In the present work, a new hydrogen added argon heat treatment process that prevents the formation of hydrides and eliminates the dehydrogenation step, is developed. Dissolved hydrogen has a good effect on sintering properties such as oxidation resistance and density of greens. This process can also reduce costs and processing time. In the experiment, commercially available Ti-6Al-4V powders are used. The powders are annealed using tube furnace in an argon atmosphere at 700oC and 900oC for 120 min. Hydrogen was injected temporarily during argon annealing to dissolve hydrogen, and a dehydrogenation process was performed simultaneously under an argon-only atmosphere. Without hydride formation, hydrogen was dissolved in the Ti-6Al-4V powder by X-ray diffraction and gas analysis. Hydrogen is first solubilized on the beta phase and expanded the beta phases’ cell volume. TGA analysis was carried out to evaluate the oxidation resistance, and it is confirmed that hydrogen-dissolved Ti-6Al-4V powders improves oxidation resistance more than raw materials.

In this study, freeze drying of a porous Ni with unidirectionally aligned pore channels is accomplished by using a NiO powder and camphene. Camphene slurries with NiO content of 5 and 10 vol% are prepared by mixing them with a small amount of dispersant at 50℃. Freezing of a slurry is performed at -25℃ while the growth direction of the camphene is unidirectionally controlled. Pores are generated subsequently by sublimation of the camphene during drying in air for 48 h. The green bodies are hydrogen-reduced at 400℃ and then sintered at 800℃ and 900℃ for 1 h. X-ray diffraction analysis reveals that the NiO powder is completely converted to the Ni phase without any reaction phases. The sintered samples show large pores that align parallel pores in the camphene growth direction as well as small pores in the internal walls of large pores. The size of large and small pores decreases with increasing powder content from 5 to 10 vol%. The influence of powder content on the pore structure is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

In this study, porous Mo-5 wt% Cu with unidirectionally aligned pores is prepared by freeze drying of camphene slurry with MoO3-CuO powders. Unidirectional freezing of camphene slurry with dispersion stability is conducted at -25℃, and pores in the frozen specimens are generated by sublimation of the camphene crystals. The green bodies are hydrogen-reduced at 750℃ and sintered at 1000℃ for 1 h. X-ray diffraction analysis reveals that MoO3- CuO composite powders are completely converted to a Mo-and-Cu phase without any reaction phases by hydrogen reduction. The sintered bodies with the Mo-Cu phase show large and aligned parallel pores to the camphene growth direction as well as small pores in the internal walls of large pores. The pore size and porosity decrease with increasing composite powder content from 5 to 10 vol%. The change of pore characteristics is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

국내에서 오래 전부터 오미자와 칠해목은 약용식물로 이용해져 왔다. 오미자의 경우 생리활성 물질인 lignan을 통하여 여러가지 효능들이 연구를 통하여 알려졌으나, 칠해목의 경우 항염증과 관련된 연구가 진행되었을 뿐, 산화 스트레스와 관련된 연구는 미비한 실정이었다. 이에 본 연구에서는 오미자․칠해목의 추출혼합물을 이용하여, 과산화수소로 산화 스트레스가 유도된 SH-SY5Y 신경세포에서의 보호 효과를 알아보고자 하였다. 과산화수소의 처리 농도의 경우, 신경세포 독성 실험을 통하여 100 μM의 농도를 본 연구에 사용하였다. 또한, 오미자와 칠해목 추출물은 SH-SY5Y 신경세포에서 세포 독성이 없음을 실험을 통해 확인하였으며, 과산화수소를 이용한 신경세포 보호효과를 확인한 결과, 30% 에탄올 추출물 50 μg/mL의 농도에서 각각의 추출물에서 가장 높은 보호 효과를 확인할 수 있었다. 이에 오미자․칠해목 추출혼합물의 최적 효능 비율을 알아보기 위해서 각각의 추출물을 다양한 수율로써 6:4, 7:3, 8:2의 비율로 신경세포 보호 활성을 확인한 결과, 오미자와 칠해목 7:3의 비율과 50 μg/mL의 농도에서 가장 높은 신경세포 보호효과가 나왔으며, 이에 본 연구에서 오미자․칠해목 추출혼합물의 최적의 비율과 처리 농도로 사용하였다. Annexin V와 PI를 이용한 SH-SY5Y 신경 세포의 세포사멸을 확인해 본 결과에서도 오지마․칠해목 추출혼합물은 SH-SY5Y 신경세포의 세포사멸를 억제시키는 것을 확인할 수 있었다. 이에 본 연구에서는 오미자․칠해목 추출혼합물이 과산화수소로 유도된 산화적 스트레스에서 SH- SY5Y 신경세포에서 보호 효과가 있다는 것을 확인할 수 있었지만, 그에 대한 메카니즘에 대한 연구는 미비한 실정이다. 이에 차후 연구에서는 오미자․칠해목 추출혼합물의 산화 스트레스에 대한 정확한 기전을 파악하기 위하여 In vitro와 In-vivo에서의 후속적 연구가 필요하다고 사료된다.

We investigate the reduction of SnO2 and the generation of syngas(H2, CO) using methane(CH4) and hydrogen(H2) or a mixed gas of methane and hydrogen as a reducing gas. When methane is used as a reducing gas, carbon is formed by the decomposition of methane on the reduced Sn surface, and the amount of generated carbon increases as the amount and time of the supply of methane increases. However, when hydrogen is used as a reducing gas, carbon is not generated. High purity Sn of 99.8 % and a high recovery rate of Sn of 93 % are obtained under all conditions. The effects of reducing gas species and the gas mixing ratio on the purity and recovery of Sn are not significantly different, but hydrogen is somewhat more effective in increasing the purity and recovery rate of Sn than methane. When 1 mole of methane and 1 mole of hydrogen are mixed, a product gas with an H2/CO value of 2, which is known to be most useful as syngas, is obtained.

수소는 반도체, 수소화 반응, 연료전지 등 다양한 산업 공정에 사용될 뿐만 아니라 높은 에너지 밀도를 가져 미래의 에너지 원으로 각광 받는다. Water Gas Shift(WGS)와 같은 일반적인 수소제조 공정에서 수소 뿐만 아니라 일산화탄소, 이산화탄소 메탄과 같은 불순물들이 포함되며, 농축 및 정제의 필요성이 있다. Pd 수소분리막을 이용한 수소 분리공정은 수소만을 선택적으로 분리하여 99% 이상의 순도를 쉽게 얻을 수 있다. 본 연구에서는 상전이법을 통하여 중공사형 알루미나 지지체를 제조하고, 무전해 도금법을 이용하여 Pd를 코팅하였다. 무전해 도금법을 이용하여 제조한 분리막을 SEM, EDS, XRD 등의 분석을 통하여 특성을 파악하였으며, 온도 및 압력에 따른 수소 분리실험을 진행 하였다. 본 연구는 “교육부 기본연구(NRF-2017R1D1A1B03036250)”의 지원으로 수행되었습니다.

Perfluorinated sulfonic acid (PFSA) ionomers have been used as polymer electrolyte membrane (PEM) materials owing to their excellent chemical durability and proton conductivity. However, the PFSA ionomers are suffering from fast hydrogen crossover and, thereby, chemical degradation in the membrane state. To solve these issues is to make reinforced membranes by filling proton-conductive PFSA ionomers in the pores of chemically robust poly(tetrafluoroethylene) (PTFE) support films. However, it is very difficult to obtain PFSA-PTFE reinforced membranes with improved hydrogen barrier property. In this study, PFSA-PTFE reinforced membranes were fabricated by immersing commercial reinforced membrane in PFSA ionomer dispersions with different chemical architectures and particle sizes and their effects were systematically investigated.

본 총설은 분리막기술이 적용된 수소생산에 대한 개론으로, 특히, 암모니아를 수소운반체로 이용하는 수소생산에 대한 연구결과를 중점적으로 서술하였다. 암모니아를 수소운반체로 적용한 수소생산은 추가적인 탄소생성이 없다는 점 외에 여러 측면에 있어 이점이 있다. 많은 연구들이 고순도 수소 분리 및 생산을 위한 분리막 개발을 위해 진행되고 있으며, 이들 중 팔라듐을 기본으로 한 분리막(예를 들어, 다공성 세라믹 또는 다공성 금속 지지체와 팔라듐 합금의 얇은 선택층으로 이루어진 분리막)에 대한 연구가 활발하다. 반면에, 효율적인 암모니아 분해를 위해서는 주로 루테늄 촉매가 적용되고 있으며, 루테늄과 지지체 및 촉진제로 이루어진 루테늄에 기반을 둔 촉매에 대한 연구발표가 다수 존재한다. 수소생산을 위한 분리막 반응기 형태로는 충전층, 유동층, 그리고 마이크로반응기 등이 있으며, 이들의 최적화 및 원활한 물질전달 연구는 현재진행형 이다. 또한, 높은 암모니아 분해율, 고순도 수소생산 및 높은 수소생산율을 얻기 위해 분리막과 촉매의 다양한 조합에 대한 연구 및 분리막과 촉매의 역할을 동시에 구현할 수 있는 분리막에 대한 연구가 발표되고 있다.

A lab-scale biofilter with fungal growth has been studied to investigate the removal of gas-phase hydrogen sulfide. The biofilter inoculated initially with the aerobic activated sludge was operated for 100 days under acidic condition, and 0.36 L/d of the buffered nutrient with 0.05 g/L Chloramphenicol and Gentamicin was injected into the biofilter. The critical removal capacity of hydrogen sulfide was up to 22 g/m³/h. The pH of the effluent liquid was stable at pH 1.5-2, corresponding to the volatile suspended solids of 20-50 mg/L. In microbial analysis through the plate count method, it was found that fungi were dominant over bacteria. The fungi isolated from biomass in the bilfilter were identified as Acidomyces acidophilus and Aspergillus fumigatus. Sulfate and thiosulfate were also detected in liquid samples, as a result of the biological sulfur oxidation in the biofilter bed. For the analysis of sulfur mass balance, the accumulated mass of sulfate and thiosulfate reached up to 67.5% of inlet sulfur. Sulfur was also detected on the biomass collected from the biofilter through Scanning electron microscopy/Energy dispersive X-ray spectroscopy.

The hydrogen reduction behavior of MoO3-CuO powder mixture for the synthesis of homogeneous Mo-20 wt% Cu composite powder is investigated. The reduction behavior of ball-milled powder mixture is analyzed by XRD and temperature programmed reduction method at various heating rates in Ar-10% H2 atmosphere. The XRD analysis of the heat-treated powder at 300oC shows Cu, MoO3, and Cu2MoO5 phases. In contrast, the powder mixture heated at 400oC is composed of Cu and MoO2 phases. The hydrogen reduction kinetic is evaluated by the amount of peak shift with heating rates. The activation energies for the reduction, estimated by the slope of the Kissinger plot, are measured as 112.2 kJ/mol and 65.2 kJ/mol, depending on the reduction steps from CuO to Cu and from MoO3 to MoO2, respectively. The measured activation energy for the reduction of MoO3 is explained by the effect of pre-reduced Cu particles. The powder mixture, hydrogen-reduced at 700oC, shows the dispersion of nano-sized Cu agglomerates on the surface of Mo powders.

Hydrogen evolution on a steel surface and subsequent hydrogen diffusion into the steel matrix are evaluated using an electrochemical permeation test with no applied cathodic current on the hydrogen charging side. In particular, cyclic operation in the permeation test is also conducted to clarify the corrosion-induced hydrogen evolution behavior. In contrast to the conventional perception that the cathodic reduction reaction on the steel in neutral aqueous environments is an oxygen reduction reaction, this study demonstrates that atomic hydrogen may be generated on the steel surface by the corrosion reaction, even in a neutral environment. Although a much lower permeation current density and significant slower diffusion kinetics of hydrogen are observed compared to the results measured in acidic environments, they contribute to the increase in the embrittlement index. This study suggests that the research on hydrogen embrittlement in ultra-strong steels should be approached from the viewpoint of corrosion reactions on the steel surface and subsequent hydrogen evolution/diffusion behavior.

Acidic and basic mixtures of odorous compounds are commonly emitted from various sources, and, in an absorption process, pH conditions in the liquid phase significantly affect the performance. In this study, the effect of pH on mass transfer in a bubble column reactor was evaluated using hydrogen sulfide and ammonia as a model mixture. Their mass transfer coefficients were then calculated. Furthermore, the total mass transfer coefficients as a function of pH were evaluated, and the experimental data were fitted into an empirical equation using dimensionless numbers. The mass transfer rates of hydrogen sulfide, the non-ionic form, increased dramatically with increasing pHs, while those of ammonia were almost unchanged because of its high solubility. As a result, a favorable pH condition for less soluble compounds must be selected to achieve high absorption capacity. The total mass transfer rates, which took into account pH effects as well as all the non-ionic and ionic constituents together, were found to be from 2.2 to 2.4 × 10−3 min−1 for hydrogen sulfide and ammonia, respectively, and they were almost constant at different pHs. The empirical equations, which were derived to obtain the best fit for the total mass transfer rates, implied that a method to increase diffusivity of each compound should be applied to improve overall mass transfer. In addition, when using the empirical equation, a mass transfer coefficient at a given set of pH and operating conditions can be calculated and used to design a water scrubbing process.