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Sift fluorene into a bowl : Manganese oxide octahedral molecular sieves (OMS-2), with the overall composition KMn8O16n.H2O, catalyze the mild, green, and efficient oxidation of 9H-fluorene to 9-fluorenone. The involvement of lattice oxygen species has been implicated in a free-radical chain mechanism. In terms of reaction kinetics, the breaking of the C-H bond is rate controlling.

 

Tandem processes involving catalysts can offer unique and powerful strategies for converting simple starting materials into more complex products in a single reaction vessel. Imines were synthesized directly from alcohols via a tandem catalytic process using manganese octahedral molecular sieves (OMS-2) as catalyst. The synthesis proceeds through two steps: an oxidation of the alcohols to carbonyls followed by the nucleophilic attack by an amine on the carbonyl to form the imine. OMS-2 acts as a bifunctional catalyst and catalyzes two mechanistically distinct processes in a single reaction vessel under the same conditions. Conversions up to 100% were obtained for benzylic alcohols with this efficient, environmentally friendly catalytic reaction. The advantages of this process are that the intermediates need not be isolated and the catalysts can be reused upon simple filtration without loss of activity.

Light hydrocarbons and H2 can be used to enhance NOx reduction efficiency and regenerate sulfur-poisoned NOx storage catalysts, and therefore are valuable for automotive exhaust gas cleaning. The processing of hydrocarbons in an alternating current (AC) discharge nonthermal plasma reactor was studied for the instant generation of light hydrocarbons and H2 at room temperature and atmospheric pressure. n-Octane and n-hexane were used as model hydrocarbons. Effects of hydrocarbon feedstock, electrode diameter, applied voltage, flow rate of carrier gas, gap size, and residence time of hydrocarbon molecules, were investigated systematically. Cracking is the only detected reaction during n-octane conversion (which might be very attractive for the cracking of heavy oil), and is the dominant reaction during n-hexane conversion. Catalytic dehydrogenation, catalytic addition, and noncatalytic cracking reactions, were discussed. The cleavage mode of single carbon–carbon bonds is revealed to be relevant to the carbon number of hydrocarbon molecules. Conversions, yields, power consumption, energy efficiencies, generation of hydrogen, etc, were determined and discussed. This study is of importance to novel processing of hydrocarbons at room temperature and atmospheric pressure, instant generation of hydrogen, cleaning of automotive exhaust gas, and chemistry in nonthermal plasma reactors.

Conversion of n -hexane, used as a model hydrocarbon, was carried out over iron and nickel electrodes in an alternating current (AC) discharge plasma and catalysis integrated technologies (PACT) reactor to instantly produce hydrogen and light alkanes and alkenes, at room temperature and atmospheric pressure. The possible application for this technology could be in automotive exhaust gas purification. Catalytic effects of metal electrodes are involved in the reactions, with iron electrodes showing obviously higher catalytic activity on addition reactions compared with nickel electrodes. Cracking of carbon–carbon bonds is the dominant reaction. Catalytic dehydrogenation of hexane is the source of hydrogen.

Manganese oxide octahedral molecular sieves having 2x2 tunnel structure (OMS-2) and synthesized by different methods were used for studying styrene oxidation with tert -butyl hydroperoxide (TBHP) as the oxidant. The catalytic activity of the as-synthesized OMS-2 materials was investigated. The physical and chemical properties of the OMS-2 materials are related to their activity in styrene oxidation. This particular study emphasizes the acid-base properties and the porous nature of these materials, and their role in styrene oxidation. Results of styrene oxidation reveal that acidity coupled with high porosity play a crucial role in these catalytic reactions. A desired acidity coupled with pore volume found in OMS-2 synthesized by reflux ethods (OMS-2R) and high-temperature methods (OMS-2HT) produces materials with higher styrene conversion and styrene oxide selectivity when compared with OMS-2 synthesized by solvent free (OMS-2S), microwave (OMS-2MW), or hydrothermal methods (OMS-2HY). Transition metal doped OMS-2 catalysts show better selectivity of styrene oxide when compared to their undoped catalysts.

Manymicroorganisms have been demonstrated to utilize petroleum fuel products to fulfill their nutritional requirement for carbon. As a result, the ability of these microbes to degrade fuel has both a deleterious affect as well as beneficial applications. This study focused on the undesired ability of bacteria to grow on fuel and the potential for some metal alloys to inhibit this biodegradation. The objective of this study was to review the pattern of growth of two reference strains of petroleum-degrading bacteria, Pseudomonas oleovorans and Rhodococcus rhodocrous , in a specific hydrocarbon environment in the presence of a commercially available alloy. The alloy formulated and supplied by Advanced Power Systems International Inc. (APSI) is sold for fuel reformulation and other purposes. The components of the alloy used in the study were antimony, tin, lead, and mercury formulated as pellets. Surface characterization also showed the presence of tin oxide and lead amalgam phases. Hydrocarbon used for the study was primarily 87-octane gasoline. The growth of the bacteria in the water and mineral-supplemented gasoline mixture over 6-8 weeks was monitored by the viable plate count method. While an initial increase in bacteria occurred in the first week, overall bacterial growth was found to be suppressed in the presence of the alloy. Results also indicate that the alloy surface characteristics that convey the catalytic activity may also contribute to the observed antibacterial activity.

Cryptomelane-type K-OMS-2 nanomaterials with high surface area (156 m2/g) have been synthesized via a low-temperature solvent-free method in a very short time (1 h). Field emission scanning electron microscopy and high-resolution transmission electron microscopy images reveal that these materials have nanorod morphologies with average diameters of about 10 nm and lengths of about 50 nm. These are different from the long fiberous morphologies of OMS-2 materials made by conventional reflux or hydrothermal methods. X-ray diffraction and Brunauer-Emmett-Teller studies indicate that these materials have small crystallite sizes (9.8 nm) and that they are mesoporous with a uniform pore size distribution centered at 12 nm. These K-OMS-2 materials show improved catalytic activity for the oxidation of alcohols compared with the conventional K-OMS-2 materials, which may be due to their higher surface areas and novel surface properties. This fast, inexpensive, and environmentally friendly solvent-free method has he potential of being used in scaled-up syntheses of K-OMS-2 and other transition-metal-ion-substituted manganese oxide nanomaterials.

Thermal decomposition of nickel acetate ( T > 300 ° C) dispersed on either silica or cordierite supports resulted in a mixture of Ni0/NiO that was catalytically active for the decomposition of methane to produce CO-free hydrogen, without the need for any pretreatment (i.e., using H 2 at high temperature (> 500 °C) for at least 2 h). The carbon yield (gC/gNi) for the catalysts supported on SiO2 (200–300 m2/g) increased with an increase in the catalyst NiO mean crystallite size. XRD and FE-SEM studies confirmed the formation of graphitic-type carbon filaments during the methane decomposition.

Transition-metal (TM) species (Mn, V, and Cr) were incorporated by an anion-exchange method into MCM-48. The TM-MCM-48 materials were characterized by XRD, HRTEM, N 2 adsorption–desorption, ESR, Raman, and NH3-TPD. The structural and textural properties of the materials are discussed, as is the nature of the TM species introduced in the mesoporous host. The catalytic activity and selectivity of the TM-MCM-48 in the oxidation of styrene with TBHP as an oxidant agent are explored. All of the catalysts produce benzaldehyde and styrene oxide as the main products. Mn-MCM-48 showed the highest selectivity for styrene oxide, but with a maximum conversion of 58%. V-MCM-48 shows the highest conversion of styrene (100%) and the highest selectivity (88%) for benzaldehyde. The Cr catalyst shows the poorest performance in terms of selectivity. The TM-MCM-48 catalysts are very active in the oxidation of styrene, and their activity depends on the nature of the transition metal used.

Films of polyions and octahedral layered Mn oxide (OL-1) nanoparticles on C electrodes made by layer-by-layer alternate electrostatic adsorption were active for electrochemical catalysis of styrene epoxidation in solution in the presence of H2O2 and oxygen. The highest catalytic turnover was obtained by using applied voltage -0.6 V vs. SCE, O2, and 100 mM H2O2. 18O isotope labeling experiments suggested oxygen incorporation from 3 different sources: mol. oxygen, H2O2, and/or lattice oxygen from OL-1 depending on the potential applied and the oxygen and H2O2 concentrations. Oxygen and H2O2 activate the OL-1 catalyst for the epoxidation. The pathway for styrene epoxidation in the highest yields required oxygen, H2O2, and a reducing voltage and may involve an activated oxygen species in the OL-1 matrix.

The metal effect of the inner electrode used for the decomposition of methane and the resulting evolution of hydrogen by discharge plasmas was investigated. Several different electrodes were used including noble metals such as palladium and other metals such as iron and copper. The noble metals showed the highest activity in methane decomposition and hydrogen production. Nickel and gold showed considerable deactivation, whereas the activity of iron decreased less. Coated electrodes with copper and tin oxide nanoparticles exhibited high activity in these reactions. The effect of the flow rate and the cleaning of the electrode were examined as further objectives of this study. The decomposition of methane and the evolution of hydrogen decreased with increasing flow rate in a neg. exponential manner due to the lower residence time. The cleaning of the electrode has a profound effect on the conversions and allows one to observe the catalytic effect of the metal electrodes, which are otherwise covered by coke produced in the reaction. A mechanism was developed using data obtained from mass spectrometry and combined gas chromatography and mass spectrometry.