Enhancement of photocatalytic hydrogen production by liquid phase plasma irradiation on metal-loaded TiO₂/carbon nanofiber photocatalysts

Chung, Kyong-Hwan,Jeong, Sangmin,Kim, Byung-Joo,An, Kay-Hyeok,Park, Young-Kwon,Jung, Sang-Chul Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.24

<P><B>Abstract</B></P> <P>Enhanced hydrogen production by photocatalytic decomposition was assessed using liquid phase plasma over metal-loaded photocatalysts. Effects of irradiation of the liquid phase plasma were evaluated in the photocatalytic hydrogen production of hydrogen. Carbon nanofiber was introduced as photocatalytic support for the Ni-loaded TiO<SUB>2</SUB> photocatalyst. The influence of addition of organic reagents into water on hydrogen evolution was also evaluated. The photocatalytic decomposition by irradiation of the liquid phase plasma without photocatalyst produced some hydrogen evolution. The rate of hydrogen evolution was improved by the metal loading on the TiO<SUB>2</SUB> surface. The carbon nanofiber acted as a useful photocatalytic support for the fixation of TiO<SUB>2</SUB>. Hydrogen evolution was enhanced by the Ni loading on the TiO<SUB>2</SUB> nanocrystallites supported on the carbon nanofiber support. Hydrogen evolution was increased significantly by the addition of organic reagents, which acted as a type of sacrificial reagent promoting photocatalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen evolution was estimated from water photocatalysis by liquid phase plasma. </LI> <LI> Enhancement of hydrogen evolution was evaluated by liquid phase plasma irradiation. </LI> <LI> Carbon nanofiber was applied as a support for a fixation of TiO<SUB>2</SUB> nanocrystallites. </LI> <LI> Rate of hydrogen evolution was improved by the metal loading on the TiO<SUB>2</SUB> surface. </LI> <LI> Hydrogen evolution was increased significantly by adding of organic reagent into water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

국내 수소 생산, 소비 및 유통 현황

김봉진,김종욱,최상진 한국수소및신에너지학회 2005 한국수소 및 신에너지학회논문집 Vol.16 No.4

This paper deals with the survey of domestic hydrogen production, consumption, and distribution. The amount of domestic hydrogen production and consumption has not been identified, and we survey the amount of domestic hydrogen production and consumption by industries. The hydrogen production industries are classified into the oil industry, the petrochemical industry, the chemical industry, and the other industry. In 2004, the amount of domestic hydrogen production was 972,601 ton, which corresponded to 1.9% of the global hydrogen production. The oil industry produced 635,683 ton(65.4%), the petrochemical industry produced 241,970 ton(24.9%), the chemical industry produced 66,250 ton(6.8%), the other industry produced 28,698 ton(2.9%). The hydrogen consumptions of corresponding industries were close to the hydrogen productions of industries except that of the other industry. Most hydrogen was used as non-energy for raw materials and hydrogen additions to the process. Only 122,743 ton(12.6%) of domestic hydrogen was used as energy for heating boilers. In 2004, 47,948 ton of domestic hydrogen was distributed. The market shares of pipeline, tube trailers and cylinders were 84.4% and 15.6%, respectively. The purity of 31,848 ton(66.4%) of the distributed hydrogen was 99.99%, and 16,100 ton(33.6%) was greater than or equal to 99.999%. Besides domestic hydrogen, we also identify the byproduct gases which contain hydrogen. The iron industry produces COG(coke oven gas), BFG(blast furnace gas), and LDG(Lintz Donawitz converter gas) that contain hydrogen. In 2004, byproduct gases of the iron industry contained 355,000 ton of hydrogen.

Hydrogen Storage and Release Properties of Transition Metal-Added Magnesium Hydride Alloy Fabricated by Grinding in a Hydrogen Atmosphere

( Sung Nam Kwon ),( Hye Ryoung Park ),( Myoung Youp Song ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.7

90 wt% MgH2+5 wt% Ni+2.5 wt% Fe+2.5 wt% Ti (called MgH2+Ni+Fe+Ti), a hydrogen storage and release material, was fabricated by grinding in a hydrogen atmosphere, and then its quantities of stored and released hydrogen as a function of time were examined. A nanocrystalline MgH2+Ni+Fe+Ti specimen was made by grinding in a hydrogen atmosphere and subsequent hydrogen storage-release cycling. The crystallite size of Mg and the strain of the Mg crystallite after ten hydrogen storage-release cycles, which were obtained using the Williamson-Hall method, were 38.6 (±1.4) nm and 0.025 (±0.0081) %, respectively. The MgH2+Ni+Fe+Ti sample after the process of grinding in a hydrogen atmosphere was highly reactive with hydrogen. The sample exhibited an available storage capacity of hydrogen (the amount of hydrogen stored during 60 minutes) of about 5.7 wt%. At the first cycle, the MgH2+Ni+Fe+Ti sample stored hydrogen of 5.53 wt% in 5 minutes, 5.66 wt% in 10 minutes and 5.73 wt% in 60 minutes at 573 K and 12 bar of hydrogen. The MgH2+Ni+Fe+Ti after activation released hydrogen of 0.56 wt% in 5 minutes, 1.26 wt% in 10 minutes, 2.64 wt% in 20 minutes, 3.82 wt% in 30 minutes, and 5.03 wt% in 60 minutes. †(Received November 6, 2015; Accepted February 13, 2016)

Synthesis of a Mg-based alloy with a hydrogen-storage capacity of over 7 wt% by adding a polymer CMC via transformation-involving milling

Song, Myoung Youp,Choi, Eunho,Kwak, Young Jun Elsevier 2018 Materials research bulletin Vol.108 No.-

<P><B>Abstract</B></P> <P>Carboxymethylcellulose sodium salt (CMC) was added to magnesium via milling in hydrogen (transformation-involving milling), and samples with compositions of 95 wt% Mg + 5 wt% CMC (named Mg-5CMC) and 90 wt% Mg + 10 wt% CMC (Mg-10CMC) were prepared. At the cycle number (CN) of three, Mg-5CMC had a very high initial hydrogenation rate (1.45 wt% H/min) and a very large effective hydrogen-storage capacity of about 7.2 wt%. It is believed that the CMC melted during milling, and that because the melted CMC was highly viscous, sliding between the Mg particles and hardened steel balls was prevented, which led to effective milling (the generation of defects and cracks and the reduction of particle sizes). To the best of our knowledge, this study is the first in which a polymer CMC was added to Mg in order to improve the hydrogenation and dehydrogenation properties of Mg.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preparation of a polymer Carboxymethylcellulose (CMC)-added Mg alloy by milling in hydrogen. </LI> <LI> Hydrogen-storage capacity of about 7.2 wt% by activated Mg-5CMC at 593 K in hydrogen of 12 bar. </LI> <LI> A very high initial hydrogen uptake rate of 1.45 wt% H/min at 593 K in 12 bar hydrogen after activation. </LI> <LI> Addition of CMC is more effective than additions of halogen compounds, oxides, or metals. </LI> <LI> First study where CMC is added by milling in hydrogen to improve hydrogen-storage properties of Mg. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Computational Kinetic Studies of Pyruvate Metabolism in Carboxydothermus hydrogenoformans Z-2901 for Improved Hydrogen Production

Rajadurai Chinnasamy Perumal,Ashok Selvaraj,Saranya Ravichandran,Gopal Ramesh Kumar 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.3

Hydrogen is considered as a renewable energy source and it is also regarded as future fuel. Currently,hydrogen production through a biotechnological approach is a research priority. Hydrogenogens, a microbial species,are of significant interest to researchers because of their ability to produce biological hydrogen. Carboxydothermus hydrogenoformans Z-2901 is one among the hydrogenogens that can grow anaerobically by utilizing pyruvate as a carbon source, and can produce molecular hydrogen. In the present study, we performed an in silico kinetic simulation using the available Kyoto Encyclopedia of Genes and Genomes (KEGG) model and reconstructed pyruvate metabolism in C. hydrogenoformans Z-2901. During this metabolism, dissimilation of pyruvate leads to the formation of energy co-factors, such as ATP and NAD+/NADH, and the level of these co-factors influences the specific growth rate of organism and hydrogen production. Our strategy for improving hydrogen production involves maximizing the ATP and NAD+ yield by modification of kinetic properties and adding new reactions in pyruvate metabolism through metabolic pathway reconstruction. Moreover,the influence of phosphoenol pyruvate carboxylase and pyruvate dehydrogenase enzyme concentration on cofactor productions was also simulated. The theoretical molar yield of ATP and NAD+ were obtained as 2.32 and 1.83mM, respectively, from 1 mM/mg of phosphoenol pyruvate (PEP) utilization. A higher yield of ATP is achieved when the PEP level reaches 5 mM/mg. This work also suggests that PEP can be considered as an alternative substrate. In conclusion, the simulation results reported in this paper can be applied to design and evaluate strategies of strain construction for optimal hydrogen yield in C. hydrogenoformans. Hydrogen is considered as a renewable energy source and it is also regarded as future fuel. Currently,hydrogen production through a biotechnological approach is a research priority. Hydrogenogens, a microbial species,are of significant interest to researchers because of their ability to produce biological hydrogen. Carboxydothermus hydrogenoformans Z-2901 is one among the hydrogenogens that can grow anaerobically by utilizing pyruvate as a carbon source, and can produce molecular hydrogen. In the present study, we performed an in silico kinetic simulation using the available Kyoto Encyclopedia of Genes and Genomes (KEGG) model and reconstructed pyruvate metabolism in C. hydrogenoformans Z-2901. During this metabolism, dissimilation of pyruvate leads to the formation of energy co-factors, such as ATP and NAD+/NADH, and the level of these co-factors influences the specific growth rate of organism and hydrogen production. Our strategy for improving hydrogen production involves maximizing the ATP and NAD+ yield by modification of kinetic properties and adding new reactions in pyruvate metabolism through metabolic pathway reconstruction. Moreover,the influence of phosphoenol pyruvate carboxylase and pyruvate dehydrogenase enzyme concentration on cofactor productions was also simulated. The theoretical molar yield of ATP and NAD+ were obtained as 2.32 and 1.83mM, respectively, from 1 mM/mg of phosphoenol pyruvate (PEP) utilization. A higher yield of ATP is achieved when the PEP level reaches 5 mM/mg. This work also suggests that PEP can be considered as an alternative substrate. In conclusion, the simulation results reported in this paper can be applied to design and evaluate strategies of strain construction for optimal hydrogen yield in C. hydrogenoformans.

분사 압력에 따른 수소 제트의 형상과 LIBs를 적용한 국부 당량비 계측

이상욱,김정호,배충식 한국분무공학회 2022 한국액체미립화학회지 Vol.27 No.2

To implement carbon-neutrality in transportation sectors until 2050, hydrogen is considered a promising fuel for internal combustion engines because hydrogen does not contain carbon itself. Although hydrogen does not emit CO2 emission from its combustion process, the low energy density in a volume unit hinders the adoption of hydrogen. Therefore, the understanding of hydrogen jet behavior and measurement of equivalence ratio must be conducted to completely implement the high-pressure hydrogen direct injection. The main objective of this research is feasibility test of hydrogen local equivalence ratio measurement by laser-induced breakdown spectroscopy (LIBs). To visualize the macroscopic structure of hydrogen jet, high-speed schlieren imaging was conducted. Moreover, LIBs has been adopted to validate the feasibility of hydrogen local equivalence ratio measurement. The hydrogen injection pressure was varied from 4 MPa to 8 MPa and injected in a constant volume chamber where the ambient pressure was 0.5 MPa. The increased injection pressure extends the vertical penetration of hydrogen jet. Due to the higher momentum supply when the injection pressure is high, the hydrogen has easily diffused in all directions. As the laser trigger timing has delayed, the low hydrogen atomic emission was detected due to the longer mixture formation time. Based on equivalence ratio measurement results, LIBs could be applied as a methodology for hydrogen local equivalence ratio measurement.

Review of Hydrogen Gas Sensors for Future Hydrogen Mobility Infrastructure

Jun-Seo Lee,안진우,배수강,이승기 한국진공학회 2022 Applied Science and Convergence Technology Vol.31 No.4

The indiscriminate use of fossil fuels has adverse effects, such as environmental pollution and climate change. Therefore, there is growing interest in using hydrogen as an eco-friendly energy source. Among the diverse applications of hydrogen energy, hydrogen mobility has attracted considerable attention because it can compensate for the limitations of existing internal combustion engines and electricity-based mobility. To this end, relevant hydrogen-based infrastructure is being built in urban areas with rapid technological advancements. However, recent explosions of hydrogen charging stations in Norway and hydrogen storage tanks in South Korea have led to anxiety and the rejection of hydrogen application infrastructure. Therefore, to ensure the stability and safe operation of newly built infrastructure for hydrogen mobility in urban areas, an advanced system is required to improve existing technologies for hydrogen safety management. A hydrogen sensor is a front-line device for identifying initial hydrogen leaks and monitoring the status of hydrogen; thus, it is a building block for safety management systems. In this review, the operating principles and state-of-the-art hydrogen sensors are described by focusing on their suitability in hydrogen mobility applications based on the possibility of miniaturization and high hydrogen selectivity.

Development of a Hydrogen Uptake-Release Mg-Based Alloy by Adding a Polymer CMC (Carboxymethylcellulose, Sodium Salt) via Reaction-Accompanying Milling

Young Jun Kwak,Eunho Choi,Myoung Youp Song 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5

The addition of carboxymethylcellulose, sodium salt (CMC) might improve the hydrogen uptake and release properties ofMg since it has a relatively low melting point and the melting of CMC during milling in hydrogen (reaction-accompanyingmilling) may make the milled samples be in good states to absorb and release hydrogen rapidly and to have a large hydrogenstoragecapacity. Samples with compositions of 95 w/o Mg + 5 w/o CMC (named Mg–5CMC) and 90 w/o Mg + 10 w/o CMC(named Mg–10CMC) were prepared by adding CMC via reaction-accompanying milling. Activation of Mg–10CMC wascompleted after about 3 hydrogen uptake-release cycles. Mg–10CMC had a higher initial hydrogen uptake rate and a largeramount of hydrogen absorbed in 60 min, U (60 min), than Mg–5CMC before and after activation. At the cycle number ofthree (CN = 3), Mg–10CMC had a very high initial hydrogen uptake rate (1.56 w/o H/min) and a large U (60 min) (5.57 w/oH) at 593 K in hydrogen of 12 bar, showing that the activated Mg–10CMC has an effective hydrogen-storage capacity ofabout 5.6 w/o at 593 K in hydrogen of 12 bar at CN = 3. At CN = 2, Mg–10CMC released 1.00 w/o H in 2.5 min, 4.67 w/oH in 10 min, and 4.76 w/o H in 60 min at 648 K in hydrogen of 1.0 bar. The milling in hydrogen of Mg with CMC is believedto generate imperfections and cracks and reduce the particle size. The addition of 10 w/o CMC was more effective on theinitial hydrogen uptake rate and U (60 min) compared with the 10 w/o additions of NbF 5 , TaF 5 , Fe 2 O 3 , and MnO, and the10 w/o simultaneous addition of Ni, Fe, and Ti. To the best of our knowledge, this study is the fi rst in which a polymer CMCis added to Mg by reaction-accompanying milling to improve the hydrogen storage properties of Mg.

수소 전주기 경제성 분석 프로그램 개발

김수현,유영돈,박혜민 한국수소및신에너지학회 2022 한국수소 및 신에너지학회논문집 Vol.33 No.6

In this study, economic analysis program was developed for economic evaluation of hydrogen production, storage/delivery, and utilization technologies as well as overseas import of hydrogen. Economic analysis program can be used for the estimation of the levelized cost of hydrogen for hydrogen supply chain technologies. This program include five hydrogen production technology on steam methane reforming and water electrolysis, two hydrogen storage technologies (high compressed gas and liquid hydrogen storage), three hydrogen delivery technologies (compressed gas delivery using tube trailer, liquid hydrogen, and pipeline transportation) and six hydrogen utilization technologies on hydrogen refueling station and stationary fuel cell system. In the case of overseas import hydrogen, it was considered to be imported from five countries (Austraila, Chile, India, Morocco, and UAE), and the transportation methods was based on liquid hydrogen, ammonia, and liquid organic hydrogen carrier. Economic analysis program that was developed in this study can be expected to utilize for planning a detailed implementation methods and hydrogen supply strategies for the hydrogen economy road map of government.

Hydrogen Healing Center : A Case Study

Su-Geun Kim 한국물학회 2020 한국물학회지 Vol.8 No.1

Application of hydrogen has numerous positive effects such as selectively scavenging effect on free radicals, which act as an causal factor of many oxidative stress-related diseases. With this, disease-prevention and anti-aging effect through hydrogen intervention have been explored and proven. In addition to health care, hydrogen also shows excellent effect on skin beauty. In 2010, we opened Hydrogen Healing Center (HEALINGTOPIA Co.) in Sunae-dong, Bundang, Seongnam, Gyeonggi-do, and gave our services to more than 3,500 customers till date. The center was opened with the goal to promote and experience hydrogen-related healthcare products (BIOSUSONARA) through introducing HEALINGTOPIA Customer Care Programs as below: (1) Far-infrared Resonance Magnetic Hydrogen Spa (Heat, Magnetic field and Hydrogen treatment) (2) Hydrogen Respirator (Hydrogen gas inhalation) (3) Hydrogen美tox (directly spraying of hydrogen and hydrogen water on the skin) (4) Drinking hydrogen water (5) Hydrogen foot bath The management category of customers and the improved result are as shown in Table 1. The annual sales growth rate of the hydrogen-related products (BIOSUSONARA) are steadily increasing because of the increase of the customers who want to use the hydrogen-related products at home in their daily life. The purchase of the customers is based on the experience of hydrogen effect at the HEALINGTOPIA center. Also, there is continuous promotion of using hydrogen-related products because of the positive results from the satisfied customers, which act has an advertising impact to other people.