Search

Electrochemical ammonia (NH3) production, an alternative to the energy-intensive Haber process, has been extensively studied based on the basis of N2 fixation; a high-yield production is hindered b... more...

The degradation of amorphous cobalt phosphides (CoPx) as an electrocatalyst for the hydrogen evolution reaction (HER) is studied in the discontinuous operation of alkaline water electrolysis cells (AWEs). Although amorphous CoPx shows a 100-fold enhancement in HER activity over nickel, the kinetic current for the HER is decreased after discontinuous operation. Under the off condition, the cathode potential of the AWE increases close to the equilibrium potential for CoPx oxidation to Co, Co(OH)2, CoOx, and CoPxOy. The irreversible oxide and hydroxide formation induces weaker interactions between Co and P, and thus the degradation of kinetics over CoPx, negatively affecting the HER even though a cathodic current is applied for recovery. A cathodic protection method is devised to mitigate the degradation of CoPx by shifting the electrode potential below the equilibrium potential of Co(OH)2. Mn is chosen as a sacrificial species, and it slows the rate of electrode degradation by negative polarization of the electrode. The results show that the co-deposition of even a small amount of Mn onto the CoPx electrode could limit the loss of HER activity during repeated discontinuous operation of the AWEs. Furthermore, in situ X-ray absorption near edge structure analysis confirms that the CoPx with co-deposited Mn does show the effect on holding the phase of CoPx during discontinuous operation. more...

Water electrolysis for hydrogen and oxygen production is a key technology in next-generation energy carrier and conversion. In particular, renewable energy sources integrated water electrolysis system has emerged due to its eco-friendly and highly energy efficient process. However, inherent limitations of renewable energy sources including intermittent and unpredictable energy production restrict stable water electrolysis cell operating. Therefore, investigation on cell performance depending on various operation conditions is absolutely required. Here, we synthesized Ni-Fe layered double hydroxide (Ni-Fe LDH) electrodes and studied their oxygen evolution reaction (OER) activities under various operational conditions matching actual environmental conditions when utilizing renewable energy sources. Changes in morphology and electrocatalytic performance were systematically studied by using XRD, FE-SEM, and EIS measurement. Our results showed that operation of water electrolysis cell in an accelerated stress condition could result in changes in morphology of crystal structure of LDH, thus restricting ions to be fully utilized at active site for OER. more...

An iron-based oxygen carrier can convert natural gas into chemicals (syngas or hydrogen) with controlled CO2 emission in a redox process. Mixed ionic-electronic conductor (MIEC)-supported iron oxides have shown high catalytic activity by facilitating inward O anion diffusion. However, their durability has been tested under limited conditions, and key factors affecting the degradation of MIEC-supported iron oxides have rarely been identified. In this work, we find that the inherent redox stability and electronic conductivity of the support material are decisive properties that determine the redox stability and activity of iron oxide/MIEC composites, such as perovskite-type La0.8Sr0.2FeO3−δ and fluorite-type Ce0.9Gd0.1O2−δ, over 100 redox cycles with the redox pair Fe – Fe2O3 at 900 °C. The low redox stability of the Fe2O3/La0.8Sr0.2FeO3−δ composite oxygen carrier is closely related to that of La0.8Sr0.2FeO3−δ and the extreme redox environment. The increased electronic conductivity of Ce0.9Gd0.1O2−δ under reducing conditions enhances the reaction rate. However, the low electronic conductivity of Ce0.9Gd0.1O2−δ under oxidizing conditions (5 × 10−4 S/cm at 750 °C) progressively promotes the formation of iron oxide product layer, resulting in low syngas selectivity (H2/CO > 2). This work helps design and select a compatible and commercially viable MIEC-supported iron oxide. more...

Reducing the iridium loading for the oxygen evolution reaction (OER) is one of the main challenges of polymer electrolyte membrane water electrolysis (PEMWE). This study introduces grape-like iridium nanoclusters supported on boron carbide (B4C) which increase iridium utilization compared to a non-supported iridium catalyst. A simple chemical reduction method with NaBH4 as a reducing agent was used to synthesize iridium nanoclusters on B4C. TEM images indicated that grape-like iridium nanoclusters were successfully dispersed on the B4C support. The catalytic performance of Ir/B4C was better than that of a commercial catalyst. To reach a current density of 10 mA/cm2, the overpotential of Ir/B4C was less than that of the commercial catalyst by 32 mV. Ir/B4C also has a mass activity 2.55 times higher than that of the commercial catalyst at 1.55 V. These improvements are attributed to the high electrochemical active surface area, the weak adsorption strength of oxygen, and the presence of Ir(OH)4 on the surface. The durability of Ir/B4C is comparable to that of the commercial catalyst at 1 mA/cm2 for 15 h and higher at 10 mA/cm2 for 3 h. B4C may weaken the oxidative dissolution of iridium by transferring electrons even though the high electrochemical surface area of iridium in Ir/B4C may reduce its durability. more...

The intermittent and volatile nature of renewable energy sources threatens the stable operation of power grids, necessitating dynamically operated energy storage. Power-to-gas technology is a promising method for managing electricity variations on a large gigawatt (GW) scale. The electrolyzer is a key component that can convert excess electricity into hydrogen with high flexibility. Recently, organic/inorganic composite separators have been widely used as diaphragm membranes, however, they are prone to increase ohmic resistance and gas crossover, which inhibit electrolyzer efficiency. Here, we show that the ceria nanoparticle and polysulfone composite separator exhibits a low area resistance of 0.16 &Omega, cm2 and a hydrogen permeability of 1.2 &times, 10&ndash, 12 mol cm&ndash, 1 s&ndash, 1 bar&ndash, 1 in 30 wt% potassium hydroxide (KOH) electrolyte, which outperformed the commercial separator, the Zirfon PERL separator. The cell using a 100 nm ceria nanoparticle/polysulfone separator and advanced catalysts has a remarkable capability of 1.84 V at 800 mA cm&minus, 2 at 30 wt% and 80 &deg, C. The decrease in the average pore size of 77 nm and high wettability (contact angle 75&deg, ) contributed to the reduced ohmic resistance and low gas crossover. These results demonstrate that the use of ceria nanoparticle-based separators can achieve high performance compared to commercial zirconia-based separators. more...

Ethylenethiourea (ETU) is one of the main metabolite of ethylenebisdithiocarbamate fungicides and potential exposure is highest for workers involved in rubber and fungicide production. Exposure of ETU induces endocrine disruption, teratogenesis, carcinogenicity, and goitrogenicity. ETU was administrated at concentration of 2 mg/kg/day for 58 weeks in C57BL/6 mice. After 58 weeks, blood samples were analyzed serum lipid profile, hepatic function dices, and plasma levels of creatine and blood urea nitrogen. Isolated kidneys were stained with haematoxylin-eosin. Analysis of miRNA expression profile was conducted on Affymetrix miRNA 4.0 Array. Chronic diet of ETU induced body weight loss, increased serum triglyceride and total cholesterol, increased plasma creatine and blood urea nitrogen, injured glomerulus and nephron tubule, induced severe hydronephrosis and polycystic kidney. ETU diet increased expression levels of the biomarker of renal injury and fibrosis in kidney. miR-17~92 cluster and miR-182-5p associated with cyst progression were increased in expression levels on the kidney. Chronic exposure to ETU at low concentrations results in functional and structural damage to the kidney, and increases cyst formation in the kidney. more...

The chemical looping strategy for hydrogen production (CLH2) offers a potentially viable option for efficient fuel conversion to hydrogen with the simultaneous capture of CO2. Typically, this process uses an iron-based composite as an oxygen carrier and syngas or methane as a fuel. The environmental and economic concerns motivate the use of abundant by-product iron oxide and the industrial off-gas for CLH2. Here we showed that H2 could be simply recovered from the industrial off-gas in a circulating fluidized bed with a mixture of the inexpensive raw material of by-product iron oxide and sand particle. The fluidization of the by-product iron oxide powder, which showed poor fluidization behavior, is improved by adding 60 vol% of sand particle. The industrial off-gas was completely converted to CO2 and H2O in a two-stage fluidized mode with a solid reactant of Fe2O3 of the binary particles, and then H2 was produced by oxidizing the reduced by-product iron oxide powder with steam. The binary particles showed consistent catalytic activity under multiple redox cycles by providing macropores with a size of ∼5 μm which facilitated gas diffusion. These findings provided valuable information for the future development of CLH2 based on by-products. more...

Alkaline water electrolysis (AWE) is a mature technology for producing hydrogen using variable renewable sources. AWE typically uses a concentrated electrolyte and a porous separator between the two electrodes to deliver ionic conductivity and to separate the released gases. The porous separator typically requires highly concentrated electrolytes (25~30 wt%) to provide high ionic conductivity. However, the circulation of the concentrated electrolyte in the electrolyzer block causes loss of Faraday efficiency and corrosion. Herein, we show that a cellulose nanocrystals (CNCs)-blended Zirconia/Polysulfone composite porous separator exhibits both low area resistance of 0.18 Ω cm2 and low hydrogen permeability of 4.7 × 10−12 mol bar−1 s−1 cm−1 at low electrolyte contents (10 wt% KOH solution). Meanwhile, a commercial Zirfon® separator exhibited poor performances of the high area resistance of 0.71 Ω cm2 and high hydrogen permeability of 305 × 10−12 mol bar−1 s−1 cm−1 under the same condition. The cell comprising the optimized composite separator displayed a remarkable capability of 1.83 V at 600 mA cm−2 with 10 wt% KOH solution for 300 h in a stable mode. Hydrophilic cellulose nanocrystals were successfully incorporated into the hydrophobic polymer network, resulting in lowering the area resistance and gas permeability of the separator. These results demonstrate that AWE equipped with (CNCs)-blended Zirconia/Polysulfone composite porous separators can achieve high performance using low concentration electrolytes, contributing to lifetime. more...

The main challenge for the anode electrocatalyst in a polymer electrolyte membrane water electrolyzer (PEMWE) is to maintain activity and stability simultaneously under the corrosive environment. We report a highly active and durable iridium electrocatalyst supported on boron carbide for the oxygen evolution reaction. The physical and electrochemical properties of the catalyst are controlled by changing the synthetic reduction temperature from 30 °C to 100 °C. The prepared Ir/B4C-100 °C catalyst shows two times higher mass activity than Ir/B4C-30 °C, even outperforming two commercial catalysts. The improved activity can be correlated to the high concentration of Ir (III) and OH species on the surface and the well-dispersed iridium nanoparticles on the support. Controlling the reduction temperature is also found to enhance iridium stability by developing the interactions between iridium and B4C. These metal-support interactions inhibit the oxidative dissolution of Ir (III) and the aggregation of iridium species. Ir/B4C-100 °C also shows better single cell performance than those of two commercial catalysts when tested in a PEMWE. The cell with the synthesized catalyst of Ir/B4C-100 °C shows a current density of 1.98 A/cm2 at 1.8 V, whereas those with two commercial catalysts exhibit values of 1.36 and 0.692 A/cm2 at 1.8 V, respectively. more...

With the growing concern about environmental issues including high CO2 emission, which is the main contributor to global warming resulting in climate change, CO2 utilization technologies have received much attention. Among diverse technologies, renewable methanol synthesis using H2 generated from the water electrolysis and the CO2 captured from various industrial processes as well as the atmosphere has received significant attention. In this context, the technical and economic feasibility analysis of renewable methanol synthesis was conducted in this study. Using a commercial process simulation program, Aspen HYSYS®, parametric studies were conducted to investigate the effects of diverse operating parameters, such as the reaction pressure, temperature, and H2/CO2 ratio, on the technical performance of this process. Under the optimum conditions of 100 bar and 493 K derived from thermodynamic studies, an economic analysis was performed to estimate the unit methanol production costs at different methanol production capacities using itemized cost estimation, sensitivity analysis, and predictive cost analysis. Predictive cost analysis was conducted to determine how the unit methanol production cost could be rendered reasonable compared to the existing one, which indicated that decreasing the renewable H2 production cost as well as increasing in the CO2 tax credit for a methanol production capacity of 100 ton per day would make the renewable methanol synthesis an economically feasible process. more...

Ni-Fe layered double hydroxide (LDH) is a potential OER electro-catalyst in water electrolysis due to its layered open structure, rapid diffusion of reactant, good anion exchange and excellent hydroxyl adsorption. Its OER activity has been well reported at constant applied voltage. However, the water electrolyser utilizes renewable energy due to which it suffers irregular power supply that consequently affects its electrode activity. Therefore, the development of a stable Ni-Fe LDH under dynamic operation conditions is required. Herein, we performed pH-controlled growth of NiFe LDH (1:1) on Fe substrate in nickel sulfate solution by oxygen sparging. The prepared LDH requires a low OER overpotential of ~270 mV vs. Hg/HgO at 200 mA/cm2 in 1M KOH solution. Considering the potentiodynamic polarization curve of Ni-Fe LDH, its OER region is above 0.5 V (vs. Hg/HgO) and shutdown region is below 0.3 V (vs. Hg/HgO). The voltage fluctuation between both regions may result in phase change and structural distortion. Therefore, three stability regimes are important to consider for an actual operational stability test; upper OER regime I (constant 0.75 V (vs. Hg/HgO)), one-minute lower to upper OER regime II (0.5 to 0.75 V (vs. Hg/HgO)) and one-minute on-off regime III (0.3 to 0.75 V (vs. Hg/HgO)). The electrochemical characterization before and after each 12 hours regime showed no degradation and steady kinetics (38 mV/dec). The morphological and surface analysis using SEM, XRD, TEM and XPS confirmed that the LDH structure remained preserve after each regime. Fig. 1: Operational stability test of Ni-Fe LDH prepared by pH-controlled growth under three regimes and embedded IR-corrected polarization curve after each regime. Figure 1 more...

We report the activation principle, the different forms of activated oxygen carriers, and the optimal activation method for iron-based oxygen carriers. The activation of an oxygen carrier is commonly referred to as the enhancement of the oxygen transfer capacity of an oxygen carrier by repeated reduction and oxidation reactions, which is mainly attributed to enhanced intraparticle ionic/gaseous diffusivity over the support material. Accurate knowledge of the activation process for an oxygen carrier is a key issue in the development of particles and optimization of a chemical looping system. In this study, we found that two key factors, the interaction between iron oxide and the support as well as the localized hematite-lower oxides stress, are fundamental reasons for the activation of iron-based oxygen carriers. The dispersion of the iron oxide in the activated particles was determined by the iron oxide–support interaction. The larger the localized stress applied at the interface between the hematite and ... more...

The three-reactor chemical-looping (TRCL) system for high purity hydrogen production and intrinsic CO2 separation is an innovative concept using a circulating oxygen carrier. The process employs iron oxide as an oxygen carrier, via which a redox reaction takes place alternately within three reactors, i.e. a fuel reactor (FR), where the natural gas is combusted to CO2 and H2O, a steam reactor (SR), where the steam is reduced to hydrogen, and an air reactor (AR), where the oxygen carrier returned to its original form by aeration. As it consists of three reactors (AR, FR, and SR) and a riser, the TRCL system has complicated hydrodynamic characteristics. In this study, a cold mode TRCL system with non-mechanical valve was designed and constructed to investigate the solid circulation characteristics. A series of hydrodynamic tests on the system was performed in which zirconia ( d ¯ ρ = 181 μ m , ρ s = 3850 kg/m3) was used as a bed material. The solid flow rate increased up to a maximum value with increasing gas velocity into the loop-seal. The gas leakages between AR and FR, and between FR and SR due to solid circulation were negligible. Furthermore, a two-dimensional (2D) computational fluid dynamics (CFD) simulation using a commercial CFD code was carried out in order to better understand the flow behavior of the gas solid mixture inside the TRCL system. more...

The BTL (biomass-to-liquid) process is an attractive process that produces liquid biofuels from biomass. The FT (Fisher–Tropsch) process is used to produce synfuels such as diesel and gasoline from gasified biomass. However, the H2S (hydrogen sulfide), COS (carbonyl sulfide) and CO2 (carbon dioxide) in the syngas that are produced from the biomass gasifiers cause a decrease of the conversion efficiency and deactivates the catalyst that is used in the FT process. To remove the acid gases, a pilot-scale methanol absorption tower producing diesel at a rate of 1 BPD (barrel per day) was developed, and the removal characteristics of the acid gases were determined. A total operation time of 500 h was achieved after several campaigns. The average syngas flow rate at the inlet of methanol absorption tower ranged from 300 to 800 L/min. The methanol absorption tower efficiently removed H2S from 30 ppmV to less than 1 ppmV and COS from 2 ppmV to less than 1 ppmV with a removal of CO2 from 20% to 5%. The outlet gas composition adhered to the guidelines for FT reactors. No remaining sulfurous components were found, and the tar component was analyzed in the spent methanol after long-term operations. more...

In this work, the decomposition of hydrogen iodide (HI) over platinum catalyst in a frame work of the development of a bench-scale Sulfur–Iodine (S–I) cycle is studied. The catalyst Pt/γ-alumina 1.0 wt% is prepared by impregnation–calcination method. The experiments of HI decomposition over the as-prepared catalyst are conducted at the temperature range of 350–550 °C and at the atmospheric pressure. The experimental data are then used to estimate new kinetic parameters for HI decomposition on the basis of Langmuir–Hinshelwood type where the surface reaction is considered as the rate-limiting step. The kinetics with the estimated parameters shows a reasonable agreement with the experimental data. It also reflects the fact that, HI conversion is significantly decreased with a small amount of iodine present in the feeding solution. Thereafter, the kinetic model is applied to the modeling of a HI decomposer for the hydrogen production rate of 1 Nm 3 /h in which hot helium gas is used to provide heat for the decomposition. Effects of heat-exchanger reactor configuration and composition of the feeding solution on the reactor size and the heat consumed are examined using the proposed model. Calculation results show that heat consumed for the co-current configuration is less than that for the counter-current configuration of the reactor. I 2 impurity and high water content in the feeding solution also result in an increase of reactor size and the heat required. more...

This work is investigated for the catalytic decomposition of hydrogen iodide (HI). Platinum was used as active material by loading on ZrO2-SiO2 mixed oxide in HI decomposition reaction. To obtain high and stable conversion of hydrogen iodide in severe condition, it was required to improve catalytic activity. For this reason, a method increasing dispersion of platinum was proposed in this study. In order to get high dispersion of platinum, zirconia was incorporated in silica by sol-gel synthesis. Incorporating zirconia influence increasing platinum dispersion and BET surface area as well as decreasing deactivation of catalysts. It should be able to stably product hydrogen for a long time because of inhibitive deactivation. HI decomposition reaction was carried out under the condition of 450℃ and 1 atm in a fixed bed reactor. Catalysts analysis methods such as N2 adsorption/desorption analysis, X-ray diffraction, X-ray fluorescence, ICP-AES and CO gas chemisorption were used to measurement of their physico-chemical properties. more...

The preliminary flowsheet of an electrodialysis cell (EDC) and membrane reactor (MR)-embedded SI cycle has been developed. The key components consisting of the preliminary flowsheet are as follows: a Bunsen reactor having a mutual separation function of sulfuric acid and hydriodic acid phases, a sulfuric acid refined column for the purification of the sulfuric acid solution, a HIx-refined column for the purification of the hydriodic acid solution, an isothermal drum coupled to a multi-stage distillation column to concentrate the sulfuric acid solution, a sulfuric acid vaporizer, a sulfuric acid decomposer, a sulfur trioxide decomposer, a sulfuric acid recombination reactor, a condensed sulfuric acid solution and sulfur dioxide/oxygen gas mixture separator, a precipitator to recover excess iodine dissolved in the hydriodic acid solution, an electrodialysis cell to break through the azeotrope of the HI/I2/H2O ternary solution, a multi-stage distillation column to generate highly concentrated hydriodic acid vapor as a top product of the column, a membrane reactor to decompose hydrogen iodide and preferentially separate the hydrogen, and a hydrogen scrubber. The material and energy balance of each component was established based on a computer code simulation using Aspen Plus™. The thermal efficiency of the EDC and MR-embedded SI process has also been evaluated and predicted as 39.4%. more...

The three-reactor chemical-looping (TRCL) process is a three-step water-splitting cycle for production of hydrogen with intrinsic CO2 separation. Iron oxide (Fe2O3), a metal oxide acting as an oxygen carrier, is a strong reducing agent for steam circulating through reactors in the TRCL process. In the present study, the reactivity of iron oxide (20 wt% Fe2O3/ZrO2) was determined in a batch reactor by exposing it to reducing and oxidizing conditions to simulate the TRCL process in a moving bed operation. The minimum steam fraction in the CH4/H2O mixture and the reduction rate were determined under a reducing atmosphere. The water conversion and the oxidation rate were obtained under oxidizing conditions. Based on the reactivity data, key parameters such as bed inventory and the solid circulation rate of the system according to the extent of the solid conversion were calculated. It is found that 170–220 kg/MWth and 300–1410 kg/MWth of oxygen carriers are needed in the fuel and steam reactor, respectively. The solid circulation rate through the reactors was calculated as 2–4 kg/s-MWth. The bed inventory showed a minimum value when the iron oxide was reduced to FeO0.5 by methane and then oxidized to FeO by steam. more...

A mathematical model for the moving bed is developed to simulate the fuel and steam reactor in the TRCL (Three-Reactor Chemical-Looping) process. An ideal plug flow of the solid and gas is assumed in modeling the fuel and steam reactor in the TRCL process. The model considered the mass, heat balances, equilibrium, physical properties, such as the heat capacity and viscosity, and kinetics. From this model, the temperature, gas conversion and solid conversion profiles can be predicted for fuel and steam reactors. The oxygen carrier inventory (the mass of the oxygen carrier) in the fuel and steam reactor was calculated with variation of the solid inlet temperature, solid conversion, Fe 2 O 3 content and steam feed rate. The temperature of the oxygen carrier to the reactor was the most sensitive parameter for determining the required inventory of the oxygen carrier. An increase in the solid inlet temperature was predicted to decrease the required inventory of the oxygen carrier. In the steam reactor, a solid inlet temperature increase over 1150 K will cause an increase in the inventory of the oxygen carrier due to the equilibrium conversion. An excessively low or high active material content will require a larger inventory of the oxygen carrier in the fuel reactor. In this study, approximately 20 wt.% of the Fe 2 O 3 content was suitable for reducing the inventory of the oxygen carrier while achieving a solid conversion of 0.9 in the fuel reactor. more...

The three-reactor chemical-looping process (TRCL) for the production of hydrogen from natural gas is quite attractive for both CO2 capture and hydrogen production. The TRCL process consists of a fuel reactor, a steam reactor and an air reactor. In the fuel reactor, natural gas is oxidized to CO2 and H2O by the lattice oxygen of the oxygen carrier. In the steam reactor, the steam is reduced to hydrogen through oxidation of the reduced oxygen carrier. In the air reactor, the oxygen carrier is fully oxidized by air. In this process, the oxygen carrier is recirculated among the three reactors, which avoids direct contact between fuel, steam and air. In this study, various candidate materials were proposed for the oxygen carrier and support, and a thermal analysis of the process was performed. The oxygen carrier for the process must have the ability to split water into hydrogen in its reduced state, which is a different chemical property from that of the chemical-looping combustion medium. The selection of the oxygen carrier and support require careful consideration of their physical and chemical properties. Fe2O3, WO3 and CeO2 were selected as oxygen carriers. Thermal analysis indicated an expected hydrogen production of 2.64 mol H2 per mol CH4 under thermoneutral process conditions. The results indicated that hydrogen production was affected mainly by the steam-conversion rate. The solid-circulation rate and temperature drop in the fuel reactor were calculated for the selected oxygen carriers with different metal oxide contents and solid-conversion rates. more...

CuFe 2 O 4 supported on ZrO 2 and CeO 2 for two-step methane reforming was evaluated to determine if it could enhance the reactivity, CO selectivity and thermal stability of CuFe 2 O 4 . Two-step methane reforming consists of a syngas production step and a water splitting step. CuFe 2 O 4 supported on ZrO 2 and CeO 2 was prepared using an aerial oxidation method. Non-isothermal methane reduction was carried out on TGA to compare the reactivity of CuFe 2 O 4 /ZrO 2 and CuFe 2 O 4 /CeO 2 . In addition, a syngas production step was performed at 900 °C and water splitting was conducted at 800 °C alternatively five times to compare the methane conversion, CO selectivity, cycle ability and hydrogen production by water splitting in a fixed bed reactor. If the 1st syngas production step results are excluded due to over-oxidation, CuFe 2 O 4 /ZrO 2 and CuFe 2 O 4 /CeO 2 showed approximately 74.0–82.8% and 60.3–87.5% methane conversion, respectively, and 44.0–47.8% and 65.2–81.5% CO selectivity, respectively. Using CeO 2 and ZrO 2 as supports effectively improved the reactivity and methane conversion compared to CuFe 2 O 4 . CuFe 2 O 4 /ZrO 2 showed high methane conversion due to the high phase stability and thermal stability of ZrO 2 but the selectivity was not improved. After 5 successive cycles, the CeFeO 3 phase was found on CuFe 2 O 4 /CeO 2 . Furthermore, methane conversion, CO selectivity and the amounts of hydrogen production of CuFe 2 O4/CeO 2 increased with increasing number of cycles. Additional test up to the 11th cycle on CuFe 2 O 4 /CeO 2 revealed that CeO 2 is a better support that ZnO 2 in terms of the reactivity and CO selectivity. more...

The reduction characteristics of CuFe2O4 and Fe3O4 by methane at 600–900 °C were determined in a thermogravimetric analyzer for the purpose of using CuFe2O4 as an oxidant of two-step thermochemical methane reforming. It was found that the addition of Cu to Fe3O4 largely affected the reduction kinetics and carbon formation in methane reduction. In the case of CuFe2O4, the reduction kinetics was found to be faster than that of Fe3O4. Furthermore, carbon deposition and carbide formation from methane decomposition were effectively inhibited. In case of Fe3O4, Fe metal formed from Fe3O4 decomposed methane catalytically, that lead to the formation of graphite and Fe3C phases. It is deduced that Cu in CuFe2O4 enhanced reduction kinetics, decreased reduction temperature and prevented carbide and graphite formation. Additionally, methane conversion and CO selectivity in the syngas production step with CuFe2O4 were in the range of 33.5–55.6% and 54.9–59.6%, respectively. more...

The Sulfur-Iodine process is in need of catalytic reactor for HI decomposition because the HI decomposition reaction rate is very slow. Nickel as an alternative catalyst for platinum was investigated in this study. Al 2 O 3 supported Ni catalysts were prepared by impregnation method. Ni amounts loaded over Al 2 O 3 were in the range of 0.1~20 wt. %. HI decompositions were carried out in the temperature range of 573 ~ 773 K using the fixed-bed quartz reactor. The difference of catalysts before and after the reaction was analyzed using BET, CO/H 2 chemisorption, XRD, XRF and SEM. It was confirmed by XRD and SEM-EDX analysis that Ni was converted to NiI 2 during the HI decomposition. Catalyst deactivation due to the formation of NiI 2 leads to a reduction of HI conversion. Although Ni of catalyst converted to NiI 2 , HI decomposition with low loading (up to 3 wt. %) catalyst showed a little decrease of HI conversion. However, with more than 5 wt. % catalyst, the initial HI conversion was considerably decreased. In the particular case of 20 wt. %, the initial conversion was increased close to 60 %, which is higher than 20 % as an equilibrium conversion at 723 K. These results showed that Ni had not only a catalytic function for HI decomposition, but also function as a sorbent to absorb I 2 produced from HI. more...

We synthesized a library of curcumin mimics with diverse alkylsulfonyl and substituted benzenesulfonyl modifications through a simple addition reaction of important intermediate, 1-(3-Amino-phenyl)-3-(4-hydroxy-3-methoxy-phenyl)-propenone (10), with various sulfonyl chloride reactants and then tested their vasodilatation effect on depolarization (50 mM K(+))- and endothelin-1 (ET-1)-induced basilar artery contraction. Generally, curcumin mimics with aromatic sulfonyl groups showed stronger vasodilation effect than alkyl sulfonylated curcumin mimics. Among the tested compounds, six curcumin mimics (11g, 11h, 11i, 11j, 11l, and 11s) in a depolarization-induced vasoconstriction and seven compounds (11g, 11h, 11i, 11j, 11l, 11p, and 11s) in an ET-1-induced vasoconstriction showed strong vasodilation effect. Based on their biological properties, synthetic curcumin mimics can act as dual antagonist scaffold of L-type Ca(2+) channel and endothelin A/B2 receptor in vascular smooth muscle cells. In particular, compounds 11g and 11s are promising novel drug candidates to treat hypertension related to the overexpression of L-type Ca(2+) channels and ET peptides/receptors-mediated cardiovascular diseases. more...