Synthesis of TS-1 from supported embryonic to nano-/micro-metersized crystalline particles: The impact of accessibility of Ti species on the catalytic performance

Titanium dioxide-modified nanosized TS-1 zeolite-supported phosphotungstic acid as a catalyst for deep catalytic oxidative desulfurization of fuel oil

“…Thereinto, TS-1 zeolite exhibits excellent catalytic performance in many oxidation reactions, especially in the heterogeneous ODS reaction. 18,19 Kong et al 20 have confirmed that TS-1 zeolite is an effective catalyst for the oxidation of thiophene (TH). Cui et al 21 have investigated the catalytic activities of TS-1, Ti-HMS, and Ti-MSU for the oxidation of TH, benzothiophene (BT), and DBT.…”

In-Situ Growth of Embryonic TS-1 on Amorphous Silica via Steam-Assisted Crystallization: Correlation of Structural Properties and Catalytic Performance of Embryonic, Crystalline, and Amorphous Titanosilicate Catalysts

“…The decrease in Ti content of TS-1 by leaching which might come from hydrolysis of the Si−O−Ti bond is in accordance with the results reported by the other groups. 13,50 Despite the decrease in the activity over the recycling either by Ti leaching and/or structural degradation, an excellent productivity of 24 mg-DBT/mg-TS-1 or (4.17 mg-S/mg-TS-1) by embryonic TS-1-LO was achieved. This productivity is about 35.6 times higher than that by a MOF catalyst in DBT oxidation which was reported recently 51 and is the highest ever achieved to our knowledge (Table S5).…”

“…36a In addition to that, the amorphous titanosilicate and TS-1 samples synthesized via the SAC process showed absorption bands at λ = 220−235 nm, 250− 270 nm, and 270−300 nm corresponding to defective Ti(OH)(OSi) 3 , amorphous pentahedral Ti(OH)(H 2 O)-(OSi) 3 , and octahedral Ti(OH)(H 2 O) 2 (OSi) 3 Ti species, respectively. 13,16,17 The absorption band at about λ = 310− 350 nm is related to anatase TiO 2 . The molar fraction of the Ti species observed correlated strongly with the synthesis conditions (Table S1).…”

“…10a A novel approach of the synthesis of supported embryonic TS-1 by a seeding-polymer-assisted method was recently reported; however, it still suffers from polymer and silica precursors phase separation and strict kinetic control. 13 The amorphous titanosilicate with better accessible active sites also have found application in the oxidation of the bulky reactants and might be a better alternative to the both embryonic and crystalline zeolites. These catalysts however are susceptible to deterioration in the presence of water, control of the nature and the microenvironment of their active sites is challenging, and their characterization is complicated.…”

“…However, other Ti species of defective Ti­(OH)­(OSi) 3 and octahedral “TiO 6 ” have shown higher activity than TiO 4 in epoxidation of olefins . In this respect, materials with different active sites have been prepared by in-/ex-situ modification of TS-1 by alkylamines and one-step active seed-assisted microwave irradiation, exhibiting higher activity in selective oxidation reactions. ,, Despite this progress, lack of low-temperature (below 40 °C) activity, low-selectivity, and high cost of synthesis in addition to accessibility issues are still major challenges of large scale application of TS-1 catalysts . The use of low cost organic templates is an alternative to prepare economically viable TS-1 catalysts; however, this approach often suffers from the resultant large-crystal zeolites.…”