Activity of molybdenum and tungsten oxycarbides in hydrodenitrogenation of carbazole leading to isomerization secondary reaction of bicyclohexyl. Results using bicyclohexyl as feedstock

Nanoparticle Size Effects on Phase Stability for Molybdenum and Tungsten Carbides

“…Trends in temperature are less pronounced than those with respect to particle size and most reports are between 800 and 1200 K (Figure b). Several synthesis protocols using molybdenum oxide precursors lead to the formation of intermediate oxycarbides at temperatures <800 K. − In these reports, the temperature is subsequently increased to >900 K to carburize the oxycarbides and obtain molybdenum carbides. Low temperatures for other synthesis routes tend to favor the formation of γ-MoC at large particle sizes and δ-MoC at small particle sizes, consistent with the expected trends in Δμ C reported in Figure a.…”

Catalytic Hydrodenitrogenation of Pyridine under Hydrothermal Conditions: A Comprehensive Study

“…Although piperidine was not to be found in this experiment, most likely because conversion of piperidine happened quickly and piperidine was consumed completely within 5 min, the hydrogenation route from pyridine to piperidine was widely reported by other research studies. − Therefore, we reasonably treat piperidine as an intermediate product in the model. Considering that hydrogenation of the nitrogen heterocyclic ring substance is a reversible reaction, − dehydrogenation of piperidine is also included in this network (eqs and ). Piperidine disappearance is involved in the following reactions: 1-piperidineethanol formation via the reaction between piperidine and formic acid (eq ), generation of 1-carbaldehyde piperidine by substitution of H on the N atom in pyridine with formic acid (eq ), formation of other piperidines via the derivative reaction (eq ), and 1-pentanol formation after ring rupture of piperidine (eq ), which further combines with piperidine and leads to formation of 1-pentyl piperidine (eq ). Next, both 1-piperidineethanol and 1-carbaldehyde piperidine can further undergo hydrogenation to form 1-ethyl piperidine (eq ) and 1-methyl piperidine (eq ), respectively. Considering that the hydrogenolysis of short-chain amines, alcohols, and hydrocarbons could occur under supercritical water conditions, − we lump those minor amines, alcohols, hydrocarbons, and gas products together as NH 2 -R, HO-R, C n H m , and GP, respectively, in the network.…”

“…Generally, path 1r has a direct or an indirect strong impact on each compound, which suggests that dehydrogenation from piperidine to pyridine cannot be negligible. Indeed, for HDN of nitrogen heterocyclic ring chemicals such as indole, quinoline, carbazole, and so forth, dehydrogenation was an indispensable and essential step during the whole reactions. For pyridine, except for path 1 and path 1r, other paths have little impact on it.…”

Investigating the Catalytic Active Sites of Mo/HZSM-5 and Their Deactivation During Methane Dehydroaromatization

“…We performed carbon monoxide (CO) chemisorption to measure the number of the accessible MoC x sites on Mo/Z5(60) at different stages of the MDA reaction, using a previously established procedure. [39][40][41] We found that as the reaction proceeded, the number of accessible MoC x sites and the methane conversion both decreased, with a positive linear correlation (Figure S10). This result suggests that the decrease in MDA activity of Mo/Z5(60) is related to the reduction in available MoC x sites, which is the result of the combined effect of the growth of MoC x into particles and the deposition of coke on these particles.…”