Nanocarbons, defined as nanometer-sized carbon clusters including fullerenes, carbon nanotubes and nano-diamonds, are one of the most fascinating materials known today. Applications for electronics and optics require controlled size and/or structure of these materials, because the physical properties are well known to closely correlate with the structures. Therefore, separation methods of nanocarbons have been investigated, in particular practical processes applicable to large-scale separation. This review describes three novel and practical methods for separating fullerenes, carbon nanotubes and nanodiamonds, which have been developed in our group. In fullerene separation, a solution of fullerene mixture including C₆₀, C₇₀ and C_>70 was filtered through a thin layer of activated carbon to provide pure C₆₀ and C₇₀. Since this process is very useful, many patents were filed, and this technology was successfully transferred to a company. Circular single-walled carbon nanotubes were obtained in high purity by use of ultrasonic atomization. While this sonochemical process has been employed only for homogeneous systems such as concentration of aqueous ethanol, this is the first example to apply the sonoprocess to solid/liquid biphasic system. Separation of nanodiamond by centrifugation was effective to obtain single-digit nanometer size diamonds as small as 4 nm from nanodiamond powder with median size of 30 nm. This process was successfully applied to large-scale separation. Filtration, sonication and centrifugation are very fundamental experimental techniques which can be used for the separation of these three types of nanocarbons. Therefore, these processes are expected to be applied to the industrial scale production of nano-carbons, which should reduce cost and increase availability.

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A novel synthetic method to prepare a highly crystalline (VO)₂P₂O₇ catalyst by the intercalation-exfoliation- reduction of VOPO₄·2H₂O in alcohol is presented. Stepwise thermal treatment of layered VOPO₄·2H₂O in alcohols, such as 2-butanol, caused intercalation, followed by exfoliation of VOPO₄·2H₂O. Further thermal treatment of the exfoliated VOPO₄ sheets in the alcohol at the reflux temperature afforded crystallites of the precursor VOHPO₄·0.5H₂O, which were 1 μm in length and 150 nm in thickness and had leaf-like shapes. On the other hand, VOHPO₄·0.5H₂O crystallites prepared by the direct reduction of VOPO₄·2H₂O with 2-butanol were large, thick, well-developed platelets with a length of 5 μm and a thickness of 250 nm. The precursor synthesized by the intercalation-exfoliation-reduction process could be transformed into a highly crystalline (VO)₂P₂O₇ phase under the reaction conditions. The resulting catalyst showed high activity and selectivity in the oxidation of n-butane due to the high crystallinity of (VO)₂P₂O₇.
The intercalation-exfoliation-reduction of VOPO₄·2H₂O in a mixture of 2-butanol and ethanol gave much smaller and thinner crystallites of VOHPO₄·0.5H₂O with uniform sizes (ca. 300 nm long and 35 nm thick). The catalyst derived from this precursor exhibited remarkably high selectivity for maleic anhydride with a maximum selectivity of ∼84% in the oxidation of n-butane. These results show that the intercalation-exfoliation-reduction of VOPO₄·2H₂O is an effective method to synthesize a highly active and selective catalyst. In addition, we showed that the size of the crystallites of VOHPO₄·0.5H₂O is a key factor in controlling the catalytic performance, especially selectivity, in the oxidation of n-butane.

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Catalysts for nitrogen oxide (NO_x) storage and reduction oxidize nitrogen monoxide (NO) emitted from automotive lean-burn engines to nitrogen dioxide (NO₂) that is then stored on doped NO_x storage materials such as barium and/or potassium compounds as nitrate ions (NO₃⁻). In a reducing atmosphere provided by a suitable engine management system, the nitrates formed are subsequently reduced and decomposed into NO_x via reactions between reducing agents in the exhaust gas such as hydrogen, carbon monoxide and hydrocarbons. The emitted NO_x is finally reduced and detoxified to nitrogen. To meet stringent emission regulations for automotive exhaust pollutants, NO_x storage and reduction catalysts must have excellent NO_x removal activity and an extremely long lifetime. These catalysts can deteriorate not only due to thermal stress, but also to sulfur poisoning. Thermal stress causes a decrease in the number of active sites through sintering of precious metals, decreases the specific surface area of the support and leads to solid-phase reaction between the NO_x storage material and the support. Sulfur is present in exhaust gas derived from gasoline fuel and it competes with NO_x for storage and reacts with the doped NO_x storage material to form sulfates. Once NO_x storage materials are sulfated, they drastically lose their NO_x storage capability. This report reviews the technologies used to overcome these issues and to improve the durability of NO_x storage and reduction catalysts against both thermal damage and sulfur poisoning. An advanced novel catalyst system for NO_x removal with synergistic NO_x storage and reduction with ammonia (NH₃) formation, storage and NO_x selective reduction by NH₃ functions is also described.

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Continuous gas-lift is one of the most commonly practiced artificial lift techniques. It assists production enhancement by continuous injection of high-pressure gas into the well tubing, which lightens the oil column. Either gas limitation or compressor capacity makes it impossible to make all the network wells produce at the optimum rate; hence the need to determine the optimal gas distribution. Gas allocation optimization is a type of nonlinear function maximization with gas injection rates as decision variables subject to physical restrictions. Various optimization methods are applied in previous works among which genetic algorithm (GA) has proposed the best efficiency for large networks. In this work, various methods are performed as a comparison to GA. Besides, ant colony optimization (ACO) is applied to the network as a new optimization tool in oil industry, as a possible alternative for GA, already proved its capability in the optimization of water distribution networks. The literature demonstrated the application capability of GA and ACO for gas-lift allocation optimization in small networks. The results proved an availability of GA and ACO for this problem, and it showed the applicability to the optimization of large-scale networks. The results are compared to similar calculations in the literature by other optimization techniques, which show promising agreement.

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Durability of the Ru/CeO₂/γ-Al₂O₃ catalyst for steam reforming of dodecane was investigated using a packed bed type tubular reactor with multiple gas sampling ports along its length. The catalyst, before and after the durability test, was characterized by BET and measurement of carbon deposition. The Ru/CeO₂/γ-Al₂O₃ catalyst showed nearly complete conversion of dodecane to H₂ enriched gas and stable performance for as long as 5000 h of time-on-stream. The technique using multiple gas sampling port allowed evaluation of the decay of the catalyst performance. The catalyst started to deactivate from the inlet of the catalyst bed, where severe carbon deposition was observed. Assuming that the number of active catalyst sites was decreased by carbon deposition, kinetic analysis was performed to evaluate the decay of catalyst activity. Steam reforming of dodecane may proceed through the formation of active hydrocarbon species bound to the active catalyst sites. At lower temperatures, the activated hydrocarbons bound to the active sites become less reactive and tend to form deposited carbon. As temperature increases, the reaction between the active hydrocarbon species and steam proceeds predominantly over carbon formation.

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The detecting and locating principle of the distributed optical fiber pipeline leakage detecting and prewarning system is proposed in this paper. In allusion to gross error which often occurred in the locating process, the optical polarization model of oil and gas pipeline fiber warning system is established in this paper, which is based on the equivalent Jones matrix of the single-mode optical fiber birefringence. By emulating the model, the reason of the gross error is the discrepancy of two signals, which means that the signals acquired by the photodetectors from the same vibroseis are not correlative. According to the theoretical model, the solution of using external polarization controller to change the polarization direction is put forward. It is proved by the experiment that the solution can solve the problem preferably and improve locating accuracy. Furthermore, theoretical guidance of the system improvement and the adjustment in optical structure can be provided based on the theoretical model.

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From the standpoint of the environmental load, it is important to develop the hydrogen production system from methane produced by the fermentation of food waste or biomass. Compared with conventional catalysts such as pellet or raschig ring type catalysts, honeycomb catalyst is consider to be suitable for this process, especially for small-scale applications because it has the advantages such as high geometric surface area and the low pressure drop. We chose the cordierite substrate of Ni catalyst from several oxides, and applied it to steam reforming, partial oxidation and autothermal reforming by using model biogas. The temperature profiles of outlet gas concentration and CH₄ conversion was investigated in these reactions. CH₄ conversion did not reach the equilibrium conversion at the outlet temperature in steam reforming. This result suggests the reaction rate was low and the catalyst bed temperature was lower than that at the outlet, due to the endothermic nature of steam reforming and poor heat conduction of the honeycomb substrate. On the other hand, CH₄ conversion in partial oxidation and autothermal reforming, which are the exothermic reactions, exceeded apparently the equilibrium conversion calculated for the outlet temperature in the temperature range below 1000 K, indicating the catalyst bed temperature was higher than that at the catalyst outlet. Optimum ratio of steam/CH₄ (S/C) and O₂/CH₄ (O₂/C) were examined for autothermal reaction of CH₄, and it was found that the highest hydrogen concentration was attained at O₂/C = 0.5 and S/C≥2.

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Synthesis of di-t-butyl polysulfide from isobutene, hydrogen sulfide and sulfur was carried out at 125°C in an autoclave over MFI zeolite catalysts isomorphously framework-substituted with Al, Ga, and B. Performances of the catalysts were studied relative to liquid dicyclohexylamine catalyst. The catalysts were prepared from zeolite powders by kneading with alumina binder, extrusion, calcination, and ion exchange. Liquid products were analyzed with elemental analyzer, X-ray fluorescence spectrometry, HPLC, GPC and ¹H-NMR. The Al- and Ga-containing zeolite catalysts were found to be active for the synthesis of di-t-butyl polysulfide. Activities of these catalysts decreased via ion exchange with K⁺ ion. A higher polysulfide yield was obtained over the Ga-containing catalyst relative to the liquid amine catalyst. The number of bridging sulfurs in the polysulfide ranged from 1 to 9, whereas the average number of bridging sulfur ranged from 4.2 to 4.7 (target 5.0). The distribution of sulfurs in the polysulfide formed over either the zeolite catalyst or the liquid amine catalyst was almost identical. Based on these results, the reaction pathway was discussed. In the case of the catalyst containing B in its framework, products were octenes, thiol, monosulfide, and a very small amount of di-t-butyl polysulfide, while the feed sulfur was not consumed. From the results of NH₃ desorption, it is assumed that the strong acid site existing on the zeolite containing Al or Ga in its framework promotes the polysulfide synthesis reaction, whereas the zeolite containing B but having no such strong acid site is incapable of cleaving the elemental sulfur chain to form polysulfide.

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10 wt%Ru-Al₂O₃ catalysts with uniform pore sizes in the range of 3-7 nm were prepared by the alkoxide method by changing the added amount of H₂O highly diluted with butanol at the gelation stage of sol-gel preparation. The prepared catalysts were used to catalyze the Fischer-Tropsch (F-T) reaction in the slurry phase under reaction conditions of T = 503 K, P = 1 MPa, H₂/CO = 2/1, and W/F = 5-10 g-catal.h/mol. The Ru crystallite size evaluated by XRD line broadening increased with pore diameter. Stable activity in the F-T reaction was obtained for more than 40 h, probably because of the uniform structure of the catalysts. CO conversion and selectivity for higher hydrocarbons increased, and selectivity for CH₄ decreased with pore size of the catalysts. The effect can be explained in terms of diffusivity of the slurry solvent and/or the products in the uniform meso-pores, suggesting that the F-T reaction results depend more on the effect of the pore size of the catalysts than the Ru particle size.

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Bifunctional platinum (0.8 wt%) catalysts containing beta and USY zeolites were tested for the hydroisomerization of n-hexadecane. The Pt/Beta(SiO₂/Al₂O₃ = 40) catalyst with moderate acid strength showed better isomerization selectivity than the Pt/USY(SiO₂/Al₂O₃ = 11) catalyst which showed higher n-hexadecane conversion but higher hydrocracking activity due to their strong acid sites. The Pt/Beta(SiO₂/Al₂O₃ = 40) catalyst showed high isomerization selectivity and improvement in cold flow property even under more than 90% conversion of n-hexadecane.

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