Deep oxidation of 1,2-dichlorobenzene over Ti-doped iron oxide

Abstract

Ti-doped iron oxides with worm-like mesopores were successfully prepared using CTAB as the structure-directing agent. The as-prepared catalysts were characterized by XRD, Raman, H2-TPR, XPS, TEM, and N2 adsorption/desorption. The catalytic properties for oxidation of 1,2-dichlorobenzene (o-DCB) were investigated. The results showed that Fe18Ti2Ox with 10 mol% Ti-doping shows the best catalytic activity, and the total conversion of o-DCB can be obtained at 350 °C. Moreover, Fe18Ti2Ox exhibits higher stability, CO2 selectivity and lower apparent activation energy. The high activity of Fe18Ti2Ox could be ascribed to the combined factors including a smaller crystallite size, excellent low-temperature reducibility, high surface active oxygen concentration and a synergic effect between TiO2 and mixed iron oxide (γ-Fe2O3 and α-Fe2O3). Acetate and formate species as intermediates were detected by in situ FTIR spectroscopy. A two-step redox mechanism of o-DCB decomposition on the surface of Ti-doped iron oxides was proposed. These results demonstrated that Ti-doped iron oxides could be developed as environmentally friendly catalysts for the deep oxidation of chlorinated volatile organic pollutants.

Catalytic Oxidation of Chlorobenzene over MnxCe1–xO2/HZSM-5 Catalysts: A Study with Practical Implications

“…A series of peaks were identified at approximately 1248, 1320, 1378, 1440, 1460, 1540, 1560, 1620, 1700, 2350, 3378, 3659, 3740 cm –1 . The peaks at 1440 and 1540 cm –1 corresponded to the stretching vibrations of CC in an aromatic ring. , The peak at 1700 was assigned to aldehyde-type species, , and that at 1248 cm –1 to the C–H vibration in a plane. , The peaks at 1320, 1378, and 1590 cm –1 corresponded to COOH– from bidentate formate and those at 1460 and 1560 cm –1 corresponded to the COOH– from acetate-type species. , The peak at 2350 cm –1 originated from CO 2 adsorption. , With an increase in the purging time, the peaks at 1440 and 1540 cm –1 (assigned to the CC on an aromatic ring) quickly decreased. This implies that the aromatic ring in CB was cleaved once in contact with the Mn 0.8 Ce 0.2 O 2 .…”

Effective Ti Doping of δ-MnO2 via Anion Route for Highly Active Catalytic Combustion of Benzene

“…To further shed light on the origin of the surface active species observed in Raman spectroscopy, XPS is used to investigate the surface elemental states of oxygen and manganese as shown in Figure 4. The O 1s spectra in Figure 4a show the relative shift of the lattice oxygen peak (∼530 eV) 21 of the T140 sample toward higher binding energy, whereas the Mn 2p and Mn 3s spectra in Figure 4c Moreover, the O 1s spectra can be decomposed into lattice oxygen, defect oxygen, and adsorbed oxygen as shown in the Supporting Information Figure S4, where it is clear that the defect related O 1s peak of T140 at ∼531 eV 30,31 is also the highest after normalized to the lattice O 1s peak. Furthermore, the different states of Mn (such as Mn 2+ , Mn 3+ , and Mn 4+ ) are also demonstrated by the average oxidation states (AOS = 8.956−1.126 ΔE3s) 8 based on the fact that the Mn ΔE3s of MnO, Mn 3 O 4 , Mn 2 O 3 , and MnO 2 are 5.79, 5.50, 5.41, and 4.78, respectively.…”

“…Moreover, the O 1s spectra can be decomposed into lattice oxygen, defect oxygen, and adsorbed oxygen as shown in the Supporting Information Figure S4, where it is clear that the defect related O 1s peak of T140 at ∼531 eV , is also the highest after normalized to the lattice O 1s peak. Furthermore, the different states of Mn (such as Mn 2+ , Mn 3+ , and Mn 4+ ) are also demonstrated by the average oxidation states (AOS = 8.956–1.126 Δ E 3s) based on the fact that the Mn Δ E 3s of MnO, Mn 3 O 4 , Mn 2 O 3 , and MnO 2 are 5.79, 5.50, 5.41, and 4.78, respectively .…”

Alkali Potassium Induced HCl/CO2 Selectivity Enhancement and Chlorination Reaction Inhibition for Catalytic Oxidation of Chloroaromatics

“…As shown in Figure a, after the adsorption of CB onto K­(1 wt %)­MCH catalyst at 200 °C, several bands appeared at 1030, 1130, 1170, 1250, 1320, 1370, 1461, 1530, 1590, and 1640 cm –1 (see Figure a). The bands at 1320, 1370, and 1590 cm –1 corresponded to −COOH from bidentate formate, and the bands at 1461 and 1530 cm –1 were ascribed to −COOH from acetate species. , The bands at 1130 and 1250 cm –1 originated from the vibration of −CH 2 in a different vibration model, and the band at 1030 cm –1 was related to the vibration of −CH. , From the DRIFT spectra, it was noted that the CB oxidation occurred upon contact with K­(1 wt %)­MCH catalyst as the bands originated from the cleavage products of aromatic ring all appeared in this catalyst. The negative band at 1640 cm –1 was assigned to the CB-adsorbed on Brønsted sites, , and that at 1170 cm –1 was attributed to the Lewis sites bound to MnO x -CeO 2 .…”

“…The bands at 1320, 1370, and 1590 cm −1 corresponded to −COOH from bidentate formate, 54 and the bands at 1461 and 1530 cm −1 were ascribed to −COOH from acetate species. 55,56 The bands at 1130 and 1250 cm −1 originated from the vibration of −CH 2 in a different vibration model, and the band at 1030 cm −1 was related to the vibration of −CH. 7,54 From the DRIFT spectra, it was noted that the CB oxidation occurred upon contact with K(1 wt %)MCH catalyst as the bands originated from the cleavage products of aromatic ring all appeared in this catalyst.…”