Nitrous oxide as oxidant for the oxidation of methane on barium hydroxyapatites in the presence and absence of tetrachloromethane

Sugiyama, Shigeru; Fujii, Yoshiharu; Abe, Keiichi; Hayashi, Hiromu; Moffat, J.B.

doi:10.1016/s1381-1169(00)00477-5

Cited by 6 publications

(3 citation statements)

References 24 publications

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“…Thus, it may be concluded that the NO x that is liberated is in the form of N 2 O. The liberated N 2 O in the product gas mixture can be used as a clean and selective oxidant, e.g., for the selective oxidative coupling of methane to ethane (Sugiyama et al) and for the oxidation of benzene to phenol (Reitzmann et al).…”

Section: Theory Of Mass Transfer With Chemical Reactionmentioning

confidence: 99%

Kinetics of Oxidation of Benzyl Alcohol with Dilute Nitric Acid

Joshi

Kataria

Sawant

et al. 2004

Ind. Eng. Chem. Res.

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The oxidation of benzyl alcohol by dilute nitric acid has been selected for the study as a typical method for the manufacture of industrially important intermediate benzaldehyde. All the reactions have been performed in the absence of any solvent. A catalytic amount of sodium nitrite is essential for the generation of active state of nitrogen. Benzyl nitrite is formed in a substantial amount as an intermediate. The effects of various parameters such as the NaNO 2 loading, nitric acid concentration, temperature, and molar ratio have been investigated. The stoichiometric requirement of nitric acid for benzyl alcohol conversion has also been determined. The probable mechanism for the oxidation of benzyl alcohol using nitric acid is proposed, showing the reversible formation of benzyl nitrite and its irreversible decomposition to benzaldehyde. The mass-transfer resistance has been eliminated for the investigation of kinetics of all the reactions in the consecutive path. The influence of chloro substitution on the oxidation rates of 2-chlorobenzyl, 4-chlorobenzyl, and 2,4-dichlorobenzyl alcohols has been presented.

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Section: Theory Of Mass Transfer With Chemical Reactionmentioning

confidence: 99%

Kinetics of Oxidation of Benzyl Alcohol with Dilute Nitric Acid

Joshi

Kataria

Sawant

et al. 2004

Ind. Eng. Chem. Res.

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“…It was proposed that CH 4 is activated by surface O − species, which are replenished by N 2 O decomposition [30a] . The addition of tetrachloromethane (TCM) to the reactant mixture was observed to suppress total oxidation in N 2 O‐OCM by replacing surface OH groups with Cl [30b] …”

Section: N2o As An Oxidant (N2o‐ocm)mentioning

confidence: 99%

Alternative Oxidants for the Catalytic Oxidative Coupling of Methane

2021

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The catalytic oxidative coupling of methane (OCM) to C2 hydrocarbons with oxygen (O2‐OCM) has garnered renewed worldwide interest in the past decade due to the emergence of enormous new shale gas resources. However, the C2 selectivity of typical OCM processes is significantly challenged by overoxidation to COx products. Other gaseous reagents such as N2O, CO2, and S2 have been investigated to a far lesser extent as alternative, milder oxidants to replace O2. Although several authoritative review articles have summarized OCM research progress in depth, recent oxidative coupling developments using alternative oxidants (X‐OCM) have not been overviewed in detail. In this perspective, we review and analyze OCM research results reporting the implementation of N2O, CO2, S2, and other non‐O2 oxidants, highlighting the unique chemistries of these systems and their advantages/challenges compared to O2‐OCM. Current outlook and potential areas for future study are also discussed.

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“…For example, humans metabolise strontium due to its crystallochemical similarity with calcium, and trace quantities in natural isotopic abundance reduces caries [57], but accumulation of the radioactive fission product 90 Sr initiates metastasis [58]. [69], or vanadate replacing phosphate [70], and fluorine displacing hydroxyl [71]. [77].…”

Section: Crystal Chemistry and Nomenclaturementioning

confidence: 99%

The incorporation of small cations in hydroxyapatite : synthesis, crystal chemistry and functionality

Low¹

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Hydroxyapatite (HAp) is an important oxide in biotechnology, and also holds promise as a heterogeneous catalyst. Its ideal composition is [(Ca F 4)(Ca T 6)(PO 4) 6 (OH) 2 ] where an adaptable framework (F) structure creates one-dimensional tunnels (T) that provide multiple ionic acceptor sites (Ca F /Ca T /P/OH) which can be adjusted to deliver specific functionality. Modification of cation and anion type and proportions, together with selection of appropriate syntheses, can be used to regulate structural distortions and phase transformations. However, first-principles crystallographic adaptation to optimize performance is less explored, especially for tailoring excipient responses and catalytic activity, which are the primary concern of this study. Bioactive and catalytic HAp is nanocrystalline and usually nonstoichiometric, especially with respect to cation vacancies, carbonate and water incorporation, and oxygen displacement of hydroxyl ions. The hypothesis explored in this thesis is that controlled doping of HAp by small cations (Fe 3+ , Zn 2+ , Mg 2+) will alter the crystal chemistry in a manner that enhances cell proliferation (biological application) and product yield (catalytic application). The selection of small cations for investigation was deduced from their abundance and essential role in bone metabolism and the potential of these metals for enhancing chemical conversion of alcohol while fixed in an environmentally benign HAp matrix. To this end, methods to synthesize homogeneous ceramic powders of single phase Fe-, Zn-, and Mg-HAps to the solid solubility limits of these metals were developed from which structure-property correlations were established. All three series were characterized with X-ray and neutron diffraction, electron microscopy, and several spectroscopies, including FTIR and NMR techniques, to corroborate crystallographic incorporation and concomitant symmetry transformations, determine phase proportions (crystalline and amorphous), and metal partitioning preferences across the Ca F /Ca T sites. Crystal structure refinement was challenging due to the fine-grain size, although in this physical form, large reactive surfaces are produced that are preferable for the targeted applications. It was found that the solid solution limit of Fe-HAps {nominally [(Ca 10-x Fe x)(PO 4) 6 (OH 2-x O x)]} was x = 0.5, with Fe 3+ entering the Ca F site at low loadings (x = 0.1) and subsequently residing in both the Ca F and Ca T at x = 0.5.

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Nitrous oxide as oxidant for the oxidation of methane on barium hydroxyapatites in the presence and absence of tetrachloromethane

Cited by 6 publications

References 24 publications

Kinetics of Oxidation of Benzyl Alcohol with Dilute Nitric Acid

Kinetics of Oxidation of Benzyl Alcohol with Dilute Nitric Acid

Alternative Oxidants for the Catalytic Oxidative Coupling of Methane

The incorporation of small cations in hydroxyapatite : synthesis, crystal chemistry and functionality

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