Synthesis of Niobium Carbonitride by Thermal Decomposition of Guanidine Oxaloniobate and Its Application to the Hydrodesulfurization of Dibenzothiophene

A Combined Experimental and Theoretical Study on the Formation of Crystalline Vanadium Nitride (VN) in Low Temperature through a Fully Solid-State Synthesis Route

“…The computed lattice parameter of the VN model was found to be 4.119 Å while for VO (considering both VN and VO models in the NaCl-type structure) a value of 4.172 Å was found. In the case of the VN model, our results deviate by less than 0.5% from experiment (4.137 Å), while for the VO model, our DFT calculations are in excellent agreement with the calculated value (4.19 Å), previously reported by Kresse et al Furthermore, the lattice parameter calculated by structure refinement of the sample thermally treated at 700 °C (4.132 Å) shows excellent agreement with our DFT calculated value (4.133 Å) for the VO 0.25 N 0.75 model, which reinforces the idea that the formation of vanadium nitride via the present route is preceded by solid-state transformations involving oxynitride species . Although slight differences between the calculated and experimental lattice parameters may be observed, the variation of these values is nearly linear with the composition, following Vegard’s law .…”

“…On the other hand, the synthesis of vanadium nitride is usually difficult, requiring elevated temperatures and long reaction times. Conventionally, they are prepared, among other methods, − , by self-propagating high-temperature synthesis (SHS), chemical vapor deposition, reduction–nitridation, direct reaction of vanadium metallic with nitrogen, carbothermal reduction and nitridation of vanadium oxides in N 2 , or temperature-programmed reactions. , …”

pH‐Specific Halide‐Dependent Materials from ZrIV/Hydroxycarboxylic Acid/Aromatic Chelator Reactivity: Architecture–Lattice Dimensionality and Spectroscopic Fingerprint Relations

“…This is attested to by the X‐ray crystal structures of 1 – 4 . The vibrations at 1665 cm –1 for 1 , 1660 cm –1 for 3 , and 1667 cm –1 for 4 are characteristic of the guanidinium cation28 and correspond to ν(C–N) vibrations, whereas the bands observed at 1549, 846, and 716 cm –1 for 4 have been assigned to 1,10‐phenanthroline stretches 29,30. Furthermore, ν(Zr–O) vibrations are present at 522 cm –1 for 1 , 507 cm –1 for 2 , 521 cm –1 for 3 , and 509 cm –1 for 4 ,31,32 whereas the bands observed at 691 cm –1 for 1 and 705 cm –1 for 2 have been assigned to ν(Zr–F) vibrations 33.…”

Adsorption and desulfurization reaction mechanism of thiophene and its hydrogenated derivatives over NbC(001) and NbN(001): an ab initio DFT study

“…Although under real conditions both surfaces present lower activities when compared with the catalysts commonly used in desulfurization processes, the results reported here are in qualitative agreement with the experimental data available for similar systems. 20,[22][23][24] It is known that butadiene is formed from the S-C bond breaking of 2,5-DHTh in a great variety of HDS reactions and catalysts. 29,42,45,65 Notably, Nagai et al have synthesized niobium nitride supported on γ-Al 2 O 3 using the CVD technique for HDS of thiophene, observing activity at ~400 °C and atmospheric pressure.…”

“…22 Schwartz et al investigated the activity of the supported bimetallic niobium oxycarbide system, NbMoOC/Al 2 O 3 , in three Mo/Nb ratios (1.2, 1.6, and 2.0), concluding that this catalyst is outstandingly active in HDN reactions and presents excellent activity in HDS of 4,6-DMDBT, higher than that of the commercial sulfided catalyst and comparable to Mo 2 C/Al 2 O 3 . 23 Recently, Chagas and co-workers 24 have investigated a new solid-state synthesis route of NbN 1−x C x phases as well as the activity of the products in HDS of dibenzothiophene, observing higher performances for their catalyst in comparison with the catalyst synthesized by the commonly used TPC methodology. Despite its interesting and promising range of applications, experimental and theoretical studies on surface properties, reaction mechanisms, and catalytic activities of niobium carbides and nitrides are still scarce.…”