• Journal of Hydrogen and New Energy
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• v.25 no.6
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• pp.586-593
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• 2014

Limited sources of fossil fuels and also global climate changes caused by $CO_2$ emissions are currently discussed around the world. As a renewable, carbon neutral and widely available energy source, biogas is regarded as a promising alternative to fossil fuels. In this study, a plasma dump reformer was proposed to produce $H_2$-rich synthesis gas by a model biogas. The three-phase gliding arc plasma and dump combustor were combined. Screening studies were carried out with the parameter of a dump injector flow rate, water feeding flow rate, air ratio, biogas component ratio and input power. As the results, methane conversion rate, carbon dioxide conversion rate, hydrogen selectivity, carbon monoxide yield at the optimum conditions were achieved to 98%, 69%, 42%, 24.7%, respectively.

• Journal of Sensor Science and Technology
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• v.27 no.2
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• pp.132-136
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• 2018

We report the development of a room-temperature hydrogen ($H_2$) gas sensor based on carbon nanotubes (CNT) yarn. To detect $H_2$ gas in room temperature, a highly ordered CNT yarn was placed on a substrate from a spin-capable CNT forest, followed by the deposition of a platinum (Pt) layer on surface of the CNT yarn. To examine the effect of the Pt-layer on the response of the CNT sensor, a comparative sensing performance was characterized on both the Pt deposited and non-deposited CNT yarn at room temperature. The Pt-CNT yarn yielded high response, whereas the non-deposited CNT yarn showed negligible response for $H_2$ detection at room temperature. Pt is a reliable and efficient catalyst that can substantially improve the detection of $H_2$ gas by chemical sensitization via a "spillover" effect. It can be efficiently utilized to increase the sensitivity and selectivity as well as to obtain fast response and recovery times.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.462-466
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• 2009

We investigated the pore properties of inorganic membranes applied for hydrogen separation industry. Inorganic membranes were derived from polysilazanes. The thermal reactions involved were studied using thermogravimetry(TG) and IR spectroscopy(FTIR) of the solids. To determine the thermal effect of pore properties, polysilazanes were pyrolysed in inert atmosphere. Pore volume and BET surface area showed the maximum value at a pyrolysis temperature of $500^{\circ}C$. For amorphous SiCN membrane derived from polysilazanes, selectivity of $H_2/N_2$ was 4.81 at $600^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.26 no.2
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• pp.14-20
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• 2022

In this study, the catalytic reaction characteristics for producing hydrogen using methanol steam reforming were investigated. Nickel and copper are frequently used in steam reforming reaction and methanol synthesis, were used as main active metals. As a support, hydrotalcite has a high specific surface area, excellent porosity and thermal stability, and has weak Lewis acid sites and basic properties. Hydrotalcite was used to identify catalysts of methanol steam reforming with catalytic activity and their properties. In this research, high reactivity was shown in the catalyst of copper metal with high reducibility. And increasing of active metal loading showed the higher the methanol conversion and hydrogen selectivity.

• Journal of the Korean Chemical Society
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• v.67 no.5
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• pp.339-347
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• 2023

In this study, a nanocomposite of multi-walled carbon nanotubes@poly(p-phenylenediamine)-Prussian blue (MWCNTs@PpPD-PB) was synthesized and employed for the electrochemical detection of hydrogen peroxide (H₂O₂). A straightforward approach was utilized to prepare an electrochemical H₂O₂ sensor using a MWCNTs@PpPD-PB modified glassy carbon electrode, and its electrochemical behavior was investigated through techniques such as electrochemical impedance spectroscopy, cyclic voltammetry, and amperometry. The modified electrode displayed a favorable electrocatalytic response towards the reduction of H₂O₂ in an acidic solution. The developed sensor exhibited linearity in the concentration range of 0.005 mM to 2.225 mM for H₂O₂, with high sensitivity (583.6 ㎂ mM^-1cm^-2) and a low detection limit (0.95 ㎛, S/N = 3) at an applied potential of +0.15 V (vs. Ag/AgCl). Additionally, the sensor demonstrated excellent selectivity, reproducibility, and stability. Moreover, successful detection of H₂O₂ was achieved in real samples.

• New & Renewable Energy
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• v.6 no.4
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• pp.30-40
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• 2010

Syngas from gasification of coal can be converted to SNG(Synthesis Natural Gas) through gas cleaning, water gas shift, $CO_2$ removal, and methanation. One of the key technologies involved in the production of SNG is the methanation process. In the methanation process, carbon oxide is converted into methane by reaction with hydrogen. Major factors of methanation are hydrogen-carbon oxide ratio, reaction temperature and space velocity. In order to understand the catalytic behavior, temperature programmed surface reaction (TPSR) experiments and reaction in a fixed bed reactor of carbon monoxide have been performed using two commercial catalyst with different Ni contents (Catalyst A, B). In case of catalyst A, CO conversion was over 99% at the temperature range of $350{\sim}420^{\circ}C$ and CO conversions and $CH_4$ selectivity were lower at the space condition over 3000 1/h. In case of catalyst B, CO conversion was 100% at the temperature over $370^{\circ}C$ and CO conversions and $CH_4$ selectivity were lower at the space condition over 4700 1/h. Also, conditions to satisfy $CH_4$ productivity over 500 ml/h.g-cat were over 2000 1/h of space velocity in case of catalyst A and over 2300 1/h of space velocity in case of catalyst B.

• Journal of Hydrogen and New Energy
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• v.28 no.5
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• pp.554-560
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• 2017

Reduction reactivity of new oxygen carriers for chemical looping combustion system were investigated using $CH_4$ as a reduction gas in a bubbling fluidized bed reactor and compared with that of former SDN70 oxygen carrier. New oxygen carriers showed good reduction reactivity at different $CH_4$ concentration. N018-R2 particle represented better reactivity than SDN70 at high $CH_4$ concentration. N018-R2 particle showed higher fuel conversion and $CO_2$ selectivity than those of SDN70 particle within the temperature range of $750-900^{\circ}C$. Moreover, attrition loss of N018-R2 particle was almost same with that of SDN70 particle. Consequently, we could select N018-R2 particle as the best oxygen carrier.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.367-373
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• 2014

In this study, the reducing agent hydrazine and precipitator NaOH were used with $NiCl_2$ as a starting material in order to compound Ni-based material with spherical nano characteristics; resulting material was used as an anode for SOFC. Synthetic temperature, pH, and solvent amounts were experimentally optimized and the synthesis conditions were confirmed. Also, a 0 ~ 0.15 mole ratio of metal(Co, Fe) was alloyed in order to increase the catalyst activation performance of Ni and finally, spherical nano $Ni_{(1-x)}-M_{(x=0{\sim}0.15)}$(M = Co, Fe) alloy materials were compounded. In order to evaluate the catalyst activation for hydrocarbon fuel, fuel gas(10%/$CH_4$+10%/Air) was added and the responding gas was analyzed with GC(Gas Chromatography). Catalyst activation improvement was confirmed from the 3% hydrogen selectivity and 2.4% methane conversion rate in $Ni_{0.95}-Co_{0.05}$ alloy; those values were 4.4% and 19%, respectively, in $Ni_{0.95}-Fe_{0.05}$ alloy.

• Membrane Journal
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• v.24 no.6
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• pp.438-447
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• 2014

The amorphous and porous borosilicate without any cracks was obtained under the following condition : 0.01~ 0.10 mole ratio of trimethylborate (TMB)/ tetraethylorthosilicate (TEOS) and the temperature of $700{\sim}800^{\circ}C$. According to the BET and SEM measurements, borosilicate heat-treated in between 700 and $800^{\circ}C$ showed the surface area of $251.12{\sim}355.62m^2/g$, the pore diameter of 3.5~4.9 nm, and the particle size of 30~60 nm. According to the TGA measurements, the thermal stability of poly[1-(trimethylsilyl)propyne](PTMSP) membrane was enhanced by inserting borosilicate. SEM observation showed that the size of dispersed borosilicate in the composite membrane was $1{\mu}m$. The results showed that the permeability of $H_2$ and $N_2$ increased and the selectivity of $H_2/N_2$ decreased upon the addition of borosilicate into PTMSP membranes. Addition of borosilicate may possibly increase the free volume, cavity and porosity of membranes indicating that permeation occurred by molecular sieving, surface and Knudsen diffusion rather than solution diffusion of gases.

• Journal of Sensor Science and Technology
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• v.31 no.3
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• pp.168-174
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• 2022

Hydrogen sulfide(H₂S) gas is a high-risk gas that can cause suffocation or death in severe cases, depending on the concentration of exposure. Various studies to detect this gas are still in progress. In this study, we demonstrate a colorimetric sensor that can detect H₂S gas using its direct color change. The proposed nanofiber sensor containing a dye material named Lead(II) acetate, which changes its color according to H₂S gas reaction, is fabricated by electrospinning. The performance of this sensor is evaluated by measuring RGB changes, ΔE value, and gas selectivity. It has a ΔE value of 5.75 × 10^-3 ΔE/s·ppm, showing improved sensitivity up to 1.4 times that of the existing H₂S color change detection sensor, which is a result of the large surface area of the nanofibers. The selectivity for H₂S gas is confirmed to be an excellent value of almost 70 %.