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This study has examined the suppression of ammonium bisulfate (NH4HSO4, ABS) formation by SO2 and the active site recovery of the catalyst deactivated by ABS as well as catalytic performance enhancement at low temperatures by simultaneously injecting liquid ammonium nitrate (NH4NO3, AN) in ammonia-selective catalytic reduction (NH3-SCR) of NOx over V2O5-Sb2O3/TiO2 (V-Sb/Ti) catalyst. The SCR reaction involving co-injection of NH3 and AN showed an improvement in catalytic performance of at least 40% at 250 °C; compared to injection of NH3 only, the simultaneous injection of NH3/AN significantly decreased catalytic deactivation by SO2, which causes a critical problem in low-temperature NH3-SCR. To study the effects of co-injection of NH3/AN in the NH3-SCR, catalytic properties of fresh, spent, and ABS deposited catalysts were analyzed using various methods such as FT-IR, XRD, XPS, and EDS. A comparative analysis between the reaction results and catalyst characterizations revealed that the co-injection of NH3/AN induces the effect of Fast-SCR, and its effect restores the active sites deactivated by ABS as well as suppresses ABS formation on the catalyst surface during the SCR reaction with SO2, thereby enhancing catalytic performance and reducing catalytic deactivation at low temperatures.

A mixture of saturated and unsaturated light hydrocarbon was used as feed gas for the production of aromatics. Natural gas liquids (NGL) from gas fields and hydrocarbon molecules obtained in the middle of conversion processes could be considered a kind of light hydrocarbon mixture. Therefore, for the conversion of the mixture into aromatics compounds, Zn-impregnated ZSM-5 catalysts were prepared and evaluated by employing different loading of Zn. In addition, the catalytic performance was tested and compared by charging physically mixed two different kinds of catalysts in the bed. The NH3-TPD result showed that the impregnation of Zn led to an increase in the number of medium-strength acid sites, whereas those of weak and strong acid sites were decreased. From the results of the catalytic activity tests, 0.5Zn/ZSM-5 showed the highest aromatics yield. As the amount of Zn loading was further increased to 1 wt.%, the yield of aromatics decreased. The test result in the case of the physically mixed catalysts showed a slightly lower yield in terms of total aromatics, but showed the highest BTX yield. To reveal the relative contribution of each hydrocarbon conversion to aromatics yield, each C2 compound was separately tested for aromatization over Zn/ZSM-5.

A nanosheet zeolite ITQ-2 formed by delamination of MCM-22 zeolite precursor was used and tested as a catalyst for the aromatization of acetylene. Along with MCM-22 (calcined form of MCM-22 zeolite precursor) zeolites, the resulting materials were successfully prepared and characterized in terms of pore structure and surface property. The performance of aromatization of ITQ-2 zeolites was comparable to that of MCM-22 zeolites. Due to the isolated and thin-layer structure, ITQ-2 zeolites had a significant fraction of external active sites. This feature seemed to result in relatively higher amount of C3–C8 aliphatic compounds rather than the C6–C8 aromatic compounds because of the shortened residence and, thus, reaction time. We first found that the cumulative C3–C8 aliphatic products in the case of ITQ-2 zeolites increased with the amounts of external surface area, while no clear relation was observed for the case of MCM-22 zeolites. Second, the initial selectivity towards aromatics was found to clearly show a linear relation with the concentration of Bronsted acid sites regardless of the used catalyst. In addition, the nanosheet ITQ-2 zeolites showed a much slower deactivation unlike the traditional microporous MCM-22 zeolites. Finally, to investigate the difference in the catalytic performance, we rebuilt the reaction pathways from acetylene to the aromatics and aliphatics.

A dielectric barrier discharge (DBD) plasma regeneration reaction was conducted at atmospheric pressure and temperature. This method was found to be very effective in removing carbon deposits after a non-oxidative aromatization from acetylene. When a fresh H-ZSM-5 catalyst was used for the aromatization, coke was by-produced and it could be ascribed to the primary reason for deactivation. By applying the DBD plasma to the deactivated catalyst bed at ambient temperature and pressure, the removal of carbon deposition with microdischarge and aeration was very effective; therefore, it is believed that additional thermal activation might not be necessary. More amount of coke was removed by supplying higher power to the catalyst bed. According to the results of XRD, physisorption, 27Al MAS NMR, and NH3-TPD analyses, it was confirmed that the structure and the acid site distribution of H-ZSM-5 were successfully retained even after the plasma treatment. Aromatization over the plasma-regenerated catalyst led to mild deactivation at the early stage and afforded comparable BTX selectivity to fresh H-ZSM-5 catalyst. Compared with the results obtained using the thermally regenerated catalyst, the structural stability was found to be higher and the BTX selectivity was kept higher during most of the reaction time for the plasma-regenerated catalyst.

The conventional zeolites and the hierarchical zeolites were employed to investigate the catalytic performance of aromatization from acetylene. In the case of the conventional MCM-22 zeolites, the effects of their Si/Al ratio on the catalytic performance were investigated by considering the conversion of acetylene, the selectivity of aromatics, and the formation of cokes. By swelling the interlayers in the MCM-22 precursor followed by pillaring the swollen spaces, hierarchical zeolites with layered nanosheets (i.e., MCM-36) were successfully prepared, characterized and tested for aromatization. With the novel hierarchical zeolite-based catalysts, the effects of structural difference as well as the Si/Al ratio were scrutinized. From the catalytic activity tests, the selectivity towards aromatic compounds through MCM-36 was significantly improved, and the amount of carbon deposition was decreased a lot, probably due to the increased number of external Bronsted acid sites. To draw such conclusion, several characterization techniques were also applied and the results were analyzed. The techniques included physisorption, XRD, FT-IR, TEM, SEM, EDX methods.

In this paper, we conducted an investigation into the use of bubbles modified with cationic surfactants in bubble coalescence inhibition and enhancement of methane-water volumetric mass transfer rate. Various cationic surfactants including hexyltrimethylammonium bromide (HTAB), octyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium bromide (DTAB), and hexadecyltrimethylammonium bromide (HDTAB) were added to aqueous solution and the methane-water volumetric mass transfer coefficient (k L a) values were determined for each of the solutions. Enhancement of methane-water k L a was observed from 14 h −1 to 69 h −1 , depending on the cationic surfactant type and concentration. Enhanced methane-water k L a in aqueous solution by addition of cationic surfactants was employed for the fermentation of methanotroph ( Methylosinus trichosporium OB3b), and cell growth rate and maximum optical density was increased by 391% and 498%, respectively.

Several different kinds of ordered mesoporous alumina (OMA)-supported and Ni-doped OMA-supported Ni catalysts have been prepared for catalytic partial oxidation of methane (CPOM) to produce hydrogen and CO gas mixture. The Ni metal was incorporated in various ways of the impregnation, the doping, and the partial doping followed by impregnation. The prepared OMA-supported catalysts showed a wormhole-like, pseudo-hexagonal structure. By incorporating Ni in the OMA matrix during synthesis of supports, the resulting catalysts showed better-distributed and less-sintered nanocrystals even after CPOM at elevated temperature for over 100 h. By employing the partial doping of Ni followed by impregnation of Ni, the prepared CPOM catalyst was found more productive due to the well-distributed and well-anchored Ni nanocrystals inside the OMA matrix and the confined ordered mesopores as well. Through the test under non-stoichiometric feed ratio, the catalyst prepared only by impregnation was found vulnerable to carbon deposition and deactivated more rapidly. Even worse, the formation rate of carbon deposition was so fast that the test could not be conducted due to the increased pressure difference. In contrast, the highly distributed Ni nanocrystals partially or fully utilizing doping were found to have stronger resistance to carbon deposition.

Ordered mesoporous silica (OMS) materials such as SBA-15, MSU-H, KIT-6, and MSU-F were utilized as catalyst supports for the catalytic partial oxidation of methane (CPOM) to produce syngas and hydrogen. The 2-D hexagonal ordered mesoporous structure was found to play a crucial role in evenly distributing Ni nanocrystals during the preparation. The OMS supports also helped maintain the position and size of the Ni nanocrystals even after partial oxidation at elevated temperatures. Various characterization techniques were utilized to assess the catalytic performance as well as to investigate the deactivation phenomena. The 2-D hexagonal and 3-D bicontinuous OMS-supported catalysts were found to have great resistance against carbon deposition. In addition, the 2-D hexagonal mesostructured catalysts showed greater resistance against sintering than other OMS-supported and the conventional refractory material-supported catalysts. Under oxygen deficient conditions in terms of stoichiometry, the OMS-supported Ni catalysts were shown to be less deactivated and more resistant against coke formation compared with Ni catalysts with conventional refractory materials.

The effect of alcohol on methane–water volumetric mass transfer coefficient (kLa) and solubility of methane was investigated in this study. Various alcohols including methanol, ethanol, 1-propanol, butanol, and pentanol were added to aqueous solution and enhancement of both methane–water kLa (from 72 h−1 to 471 h−1) and solubility (from 21.72 mg/L to 30.41 mg/L) was observed, depending on alcohol type and concentration. Among all alcohols, 1-propanol exhibited largest enhancement via bubble coalescence inhibition effect. Enhanced methane–water kLa and methane solubility in aqueous solution were employed for the fermentation of Methylosinus trichosporium OB3b, and cell growth rate and maximum optical density were increased by 700% and 730%, respectively, by addition of 1-propanol.

All-silica DDR (decadodecasil 3R, Si-DDR) zeolites with a pore size of 0.36 × 0.44 nm 2 are highly desirable for separating CO 2 (0.33 nm) from N 2 (0.364 nm) on the basis of the size difference. Despite their potential as CO 2 separators, the synthetic protocols that allow for the mono-dispersed DDR zeolite particles have not been systematically investigated. Here, we found that a seeded growth of irregular Si-DDR particles, obtained by non-seeded growth, resulted in mono-dispersed, diamond-like Si-DDR particles. Regardless of the origin of seeds, the size of the Si-DDR particles was decreased with increasing seed amount. Adsorption isotherms of CO 2 , N 2 , and H 2 O, the three main components in the flue gas from coal-fired power plants, in Si-DDR particles and the corresponding heats of adsorption (∼25–27, ∼15–22, and ∼32–40 kJ·mol −1 , respectively) were comparable and in good agreement with the literature data. The resulting CO 2 /N 2 ideal sorption and permeation selectivities were estimated to be ∼15.3–18.0 and ∼7.7–9.0 at 303 K, respectively, indicating that Si-DDR zeolites can serve as adsorbents and membranes for CO 2 /N 2 separations. In addition, we demonstrated that Al atoms could be incorporated into the DDR framework via seeded growth. The adsorption of H 2 O depends considerably on the concentration of defects (mainly OH groups) present in the Si-DDR framework and more strongly on Al species incorporated into the DDR framework.

Klebsiella pneumoniae is known to produce 2,3-butanediol (2,3-BDO), a valuable chemical. In K. pneumoniae, the 2,3-BDO operon (budBAC) is involved in the production of 2,3-BDO. To observe the physiological role of the 2,3-BDO operon in a mixed acid fermentation, we constructed a budBAC-deleted strain (SGSB109). The production of extracellular metabolites, CO2 emission, carbon distribution, and NADH/NAD(+) balance of SGSB109 were compared with the parent strain (SGSB100). When comparing the carbon distribution at 15 hr, four significant differences were observed: in 2,3-BDO biosynthesis, lactate and acetate production (lactate and acetate production increased 2.3-fold and 4.1-fold in SGSB109 compared to SGSB100), CO2 emission (higher in SGSB100), and carbon substrate uptake (higher in SGSB100). Previous studies on the inactivation of the 2,3-BDO operon were focused on the increase of 1,3-propanediol production. Few studies have been done observing the role of 2,3-BDO biosynthesis. This study provides a prime insight into the role of 2,3-BDO biosynthesis of K. pneumoniae.

Biomass-derived saccharides were used to form a support for Rh-based catalytic nanocrystals for synthesizing higher alcohols such as ethanol, propanol, and butanol from synthesis gas. Using hydrothermal synthesis with the saccharide and metal precursors in one pot, Rh-based nanocrystals encapsulated in carbon spheres were successfully manufactured at elevated temperature and pressure. These types of catalysts were found to show a significantly higher selectivity for C 3 and C 4 alcohols as well as C 2 oxygenates. Through comparative experiments, ordered mesoporous carbons were also found another good catalyst supports for higher alcohol synthesis. The size and morphology of carbon sphere supported Rh-based catalyst were examined by scanning electron microscopy, and each incorporated metal species was identified by elemental analysis. Transmission electron microscopy was used to investigate the size and size distribution of nanocrystals. More importantly, CO gas adsorption experiment with FT-IR spectrometer elucidated that the carbon supported Rh-based catalysts in this study were found to increase the amount of active intermediates adsorbed on the catalyst surface.

Methyl-functionalized mesoporous silica SBA-15, synthesized from tetraethyl-orthosilicate (TEOS) and methyltriethoxysilane (MTES), were employed as additives for the enhancement of volumetric mass transfer coefficient (kLa) of methane in aqueous solution. The surface functional group, highly ordered structure, and exceptionally high surface area exerted great influence on mass transfer rate of methane in aqueous solution. Especially, the fraction of surface functional groups controlled by adjusting the ratio of TEOS to MTES was found to be a crucial factor. Mesoporous characteristics of synthesized materials were investigated via BET surface area analysis, small angle X-ray diffraction, and FT-IR spectroscopy. At an optimal molar ratio (20:1) of TEOS and MTES, an 88% enhancement of kLa for methane in water was observed at 30 °C.

The maximum solubility of methane was determined in aqueous solution of Al 2 (SO 4 ) 3 , MgSO 4 , K 2 SO 4 , Na 2 SO 4 , AlCl 3 , MgCl 2 , KCl, NaCl, MgBr 2 , KBr, and NaBr with various concentration (1, 3 and 5 wt%) at ambient pressure. Salting-out effect was observed in all electrolyte solutions, exhibiting lower solubility of methane compared to that in pure water. In general, electrolyte solutions comprising cations/anions with high charge valency and small ionic radius exhibited stronger salting-out effect due to large charge density of the corresponding ions. Furthermore, anions exhibited larger influence on the degree of salting-out compared to cations. Scaled particle theory was employed to corroborate the trend of the experimental solubility of methane in electrolyte solutions.

In Fischer–Tropsch synthesis (FTS), cobalt carbide (Co2C) is not a catalytically active material, but rather an undesired cobalt phase associated with low catalytic performance. It is known that Co2C can be easily transformed back to metal cobalt in a H2 environment at 220 °C. The transformed metal cobalt (hcp phase) even shows higher catalytic activity in low-temperature FTS, compared with the reduced cobalt metal from the cobalt oxide species. In this study, to obtain Co2C with high catalytic activity in FTS, we determined the optimum conditions for effective metal cobalt carburization and Co2C hydrogenation by monitoring the phase transformation of cobalt using X-ray absorption spectroscopy (XAS) and temperature-programmed hydrogenation (TPH). We also verified that the transitions effectively occur under the same conditions as those for FTS (2.0 MPa, 220 °C). Based on the conditions determined for the transitions, the deactivated cobalt catalyst can be completely regenerated in the FT reactor by simply altering the injected gases from syngas to CO and then H2. Moreover, the regenerated catalyst shows enhanced catalytic performance compared with the fresh catalyst. The selective formation of hcp cobalt metal via carburization and hydrogenation of the spent catalyst was found to be the key for both the improved catalytic activity and the effective regeneration in situ. As a result, the formation of Co2C, which is mainly considered a nuisance, could provide valuable applications in investigations into catalyst activation and regeneration in FTS.

In order to increase 1,3-BD yield, ordered mesoporous materials (OMMs) was synthesized and used as supporting materials of heterogeneous catalysts for ethanol conversion into 1,3-BD. To make acidic and basic sites acting as active sites on the surface of catalysts, a moderate (5 wt%) amount of zinc oxide (ZnO) and zirconium oxide (ZrO2) were impregnated on as-prepared various supporting materials at a time. Prepared catalysts showed different acid-base properties according to used supporting materials. The ordered mesoporous silicas (OMSs) based catalysts were proven to exhibit higher ethanol conversions and 1,3-BD selectivities because they have not only adequate number and strength of acidic sites and basic sites but also very regular mesoporous structure. Especially ZnO-ZrO2/KIT-6 revealed a higher 1,3-BD selectivity above 54.0% at ethanol conversion of 82.5% at 400 °C. On the other hand, the selectivity of diethylether (DEE) was grown to over 68% in the case of ordered mesoporous alumina (OMA) based catalyst for example ZnO-ZrO2/OMA catalyst with a higher ethanol conversion above 80% at the same temperature. A similar type of catalyst with the ZnO-ZrO2/KIT-6, ZnO-ZrO2/a-SiO2 exhibited relatively low ethanol conversion and selectivity toward 1,3-BD. Through these results, it was confirmed that adequate number and strength of strong acidic and basic sites are key factors for full conversion of ethanol to 1,3-BD with well-developed ordered mesoporous structure.

Structurally well-defined ordered mesoporous carbon (OMC)-supported uniform and specifically size-controlled Rh nanoparticle (NP) catalysts with low Rh content were prepared by three different methods (polyol, organometallic, and sonochemical) for higher alcohol synthesis from syngas. During the reaction, the size-confined Rh NPs in OMC were uniformly sintered, and the size of the aggregated Rh NPs was within the optimum metal size range for syngas-to-alcohol (STA) reaction. The catalytic reactions and TEM analyses clearly show that the uniform Rh NPs with a specific size in the OMC supports increase the STA catalytic performance by enhancing the CO insertion and reducing methane formation. Moreover, additional chain growth reactions for the synthesis of C3 and C4 alcohols could be produced by the use of uniform Rh nanoparticles on OMC supports.

We investigate the effect of surface area of the lithium manganese spinel (LMO) cathode on the high-temperature storage performance of lithium-ion pouch cells. Using ~200 mAh design capacity, pouch cells were fabricated and their storage performance at high temperature was investigated according to changes in the LMO surface area. Cell performance and electrode analysis revealed that LMO with a large surface area exhibited a poor storage with a large decrease in capacitance and a more severe increase in resistance. This was mostly attributed to the change in surface morphology of anodes in each cell, indicative of the fast growth of a solid electrolyte interface film caused by high dissolution of Mn2+ ions in the high-surface-area LMO.

The merits of increasing the width of the catalytic bed in the channel-type Fischer–Tropsch synthesis reactor module were considered in the present study. Computational fluid dynamics (CFD) modeling was applied to evaluate the effect of different numbers of layers in the gas distributor on the distribution of inlet flows; the use of more than four layers could guarantee that the fraction of dead volume was less than 3%. To obviate the use of the distributor in the cooling channel and successfully dissipate the heat released in the highly exothermic Fischer–Tropsch synthesis, a cross-current flow pattern was considered. In addition, the CFD model including the kinetic reaction rate was validated by comparison of the experimental and simulated results. The cooling performance of the cross-current channel was found to be as good as that of the counter-current case. Further analysis also showed that even when the height of the catalytic bed was increased, the temperature of the bed was maintained below the allowable limit.

The functionality of ultrasound in early cancer detection is limited because of its relatively low contrast resolution. Because it has a high degree of echogenicity, a microbubble contrast agent is often used to overcome this intrinsic limitation of imaging at low-contrast resolution. A targeted and drug-loaded microbubble contrast agent for simultaneous diagnosis and therapy has recently been investigated. However, no optimized theragnosis ultrasound microbubbles have been developed. Paclitaxel (PTX)-encapsulating human serum albumin nanoparticles (PTX-HSA-NPs) were conjugated onto an ultrasound microbubbles (PTX-HSA-NPs-MBs) fabricated in the laboratory to result in a narrow size distribution (1.7 ± 0.7 μm) and an optimal resonance frequency of 3 MHz. After intravenous injection of HSA-NPs-MBs, echogenicity in the tumor xenografted with breast cancer MCF-7 cells was significantly enhanced, showing the possibility of early cancer diagnosis. Mice injected with PTX-HSA-NPs-MBs showed higher survival rates in comparison with control groups, demonstrating the possibility of theragnosis. In the present study, the conjugation of PTX-HSA-NPs onto the ultrasound microbubbles simultaneously provided (1) enhanced ultrasound signal generation, (2) sufficient drug-loading capacity, (3) ability to deliver drugs to a preferred tumor site, and (4) increased stability in blood circulation.

Hybrid supercapacitors (battery-supercapacitor hybrid devices, HSCs) deliver high energy within seconds (excellent rate capability) with stable cyclability. One of the key limitations in developing high-performance HSCs is imbalance in power capability between the sluggish Faradaic lithium-intercalation anode and rapid non-Faradaic capacitive cathode. To solve this problem, we synthesize Nb2O5@carbon core-shell nanocyrstals (Nb2O5@C NCs) as high-power anode materials with controlled crystalline phases (orthorhombic (T) and pseudohexagonal (TT)) via a facile one-pot synthesis method based on a water-in-oil microemulsion system. The synthesis of ideal T-Nb2O5 for fast Li(+) diffusion is simply achieved by controlling the microemulsion parameter (e.g., pH control). The T-Nb2O5@C NCs shows a reversible specific capacity of ∼180 mA h g(-1) at 0.05 A g(-1) (1.1-3.0 V vs Li/Li(+)) with rapid rate capability compared to that of TT-Nb2O5@C and carbon shell-free Nb2O5 NCs, mainly due to synergistic effects of (i) the structural merit of T-Nb2O5 and (ii) the conductive carbon shell for high electron mobility. The highest energy (∼63 W h kg(-1)) and power (16 528 W kg(-1) achieved at ∼5 W h kg(-1)) densities within the voltage range of 1.0-3.5 V of the HSC using T-Nb2O5@C anode and MSP-20 cathode are remarkable.

We compared four types of ZIF-8 with varying sizes and shapes to determine their thermal-structural stability and derive appropriate thermal activation conditions and correlation between structural characteristics and adsorption properties. Under air, the ZIF-8 phase for all the samples was converted completely into the zinc oxide phase above ∼300 °C, though thermalgravimetric analysis (TGA) indicated that the original structure was stable to ∼300–350 °C. Longer exposures (∼30 d) suggested that thermal activation at ∼200 °C was appropriate for the removal of guest and/or solvent molecules under air without structural damage. Despite no noticeable change in X-ray diffraction (XRD) patterns after activation at 250 °C under air, the resulting BET surface areas and CO2 adsorption amounts (at 1 bar and 30 °C) of ZIF-8s were reduced to ∼44–54 and ∼72–87%, respectively, as compared to those of appropriately activated ZIF-8s. It appears that after the activation at 250 °C under air, some Zn and N atoms were disso...

Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k L a). The feasibility of the new reactor was demonstrated by measuring k L a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k L a value of 102.9 h−1 was obtained.

In this study, we aimed to develop recombinant Saccharomyces cerevisiae with increased long-chain fatty acids by expressing essential genes involved in fatty acid synthesis elongation cycle. The relation of β-ketoacyl-ACP synthase II (fabF) from S. cerevisiae YPH500 and 3-oxoacyl-[acyl-carrier-protein] reductase (fabG), 3-hydroxyacyl-thioester dehydratase (FabZ), enoyl-ACP reductase (FabK), and acyl-ACP thioesterase (EC.3.1.2.14) from Streptococcus pyogenes MGAS 10270 regarding fatty acid production was investigated. These genes were separately cloned, and the effects of respective genes on fatty acid production were analyzed. Compared with the wild type S. cerevisiae, fabF recombinant (SGJY01) showed about 1.8-fold enhanced fatty acid production. We also exhibited thermal regulation in the fatty acid composition of SGJY01 changed at lower temperatures. The fabF recombinant and wild-type were cultured at different temperatures (30, 20, and 10°C), resulting the unsaturated fatty acids (C16:1 and C18:1) increased up to 2.4-fold as compared to the wild-type. Of particular interest is that the proportion of unsaturated fatty acids was increased approximately 11.8% at 10°C compared to 30°C, although the proportion in the wild-type remained unchanged.

Metal/ordered mesoporous aluminosilicates (OMAS) have received great attention as bifunctional Fischer–Tropsch (FT) catalysts that directly convert syngas into liquid fuels. However, both synthesis of OMAS with large pores and efficient pore confinement of metal nanoparticles still remain challenging. Here, we report a simple method to synthesize Ru nanoparticles confined in the nanochannels of OMAS (Ru@OMAS). This method eliminates laborious multi-processes that are typically required for pore confinement of metal nanoparticles. We prepare three types of Ru@OMAS with different Si/Al molar ratios (denoted as Si/Al-x, x = 10, 30, and 50) having the same large pore size (∼30 nm) and Ru NP loading (3 wt%). Changing the Si/Al ratio strongly affects the number/strength of acid sites and the metal–support interaction, thereby mediating the catalytic activity and product selectivity. With increasing Al content (decreasing Si/Al ratio), support's acidity and metal–support interactions increase, whereas the reducibility of Ru decreases significantly. As a consequence, among the Si/Al-x catalysts, the Si/Al-50 shows the highest selectivity (63.6%) for liquid fuels (C5–C20) and excellent FT activity (CO conversion of 47.8%) due to its mild acidity and relatively good reducibility.

An organic radical polymer (ORP) was prepared by radical polymerization and following oxidation into nitroxyl radical. Two different oxidation methods were employed and their radical concentrations were measured using electroparamagnetic resonance spectroscopy (EPR) and UV-visible absorption (UV-vis) spectroscopy. From these measurements, H2O2-Na2WO4 oxidation method exhibited a complete oxidation, which resulted in 97.6% spin concentration. Also, it was revealed that convenient and cheap UV-vis measurement was useful for preliminary radical concentration comparison. After applied as a cathode material in lithium ion batteries, ORP electrode showed a high initial capacity (110 mAh g), a good initial efficiency (96%), a very high rate performance (70% charging during 1.2 min) and stable cycle performance.

A series of core–shell cobalt oxide catalysts were prepared by tuning the pore diameter of mesoporous silica shell and the influence of pore dimensions on Fischer–Tropsch synthesis was studied. TEM images of core–shell 20Co3O4@MSN-x catalysts showed an increase in the silica shell porosity with increasing molar ratio of the swelling agent to tetraethyl orthosilicate used during catalyst preparation. As a result of this porosity increase, the dispersion of congregated core Co oxide particles within the shell increased, resulting in multiple core centers. Reference catalysts were synthesized using conventional supports, and the effects of pore dimensions on the activity and hydrocarbon selectivity of the reference and the prepared core–shell catalysts were compared. In the experiments performed, 20Co3O4@MSN-x catalysts showed an increase in their CO conversion and C5+ selectivity with increasing silica shell porosity. Moreover, the prepared core–shell catalysts demonstrated higher selectivity toward C5–C18 ...

A kinetic model for the synthesis of methanol over commercial catalysts was developed based on the adsorption of CO and CO2 onto various active sites of Cu, while the kinetic parameters were estimated by fitting 118 experimental sets of data under a variety of conditions. When both CO and CO2 hydrogenations take place, CO conversion was influenced by the change in temperature as well as in space velocity and pressure, while CO2 conversion was minimally influenced as a result of its correlation to the water–gas shift reaction. However, the CO and H2 fractions significantly influenced both conversions. The analysis based on the model developed in this investigation clearly confirmed that the contribution of each reaction and the maximum methanol concentration was expressed as a function of temperature and the CO fraction. Additionally, catalysts with varying particle sizes were used to evaluate the effect of the internal diffusion limitation on catalytic performance and the effectiveness factors were subsequently calculated and regressed with respect to the particle size.

In this study, kinetic models were developed for the mixed reforming and synthesis of methanol (MeOH). The effectiveness of the reforming model in our previous work was proven in an experimental study using a bench-scale reactor, while the intrinsic rate model and effectiveness factors were developed to represent the MeOH synthesis. For a 10-ton-per-day production of MeOH, the rate model was used to determine the size of a reforming reactor so that the supplied heat could be used exclusively to engage the reaction (not for the heat-up of the reactant), while the MeOH reactor was specified using the reported values. The process model was then used to evaluate various effects of the following factors on the MeOH production rate: (1) reaction temperature, (2) CO2 fraction in the feed, and (3) the recycle route of the unreacted gas either to the feed or to the MeOH reactor. Additionally, an analysis was conducted with respect to both the overall and local CO2 conversions in each reactor, and it was shown that a trade-off existed between the maximum MeOH production rate and the maximum CO2 utilization, regardless of the existence of a recycle stream.

Two process models for carbon dioxide utilized gas-to-liquids (GTL) process (CUGP) mainly producing light olefins and Fischer-Tropsch (F-T) synthetic oils were developed by Aspen Plus software. Both models are mainly composed of a reforming unit, an F-T synthesis unit and a recycle unit, while the main difference is the feeding point of fresh CO2. In the reforming unit, CO2 reforming and steam reforming of methane are combined together to produce syngas in flexible composition. Meanwhile, CO2 hydrogenation is conducted via reverse water gas shift on the Fe-based catalysts in the F-T synthesis unit to produce hydrocarbons. After F-T synthesis, the unreacted syngas is recycled to F-T synthesis and reforming units to enhance process efficiency. From the simulation results, it was found that the carbon efficiencies of both CUGP options were successfully improved, and total CO2 emissions were significantly reduced, compared with the conventional GTL processes. The process efficiency was sensitive to recycle ratio and more recycle seemed to be beneficial for improving process efficiency and reducing CO2 emission. However, the process efficiency was rather insensitive to split ratio (recycle to reforming unit/total recycle), and the optimum split ratio was determined to be zero.

A channel-type reactor for the cobalt-based Fischer–Tropsch synthesis reaction was considered and a commercial software package (COMSOL Multiphysics) was used to simulate the profiles of conversion and temperature in the reactor under a variety of conditions. The CO consumption rate was calculated using a lumped kinetic model, and kinetic parameters and the heat transfer coefficient between the reaction module and the atmosphere were estimated to reduce deviations from the experimental measurements. Comparison between simulation results and experimental data corroborated the validity of the developed model with errors lower than 7.00% and 0.15% for CO conversion and temperature in the catalytic bed, respectively. Further examination showed that the increased heat transfer rate in the channel-type reactor resulted in nearly isothermal operation in the catalytic bed, and the temperature was satisfactorily controlled even when the modules were numbered-up for high capacity. In addition, the effect of coolant flow-rate was evaluated to determine operating conditions in the case of numbering-up of reaction modules.

Two-dimensional hexagonally ordered mesoporous carbon nanoparticles (MCNs) were synthesized using the templating synthesis method. MCNs were introduced as supports for the catalytic thermochemical conversion of syngas to higher alcohols. The catalytic test of the promoted Rh/MCNs was performed using a fixed bed reactor. The catalytic results reveal that the nano-sized MCN-supported catalysts exhibited higher C2+ alcohol production with a high ethanol selectivity compared with the micro-sized ordered mesoporous carbon-supported catalysts. The promoted Rh/CMK-5-MCN with a hollow framework configuration exhibited a superior space–time yield of the total C2+ alcohols compared with the promoted Rh/CMK-3-MCN with a rod carbon framework. It indicates that the promoted Rh/MCNs exhibited different catalytic activities and selectivities of higher alcohols, which is attributed to the Rh particle size and the reactant accessibility to active sites through the morphological effects of the MCNs.

A dielectric barrier discharge (DBD) plasma reactor was employed for non-oxidative coupling of methane. The coupling reaction in the DBD plasma bed was conducted near atmospheric pressure and room temperature. In the bed, dielectric materials such as ordered mesoporous silica (KIT-6), sea sand silica, and α-Al2O3 were employed. This non-catalytic reaction system could successfully activate C H bond to produce methyl radicals and light hydrocarbons without additional thermal energy and oxidant molecules. The gap distance between dielectric particles was determined by their sizes, which was experimentally shown. The effects of gap distance were found significant on the conversion and the selectivity. The existence of maximum conversion at a specific gap distance was experimentally observed and could be described successfully by using a newly developed concept of micro-electrodes. Based on the concept, the minimum threshold electric potential difference between the dielectric particles could be successfully estimated, where the conversion was shown to be maximized. Furthermore, it seemed quite possible to control the compositions of ethane, ethylene, and acetylene by properly adjusting the size or the gap distance of particles.

A computational fluid dynamics (CFD) model for the Fischer–Tropsch synthesis (FTS) reaction was developed for a compact modular multichannel reactor with microchannel heat exchangers installed between catalytic bed channels. In addition to detailed levels of balance equations, the kinetic parameters for lumped FTS reaction rates and a convective heat transfer coefficient were estimated by fitting experimental data and the validity of model was corroborated by the comparison between experimental and simulated results. The model was used to evaluate the cooling performance of microchannel heat exchangers with varying flow rates, and several reactor specifications including the use of all catalytic bed channels, no inert materials, and reactors arranged in series were considered. When the number of catalytic bed channels was increased, the increase of CO conversion was observed with a maximum temperature within the operating range, but a possible thermal runaway could be expected due to high sensitivity to feed temperature change. In-series reactors also confirmed the increased conversion and the safe operation of the second reactor, and proved to be a major advantage for this reactor arrangement.

Hierarchical structure with macropores interconnecting mesopores of carbon material can remarkably improve the rate performance of electric double layer capacitor. However, pre-formed hard templates such as silica particles or polymer beads have been used in most synthetic procedures for them, resulting in an increase of manufacturing cost and time. Herein, we report novel method for synthesizing hierarchically structured macro/mesoporous partially graphitized carbon (MMPGC) for high power supercapacitor electrode material without pre-formed hard template. Instead of hard template, emulsion/block co-polymer co-template was used for generating macropores and mesopores, respectively. As a supercapacitor electrode material, MMPGC showed higher capacity retention at high current than ordered mesoporous carbon, which is characterized by cyclic voltammetry, galvanostatic charge–discharge. In addition, the effect of macropores and partially graphitized wall on reducing resistance of supercapacitor electrode was analyzed in detail with electrochemical impedance spectroscopy fitting method.

The low-temperature rapid transition of cobalt carbide to metal cobalt species in a H 2 environment was studied using in situ analyses, including temperature-programmed decarburization, in situ diffuse reflectance infrared Fourier-transform spectroscopy, X-ray absorption spectroscopy, and time-resolved gas chromatography profiles, during hydrogenation of cobalt carbide. Cobalt carbide was readily prepared by treatment of cobalt metal species in pure CO. By monitoring the evolution of cobalt carbide during hydrogenation, the analysis results give direct evidence for the formation of the cobalt metal hexagonal close packed (hcp) phase and light hydrocarbons (methane, ethane, and propane) as the products of hydrogenation of carbonaceous species on/in the cobalt carbide and clearly demonstrate that hydrogenation was completed at 220 °C in excess H 2 within 2 h. As a result of the low-temperature transition of cobalt carbide, before slurry-phase Fischer–Tropsch (FTS), an activated metal cobalt catalyst was easily obtained in situ by H 2 bubbling at 220 °C, in the slurry phase. Moreover, the cobalt metal hcp phase derived from cobalt carbide exhibited significantly improved catalytic performance in FTS compared with the cobalt metal face-centered cubic phase obtained by cobalt oxide catalyst reduction. These results not only broaden and deepen fundamental understanding of the hydrogenation of cobalt carbide but also provide a potential facile activation route for cobalt catalysts for the synthesis of clean hydrocarbon fuels from syngas.

The influence of carbon–silica hybrid supports on cobalt catalysts in Fischer–Tropsch synthesishas been investigated. Mesoporous carbon–silica hybrid supports were synthesized through a hydrogen-bonding-assisted self-assembly route by loading different amounts of silica (0 to 45 %) as a framework composition with mesoporous carbon. These carbon and hybrid supports were then impregnated with 15 wt. % cobalt and the resulting catalysts were characterized by various physicochemical, gravimetric, and spectroscopic methods. The dispersion of silica in the framework of mesoporous carbon modified the surface chemistry and enhanced the wetting properties of the support. Hence, the dispersion and reducibility of cobalt over the hybrid supports increased compared to those of the carbon-supported catalyst. However, above the optimum silica incorporation of 34 %, the possibility of phase separation and structural transformation of silica at the high carbonization temperature decreased the dispersion and reducibility of the supported Co catalysts. The carbon-supported catalyst showed a quick drop in the activity during the initial stages of the reaction due to the migration of cobalt particles over the hydrophobic and inert support surface. On the contrary, carbon–silica hybrid supports inhibited the mobility of cobalt particles and produced a higher density of active Co0 sites, leading to a higher initial activity. Carbon–silica-supported catalysts with a silica content of up to 34 % were found to exhibit excellent steady state Fischer–Tropsch synthesis activity and C5+ selectivity compared to only carbon and carbon–silica-supported catalyst with >34 % silica incorporation.

Saccharide was incorporated into Co/Al 2 O 3 by impregnating sucrose and a cobalt precursor on a phosphorus-treated γ-Al 2 O 3 support (P-Al 2 O 3 ), to control the catalyst size, shape, and reducibility. The effects of P-Al 2 O 3 on the relationship between C 5+ productivity, dispersion, and reducibility were investigated and compared with our previous work based on the high surface area γ-Al 2 O 3 . Powder X-ray diffraction results for Co/P-Al 2 O 3 revealed that the addition of P increased the average size of the cobalt oxide crystals due to weakened interactions between the metal and the support, which led to the increased reducibility while compromising the dispersion. The extraordinarily enhanced hydrothermal stability of the catalysts was corroborated with the help of FT-IR analysis. Activity tests were conducted in a fixed-bed reactor as well as in a slurry phase reactor charged with Co/P-Al 2 O 3 catalysts to investigate the reactor behavior. The addition of a saccharide, such as sucrose, efficiently increased the dispersion capability and regulated crystal shape to overcome the lowered dispersion caused by phosphorus treatment. The effect of sucrose on crystal size and shape of Co/P-Al 2 O 3 was verified through TEM imaging and XRD analysis. The control of crystal size and shape was found to be crucial to attain maximum productivity, in addition to dispersion and reducibility.

Co3O4 nanoparticles (NPs) with a narrow particle size distribution were fabricated via a facile and novel method using mesoporous carbon materials (CMK-3, MSU-F-C) as sacrificial templates. The particle size distribution of the Co3O4 NPs varied depending on the pore size of the templates. Synthesis of the NPs with concurrent complete removal of the templates was achieved at 593 K, which is lower than the temperatures utilized in previous reports. It was verified that the carbon template was decomposed by catalytic oxidation with cobalt and NOx species generated by thermal decomposition of the cobalt nitrate precursor in air. The prepared NPs, and particularly the Co3O4 NPs synthesized from CMK-3, acted as excellent catalysts for the Fischer–Tropsch synthesis (FTS). The high catalytic performance was associated with the optimum particle size (6–10 nm) of the nanoparticles for FTS and enhanced reducibility.