• Transactions of the Korean hydrogen and new energy society
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• v.30 no.5
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• pp.428-435
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• 2019

A comparative evaluation of engine cleanliness was performed on the transport gasoline blended with bio- alcohols, and this study was considered to achieve the aim of greenhouse gas reduction in Korea. In particular, the fuel blended with bio-ethanol and bio-butanol showed the best engine cleaning performance both on combustion chamber deposits and intake valve deposits. The deposit control gasoline additive was effective to remove intake valve deposits. In contrast, the amount of combustion chamber deposits were tend to increase even though fuels blended with bio-alcohols were used. In overall, fuels blended with bio-alcohols, compared to fossil fuels, still showed outstanding performance in terms of engine cleanliness.

• Clean Technology
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• v.29 no.3
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• pp.163-171
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• 2023

Hydrogen has been gaining a lot of attention as a possible clean energy source that can aid in reaching carbon neutrality. Currently, hydrogen production has relied on the steam reforming of fossil fuels. However, due to the carbon dioxide emissions caused by this process, hydrogen production based on the steam reforming of bio-oil derived from biomass has been proposed as an alternative approach. In order to use this alternative approach efficiently, one of the key issues that must be overcome is that the complexity of bio-oil, which has a large molecular weight and diverse functional groups of hydrocarbons, promotes the catalytic deactivation of nickel-based catalysts. In this review, research efforts to improve nickel-based catalysts for the steam reforming of bio-oil have been discussed in terms of the active phase, support, and promoters. The active phases are involved in activating C-C and C-H bonds of high-molecular-weight hydrocarbons, and noble and transition metals can be utilized. In terms of the support and promoters, the catalytic deactivation of Ni-based catalysts can be inhibited by utilizing reactive lattice oxygen for support or by suppressing the acidity. The development of active and stable Ni-based reforming catalysts plays a critical role in clean hydrogen production based on bio-oils.

• Clean Technology
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• v.27 no.1
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• pp.69-78
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• 2021

Vegetable oils, such as palm oil and cashew nut shell liquid (CNSL), are used as major raw materials for bio-diesel in transportation and bio-heavy oil in power generation in South Korea. However, due to the high unsaturation degree caused by hydrocarbon double bonds and a high content of oxygen originating from the presence of carboxylic acid, the range of applications as fuel oil is limited. In this study, hydrotreating to saturate unsaturated hydrocarbons and remove oxygen in mixed bio-oil containing 1/1 v/v% palm oil and CNSL on monometallic catalysts (Ni and Cu) and bimetallic catalysts (Ni-Zn, Ni-Fe, Ni-Cu Ni-Co, Ni-Pd, and Ni-Pt) was perform under mild conditions (T = 250 ~ 400 ℃, P = 5 ~ 80 bar and LHSV = 1 h-1). The addition of noble metals and transition metals to Ni showed synergistic effects to improve both hydrogenation (HYD) and hydrodeoxygenation (HDO) activities. The most promising catalyst was Ni-Cu/��-Al2O3, and in the wide range of the Ni/Cu atomic ratio of 9/1~1/4, the conversion for HYD and HDO reactions of the catalysts were 90-93% and 95-99%, respectively. The tendency to exhibit almost constant reaction activity in these catalysts of different Ni/Cu atomic ratios implies a typical structure-insensitive reaction. The refined bio-oil produced by hydrotreating (HDY and HDO) had significantly lower iodine value, acid value, and kinetic viscosity than the raw bio-oil and the higher heating value (HHV) was increased by about 10%.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.598-601
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• 2007

셀룰로오스, 헤미셀룰로오스, 리그닌으로 구성된 목질계 바이오매스를 이용한 가스화의 경우 30%의 리그닌 성분이 열에 안정한 상태인 타르로 형성되면서 가스화 후단공정에서의 정제, 발전 등에 직접 사용하기 어려우며, 가스화 효율을 저하시키는 원인이 된다. 이의 문제 해결을 위하여 본 연구에서는 촉매를 이용한 수증기 개질 반응을 통하여 타르를 합성가스로 개질시킬 수 있는 방법을 모색하기 위하여 다양한 온도, 촉매, 스팀 주입량 및 촉매크기에 따른 전환율, 생성가스 특성을 알아보았다. 타르 대상 물질로는 타르 내 상당부분을 차지하고 있는 톨루엔을 이용하였다. 일반적으로 반응온도, 스팀 주입량이 증가할수록 수소 생성량이 증가하였으며, 지르코니아로 증진된 니켈 촉매의 경우 600$^{\cdot}C$ 에서도 100%의 높은 전환율을 보였다. 일반적인 가스화기에서 배출되는 타르의 농도보다 10배 높은 조건에서도 100%의 높은 전환율을 얻을 수 있었으며, 이를 통하여 실제 공정으로의 적용시에도 후단 공정의 부담을 줄일 수 있는 개질기로 적용 가능할 것으로 보인다.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.275-281
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• 2013

This study was conducted to increase the amount of bio-hydrogen production from microalgae(Chlorella vulgaris) in batch reactors by thermal pre-treatment. The optimization of thermal pre-treatment was conducted using statistic experimental design of response surface methodology. Two experimental parameters of temperature and reaction time were considered. The optimization condition was founded at the coded variables of <0.52, -0.07> corresponding to the experimental of heating temperature of $95.6^{\circ}C$ and reaction time of 57.9 min, respectively. Under the optimal condition, the maximum hydrogen production was predicted to 25.3mL $H_2/g$ dry cell weight (dcw), which was 9.1 times higher value of control(2.8mL $H_2/g$ dcw).

• Journal of Energy Engineering
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• v.15 no.2 s.46
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• pp.96-106
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• 2006

Among several different hydrogen production technologies, solar hydrogen system for water splitting is the only clean and sustainable energy supplier. Hydrogen production by water-splitting utilizing solar energy has attracted considerable interest since the pioneering work of Honda and Fujishima in 1979, who discovered that water can be photo-electrochemically decomposed into hydrogen and oxygen using a semiconductor ($TiO_2$) electrode under UV irradiation. Most efforts to utilize solar ray lead to explore visible responding photocatalysts, PEC cells and other fusion technology like bio-photocatalytic conversion. In this paper, photon utilization technologies for water splitting have been briefly reviewed except solar thermal utilization technology.

• Clean Technology
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• v.20 no.4
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• pp.406-414
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• 2014

Biogas is a gaseous mixture produced from microbial digestion of organic materials in the absence of oxygen. Raw biogas, depending upon organic materials, digestion time and process conditions, contains about 45-75% methane, 30-50% carbon dioxide, 0.3% of hydrogen sulfide gas and fraction of water vapor. To achieve the standard composition of the biogas the treatment techniques like absorption or membrane separation was performed for the resourcing of biogas. In this paper the experimental results of the methane purification in simulated biogas mixture consisted of methane, carbon dioxide and hydrogen sulfide were presented. The composite membrane is manufactured within polysulfone in order to increase the separation performances for the gaseous mixtures of $CO_2$ and $CH_4$ which are main components of the biogas. The effects of feed pressures and mixed gas on the separation of $CO_2-CH_4$ by membrane are investigated. Chelate chemical was utilized to treat the purification of methane from the $H_2S$ concentration of 0.3%.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.551-564
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• 2021

The use of clean energy based on the hydrogen economy is increasing rapidly due to the greenhouse gas reduction policies and the increase in the need for hydrogen. Currently, South Korea government have been considering a plan to construct hydrogen refueling stations at expressway service area for the purpose of supplying hydrogen vehicles. In the case of a hydrogen refueling stations, a quantitative risk assessment (QRA) must be performed because it includs and uses a high pressurized hydrogen storage tank. In this study, QRA was conducted using societal risk and F-N curve by the consequence assessment (CA) of jet fire and explosion according to the population density, capacity of the high pressurized hydrogen storage tank and frequency assessment (FA) data to the general hydrogen refueling stations systems in expressway service area. In the cases of jet with a leak diameter of 7.16 mm, regardless of expressway service area location, the societal risk was over 1E-04 that was acceptable for as Low As reasonably practicable (ALARP) region (workforce), but unacceptable for ALARP region (public). In the cases of gas explosion, all expressway service area satisfy ALARP region. In the case of the population density is over 0.0727, QRA for constructing the hydrogen refueling stations, must be conducted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.41-46
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• 2018

In this research, numerical analysis was performed to determine the effects of hydrogen on biogas combustion for homogeneous charged compression ignition (HCCI) engines. The target engine specifications were a 2300cc displacement volume, 13:1 compression ratio, 15kW of electricity, and 1.2 bar boost pressure. The engine speed was fixed to 1800rpm. By varying the excess air ratio and hydrogen contents, the cylinder pressure, nitric oxide, and carbon dioxide were measured as a function of the hydrogen contents. According to preliminary studies related to the reaction mechanism for methane combustion and oxidation, a GRI 3.0 mechanism as the base mechanism was selected for HCCI combustion calculations describing the detailed reaction mechanism. By adding hydrogen, NO was increased while $CO_2$ was decreased. The cylinder pressure was also increased, having advanced timing for the maximum cylinder pressure and pressure rise region. Furthermore, lean operation limits were extended by adding hydrogen to the HCCI engine.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.94-100
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• 2016

Hydrogen production via steam reforming of bio-oil from algal biomass over fast pyrolysis with commercial catalysts was carried out. Aqueous bio-oil obtained by phase separation from a crude oil over fast pyrolysis was used as a reactant and comparison studies for activity over different catalysts (FCR-4-02, POS-7, Cat. A, RUA), reaction temperature, and steam/carbon (S/C) ratios were performed. Experimental results showed that different catalytic activities were observed with different S/C ratios and catalyst composition and the highest hydrogen yield of 70% was obtained with a POS-7 catalyst at a S/C ratio of 10 and 1073 K.