Production of elemental sulfur and ammonium thiosulfate by H2S oxidation over Nb2O5 supported on Fe-pillared clay

V 2 O 5 /TiO 2-type catalysts are widely applied for selective catalytic NO reduction by NH 3 (NH 3-SCR), but enhanced sulfur tolerance and low-temperature activity are required. Herein, V 2 O 5 / TiO 2 À SiO 2 À MoO 3 (V/TSM) was demonstrated to have excellent catalytic activity and durability for NH 3-SCR in the presence of SO 2 at temperatures lower than 200°C. The deactivation mechanism and factors influencing SO 2 durability were investigated using catalytic durability tests, Fourier-transform infrared spectroscopy, and temperature-programmed desorption/ decomposition. Our results revealed that (NH 4) 2 S 2 O 3 and NH 4 HSO 4 form on catalyst surfaces by NH 3 À SO 2 À H 2 O reactions at low temperatures, resulting in catalyst deactivation via pore blockage. However, V/TSM was found to possess an increased number of active sites for decomposing deposited ammonium sulfate salts. The decomposition activity was related to the solid acidity, which enhanced SO 2 desorption and reactions between ammonium sulfate salts and NO. These findings will contribute to the development of catalysts with improved lifetimes for NH 3 À SCR.

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“…Kim et al. reported that ATS is formed from sulfur atoms or H 2 S through Equations (6) or (7) [53] .

true (NH_{4})_{2} SO_{3} + normalS \to (NH_{4})_{2} normalS_{2} normalO_{3}

true 3 (NH_{4})_{2} SO_{3} + SO_{2} + 2 H_{2} normalS \to 3 (NH_{4})_{2} normalS_{2} normalO_{3}

…”

Section: Resultsmentioning

confidence: 99%

Deactivation Mechanism and Enhanced Durability of V₂O₅/TiO₂–SiO₂–MoO₃ Catalysts for NH₃−SCR in the Presence of SO₂

et al. 2020

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“…They concluded that increasing the strength of Lewis acid sites leads to allylic oxidation. M. Kim et al 85 showed that by incorporating niobium pentoxide in Fe-pillared clay, both the thermal stability and surface acidity of the nal catalyst Nb 2 O 5 / Fe-PILC were improved, hence resulting in a higher activity in H 2 S oxidation. From these results, it can be stated that our materials could be potential catalysts for certain applications that require the activation of the allylic position without affecting the double bond.…”

Section: Catalytic Activity Studymentioning

confidence: 99%

Allylic oxidation of cyclohexene over ruthenium-doped titanium-pillared clay

et al. 2015

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ARTICLE This journal isRuthenium-doped H-Montmorillonite (H-Mont) and Ti-pillared clay (Ti-PILC) were prepared then studied for oxidation of cyclohexene, with tert-butylhydroperoxide (TBHP) as the oxygen source. The Ti-PILC support was prepared by hydrolysis of Ti(OC 3 H 7 ) 4 with HCl. The synthesized Ru/Ti-PILC and Ru/H-Mont catalysts were characterized by chemical analysis, surface area/pore volume measurements, Fourier transform infrared (FTIR) spectroscopy, Xray powder diffraction (XRD), and UV-vis-diffuse reflectance spectroscopy (UV-vis-DRS). Both catalysts can selectively oxidize cyclohexene through allylic oxidation to give 2cyclohexene-1-one as the major product, and 2-cyclohexene-1-ol as the minor product. The influence of reaction time, temperature, catalyst amount, and substrate/oxidant ratio was also investigated to find the optimal reaction for cyclohexene oxidation to get the highest conversion. Indeed, when the 5%Ru/Ti-PILC was employed as catalyst, 59 % of cyclohexene conversion, 87 % of selectivity for 2-cyclohexene-1-one and 13 % of selectivity for 2cyclohexene-1-ol were obtained under ambient pressure, at 70 °C, for a 6 h reaction time. The catalysts were reused in four consecutive runs.

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“…Insert of the Figure 2 shows that the BJH pore size distribution of all samples presents a unimodal and narrow peak, centred at 15 Å. However, an increase in the ruthenium oxide loading onto the Ti-PILC support (SBET= 278 m 2 .g -1 ) [35] decreased the surface area, probably because of pore blockade resulting from their progressive filling with ruthenium species (Table 1) [41][42][43]. Figure 3 shows the FTIR spectra of 1, 2, and 3 %Ru/Ti-PILC materials.…”

Section: Characterization Of Samplesmentioning

confidence: 98%

Ruthenium-doped Titania-pillared Clay for The Selective Catalytic Oxidation of Cyclohexene: Influence of Ru Loading

Dali¹,

Rekkab-Hammoumraoui

Korso

et al. 2019

Bull. Chem. React. Eng. Catal.

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A series of ruthenium-based catalysts supported on acid-activated montmorillonite (PILC) and interspersed with titanium (Ru/Ti-PILCs) were prepared with various amounts of ruthenium. Their catalytic performances in the selective oxidation of cyclohexene, using tert-butylhydroperoxide (TBHP) as oxidant were checked. The clay structure modification by acid activation and impregnation of transition metals resulted in an enhanced Lewis and Bronsted acidities. The Ru/Ti-PILCs materials were characterized using X-ray diffraction (XRD), surface area and pore volume measurements, surface acidity followed by Fourier transform infrared (FTIR) spectroscopy, chemical analysis, and Scanning Electron Microscopy (SEM). It was found that all catalysts can selectively oxidize cyclohexene through allylic oxidation leading mainly to 2-cyclohexene-1-one (Enone) as the major product, and 2-cyclohexene-1-ol (Enol) as secondary product. With the 5 %Ru/Ti-PILC, it was possible to reach 59 % cyclohexene total conversion, and 87 % selectivity into 2-cyclohexene-1-one and 13 % selectivity into 2-cyclohexene-1-ol. external surface of the material is active, as large organic molecules cannot dodge in and out layers. Moreover, though non-polar molecules have reduced dimensions, they cannot penetrate into the material due to the hydrophilic character of the layers [3]. In order to obtain thermally stable materials with a greater interlayer distance, cations can be intercalated between the clay layers. These cations act as pillars that help in keeping the silicate layers separated, even in the absence of solvents.

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Production of elemental sulfur and ammonium thiosulfate by H2S oxidation over Nb2O5 supported on Fe-pillared clay

Cited by 10 publications

References 38 publications

Deactivation Mechanism and Enhanced Durability of V₂O₅/TiO₂–SiO₂–MoO₃ Catalysts for NH₃−SCR in the Presence of SO₂

Deactivation Mechanism and Enhanced Durability of V₂O₅/TiO₂–SiO₂–MoO₃ Catalysts for NH₃−SCR in the Presence of SO₂

Allylic oxidation of cyclohexene over ruthenium-doped titanium-pillared clay

Ruthenium-doped Titania-pillared Clay for The Selective Catalytic Oxidation of Cyclohexene: Influence of Ru Loading

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Production of elemental sulfur and ammonium thiosulfate by H2S oxidation over Nb2O5 supported on Fe-pillared clay

Cited by 10 publications

References 38 publications

Deactivation Mechanism and Enhanced Durability of V2O5/TiO2–SiO2–MoO3 Catalysts for NH3−SCR in the Presence of SO2

Deactivation Mechanism and Enhanced Durability of V2O5/TiO2–SiO2–MoO3 Catalysts for NH3−SCR in the Presence of SO2

Allylic oxidation of cyclohexene over ruthenium-doped titanium-pillared clay

Ruthenium-doped Titania-pillared Clay for The Selective Catalytic Oxidation of Cyclohexene: Influence of Ru Loading

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Deactivation Mechanism and Enhanced Durability of V₂O₅/TiO₂–SiO₂–MoO₃ Catalysts for NH₃−SCR in the Presence of SO₂

Deactivation Mechanism and Enhanced Durability of V₂O₅/TiO₂–SiO₂–MoO₃ Catalysts for NH₃−SCR in the Presence of SO₂