Enhanced Selective H₂S Oxidation Performance on Mo₂C-Modified g-C₃N₄

Abstract

Direct catalytic selective oxidation of H2S to sulfur at low temperature has been drawing attention. Molybdenum carbide (Mo2C), in which the excess occupied orbitals provide more back-donation chances for the adsorbents’ π-orbitals, shows activity in electrocatalysis, photocatalysis, thermocatalysis, etc. that are comparable to those of noble metals. This work reports for the time the use of Mo2C and Mo2C-modified g-C3N4 for catalytic selective oxidative desulfurization. The density functional theory calculation indicates that Mo2C facilitates the adsorption of H2S molecule and the HS group. Furthermore, the Mo2C-modified g-C3N4 shows a sulfur yield of as high as 99.0% at 190 °C, much higher than that of g-C3N4 (46.0%). The good stability of the catalyst was demonstrated by X-ray diffraction, Fourier transform infrared spectra, and so on. Remarkably, the H2S conversion of the Mo2C-modified g-C3N4 remains constant (95.0%) at 190 °C for as long as 30 h. As a first demonstration using carbides in selective H2S oxidation, this work provides an opportunity to develop a novel class of potential catalysts.

Fabrication of a Sb2MoO6/g-C3N4 Photocatalyst for Enhanced RhB Degradation and H2 Generation

“…The spectrum of 7.5% SMCN (Figure a) comprised C, N, O, Mo, and Sb elements, which demonstrates the existence of Sb 2 MoO 6 and g-C 3 N 4 in 7.5% SMCN. There are three peaks in the C 1s spectrum, as shown in Figure b, which are at 284.6, 286.9, and 288.2 eV, corresponding to sp 2 C–C bonds, sp 2 C atoms connected with −NH 2 , and sp 2 N–CN. , Figure c displays the high-resolution spectrum of N 1s at 398.8, 399.9, and 401.2 eV, which are assigned to sp 2 C–NC in a triazine ring, tertiary nitrogen of N–(C) 3 bonds, and C–NH x . , As displayed in Figure d, peaks of O 1s at 528.6 and 531.2 eV, respectively, correspond to lattice oxygen in metal oxide and oxygen in OH – . ,, As for the spectrum of Mo 3d, as shown in Figure e, peaks located at 232.4 and 235.6 eV are assigned to Mo 3d 1/2 and Mo 3d 3/2 . , Spectra of Sb at 530.1 and 539.5 eV, as shown in Figure f, are attributed to Sb 3d 5/2 and Sb 3d 3/2 . Furthermore, binding energy of C and N elements in SMCN is slightly shifted to a higher level, while O, Mo, and Sb elements move toward the direction of low binding energy, which can be attributed to interaction among the elements.…”

“…24,35 Figure 5c displays the highresolution spectrum of N 1s at 398.8, 399.9, and 401.2 eV, which are assigned to sp 2 C−NC in a triazine ring, tertiary nitrogen of N−(C) 3 bonds, and C−NH x . 24,36 As displayed in Figure 5d, peaks of O 1s at 528.6 and 531.2 eV, respectively, correspond to lattice oxygen in metal oxide and oxygen in OH − . 33,37,38 As for the spectrum of Mo 3d, as shown in Figure 5e, peaks located at 232.4 and 235.6 eV are assigned to Mo 3d 1/2 and Mo 3d 3/2 .…”

Hierarchical N-Doped Carbons Endowed with Structural Base Sites toward Highly Selective Adsorption and Catalytic Oxidation of H2S

“…usually exhibit superior activities in H 2 S selective oxidation. , However, the metal active sites can easily react with H 2 S to form metal sulfides and/or sulfates species, thus resulting in poor sulfur selectivity and long-term stabilities. − In comparison to metallic catalysts, the metal-free ones, especially for the nitrogen base sites-decorated porous materials, show superior sulfur tolerance due to the controllable and versatile structural base sites. − The structural base sites show strong interaction with H 2 S so as to facilitate the dissociation of H 2 S to HS – and H + , and they can also activate O 2 to produce active oxygen radicals, thus promoting the selective oxidation of H 2 S to elemental sulfur. ,, Significantly, the nitrogen base sites may not react with H 2 S to form sulfates. Furthermore, nitrogen-decorated metal-free catalysts, such as porous N-doped carbons, g-C 3 N 4 , and porous polymers, − have been considered as promising candidates for the selective oxidation of H 2 S, owing to their unique features including large Brunauer–Emmett–Teller (BET) surface areas, versatile nitrogen base sites, diverse building blocks, and tunable porous structures. − In addition, their alkalinity could be easily regulated by adjusting the microstructure environment and nitrogen base sites. − …”

High-Temperature Selective Oxidation of H2S to Elemental Sulfur on a β-SiC-Supported Cerium Catalyst

“…Recently, carbon-based catalysts such as porous carbons (PCs) and g-C 3 N 4 received great attention for H 2 S selective oxidation because many carbon materials have two-dimensional structures and enriched defects, which could regulate the electron density and improve O 2 activation. − Furthermore, the physical structure and properties of silicon carbide (SiC) are similar to carbon materials. As reported, SiC-supported catalysts were reactive for the oxidation of H 2 S and considerable sulfur selectivity can be obtained due to the high thermal connectivity of the SiC support .…”