Formation Of Acetone Research Articles

Recycling of spent oil bleaching earth as source of glycerol for the anaerobic production of acetone, butanol, and ethanol with Clostridium diolis and lipolytic Clostridium lundense

A major part of edible oil is subjected to bleaching procedures, primarily with minerals applied as adsorbers. Their recycling is currently done either by regaining the oil via organic solvent extraction or by using the spent bleaching earth (SBE) as additive for animal feed, etc. As a new method, the reutilization of the by‐product SBE for the microbiologic formation of acetone, butanol, and ethanol (ABE) is presented as proof‐of‐concept. The SBE was taken from a palm oil cleaning process. The recycling concept is based on the application of lipolytic clostridia strains. Due to considerably long fermentation times, co‐fermentation with Candida rugosa and enzymatic hydrolyses of the bound oil with a subsequent clostridia fermentation are shown as alternative routes. Anaerobic fermentations under comparison of different clostridia strains were performed with glycerol media, enzymatically hydrolyzed palm oil and SBE. Solutes, side product compositions and productivities were quantified via HPLC. A successful production of ABE solutes from SBE has been done with a yield of 0.15 g butanol per gram of bound glycerol. Thus, the biotechnological recycling of the waste stream is possible in principle. Inhibition of the substrate suspension has been observed. A chromatographic ion‐exchange of substrates increased the biomass concentration.

Selective oxidation of hydrocarbons on supported Au catalysts

The importance of proximity of isolated TiOx cluster to Au surface for the formation of acetone in the selective oxidation of propane was investigated using a model system of Au particles decorated with mononuclear TiOx units dispersed in silica clusters. The results showed that no acetone was formed without TiOx, and its formation was more prominent on a sample containing a higher density of TiOx. Covering a Au/TiO2 catalyst with a layer of TiOx-containing silica changed the product selectivity from predominently propene to acetone. The data strongly supported the importance of isolated TiOx clusters near the Au surface in acetone formation, and suggested the relevance of Au-TiOx interface sites. Such interface sites might also be important in selective propene epoxidation that was coupled to CO oxidation in a H2O-methanol mixture. Using oxygen isotope labeling technique, it was found that the proximal source of oxygen in propene oxide was not from H2O but from O2. The observation was consistent with a methyl hydroperoxide intermediate, which could be formed by oxidation of a Ti methoxy at the Au-support interface.

Structure and catalytic properties of sulfated zirconia foams

Porous sulfated zirconia foams were manufactured by a simple methodology based on the sol–gel process combined with a liquid foam template that used a surfactant mixture. A block copolymer (Pluronic F-127) and an anionic surfactant [sodium dodecylsulfate (SDS)] were mixed in different proportions in order to optimize the porous and surface properties of the ceramic material. By adjusting the SDS/Pluronic ratio, it was possible to obtain sulfated zirconia with a combination of macropores and mesopores that provided high porosity (≈90 %) and surface area (≈80 m2 g−1). The sulfate groups linked to the zirconia surface stabilized the tetragonal phase, to the detriment of the thermodynamically stable monoclinic phase. The sulfate groups and the tetragonal phase decreased as a function of the amount of SDS in the liquid foam template. The combined porous and structural characteristics, together with surface acidity, provided enhanced catalytic activity when the sulfated zirconia foams were employed in the isopropanol dehydration reaction. A further benefit was the selectivity towards propene and negligible formation of acetone.

Catalytic Air Freshening Diffusers Based on Isopropyl Alcohol - A Major Source of Acetone Indoors

Air fresheners are used in indoor environments for perfuming the ambience and/or masking unpleasant smells. There are several types of air fresheners on the market including those belonging to the family of catalytic diffusers. The fuel of these devices is frequently 2-methylpropanol, which, while operating, is oxidised to acetone. The acetone emission of a catalytic diffuser was measured for two fragrances under controlled laboratory conditions as well as in a private household. Emission rates were 530 mg/h and 660 mg/h respectively. Acetone concentrations of approximately 700 μg/m^3 were measured in a private household three hours after the diffuser was extinguished. Besides isopropyl alcohol, one of the two fragrances contained 2-methylpropanol as a fuel component, which is oxidised to 2-methylpropanal. The emission rate for 2-methylpropanal was 11 mg/h. Catalytic diffusers containing isopropyl alcohol as fuel were identified as being a major indoor source of acetone. Although not a legal requirement, the secondary formation of acetone should be included in product information along with a list of product constituents. As an alternative, a less easily oxidisable solvent could be used.

Stainless steel wire mesh-supported Co3O4 catalysts in the steam reforming of ethanol

Structured catalysts consisting of either undoped or potassium-doped mesoporous Co3O4 nanowires supported on stainless steel wire meshes (SSWM) and prepared by the ammonia evaporation-induced method were tested in the ethanol steam reforming (ESR) reaction. The undoped catalyst was strongly reduced to elemental Co in ESR conditions, causing a decrease in catalytic activity, the undesired formation of acetone, the premature deactivation of the catalyst due to coke deposition and the detachment of particles from the SSWM. Doping the catalyst with potassium (molar K/Co around 0.05) produced an increase in the surface area of the catalysts and a significant enhancement of the catalytic performance in terms of H2 TOF, carbon selectivity towards CO2 and stability. The presence of potassium prevented the over-reduction of the Co3O4 particles to elemental Co, thereby avoiding the detrimental effects of this phase. Comparison with cobalt-based catalysts described in the literature confirm that the doped catalysts produced in this work are more active and present better values of carbon selectivity towards CO2 than structured catalysts previously reported.

Visible light activated photocatalytic behaviour of rare earth modified commercial TiO2

A commercial TiO2 nanopowder, Degussa P25, was modified with several rare earth (RE) elements in order to extend its photocatalytic activity into the visible range. The mixtures were prepared via solid-state reaction of the precursor oxides, and thermally treated at high temperature (900 and 1000°C), with the aim of investigating the photocatalytic activity of the thermally treated samples. This thermal treatment was chosen for a prospective application as a surface layer in materials that need to be processed at high temperatures.The photocatalytic activity (PCA) of the samples was assessed in gas–solid phase – monitoring the degradation of isopropanol (IPA) – under visible-light irradiation. Results showed that the addition of the REs lanthanum, europium and yttrium to TiO2 greatly improved its photocatalytic activity, despite the thermal treatment, because of the presence of more surface hydroxyl groups attached to the photocatalyst's surface, together with a higher specific surface area (SSA) of the modified and thermally treated samples, with regard to the unmodified and thermally treated Degussa P25. The samples doped with La, Eu and Y all had excellent PCA under visible-light irradiation, even higher than the untreated Degussa P25 reference sample, despite their thermal treatment at 900°C, with lanthanum producing the best results (i.e. the La-, Eu- and Y-TiO2 samples, thermally treated at 900°C, had, respectively, a PCA equal to 26, 27 and 18ppmh−1 – in terms of acetone formation – versus 15ppmh−1 for the 900°C thermally treated Degussa P25). On the other hand, Ce–TiO2s had no significant photocatalytic activity.

Study of acid–base properties of supported heteropoly acids in the reactions of secondary alcohols dehydration

The dehydration of secondary alcohols (propan-2-ol and 4-methylpentan-2-ol) was catalyzed by heteropolyacids (HPAs) supported on different solids. Catalysts prepared with 20wt.% of HPAs were calcined at 400°C and characterized by X-ray diffraction, Raman spectroscopy, XPS and N2 adsorption measurements. Stability of the Keggin structure of supported HPAs and changes in textural properties of catalysts were analyzed. The catalytic conversion of alcohols to olefins and ethers has been studied over the catalysts prepared. All catalysts presented activity in the reactions, but only molybdophosphoric acid supported on ZrO2 (MoP-Z) showed selectivity in the formation of acetone and methyl isobutyl-ketone (MIBK). Catalysts with tungstosilicic acid (WSi) and Tungstophosphoric acid (WP) were active in the formation to DIPE. The acid–base properties of the catalysts play a key role in route of the reaction mechanism.

Acetone in Orion BN/KL

As one of the prime targets of interstellar chemistry study, Orion BN/KL clearly shows different molecular distributions between large nitrogen- (e.g., C2H5CN) and oxygen-bearing (e.g., HCOOCH3) molecules. However, acetone (CH3)2CO, a special complex O-bearing molecule, has been shown to have a very different distribution from other typical O-bearing molecules in the BN/KL region. We searched for acetone within our IRAM Plateau de Bure Interferometer 3 mm and 1.3 mm data sets. Twenty-two acetone lines were searched within these data sets. The angular resolution ranged from 1.8 X 0.8 to 6.0 X 2.3 arcsec^2, and the spectral resolution ranged from 0.4 to 1.9 km s-1. Nine of the acetone lines appear free of contamination. Three main acetone peaks (Ace-1, 2, and 3) are identified in Orion BN/KL. The new acetone source Ace-3 and the extended emission in the north of the hot core region have been found for the first time. An excitation temperature of about 150 K is determined toward Ace-1 and Ace-2, and the acetone column density is estimated to be 2-4 X 10^16 cm-2 with a relative abundance of 1-6 X 10^-8 toward these two peaks. Acetone is a few times less abundant toward the hot core and Ace-3 compared with Ace-1 and Ace-2. We find that the overall distribution of acetone in BN/KL is similar to that of N-bearing molecules, e.g., NH3 and C2H5CN, and very different from those of large O-bearing molecules, e.g., HCOOCH3 and (CH3)2O. Our findings show the acetone distribution is more extended than in previous studies and does not originate only in those areas where both N-bearing and O-bearing species are present. Moreover, because the N-bearing molecules may be associated with shocked gas in Orion BN/KL, this suggests that the formation and/or destruction of acetone may involve ammonia or large N-bearing molecules in a shocked-gas environment.

CO Activation by (Diphosphane)platinum(0): Carbonate and Acetone Formation – Experimental and Mechanistic Study

AbstractThe platinum(II) complex [(dcpp)Pt(C7H7)H] (1) [dcpp = 1,3‐bis(dicyclohexylphosphanyl)propane] reacts under 1 atm of CO to form the bis(carbonyl) complex of Pt0, [(dcpp)Pt(CO)2] (2). Complex2slowly crystallizes in toluene solution to form crystals of the Pt0dimer [(dcpp)(η1‐CO)Pt{μ‐C(O)}Pt(dcpp)] (3) in which one Pt atom is only three‐coordinated with the diphosphane dcpp and one μ‐C(O), while the other is coordinated in a tetrahedral arrangement with one μ‐C(O) and one η1‐CO. Complexes2and3were characterized in solution by31P NMR spectroscopy, and complex3readily reacts with O2to form the carbonate complex, [(dcpp)Pt(CO3)] (4). The reaction of the dimeric complex3with MeI allows the insertion of a methyl group into the carbonyl group to form the PtIIcomplex [(dcpp)Pt(C(O)Me)I] (5). Reaction of another equivalent of MeI with complex5leads to the formation and elimination of acetone and the bis(iodide) complex [(dcpp)PtI2] (6). X‐ray crystal structures of complexes3and4are reported along with DFT calculations and mechanistic studies of the formation of3,4,5, and6.

Surface reaction of 2‐propanol on modified Keggin type polyoxometalates: In situ IR spectroscopic investigation of the surface acid–base properties

AbstractIn order to investigate the influence of modified Keggin‐polyoxometalates and supported gold particles on reactivity and reaction pathways in thermal 2‐propanol oxidation, titanium‐substituted, insoluble Cs+‐salts of the Keggin‐heteropolytungstate (H3PW12O40) Cs3PW12O40 1, Cs5PW11TiO40 · nH2O 2, and supported gold composite Au/Cs5PW11TiO40 · nH2O 3 were synthesized and characterized as molecular model catalysts. The Ti‐substituted polyoxometalate 2 did not show any observable activity in the gas phase oxidation of 2‐propanol. The presence of gold nano‐particles activates the supporting polyoxometalate 3 and enhances formation of different oxidation products (acetone, diisopropyl ether) depending on the presence of different types of active sites. The formation of the diisopropyl ether involves two adjacent 2‐propanol molecules adsorbed on two different types of active sites, whereas the dehydrogenation reaction for the acetone formation involves the initial adsorption of 2‐propanol on one type of active site.

Au/xCeO2/Al2O3 catalysts for VOC elimination: oxidation of 2-propanol

2-Propanol oxidation (1 mol% in air) was investigated over 1%Au/CeO2, 1%Au/Al2O3 and 1%Au/xCeO2/Al2O3 (x = 1.5, 3, 5 and 10 wt%) catalysts and the corresponding pure supports. The effects of the catalyst activation procedure (calcination or reduction), cerium oxide morphology and loading, the presence/absence of O2 in the feed, and stability of activity were studied. The nature of the support strongly influences the 2-propanol oxidation pathway, and one can distinguish three reaction temperature ranges: low (50–150 °C), intermediate (175–250 °C) and high (>300 °C). In the low temperature range, only acetone is formed whatever the nature of the support. On Au/Al2O3 and Au/xCeO2/Al2O3 catalysts propene becomes the main reaction product by increasing the temperature, followed by CO2 formation at higher temperature. The acidic character of Al2O3 and CeO2/Al2O3 promotes the propene formation whereas the basic one of CeO2 favors the formation of acetone, and the gold catalysts also present an acidic–basic behavior, which depends largely on the reaction temperature. Replacing air with He during the catalytic run over Au/Al2O3 and Au/CeO2 provides evidence of how O2 is activated by Au, revealing, as expected, that dehydrogenation to form acetone and total oxidation to CO2 require both O2 and Au as the catalyst, whereas dehydration to form propene does not require O2. For both calcined and reduced catalysts, the catalytic activity towards total oxidation varies in the order: Au/CeO2 > Au/xCeO2/Al2O3 > Au/Al2O3.

Kinetics and mechanism of glycerol photo-oxidation and photo-reforming reactions in aqueous TiO2 and Pt/TiO2 suspensions

The kinetics and mechanism of glycerol photo-oxidation and photo-reforming reactions have been investigated over irradiated TiO2 and Pt/TiO2 suspensions. It has been found that, in the presence of O2, oxidation of glycerol to CO2 takes place readily over TiO2 photocatalyst and that the reaction rate is enhanced substantially in the presence of dispersed Pt crystallites. The rate of the photo-reforming reaction is very slow over bare TiO2 and increases significantly over the platinized sample. Analysis of reaction intermediates and final products in the gas and liquid phases indicates that both oxidation and reforming reactions proceed via the same general reaction pathways. The initial transformation steps involve hydrogenolysis of glycerol to propylene glycol and dehydration of glycerol to glyceraldehyde. Subsequent dehydration, dehydrogenation and decarbonylation reactions lead to the formation of various reaction intermediates, including glycoaldehyde, 2-oxopropanol, acetaldehyde, acetone, ethanol and methanol, which are eventually transformed to gas-phase CO2 (and H2 under photo-reforming reaction conditions). It is concluded that oxidation of glycerol to CO2 over irradiated TiO2 photocatalysts may take place by using either O2 or H2O as the oxidizing species. The overall reaction rate depends on the nature of the oxidant and is enhanced in the presence of Pt co-catalyst.

Thiolase engineering for enhanced butanol production inClostridium acetobutylicum

Biosynthetic thiolases catalyze the condensation of two molecules acetyl-CoA to acetoacetyl-CoA and represent key enzymes for carbon-carbon bond forming metabolic pathways. An important biotechnological example of such a pathway is the clostridial n-butanol production, comprising various natural constraints that limit titer, yield, and productivity. In this study, the thiolase of Clostridium acetobutylicum, the model organism for solventogenic clostridia, was specifically engineered for reduced sensitivity towards its physiological inhibitor coenzyme A (CoA-SH). A high-throughput screening assay in 96-well microtiter plates was developed employing Escherichia coli as host cells for expression of a mutant thiolase gene library. Screening of this library resulted in the identification of a thiolase derivative with significantly increased activity in the presence of free CoA-SH. This optimized thiolase comprised three amino acid substitutions (R133G, H156N, G222V) and its gene was expressed in C. acetobutylicum ATCC 824 to assess the effect of reduced CoA-SH sensitivity on solvent production. In addition to a clearly delayed ethanol and acetone formation, the ethanol and butanol titers were increased by 46% and 18%, respectively, while the final acetone concentrations were similar to the vector control strain. These results demonstrate that thiolase engineering constitutes a suitable methodology applicable to improve clostridial butanol production, but other biosynthetic pathways involving thiolase-mediated carbon flux limitations might also be subjected to this new metabolic engineering approach.

Acetone in the atmosphere of Hong Kong: Abundance, sources and photochemical precursors

Intensive field measurements were carried out at a mountain site and an urban site at the foot of the mountain from September to November 2010 in Hong Kong. Acetone was monitored using both canister air samples and 2,4-dinitrophenylhydrazine cartridges. The spatiotemporal patterns of acetone showed no difference between the two sites (p > 0.05), and the mean acetone mixing ratios on O3 episode days were higher than those on non-O3 episode days at both sites (p < 0.05). The source contributions to ambient acetone at both sites were estimated using a receptor model i.e. Positive Matrix Factorization (PMF). The PMF results showed that vehicular emission and secondary formation made the most important contribution to ambient acetone, followed by the solvent use at both sites. However, the contribution of biogenic emission at the mountain site was significantly higher than that at the urban site, whereas biomass burning made more remarkable contribution at the urban site than that at the mountain site. The mechanism of oxidation formation of acetone was investigated using a photochemical box model. The results indicated that i-butene was the main precursor of secondary acetone at the mountain site, while the oxidation of i-butane was the major source of secondary acetone at the urban site.

Origins of the deactivation process in the conversion of methylbutynol on zinc oxide monitored by operando DRIFTS

The catalytic behavior of zinc oxide samples was studied thanks to a model methylbutynol (MBOH) conversion reaction. The formation of acetone and acetylene is indicative of the basic properties of the zinc oxide surface. This basic catalyst, whose conversion level depends on the nature of the pre-treatment, was found to deactivate versus time on stream. Poisoning the basic sites by CO2 pre-adsorption only affects the active sites working at the beginning of the reaction, those still working at steady state being not impacted. This is consistent with the modification of the strength and population of the active sites during the catalytic reaction. Indeed, from operando DRIFTS experiments, at the beginning of the reaction, the strong acid base pairs generated upon inert treatment at 773K promote the self aldol condensation of acetone, leading to oligomers. This reaction also produces water, which dissociates on the surface, filling up oxygen vacancies. This contributes to the lowering of the strength of the active sites, resulting in the quenching of polymerization of acetone at a certain stage, at the benefit of the increase of the amount of diacetone alcohol. Consistently, pre-adsorption of water was shown to lead to a decrease of the conversion level, resulting in a conversion profile similar to that obtained after 10min of reaction in the absence of pre-adsorbed water. The poisoning mechanism proposed is based on the evolution of the IR bands versus time and is in line with the evolution of the deactivation profile versus time. It is concluded that both the control of the conversion level and the dependence of the reaction toward deactivation are associated to the formation of oxygen vacancies during the pre-treatment step but also on their stability in the conditions on the implemented catalytic reaction.

Targeted mutagenesis of the Clostridium acetobutylicum acetone–butanol–ethanol fermentation pathway

The production of the chemical solvents acetone and butanol by the bacterium Clostridium acetobutylicum was one of the first large-scale industrial processes to be developed, and in the first part of the last century ranked second in importance only to ethanol production. After a steep decline in its industrial use, there has been a recent resurgence of interest in the acetone–butanol–ethanol (ABE) fermentation process, with a particular emphasis on butanol production. In order to generate strains suitable for efficient use on an industrial scale, metabolic engineering is required to alter the AB ratio in favour of butanol, and eradicate the production of unwanted products of fermentation. Using ClosTron technology, a large-scale targeted mutagenesis in C. acetobutylicum ATCC 824 was carried out, generating a set of 10 mutants, defective in alcohol/aldehyde dehydrogenases 1 and 2 (adhE1, adhE2), butanol dehydrogenases A and B (bdhA, bdhB), phosphotransbutyrylase (ptb), acetate kinase (ack), acetoacetate decarboxylase (adc), CoA transferase (ctfA/ctfB), and a previously uncharacterised putative alcohol dehydrogenase (CAP0059). However, inactivation of the main hydrogenase (hydA) and thiolase (thl) could not be achieved. Constructing such a series of mutants is paramount for the acquisition of information on the mechanism of solvent production in this organism, and the subsequent development of industrial solvent producing strains. Unexpectedly, bdhA and bdhB mutants did not affect solvent production, whereas inactivation of the previously uncharacterised gene CAP0059 resulted in increased acetone, butanol, and ethanol formation. Other mutants showed predicted phenotypes, including a lack of acetone formation (adc, ctfA, and ctfB mutants), an inability to take up acids (ctfA and ctfB mutants), and a much reduced acetate formation (ack mutant). The adhE1 mutant in particular produced very little solvents, demonstrating that this gene was indeed the main contributor to ethanol and butanol formation under the standard batch culture conditions employed in this study. All phenotypic changes observed could be reversed by genetic complementation, with exception of those seen for the ptb mutant. This mutant produced around 100mM ethanol, no acetone and very little (7mM) butanol. The genome of the ptb mutant was therefore re-sequenced, together with its parent strain (ATCC 824 wild type), and shown to possess a frameshift mutation in the thl gene, which perfectly explained the observed phenotype. This finding reinforces the need for mutant complementation and Southern Blot analysis (to confirm single ClosTron insertions), which should be obligatory in all further ClosTron applications.

Nonconventional treatment of sewage sludge using cement kiln dust for reuse and catalytic conversion of hydrocarbons

Sewage sludge represents a critical environmental issue in Egypt. Large quantities of CKD are emitted from cement factories. It has negative impacts on humans, animals, plants, lands, water, and all remaining environment. It causes serious problems on the national level. Besides using CKD for sludge treatment and reuse as soil conditioner, a new scenario is to use it as catalytic convertor of some hydrocarbons. Results showed that CKD is used to separate the organic matters and suspended solids, reduce the organic micropollutants, scavenge heavy metals, and destruct viruses, parasites, and all pathogenic bacteria. The dehydrogenation of isopropanol to acetone and alcohol condensation of the produced acetone to give methyl isobutyl ketone over different catalyst samples was studied using a flow technique under normal pressure. Results revealed that treatment of raw sludge led to an increase in catalytic activity toward acetone formation by 50 % at 400 °C. A treatment system was proposed for continuous operation.

A modified pathway for the production of acetone in Escherichia coli

A modified synthetic acetone operon was constructed. It consists of two genes from Clostridium acetobutylicum (thlA coding for thiolase and adc coding for acetoacetate decarboxylase) and one from Bacillus subtilis or Haemophilus influenzae (teIIsrf or ybgC, respectively, for thioesterase). Expression of this operon in Escherichia coli resulted in the production of acetone starting from the common metabolite acetyl-CoA via acetoacetyl-CoA and acetoacetate. The thioesterases do not need a CoA acceptor for acetoacetyl-CoA hydrolysis. Thus, in contrast to the classic acetone pathway of Clostridium acetobutylicum and related microorganisms which employ a CoA transferase, the new pathway is acetate independent. The genetic background of the host strains was crucial. Only E. coli strains HB101 and WL3 were able to produce acetone via the modified plasmid based pathway, up to 64mM and 42mM in 5-ml cultures, respectively. Using glucose fed-batch cultures the concentration could be increased up to 122mM acetone with HB101 carrying the recombinant plasmid pUC19ayt (thioesterase from H. influenzae). The formation of acetone led to a decreased acetate production by E. coli.

Acid–base properties of γ-Al2O3 and MgO–Al2O3 supported gold nanoparticles

Gold nanoparticles supported on γ-alumina and magnesia-doped γ-alumina were synthesized by co-precipitation via a modified sol–gel method. The syntheses were found to produce catalysts with controllable acidity; the presence of either gold or magnesia produced catalyst possessing unbalanced density of acidic and basic sites, while the addition of both gold and magnesia produced catalyst possessing balanced density of relatively stronger acidic and basic sites. The variation of the acid–base strengths of the synthesized catalysts was assessed by using NH3-TPD, CO2-TPD, and infrared analysis of adsorbed CO2 and correlated to their catalytic activity in 2-propanol decomposition probe reaction. Catalysts containing magnesia and gold were found to exhibit base catalytic properties through their greater selectivity for acetone formation, while plane γ-alumina and γ-alumina doped with magnesia or gold exhibited acid catalytic properties through their selectivity for propene formation.

Liquid-phase oxidation of propylene glycol using heavy-metal-free Pd/C under pressurized oxygen

The liquid-phase oxidation of propylene glycol using Pd/C undoped with any heavy metal such as tellurium in the presence of aqueous NaOH under pressurized oxygen resulted in a significant production of lactic acid and a minimal amount of hydroxyl acetone, although, under these conditions, sodium lactate as sodium analogue of lactic acid has been known to easily convert to sodium pyruvate. The advantageous effect of doping Pd/C with a heavy metal, which has been reported for various catalytic reactions in an aqueous phase, was not observed in the present oxidation. Previous papers have reported that oxidation using heavy-metal-free Pd/C and Pd/C doped with a heavy metal at atmospheric pressure and a pH 8 produced pyruvic acid via the formation of hydroxyl acetone and lactic acid, respectively, and that Pd/C doped with a heavy metal rather than Pd/C was suitable for the formation of pyruvic acid from propylene glycol. However the results of the present study show that the use of pressurized oxygen conditions as used in the present study can result in the exclusion of doping with a heavy metal in the preparation of the catalyst, which is amenable to green chemistry.