Deactivation of a mixture of Rh/Al₂O₃ and CeO₂–ZrO₂ (CZ) by high-temperature ageing was clearly observed in three-way catalytic reactions under lean/rich perturbation conditions. The light-off temperature at which 50 % conversion was achieved was increased in the order of fresh < stoichi. ≈ rich < rich/lean < lean ageing conditions. Rh dispersion and presence of isolated Rh sites, revealed from in-situ FT-IR spectroscopy following CO adsorption, were responsible for the high light-off activity. NO conversion in higher temperature regions under lean/rich perturbation conditions was influenced by the ageing atmosphere. H₂-TPR measurements suggested the formation of Rh–CZ interactions with different strengths depending on the atmosphere during high-temperature ageing. The strength of the Rh–CZ interaction was suspected to be important to achieve high NO conversion in higher temperature regions.

Dimethyl ether (DME) steam reforming reaction is a sequential reaction of DME hydrolysis (catalyst: solid acid) followed by methanol steam reforming (catalyst: Cu-based catalyst). Combination of the catalysts can produce H₂ from DME and H₂O in one pass. DME hydrolysis proceeds slowly at low temperatures, so the catalyst for DME steam reforming must be operated at relatively high temperatures (300-400 °C). Since this temperature range is higher than that of the typical methanol steam reforming reaction (200-300 °C), a methanol steam reforming catalyst must be developed to operate at 300 °C or higher, with high activity and durability. This study focused on spinel-type oxide MgAl₂O₄, which has a high surface area and high durability, and found a new catalyst precursor, Mg_1–xCu_xAl₂O₄. Spinel-type oxide-supported Cu catalyst was synthesized by reducing the catalyst precursor with H₂. The synthesized Cu catalyst combined with γ-Al₂O₃, which is a solid acid catalyst, exhibited high DME steam reforming reaction activity. The optimum ratio of the Cu catalyst and γ-Al₂O₃ was in the range of 1 to 2 by weight. This catalyst can be regenerated by calcining in air.

Effects of arylimido ligands on the ring-opening metathesis polymerization (ROMP) of norbornene (NBE), norbornadiene (NBD), and tetracyclododecene (TCD) were investigated using a series of (arylimido)niobium(V)–alkylidene complex catalysts, Nb(CHSiMe₃)(NAr)[OC(CF₃)₃](PMe₃)₂ [Ar = 2,6-Me₂C₆H₃ (1), 2-MeC₆H₄ (2), 2,6-Cl₂C₆H₃ (3)]. The catalytic activity in ROMP of NBE for 1 was higher than for 2 and 3 (toluene at 25 °C, initial NBE concentration 0.44 mmol/mL), and the activity increased at 50 °C. Further increase in the activity (TOF 236 s^–1) was observed using 3 with addition of 1.0 equiv. of PMe₃, and activity was higher than that for the analogous vanadium(V)–alkylidene. These complexes (1-3) could also catalyze ROMP of NBD and TCD and the activities were higher than that for the ROMP of NBE. The dichlorophenylimido analogue (3) showed the highest activity for the ROMP of TCD, whereas 1 showed higher activity than 2 and 3 for the ROMP of NBD.

Nanostructured Cu/ZnO catalysts were prepared by a simple solid-state method, using cheap metal nitrates as raw materials. Special attention was paid to the influence of different chelating agents such as citric acid, formic acid and oxalic acid on the physicochemical properties of Cu/ZnO catalysts, which were characterized by detailed investigations. CuO crystallite size, oxygen vacancies and surface compositions were clearly affected by chelating agent types, leading to different CuO–ZnO interactions in the calcined catalysts as well as distinct reducibility. Different chelating agents also had significant effects on specific surface area, metallic Cu⁰ surface area, and Cu crystallite size, as well as ZnO (002) plane to ZnO (100) plane ratio (I₍₀₀₂₎/I₍₁₀₀₎) calculated based on the peak intensity of XRD patterns of the reduced samples, so influencing the catalytic activity for low-temperature methanol synthesis from syngas containing CO₂. The structure-activity correlations, particularly the relationships between space time yield (STY) of methanol with Cu⁰ surface area and I₍₀₀₂₎/I₍₁₀₀₎ ratio, were evaluated. Cu/ZnO catalyst prepared with oxalic acid showed the highest STY value, which was 2.3 and 5.3 times higher that of the catalysts obtained with citric acid and formic acid, respectively. The excellent catalytic performance was due to its greater Cu⁰ surface area, higher specific surface area and smaller Cu crystallite size. Stronger interactions between Cu and ZnO in the reduced samples were also favorable for enhancing catalytic activity for low-temperature methanol synthesis.

The computer technologies of machine learning and multiobjective optimization were introduced to develop the catalyst for fluid catalytic cracking (FCC). Response surface methodology was applied for a training set consisting of 1000 data points with varied catalyst compositions which consist of a variety of catalysts compositions, feedstock properties, pseudo-equilibrium conditions, cracking performance test conditions as input parameters and the cracking test results as outputs. At first, response surface model (RSM) was obtained with four approximation methods, among which the radial basis function (RBF) method was found to give the highest score accurate RSM with the smallest average error and the highest coefficient of determination among them. Then the virtual experiments were carried out with the RSM applied with multiobjective genetic algorithm (MOGA) to optimize the catalyst design considering the multiobjective; to yield less bottoms, less coke, more gasoline and less gas. After 5000 virtual experiments with RSM were carried out, we found that the pareto front was obtained. Finally, the optimum catalyst design was selected from the designs on the pareto front. As a result, the selected catalyst design showed 2.7 % higher gasoline yield and was confirmed to show the excellent performance over conventional FCC catalyst.

NiO and CeO₂ were prepared via flame spray pyrolysis. The specific surface area and total pore volume were 251 m² g^–1 and 2.3 cm³ g^–1 for NiO and 338 m² g^–1 and 3.3 cm³ g^–1 for CeO₂, respectively. The high porosity and surface area of the NiO allowed deposition of small CeO₂ particles (∼5 nm) by the impregnation of cerium acetate monohydrate. The particles were reduced using 5 % H₂ at 500 °C for 1 h which converted NiO to metallic Ni. During the reduction, the growth of Ni particles was hindered by CeO₂ particles. Consequently, the Ni size was relatively small (∼20 nm) despite the extremely high Ni content (80 wt%), as observed by scanning transmission electron microscopy. In contrast, incorporation of Ni using nickel acetate tetrahydrate into the CeO₂ support resulted in formation of inhomogeneous Ni particles (20-100 nm) after H₂ reduction. H₂ chemisorption measurement showed the surface area of Ni particles in the former catalyst was 13.7 m² g^–1, which was 2.4 times larger than that in the latter catalyst. The former catalyst exhibited remarkable performance for CO₂ methanation (47 % CO₂ conversion at 250 °C), 2 times higher than in the latter catalyst.

Iridium catalysts supported on anatase with high surface area showed excellent activities for the acceptor-less dehydrogenation synthesis of benzoxazoles from 2-aminophenol and primary alcohols. The catalytic activity greatly depended on the titania supports, iridium precursors, and loading of iridium species. Catalysts supported on anatase JRC (Japan Reference Catalyst)-TIO-10 showed the highest activity for the dehydrogenative reaction. Preparation of catalysts using [Ir(cod)Cl]₂ (cod = 1,5-cyclooctadiene) as an iridium precursor resulted in higher activity than using Ir(acac)₃ (acac = acetylacetonate). Various primary alcohols were reacted to give corresponding benzoxazoles in high to moderate yields. The catalyst could be recycled without significant loss of activity, and no leaching of iridium species occurred into the solution. The hot filtration test strongly suggested that the catalysis occurs on the catalyst surface. Highly dispersed iridium species of less than 2 nm in diameter, which could be reduced at low temperature, were responsible for the excellent activity.

Methods to catalytic conversion of glucose into lactic acid (LA), which is a versatile platform chemical, have been widely investigated. Herein, various kinds of metal oxide catalysts were used for lactic acid (LA) production from glucose under strong homogeneous base-free conditions. Among the metal oxides tested, Y₂O₃ afforded LA in moderate yield (33 %) together with trioses (dihydroxyacetone and glyceraldehyde) and fructose. It was found that the Y₂O₃/SiO₂ catalyst can effectively catalyze the transformation of glucose into LA. Compared to Y₂O₃, the LA yield was remarkably improved (45 %). The characterization results showed that Y(OH)₃ was highly dispersed on the Y₂O₃/SiO₂ catalyst, acting as a Brønsted base and promoting LA formation from pyruvaldehyde (PA). Brønsted acid sites (hydroxyl groups) located at the interface between Y(OH)₃ and SiO₂ promoted the dehydration of trioses to form PA. The acid and base sites on the Y₂O₃/SiO₂ catalyst functioned in concert to ensure that the overall reaction proceeded efficiently.

MFI-type zeolites and MWW-type zeolites containing Zn and/or Ga species were directly synthesized through the hydrothermal treatment of an amorphous gel containing Zn and/or Ga species with a high metal content in the absence of Al species. The metal-containing zeolites were applied to the aromatization of n-hexane to evaluate the catalytic performances. Ga-containing zeolites exhibited much higher catalytic activities than Zn-containing zeolites. The Ga-containing zeolites predominantly produced benzene through the dehydrocyclization of n-hexane among benzene, toluene, and xylenes (BTX), although cracked compounds were mainly produced. Higher crystallinity of the MFI zeolite containing both Zn and Ga species led to higher catalytic performances for both the dehydrocyclization and cracking. Furthermore, higher Ga content in the MFI zeolite containing both Zn and Ga species, which corresponds to lower Zn/Ga molar ratio, improved the catalytic activity for the aromatization of the cracked compounds to produce toluene and xylenes, whereas the selectivity for benzene was independent of the Ga content.

A good binary solvent for asphaltene was identified using Hansen solubility parameter (HSP) analysis, and aggregation behaviors were determined by small-angle X-ray scattering (SAXS) measurements. The pure solvents showed poor performance in dissolving asphaltene, whereas a mixed solvent system of 83 vol% benzyl benzoate and 17 vol% hexane dissolved up to ∼16 wt% asphaltene. SAXS profiles at 10,000 mg/L of asphaltene in the binary solvent showed disappearance of nanoaggregates. These findings will be useful when developing mechanisms for controlling asphaltene aggregation/disaggregation in the crude oil industry.