Kyoji Ohdan

Oxidative dehydrogenation of lactic acid to pyruvic acid over iron phosphate catalyst

Abstract Vapor-phase air oxidation of lactic acid has been carried out using an iron phosphate catalyst with a P Fe atomic ratio of 1.2. It was found that lactic acid is selectively converted to form pyruvic acid by oxidative dehydrogenation. The one-pass yield reached 50 mol-%. The effects of the reaction variables on the formation of pyruvic acid were studied.

Effects of the method of preparing iron orthophosphate catalyst on the structure and the catalytic activity

Abstract Catalytic activity of iron orthophosphate [FePO 4 ] was studied using oxidative dehydrogenation of lactic acid to pyruvic acid as a reaction probe. The structure and surface area are different depending on the differences in the source of starting materials as well as in the preparing methods. However, the specific activity, activity per unit surface area, is little affected with the variation in the structure. By the reduction and reoxidation, the catalytic activity clearly increases.

Catalysis and characterization of Pd/NaY for dimethyl carbonate synthesis from methyl nitrite and CO

A vapor phase synthesis of dimethyl carbonate (DMC) from carbon monoxide and methyl nitrite (MN) has been carried out over Pd/NaY catalysts at 383 K, DMC was produced in a good yield. The selectivity to DMC was >85% on the basis of consumed CO or MN. The by-products were dimethyl oxalate, CO2, N2O, methyl formate and dimethoxymethane. The catalytic properties of Pd/NaY were investigated as a function of Pd content and calcination temperature. It was found that 1 wt.% Pd/NaY calcined at 473 K in air was the optimum catalyst for the present DMC synthesis. The oxidation state and dispersion of Pd in the Pd/NaY catalysts were characterized by EXAFS and XPS. It was revealed that Pd(NH3)42+ in 1 wt.% Pd/NaY changed into Pd metal clusters during the catalytic reaction. Pd metal clusters/NaY showed a stable activity for the DMC synthesis even after 700 h. These results suggest that the cage structure of NaY and anchoring effects of protons suppress Pd metal sintering and stabilize very small Pd metal clusters (Pd13) in the zeolite cages during the reaction.

Effects of differences in the structures of iron phosphates on the catalytic action in the oxidative dehydrogenation of lactic acid to pyruvic acid

Abstract Oxidative dehydrogenation of lactic acid to pyruvic acid was performed at 230°C over iron phosphates, with a P/Fe atomic ratio of 1.2, consisting of different structures and oxidation states: these included FePO 4 , Fe 2 P 2 O 7 , Fe 3 (P 2 O 7 ) 2 , and a phase designated as Y-phase. The catalysts consisting of both Fe 2+ and Fe 3+ ions showed a higher activity than FePO 4 and Fe 2 P 2 O 7 . During use in the reaction for more than 24 h, FePO 4 was transformed to another unknown phase consisting of both Fe 2+ and Fe 3+ ions, which is designated here as M-phase. The best performances were obtained with the catalyst consisting of M-phase. The optimum oxygen feed rate to form the M-phase is in the range of 10 to 15 mmol/h, when the feed of lactic acid is 20 mmol/h. The M-phase was stable under the reaction conditions used and was not reoxidized by air even at 300°C.

Oxidative dehydrogenation of isobutyraldehyde to methacrolein over iron phosphate catalyst

The oxidative dehydrogenation of isobutyraldehyde was studied at 400°C in the presence of a large amount of steam using an iron phosphate with a P/Fe atomic ratio of 1.2 as the catalyst. The main products were methacrolein, CO, and CO2; methacrylic acid was not formed from isobutyraldehyde unlike the case of the reaction over heteropoly compound catalysts. Even in the absence of catalyst, large amounts of isobutyraldehyde were consumed, although the conversion of isobutyraldehyde increased as the contact time increased. With an oxygen/isobutyraldehyde molar ratio of 0.9, the yield of methacrolein reached 68 mol% with a conversion of 88% (nominal selectivity to methacrolein of 77 mol%). The true selectivity to methacrolein on the catalyst was estimated to be 90 mol%. It was found that the fresh catalyst consisting of only Fe3+ ions was reduced to iron(II) pyrophosphate via an unidentified intermediate phase during the reaction. The effects of oxygen and water on the catalytic behavior and the structures of catalyst were studied.

Ferromagnetic amorphouslike oxide films of the Fe2O3‐Bi2O3‐PbTiO3 system prepared by rf‐reactive sputtering

In this paper, the magnetic properties of ferromagnetic oxide films of the ternary Fe2O3‐Bi2O3‐PbTiO0 system prepared by rf‐reactive sputtering are presented. As‐sputtered films deposited at a substrate temperature below 400 °C are amorphous and behave paramagnetically. Amorphous films like these whose composition corresponds to the perovskite solid solution of BiFeO3 ‐PbTiO3 become crystalline with a perovskite structure on annealing in air, but no distinct spontaneous magnetization appears. On the contrary, in certain compositions in the Fe2O3 ‐Bi2O3 ‐PbTiO3 system, the samples retain a glassy (or amorphouslike) state even when the samples were annealed at around 600 °C. Also a spontaneous magnetization appears at room temperature. The maximum room‐temperature saturation magnetization 4πMs achieved in this system is 1.67 kG with the composition 0.74Fe2O3 ‐0.16Bi2O3 ‐0.10PbTiO3. Experiments imply that the amorphous state is essential for establishment of strong ferromagnetism in the sputtered oxide films...

Formation of methacrylic acid by oxidative dehydrogenation of isobutyric acid: Promoters of iron phosphate catalysts

Abstract Various foreign ions were added as promoters into iron phosphate catalysts and their effects on performance in oxidative dehydrogenation of isobutyric acid to methacrylic acid were studied. The best performance was obtained with Pb2+ promoters and the optimum P/Pb/Fe atomic ratio was found to be in the range of 1.2-1.3/0.15/1 to 1.3-1.4/0.3/1. Properties and catalytic performance of an iron-lead binary phosphate with a P/Pb/Fe atomic ratio of 1.4/0.3/1 were compared with those of an iron phosphate with a P/Fe atomic ratio of 1.2. It was concluded that the Pb2+ promoter which exists in the catalyst in the form of Pb2P2O7, plays a role in suppressing the consecutive oxidation of the produced methacrylic acid to COx. The effects of the Pb2+ promoter were also discussed on the basis of the data of X-ray diffraction spectra, surface area, acidic properties, and reducibility.

Polymerization and copolymerization of N-cyclododecylmaleimide

Abstract Homopolymerizations and copolymerizations of N-cyclododecylmaleimide (CDMI) were performed at 60°C in the presence of azobisisobutyronitrile (AIBN) as an initiator in tetrahydrofuran. The initial rate of polymerization was Rp = k[AIBN]0.50[CDMI]3.4, where k is the rate constant. Overall activation energy (E) and frequency factor (A) were 19.2 kcal mol−1 and 2.0 × 109 s−1, respectively. The monomer reactivity ratios in the copolymerization of CDMI (M1) with styrene (ST; M2) or methyl methacrylate (MMA; M2) and Alfrey-Price Q, e values were determined as: r1 = 0.10, r2 = 0.102, Q1 = 1.77, e1 = 1.34 in CDMI-ST system; r1 = 0.19, r2 = 1.31, Q1 = 0.91, e1 = 1.58 in CDMI-MMA system. The thermostabilities of the polymers and copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis.

Oxidative dehydrogenation of isobutyronitrile to methacrylonitrile over iron phosphate catalyst

Abstract The oxidative dehydrogenation of isobutyronitrile was studied using an iron phosphate with a P/Fe atomic ratio of 1.2 as the catalyst. The main products were methacrylonitrile, acetone, and carbon oxides with a small amount of cyanic acid. The selectivities to methacrylonitrile were about 70 mol-% at an isobutyronitrile conversion of around 85% in the presence water vapor. On the other hand, in the absence of water vapor, the selectivity reached 80 mol-% and a marked amount of carbon deposit was observed, though the activity was relatively stable. The activity of a fresh catalyst consisting of only Fe 3+ ions is low, but it increases with an increase in the time-on-stream up to about 10 h and then levels off with a further increase. It was also found that the selectivity to methacrylonitrile increases at the expense of a decrease in acetone, as the reaction temperature rises. The variations in the structures and valence states of iron ions due to the use in the reaction and their effects on the catalytic performances were also studied.

Effects of valence states of iron in iron phosphates on the catalytic activity in oxidative dehydrogenation of isobutyric acid

Oxidative dehydrogenation of isobutyric acid to methacrylic acid was studied over an iron phosphate catalyst with a P/Fe atomic ratio of 1.2. The freshly prepared catalyst consisting of Fe3+ is reduced with isobutyric acid to iron(II) pyrophosphate [Fe2P2O7] via a bluish black intermediate. Under the reaction conditions, the fresh catalyst is reduced gradually to the intermediate and the Fe2P2O7 is also reoxidized to the intermediate. However, both the catalytic activity and the selectivity were scarcely affected with a large variation in the valence states of iron in the bulk of iron phosphate. On the other hand, the studies on the reaction in the absence of oxygen revealed that the reaction is promoted by the redox cycle of iron phosphate.