Unsupported and supported molybdenum nitrides are reviewed in the fields of preparation, structure, surface and catalytic properties. The molybdenum nitrides with large surface area were synthesized in a temperature-programmed reactions of MoO₃ with NH₃ or a N₂/H₂ mixture. Increased space velocities, reduced reactant particle sizes, and reduced heating rates led to molybdenum nitrides with greater surface area by formation of a MoO_xN_1-x intermediate. The structure and composition of the molybdenum nitrides and preferential adsorption of N₂, H₂, and CO are reported. Molybdenum nitrides are effective and active in ammonia synthesis and its decomposition, hydrogenolysis and hydrogenation of aromatics, especially in hydrodenitrogenation, in which molybdenum nitrides, as catalysts, were compatible with sulfided Ni-Mo and Co-Mo catalysts. The nitride catalysts were found significantly active for the direct removal of sulfur from dibenzothiophene, in the hydrodesulfurization of dibenzothiophene. The behavior of adsorbed N₂ and NH₃ on the Mo catalyst are discussed together with temperature-programmed desorption and reactions. The scheme for transformation of MoO₃ to Mo₂N via MoO₂ was investigated. Active sites on the molybdenum nitrides for HDN are also discussed.

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Initial homolytic reaction of zinc dialkyldithiophosphates, [(RO)₂PS₂]₂Zn (ZDTPs, R=iso-Pr and iso-Bu), with cumene hydroperoxide, in benzene solution, has been investigated by applying ³¹P NMR and mass spectrometry. It is confirmed that the reaction proceeds in two stages, i.e., a rapid oxidation of ZDTPs to 'basic' ZDTPs, [(RO)₂PS₂]₆Zn₄O, followed by a slower oxidation of basic ZDTP. Rate constants and Arrhenius parameters for these reactions are determined by analyzing the change in the ³¹P NMR spectra in temperature ranges of 0-34°C for ZDTPs and 30-60°C for basic ZDTPs. Concentration-time profiles for the reactions of ZDTP and basic ZDTP with cumene hydroperoxide, respectively, are calculated at 70°C, where the rate of decomposition of cumene hydroperoxide was previously determined in detail, by using kinetic parameters, which were obtained in this study. It is revealed that ZDTP itself disappears rapidly under this condition and that basic ZDTP formed by the rapid oxidation of ZDTP plays a major role in the initial homolytic decomposition of hydroperoxide. A large tetrahedral cluster molecule of basic ZDTP was detected for the first time in the reaction solution by high resolution mass spectrometric analysis. The molecular ion of basic ZDTP is split into several peaks according to the isotope ratios of the elements, which construct the basic ZDTP. The molecular ion of basic ZDTP is accompanied by several groups of smaller molecular ions, which isotope splitting is almost identical with that of the basic ZDTP. These smaller molecules have molecular weights of basic ZDTP minus 16n and, are assigned basic ZDTP analogous, [(RO)₂PS₂]_(6-n) [(RO)₂P(O)S]_nZn₄O by detailed analysis of the ³¹P NMR spectra. It is first clarified thus, that the progressive oxidation of basic ZDTP by hydroperoxide proceeds in such a way as to change the (RO)₂PS₂ ligand to (RO)₂P(O)S ligand. During this reaction, the tetrahedral zinc skeleton of the basic ZDTP is not apparently disrupted.

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Co-Mo/Al₂O₃ catalysts prepared by an impregnation method using NTA (nitrilotriacetic acid) as a chelating agent, were used to test the hydrodesulfurization (HDS) activity of benzothiophene and to observe the effect of XPS (X-ray photoelectron spectroscopy). The NTA-added catalysts showed ca. 20% higher HDS activity than that of conventional catalysts. The result of the activity test as a function of Co/Mo ratio suggested that the same highly active sites were formed when Co/Mo ratio (atom/atom) was less than ca. 0.3, and above 0.3 less active Co species was formed. It was also suggested that NTA contributed to the formation and to increasing the number of highly active sites. When the NTA-added catalysts were calcined before sulfidation, the increment of HDS activity was reduced by half. XPS measurements for catalyst precursors (before sulfidation) revealed that, when they were not calcined, the Co concentration at the surface of the catalysts prepared by the NTA method was higher than that of the conventionally prepared catalysts. Accordingly, it was suggested that NTA has a role of increasing Co surface density; thus, increasing the catalytic activity.

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The iron manufacturing industry has been required to reduce emission of carbon dioxide and exergy consumption for the protection of the global environment. For the purpose, to resolve this problem, partial replacement of coke by auxiliary fuels in the energy source of blast furnaces and the conversion of CO and CO₂ in the blast furnace stack-gas into methanol were investigated over 25.7Cu-60ZnO-14.3Al₂O₃(mol%) catalyst. The performance of a blast furnace fired with natural gas, coal water mixture (CWM), coal oil mixture (COM) and pulverized coal was predicted by a mathematical model, based on heat and mass balances. In the prediction, firing rate of auxiliary fuels was determined to keep the theoretical flame temperature unchanged in the raceway region of the blast furnace.
As a result, the auxiliary fuel firing led to hydrogen enriched and lean nitrogen concentration in the blast furnace stack-gas. In the methanol synthesis experiment, forty fold higher yield of methanol on the carbon basis was observed by increasing the H₂/(CO+CO₂) ratio in the reactant gas from 0.05 to 0.5, where 0.05 corresponds to the value for the conventional blast furnace. The methanol yield was also increased with decreased nitrogen. This implied that controlled firing auxiliary fuels into the blast furnace is advantageous from the view of subsequent methanol synthesis.
The greenhouse gas emission was reduced by the auxiliary fuel injection. The exergy consumption was also decreased by the injection of CWM, COM and pulverized coal. In particular, COM was the most effective for the reduction of GHG emission and exergy consumption, and for methanol synthesis from the blast furnace stack-gas. In the blast furnace operation where 384kg-coke/tHM and 100kg-COM/tHM were supplied, the total amount of GHG emission was reduced from 535 to 501kg-C/tHM and the sum of exergy consumption also decreased from 9.0 to 8.3GJ/tHM, when compared to that of the operation without COM injection.

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Experiments for simultaneous removals of SO₂ and NO were conducted in a laboratory-scale powder-particle Fluidized bed reactor of 0.053m inside diameter and 1.0m in length above the distributor in a temperature range of 573-873K. Fine powders, sorbent of SO₂, are continuously fed to the fluidized bed, in which coarse fluidized medium particles are fluidized. Iron oxide dust, a by-product of steel mills which contains considerable amounts of iron oxides, was used as sorbent of SO₂ to find a cheap sorbent for removal of SO_x. Two kinds of coarse particles of inactive silica sand and active WO₃/TiO₂ catalyst for removal of NO_x were used as particles for fluidized medium. Influences of various operating parameters, including reaction temperature, mole ratio of Fe/S, superficial gas velocity, static height of bed, concentration of SO₂ at inlet, concentration of NH₃ at inlet and kinds of particles for fluidized medium on removal of SO₂ were investigated. Furthermore, the effects of reaction temperature, concentration of NH₃ at inlet and kinds of particles for fluidized medium on removal of NO were also studied. Experimental results indicated that the iron oxide dust showed potential capacity as low-cost sorbent of SO₂ and weak catalytic activity for reduction of NO. A removal of SO₂ of 60% was achieved at temperature of 773K and mole ratio of Fe/S of 3, while a nearly 100% removal of NO was attained when NH₃/NO was equal to 1, with the use of catalyst for removal of NO_x as particle for fluidized medium.

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Isomerization of n-pentane to isopentane was studied on a series of ZSM-5-containing catalysts in hydrogen and nitrogen atmosphere. H-ZSM-5 alone exhibited dull n-pentane conversion and isopentane selectivity. Pt/H-ZSM-5 catalyst, which is a typical bifunctional catalyst for skeletal Isomerization of normal paraffins, exhibited vigorous activity, giving almost equilibrium conversion. Hybrid catalysts, prepared by physically mixing H-ZSM-5 and Pt/SiO₂, Pt/Al₂O₃, Pt/TiO₂ or Pd/SiO₂, exhibited lively activity and selectivity, comparable to those of Pt/H-ZSM-5, while H-ZSM-5, Pt/SiO₂ and Pt/Al₂O₃ showed dull catalytic performance for the reaction. Hybrid catalyst containing palladium exhibited catalytic performance comparable to those of Pt-hybrid catalyst. Palladium ion-exchanged ZSM-5 catalyst, however, did not. For the hybrid catalyzed reaction, the state of mixing of H-ZSM-5 and Pt/SiO₂ exhibited strong influences on the activity and isopentane selectivity. Other hybrid catalysts, which are composed of Pt/SiO₂ and USY or mordenite, also exhibited brisk isomerization reactivities. In the absence of hydrogen, however, the conversion of npentane was quite dull and the oligomerization reaction was dominant. These results suggest that spilt-over hydrogen plays an important role in alkane activation and the stabilization of intermediates (isomerized carbenium ion) to give high degree of isomerization selectivity.

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Solid-liquid equilibria of the four binary systems of quinoline-indole, isoquinoline-indole, 2-methylquinoline-indole, and 2-methylquinoline-isoquinoline were determined, using a visual observation method and differential scanning calorimetry in temperature range from 250 to 330K. Eutectic phase diagrams were confirmed for these four systems. In the three systems containing indole, it was found that addition compounds formed. For isoquinoline-indole and 2-methylquinoline-indole systems, stoichiometry rations of the first component to indole of the addition compounds were 1:1. From infrared spectroscopy analysis, a N-H…N type hydrogen bonding between isoquinoline and indole was confirmed. For quinoline-indole system, two types of addition compound were observed, of which stoichiometry rations of quinoline to indole were 1:1 and 2:1. From dissociation equilibrium relations and material balances, the equations for mole fractions of pure and addition compounds were derived, using dissociation constants as variables. Based on these equations, solid-liquid equilibria for the systems which form addition compounds were correlated.

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The gross heat of combustion and cetane number of diesel fuels have been predicted from the experimental values of refractive index; moreover, cetane number has also been predicted from the gross heat of combustion. These predicted values have agreed well with the experimental values. The effects of aromatic hydrocarbons (aromatics, single-ring aromatics, polynuclear aromatics) on such physical properties as density, refractive index, distillation temperature, kinematic viscosity, gross heat of combustion and cetane number of diesel fuels have been studied systematically. Density, refractive index, and distillation temperature (50% and 90%) increased with increasing mole fraction of polynuclear aromatics, but the gross heat of combustion and cetane number of diesel fuels decreased. The results showed that polynuclear aromatics affected the physical properties and cetane number of diesel fuels.

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To provide an insight into the relation between structural characteristics of petroleum heavy oils and their thermal cracking properties, structural analysis of three kinds of deasphalted oils (DAO) by chromatographic separation, followed by ¹H and ¹³C NMR and Curie-point pyrolysis of the oils and their fractions (S: saturates, A: aromatics, and P: polar compounds), was carried out. The oils employed were prepared from the vacuum residues of two Indonesian crudes (Minas and Duri) and an Arabian mixture (AL/AM) using pentane as solvent. The results of structural analysis suggested that aliphatic portion of Minas and Duri-DAO consisted mainly of straight paraffins, whereas a considerable portion of AL/AM-DAO consisted of naphthenic structures. The Curie-point pyrolysis at 670°C indicated that, irrespective of the oils, the amount of coke from their fractions decreased following the order P>A>S. It was also found that the coke formation from each P or A fraction could be suppressed by adding the saturate fraction, AL/AM-DAO-S, whereas in the case of using Minas- or Duri-DAO-S, no effect of the addition was observed. These results suggest a possibility that unique properties of AL/AM-DAO-S observed may be due to the presence of a considerable amount of active hydrogen in the naphthenic components.

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In order to investigate the change in the surface structure of sulfided Mo/Al₂O₃ induced by addition of Fe, Co, or Ni, Mo K-edge EXAFS, IR study of NO adsorbed on the catalyst, and NO uptake measurements by pulse method were used. The EXAFS measurements suggested that addition of Co did not affect MoS₂-like structure much, addition of Fe slightly prevented the formation of the MoS₂-like structure, and addition of Ni promoted but slightly. IR spectra were measured to examine the behavior of NO adsorbed on the promoter and Mo sites. This study revealed that NO adsorption on Mo sites was inhibited by the presence of every promoter examined. It was suggested that Fe atoms as well as Co or Ni atoms were able to occupy the edge positions of small MoS₂ crystals. NO uptake measurements showed that addition of Fe increased the coordinatively unsaturated sites on the catalyst surface more than that of Co or that of Ni. These results suggested that the degree of promoter dispersion, which utilized the edge positions of small MoS₂-like particles, decreased in the following order: Fe>Co>Ni. The addition of Fe was, however, not effective for promoting hydrodesulfurization as was reported in our previous paper.

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For the purpose to elucidate the adductibility of 2, 6-diethylnaphthalene (2, 6-DEN) and 2, 6-diisopropylnaphthalene (2, 6-DIPN) with thiourea, equilibrium constants for thiourea adduction of 2, 6-DEN and 2, 6-DIPN were measured at temperatures ranging from 0 to 30°C. Heats of the thiourea adduction and compositions of the relevant adducts were also obtained.
The equilibrium constants for the decomposition of thiourea adduct of 2, 6-DEN and 2, 6-DIPN were determined to be 1.56×10^-2-5.19×10^-2 and 1.36×10^-2-6.84× 10^-2, respectively. These equilibrium constants are greater than those for urea adduction of hexadecane and less than those for thiourea adduction of isoparaffins and naphthenes. This result suggests that the formation of the adducts of thiourea with 2, 6-DEN and 2, 6-DIPN proceeds advantageously in comparison with the reaction of thiourea with isoparaffins and naphthenes. The thiourea adduction of 2, 6-DEN and 2, 6-DIPN was exothermic and the heats of adduction were observed to be 28 and 37kJ•(mol•2, 6-dialkylnaphthalene)^-1, respectively. These values are considerably greater than those of thiourea adducts of isoparaffins and naphthenes, indicating that the stability of 2, 6-dialkylnaphthalene-thiourea adducts is greater than those of other thiourea adducts. Compositions of these adducts, molar ratios of thiourea to 2, 6-dialkylnaphthalene, were determined to be 5.9±0.1.

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