• Title/Summary/Keyword: Carbon-based Catalyst

Search Result 198, Processing Time 0.022 seconds

Room Temperature Hydrogen Gas Sensor Based on Carbon Nanotube Yarn (상온감지 가능한 탄소나노튜브 방적사 기반의 수소 감지 센서)

  • Kim, Jae Keon;Lee, Junyeop;Kong, Seong Ho;Jung, Daewoong
    • Journal of Sensor Science and Technology
    • /
    • v.27 no.2
    • /
    • pp.132-136
    • /
    • 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.

Hydorgen Production by Catalytic Decomposition of Propane Over Cabon-Based Catalyst (탄소계 촉매를 이용한 프로판 분해 반응에 의한 수소 생산)

  • Yoon, Suk Hoon;Han, Gi Bo;Lee, Jong Dae;Park, No-Kuk;Ryu, Si Ok;Lee, Tae Jin;Yoon, Ki June;Han, Gui Young
    • Korean Chemical Engineering Research
    • /
    • v.43 no.6
    • /
    • pp.668-674
    • /
    • 2005
  • It is reported that a method for the hydrogen production from the propane decomposition using carbon black as a catalyst is more effective than from the methane decomposition. Since the by-products like CO and $CO_2$ are not produced by the direct decomposition of propane, it is considered as an environmentally sustainable process. In this study, hydrogen was produced by the direct decomposition of propane using either commercial activated carbon or carbon black at atmospheric pressure in the temperature range of $500-1,000^{\circ}C$. Resulting products in our experiment were not only hydrogen but also several by-products such as methane, ethylene, ethane, and propylene. Hydrogen yield increased as temperature increased because the amount of those by-products produced in the experiment was inversely proportional to temperature. The achieved hydrogen yield at $750^{\circ}C$ with commercial DCC N330 catalyst was 22.47% in this study.

A Study on NH3-SCR Vanadium-Based Catalysts according to Tungsten Content for Removing NOx Generated from Biogas Cogeneration (바이오가스 열병합 발전에서 발생하는 NOx 제거를 위한 텅스텐 함량에 따른 NH3-SCR 바나듐계 촉매 연구)

  • Jung, Min Gie;Hong, Sung Chang
    • Clean Technology
    • /
    • v.27 no.4
    • /
    • pp.315-324
    • /
    • 2021
  • In this study, a vanadium catalyst study was conducted on the various characteristics of the exhaust gas in the Selective-Catalytic-Reduction (SCR) method in which nitrogen oxides emitted from cogeneration using biogas are removed by using ammonia as a reducing agent and a catalyst. V/W/TiO2, a commercial catalyst, was used as the catalyst in this study, and the effect was confirmed according to the tungsten content under various operating conditions. As a result of the NH3-SCR experiment, the denitrification performance was confirmed at 380 ~ 450 ℃ more than 95%, and durability to trace amounts of SO2 was confirmed through the SO2 durability experiment and TGA analysis. As a result of H2-TPR analysis, the higher the tungsten content, the better the redox properties. Accordingly, enhanced oxidizing properties were confirmed in the oxidation test for a trace amount of carbon monoxide emitted from the cogeneration. In NH3-DRIFTs analysis, it was confirmed that the higher the tungsten content, the higher both the Bronsted/Lewis acid sites and the better the thermal durability when tungsten is added to the catalyst. Based on the experiments under various operating conditions, it is considered that a catalyst with a high tungsten content is suitable to be applied to cogeneration using biogas.

Development of a Catalyst/Sorbent for Methane-Steam Reforming (메탄스팀개질반응용 촉매흡착제 개발에 관한 연구)

  • Cho, Yong-Hoon;Na, Jeong-Geol;Kim, Seong-Soo;Kim, Jin-Gul;Chung, Soo-Hyun
    • Korean Chemical Engineering Research
    • /
    • v.44 no.3
    • /
    • pp.307-313
    • /
    • 2006
  • In order to improve the efficiency of methane steam reforming process, a part of the system which produces hydrogen from heavy hydrocarbon resources such as coal, we combined metal catalyst with CaO sorbent and fabricated catalyst/sorbent. To increase the porosity and the compressive strength of sorbent, carbon black and ${\alpha}-alumina$ were mixed with CaO powder during preparation. The effects of sorbent composition on the physical properties were investigated by SEM, TGA, BET, XRD, abrasion strength measuring device and adsorption-desorption instrument. Sorbent with 5 wt% $Al_2O_3$ and 10 wt% carbon black showed the best physical features with $7.61kg_f$ strength and 47% $CO_2$ adsorption capability. Various metal catalysts such as Ni, Co and Fe were supported on the sorbent developed and 10 wt% Ni/sorbent was selected for methane steam reforming process based on the result of reaction experiment. The reaction system using the catalyst/sorbent showed better $H_2$ productivity compared to the detached system with catalyst and sorbent, indicating the effectiveness of the system developed in this study.

A Study on the Influence of the Structural Characteristics of Cu/CeO2 Catalyst on the Low-Temperature Oxidation of Carbon Monoxide (Cu/CeO2 촉매의 구조적 특성이 일산화탄소 저온 산화반응에 미치는 영향 연구)

  • Kim, Min Su;Choi, Gyeong Ryun;Kim, Se Won;Hong, Sung Chang
    • Clean Technology
    • /
    • v.26 no.4
    • /
    • pp.286-292
    • /
    • 2020
  • This study confirmed the effect of the Cu/CeO2-X catalyst on the CO oxidation activity at low temperature through the catalyst's structure and reaction characteristics. The catalyst was prepared by the wet impregnation method. Cu/CeO2_X catalysts were manufactured by loading Cu (active metal) using CeO2 (support) formed at different calcination temperatures (300-600 ℃). Manufactured Cu/CeO2_X catalysts were evaluated for the low-temperature activity of carbon monoxide. The Cu/CeO2_300 catalyst showed an activity of 90% at 125 ℃, but the activity gradually decreased as the calcination temperature of the CeO2-X and Cu/CeO2_600 catalysts showed an activity of 65% at 125 ℃. Raman, XRD, H2-TPR, and XPS analysis confirmed the physicochemical properties of the catalysts. Based on the XPS analysis, the lower the calcination temperature of the CeO2 was, the higher the unstable Ce3+ species (non-stoichiometric species) ratio became. The increased Ce3+ species formed a solid solution bond between Cu and CeO2-X, and it was confirmed by the change of the CeO2 peak in Raman analysis and the reduction peak of the solid solution structure in H2-TPR analysis. According to the result, the formation of the solid solution bond between Cu and Ce has been enhanced by the redox properties of the catalysts and by CO oxidation activity at low temperatures.

The Effect of Pt and La Promoted on Cobalt-Based Catalyst for CO2 Dry Reforming (이산화탄소 건식 개질반응을 위한 코발트계 촉매에서 Pt와 La의 영향)

  • Lee, Hye-Hyun;Song, Sang-Hoon;Chang, Tae-Sun;Hong, Ji-Sook;Suh, Jeong-Kwon;Lee, Chang-Yong
    • Applied Chemistry for Engineering
    • /
    • v.22 no.2
    • /
    • pp.161-166
    • /
    • 2011
  • The $CO_2$ dry reforming reaction, which converts carbon dioxide to hydrogen and carbon monoxide, is typical endothermic reaction, and also known as adverse reaction owing to thermodynamics. In order to overcome the problem, the development studies of suitable catalyst based on precious metals for high durability of thermal and optimization of life time have been examined but it had economical problem by high cost. In this study, we confirmed optimum contents of Pt and La with such different contents of Pt (0.02~0.2 wt%) or La (2~20 wt%) over $Co/SiO_2$ which prepared for excellent activity and cost-effective catalysts. As a result, the promoted catalysts with 0.04 wt% Pt or 9 wt% La over $Co/SiO_2$ showed the highest activity which is 57% and 55% $CO_2$ conversion respectively. Also, the particle size of cobalt on the promoted catalysts with 0.04 wt% Pt or 9 wt% La by characterization of catalyst could confirm the smallest particle size in this study. Therefore, it could know that particle size of cobalt had effected the stability and reactivity of catalysts due to the contents of Pt and La.

Catalytic Effects on Graphitized Carbon Fibers of Graphitization Catalysts Introduced during Hot-Water Stretching (열수 연신시 흑연화 촉매 도입에 따른 탄소섬유의 흑연화 촉진효과)

  • Hyun-Jae Cho;Hye Rin Lee;Byoung-Suhk, Kim;Yong-Sik, Chung
    • Composites Research
    • /
    • v.37 no.3
    • /
    • pp.162-169
    • /
    • 2024
  • In this study, PAN(polyacrylonitrile)-based precursor fibers were produced through a wet-spinning process, and their morphologies and graphitization behavior were investigated in the presence of two graphitization catalysts (Ca, Ni). The graphitization catalysts were introduced into the formed pores during hot-water stretching of wet-spun PAN-based precursor fibers. The catalytic effects of graphitization catalysts were examined through crystal structure and Raman analysis. At a relatively low temperature of 1500℃, the graphitization was not significantly affected, whereas at a high temperature of 2400℃, the obtained ID/IG value of graphite fiber (GF-Ni100) was decreased by about twice (~0.28) compared to the untreated fibers (GF-AS~0.54). By comparing the ID/IG values (GF-Ca100~0.42: GF-Ni100~0.28) of Ca and Ni graphitization catalyst, it was found that the degree of graphitization of Ni graphitization catalyst showed higher influence than that of Ca graphitization catalyst. Moreover, 2D band was also observed, indicating that the graphite plane structures composed of multiple layers were developed. XRD results confirmed that the crystal inter-planar distance (d002) of the graphite crystal was slightly decreased after the treatment with the graphitization catalyst, But, the crystal size of Ca-treated graphite fiber (GF-Ca100) was increased by up to ~5 nm.

Synthesis of Carbon Nanofibers Based on Resol Type Phenol Resin and Fe(III) Catalysts

  • Hyun, Yu-Ra;Kim, Hae-Sik;Lee, Chang-Seop
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.10
    • /
    • pp.3177-3183
    • /
    • 2012
  • The carbon nanofibers (CNFs) used in this study were synthesized with an iron catalyst and ethylene as a carbon source. A concentration of 30 wt % iron(III) acetylacetonate was dissolved in resol type phenol resin and polyurethane foam was put into the solution. The sample was calendered after being cured at $80^{\circ}C$ in air for 24 h. Stabilization and carbonization of the resol type phenol resin and reduction of the $Fe^{3+}$ were completed in a high-temperature furnace by the following steps: 1) heating to $600^{\circ}C$ at a rate of $10^{\circ}C/min$ with a mixture of $H_2/N_2$ for 4 h to reduce the $Fe^{3+}$ to Fe; 2) heating to $1000^{\circ}C$ in $N_2$ at a rate $10^{\circ}C/min$ for 30 minutes for pyrolysis; 3) synthesizing CNFs in a mixture of 20.1% ethylene and $H_2/N_2$ at $700^{\circ}C$ for 2 h using a CVD process. Finally, the structural characterization of the CNFs was performed by scanning electron microscopy and a synthesis analysis was carried out using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Specific surface area analysis of the CNFs was also performed by $N_2$-sorption.

Hot-filament 플라즈마화학기상증착법 이용한 패턴된 DLC층 위에 탄소나노튜브의 선택적 배열

  • Choe, Eun-Chang;Park, Yong-Seop;Hong, Byeong-Yu
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2010.08a
    • /
    • pp.293-293
    • /
    • 2010
  • Carbon nanotubes (CNTs) have attracted considerable attention as possible routes to device miniaturization due to their excellent mechanical, thermal, and electronic properties. These properties show great potential for devices such as field emission displays, CNT based transistors, and bio-sensors. The metals such as nickel, cobalt, gold, iron, platinum, and palladium are used as the catalysts for the CNT growth. In this study, diamond-like carbon (DLC) was used for CNT growth as a nonmetallic catalyst layer. DLC films were deposited by a radio frequency (RF) plasma-enhanced chemical vapor deposition (RF-PECVD) method with a mixture of methane and hydrogen gases. CNTs were synthesized by a hot filament plasma-enhanced chemical vapor deposition (HF-PECVD) method with ammonia (NH3) as a pretreatment gas and acetylene (C2H2) as a carbon source gas. The grown CNTs and the pretreated DLC filmswere observed using field emission scanning electron microscopy (FE-SEM) measurement, and the structure of the grown CNTs was analyzed by high resolution transmission scanning electron microscopy (HR-TEM). Also, using energy dispersive spectroscopy (EDS) measurement, we confirmed that only the carbon component remained on the substrate.

  • PDF

Carbon nanotubes formation on clay and fly ash from catalytic thermal decomposition of recycled polypropylene

  • Nur A. Atikah Kamaruddin;Norzilah A. Halif;Siti A. Hussin;Mohd. N. Mazlee
    • Advances in materials Research
    • /
    • v.13 no.3
    • /
    • pp.173-181
    • /
    • 2024
  • Fly ash, plastic waste, and clay are mineral materials and residues commonly found in Malaysia. In this study, these materials were fully utilized as raw materials for synthesizing carbon nanotubes (CNTs). Recycled polypropylene, previously used as a food container, served as a carbon source. Fly ash and clay were explored as potential substrates for CNTs growth. The recycled polypropylene was thermally decomposed at 900 ℃ in an inert environment for 90 minutes. Carbon atoms released during this process were deposited on fly ash and clay substrates, which had been immersed in a ferrocene solution to provide a metal catalyst for CNTs growth. The deposited products were characterized using a Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). Morphological analysis revealed that both fly ash and clay were coated with fiber-like structures, confirmed to be CNTs based on a diffraction peak around 26° from the XRD pattern. In conclusion, clay and fly ash demonstrate the potential to be utilized as substrates for CNTs formation.