanced performance of gas phase propylene epoxidation with H2 and O2

“…The discovery of titanium silicalite-1 (TS-1) is regarded as a milestone in the zeolite catalysis research field. 1 This is because it is an active, highly selective, and environmentally benign catalyst for many industrially important organic oxidation reactions in the presence of H 2 O 2 solution. 2–4 TS-1 zeolites catalyze several oxidation reactions, especially the epoxidation of propylene.…”

Creation of Hierarchical Titanosilicate TS‐1 Zeolites

“…[ 1–8 ] They are strictly built up from tetrahedral TO 4 units (T: Si or Al atoms) by sharing the vertex oxygen atoms, while some other elements such as P, Ti, Ge, Ga, Fe, W, or Mo can also be isomorphically incorporated into the zeolite frameworks. [ 9–15 ] The resultant zeolites are vested with a specific catalytic activity which originates from the intrinsic catalytic function of the transition metals. [ 16–18 ] Notably, titanosilicate zeolites, with the incorporation of titanium atoms into the framework, can act as redox catalysts, providing new choices for several industrial processes catalyzed by homogeneous catalysts, especially the liquid‐phase selective oxidation reactions.…”