Catalytic Air Oxidation Research Articles

Catalytic Air Oxidation of Biomass‐Derived Carbohydrates to Formic Acid

An efficient catalytic system for biomass oxidation to form formic acid was developed. The conversion of glucose to formic acid can reach up to 52% yield within 3 h when catalyzed by 5 mol% of H(5)PV(2)Mo(10)O(40) at only 373 K using air as the oxidant. Furthermore, the heteropolyacid can be used as a bifunctional catalyst in the conversion of cellulose to formic acid (yield=35%) with air as the oxidant.

Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot

To comply with the stringent emission regulations on soot, diesel vehicles manufacturers more and more commonly use diesel particulate filters (DPF). These systems need to be regenerated periodically by burning soot that has been accumulated during the loading of the DPF. Design of the DPF requires rate of soot oxidation. This paper describes the kinetics of catalytic oxidation of diesel soot with air under isothermal conditions. Kinetics data were collected in a specially designed mini-semi-batch reactor. Under the high air flow rate assuming pseudo first order reaction the activation energy of soot oxidation was found to be, Ea = 160 kJ/ mol. ©2010 BCREC UNDIP. All rights reserved ( Received: 14th June 2010, Revised: 18th July 2010, Accepted: 9th August 2010 ) [How to Cite : R. Prasad, V.R. Bella. (2010). Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot. Bulletin of Chemical Reaction Engineering and Catalysis , 5(2): 95-101. doi:10.9767/bcrec.5.2.796.95-101 ] [DOI: http://dx.doi.org/10.9767/bcrec.5.2.796.95-101 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/796 ] Cited by in: ACS 1 |

Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot

To comply with the stringent emission regulations on soot, diesel vehicles manufacturers more and more commonly use diesel particulate filters (DPF). These systems need to be regenerated periodically by burning soot that has been accumulated during the loading of the DPF. Design of the DPF requires rate of soot oxidation. This paper describes the kinetics of catalytic oxidation of diesel soot with air under isothermal conditions. Kinetics data were collected in a specially designed mini-semi-batch reactor. Under the high air flow rate assuming pseudo first order reaction the activation energy of soot oxidation was found to be, Ea = 160 kJ/ mol. © 2010 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Oxidative Desulfurization of Jet and Diesel Fuels Using Hydroperoxide Generated in Situ by Catalytic Air Oxidation

The objective of this work is to explore the potential of carrying out oxidative desulfurization using air as an oxidant. The liquid fuels to be desulfurized were first contacted with air to produce hydroperoxides in situ, which were then used as selective oxidants to oxidize the sulfur compounds. Unsupported CuO was tested as a catalyst for producing hydroperoxides in the fuel at 120 °C in the presence of air. Air oxidation was also carried out in the presence of Al2O3-supported CuO and also noncatalytically. Unsupported CuO was substantially more active than the other two cases. The yield of the hydroperoxides depends strongly on the catalyst and the reaction temperature; the yield decreased in the order of 120 °C > 140 °C ≫ 100 °C but the rate of oxidation to produce hydroperoxides decreased in the order of 140 °C > 120 °C ≫ 100 °C. It was found that more hydroperoxides could be generated in diesel fuel than in jet fuel, which might be related to the higher concentration of alkyl aromatics in diesel fu...

Oxidation of bisnaphthols to spironaphthalenones, revisited

Abstractmagnified imageBis(2‐hydroxy‐1‐naphthyl)methane derivatives have been efficiently converted to their corresponding spirans through three methods, i.e. oxidation by TCCA under mild reaction conditions, Ph3Bi catalyzed air oxidation, and by electrochemical reaction. The first two methods are diastereoselective and give either of the two possible diastereomers, while the electrochemical method produces equal amounts of these diastereomers.

A method for polyaniline coatings on solid polystyrene surfaces and electroless copper deposition

A new efficient method is presented for electroless copper deposition on solid polystyrene surfaces via polyaniline (PANI) coatings. It was demonstrated that, partial polymerization of aniline by catalytic air oxidation in the presence of dissolved polystyrene (PS) (M n: 87.000 K) gives viscous solution of PANI-PS mixture in aniline. Direct application of the polymerization mixture with copper catalyst onto polystyrene sheets (5 × 15 cm) resulted in extension of the polymerization by air oxygen to give a smooth PANI-PS composite layer on the host surface. Treatment of the surface with a similar PANI solution without PS gave Emeraldine base film with homogenously dispersed copper. Reduction of the surface copper by diluted hydrazine (5%) yielded zero-valent copper serving as seed points for accumulation of more copper from an electroless plating solution in the following process. Experiments showed that, the method presented offers a simple pathway to produce excellent copper deposits on PS substrate. This method is superior to traditional electroless plating process, since tedious surface etching and expensive palladium activation steps are being avoided. The surface characteristics were examined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), adhesion tests and contact angle measurements. The results showed that, the electroless plating process gives a homogeneous and highly robust copper layer with 34.2 μm of thickness within 48 h. Adhesion of the copper layer to the underlining surface was satisfactory as inferred from pull-off measurements (1.6 N/mm 2).

Catalytic air oxidation of olefins using molybdenum dioxo complexes with dissymmetric tridentate O,N,S-donor Schiff base ligands derived from o-hydroxyacetophenone and S-benzyldithiocarbazate or S-methyldithiocarbazate

We report the homogeneous catalytic air oxidation of 1-hexene, cyclohexene and styrene using cis-[MoO 2(hap-SBDTC)(solv)] ( 1b) and cis-[MoO 2(hap-SMDTC)(solv)] ( 2b), where hap-SBDTC and hap-SMDTC are Schiff bases derived from o-hydroxyacetophenone (hap) and S-benzyldithiocarbazate (SBDTC) or S-methyldithiocarbazate (SMDTC), respectively. Both hap-SBDTC and hap-SMDTC are dissymmetric tridentate O,N,S-donor Schiff base ligands. The catalytic tests were performed in DMF solvent at 60 °C under 1 atm O 2.The olefin conversion was determined using gas chromatography. The percentage conversion of the above-mentioned substrates at the end of 6 h was in the range 86–98%. The final oxidation products were found to be 1-hexanal for 1-hexene, styrene epoxide and phenyl acetaldehyde (81:19) for styrene and cyclohexene epoxide and 2-cyclohexen-1-ol (85:15) in the case of cyclohexene. The oxidation reaction typically followed pseudo-order kinetics; however, a two-stage first order reaction is evident with complex 2b. This is attributed to less steric and electron-donating methyl substitution on S in 2b that possibly imparted a higher reactivity accompanying the formation of an intermediate in a relatively faster reaction step prior to the formation of final oxidation products. A reaction mechanism that explains the experimental results is proposed.

The formation of disulfides by the [Fe(nta)Cl 2] 2− catalyzed air oxidation of thiols and dithiols

The complexes (cnt) 2[Fe(nta)Cl 2], where nta = nitrilotriacetate and cnt = Et 4N + or PyH +, catalyze the air oxidation of thiols to disulfides under ambient conditions. Dithiols are converted to linear and cyclic oligomers that differ in their terminal groups as a function of the counterion, cnt. Cysteine ethyl ester was converted to the corresponding cystine diethylester in high yield.

Synthesis and Characterization of Palladium(II) Complexes with 2‐(2′‐Pyridyl)quinoline. Catalytic Air Oxidation of Olefins by Palladium(II) Complexes

AbstractPalladium(II) complexes of 2‐(2′‐pyridyl)quinoline (PQ), namely [PdX2(PQ)] (X = Br−, I−, N3−, NO2−, SCN−, acac) and [PdCl(NO3)(PQ)] have been synthesized via substitution reactions of [PdCl2(PQ)] with an excess of sodium salts and acetylacetone. The complexes have been characterized by elemental analysis, conductivity measurements, IR, 1H and 13C NMR spectroscopy. Selected complexes have been further characterized using electrospray ionization (ESI) and ion trap mass spectroscopy (ITMS). Some complexes are found to catalyze the rapid air oxidation of α‐olefins under Wacker oxidation. The chlorohydrin products are produced in good to excellent yields while oxidation products are obtained in low yields. The [PdCl2(PQ)] complex is found to have the highest catalytic activity.

A Novel Approach to the Efficient Oxygenation of Hydrocarbons under Mild Conditions. Superior Oxo Transfer Selectivity Using Dioxiranes

The design of efficient and general methods for the selective oxyfunctionalization of unactivated carbon-hydrogen bonds continues to represent a major challenge for the community of chemists, despite the fact that the oxidation of alkanes is a major feature of the chemical economy. A low level of selectivity is characteristic of large-scale oxidation of hydrocarbons performed under customary industrial oxidizing conditions (e.g., the catalytic air oxidation of cycloalkanes); in these processes, selectivity is difficult to control, because they are often impacted by the usual problems associated with free-radical chain reactions. Thus, in the last decades much work has been devoted to the search for general methods of selective oxidation that could be applied to a variety of satured hydrocarbons. In this context, just a few leading methods appear encouraging at the present time. This Account addresses a new approach developed in our laboratory, consisting in the application of isolated dioxiranes, a class of powerful yet selective oxidants. We contend that the method shows promise to contribute resolution of a well-recognized general problem in the existing chemistry of alkanes, that is, to achieve efficient oxyfunctionalizations with high selectivity for simple as well as structurally complex targets.

Catalytic air oxidation of manganese in synthetic waters

Abstract An attempt was made to study the oxidation of manganese by air in synthetic waters. A series of batch experments were performed at differnet values of concentration, temperature and pH. Unoxidized manganese in the solution was determined by formaldoxime spectrometric method. Results of these studies indicated that the air oxidation of manganese soluble in water can be effectively performed in basic media and that oxidation yield increasedwith an increase in pH and concentration. The yield was very high in the presence of manganese dioxide, sepiolite or clinoptilolite in solution and, the oxidation was almost completed especially at high values of pH and concentration. The reaction was found to be first order with respect to Mn2+ with a very low activation energy. A yield of 62% was obtained for the air oxidation of wastewater taken from the treatment plant of Corum Municipality.

14-Hydroxylation of Opiates: Catalytic Direct Autoxidation of Codeinone to 14-Hydroxycodeinone

Codeinone (3) was efficiently and directly converted to 14-hydroxycodeinone (1) by catalytic air oxidation in aqueous solution. A number of simple manganese and copper salts were identified to be effective catalysts, including MnSO4, KMnO4, and CuSO4. An appropriate reducing agent, such as sodium thiosulfate, is required in the reaction mixture presumably for the reduction of a detrimental peroxide intermediate. This discovery allows the more abundant codeine to be employed as the starting material for the synthesis of 14-hydroxylated opiate drugs without recourse to a thebaine-like intermediate. These discoveries were inspired from our study of microbial transformation of codeine to 14-hydroxycodeine by Mycobacterium neoaurum, where we found the actual 14-hydroxylation step is a chemical reaction rather than an enzymatic reaction, as previously believed.

Practical Process for the Air Oxidation of Cresols: Part B. Evaluation of the Laboratory-Scale Oxidation Process

Mechanistic proposals and predictions made in a preceding paper (Part A) were evaluated by carrying out the catalytic air oxidation of p-cresol in an alternative solvent system, comprising either a...

Practical Process for the Air Oxidation of Cresols: Part A. Mechanistic Investigations

The catalytic air oxidation of p-cresol and 2,6-di-tert-butyl-4-methylphenol to the corresponding benzaldehydes was investigated to determine the mechanism at work in these oxidation reactions. A number of intermediates and byproducts, mainly in the form of dimers, were observed during the course of the reactions, and their structures were elucidated by spectroscopic and chromatographic methods. The existence of these compounds in the reaction mixtures, and their proposed methods of formation, provided further insight into the mechanism involved in these oxidations.

Catalytic air oxidation of tertiary arylphosphines in the presence of tin(IV) iodide

Arylphosphines including Ph 3P, o-C 6H 4(PPh 2) 2 and Ph 2PCH 2CH 2PPh 2 are cleanly and quantitatively converted into the corresponding phosphine oxides on reaction with dry air or dioxygen in CH 2Cl 2 solution in the presence of catalytic amounts of SnI 4.

One-pot, two-step, practical catalytic synthesis of 2,5-diformylfuran from fructose.

[reaction: see text] A practical, one-pot, two-step catalytic method is described for the synthesis of 2,5-diformylfuran (DFF) from fructose via dehydration to 5-(hydroxymethyl)furfural (HMF), followed by in situ catalytic air-oxidation.

Catalytic air oxidation of ambient temperature hydrocarbons

Catalytic air oxidation of the aliphatic hydrocarbons n-decane, hexanes, gasoline and diesel fuel was conducted at ambient temperature with novel iron catalysts. The concentration of n-decane in water was reduced from 1.42 g in 100 ml to 0.07 g in 100 ml in 5 h at room temperature forming carbon monoxide and water by means of intermediate aldehydes. Results of FT–IR and GC–MS analyses demonstrated formation of aldehydes and unsaturated alcohols. Carbon monoxide was detected on catalyst residues and in the vapor phase. The indicated catalytic reaction mechanisms are discussed.

Optimum cleaning-in-place conditions for stainless steel microfiltration membrane fouled by terephthalic acid solids

Terephthalic acid (TPA) is a raw material of polyester fiber and polyethylene terephthalate. When TPA is produced by catalytic air oxidation of p-xylene in the presence of acetic acid solvent, most of produced TPA exists in the form of crystalline suspended solids. A microfiltration process may be used to recover TPA, but the microfilters are subjected to fouling and therefore cleaning-in-place (CIP) regimes need to be developed. In this research, the effects of variations to CIP conditions were investigated on the flux recovery accomplished in a TiO 2-sintered stainless steel microfiltration membrane (0.1 μm pore size) fouled with TPA. The extent of flux recovery was estimated as the ratio of the stabilized flux obtained during CIP to the water flux value achieved under corresponding operational conditions. Based upon batch solubility tests, sodium hydroxide (NaOH) was chosen as the major cleaning agent for the present experiment. The extent of flux recovery increased with increasing NaOH concentration over the range of 3–4% (w/v) NaOH, but decreased at NaOH concentrations above 4%. The flux recovery was favored at high cross-flow velocities, high temperatures and low transmembrane pressures. A high temperature run of cleaning did not produce any adverse effects up to 70 °C. The addition of surfactants (SDS and Tween 80) to the caustic cleaning agent led to a significant reduction in cleaning efficiency.

Aqueous emulsion containing fluorous cobalt species in supercritical CO2 for catalytic air oxidation of toluene.

An aqueous emulsion containing ionic Co2+ and Br- species stabilised by fluorous surfactant-like species in supercritical CO2-air mixture acts as a nano-reactor with excellent interfacial contacts of all necessary hydrophilic/hydrophobic species, which renders safe operation of catalytic aerial oxidation of toluene at high yields.

Oxidation of ketone by palladium(II). α-Hydroxyketone synthesis catalyzed by a bimetallic palladium(II) complex

A bimetallic palladium(II) complex containing a triketone ligand and a bridging dinitrogen ligand oxidizes ketones in aqueous THF to α-hydroxyketone by a direct air oxidation. While the normal synthesis of α-hydroxyketones involves a series of reactions, this synthesis performs the transformation in one step in a catalytic air oxidation. This synthesis does not involve an olefin and is almost unprecedented in transition metal catalysis. Its main virtue is its simplicity and actually it is an enolization reaction. Methanesulfonic acid is used to accelerate the enolization of ketones. The reaction is carried out in the presence of CuCl 2 and/or dioxygen only. In particular, it is found that the hydroxyketone formation does not require the presence of CuCl 2. Matrix assisted laser desorption ionization (MALDI) and time-of-flight mass spectrometry (TOFMS) are used to record the mass spectra of α-hydroxyketones products. α-Cyano-4-hydroxycinnamic acid (CHCA) matrix promoted the molecular ion detection when 180 pmol of α-hydroxyketones is introduced into the TOFMS.