Emission Characteristics Of Samples Research Articles

Briquette preparation with biomass binder

ABSTRACT Residential coal combustion is regarded as a major contributor to severe haze pollution in China, and clean briquettes are supported as a way of reducing emissions. In this study, Shendong coal (SC) and a composite binder made from maize straw (MS) were used to prepare a briquette with higher combustion characteristics and lower pollution emissions by using a newly designed method. Thermochemistry and emission characteristics of samples were studied by using a thermogravimetric analyzer and a tube combustion experimental system, respectively. The results showed that for a 20% biomass mass fraction with <0.5 mm particle size, biomass treatment with alkali agents or the addition of a sulfur-fixing agent resulted in significantly reduced SO2 emission; however, molding the sample increased total SO2 emissions, particularly in the early stages. NO emission decreased markedly with biomass, alkali-treatment or the addition of a sulfur-fixing agent. However, NO emission increased when the biomass had a particle size of 0.5–2 mm and when the sample was molded.

KrF laser surface treatment of carbon nanotube cathodes with and without reactive ion etching

Electron emission characteristics of carbon nanotube cathodes with and without reactive ion etching (RIE) followed by KrF laser irradiation were investigated. The emission characteristics of samples without RIE process, such as emission current density, turn-on field, and emission pattern, strongly depend on the laser power density, which is caused by a photon process at low laser power densities of 2–4MW∕cm2 and a thermal ablation at high power densities of 10–14MW∕cm2. The emission characteristics of samples with RIE, however, show little change when the laser power density is varied. Surface morphologies of CNT cathodes with RIE process show little change by laser treatment compared to the case of CNT cathodes without RIE process.

Electronic Structure and Field‐Emission Properties of Nitrogen‐Doped Carbon Nanotubes

Nitrogen‐doped carbon nanotubes have been synthesized by thermal decomposition of acetonitrile vapor over Ni/Co catalysts with varied ratio of metals. X‐ray photoelectron spectroscopy revealed that nitrogen atoms are embedded into tube walls in two different forms at least: (1) three‐coordinated nitrogen and (2) pyridinic‐like nitrogen. The ratio between these forms depends on the catalyst composition. Electronic structure of nitrogen‐doped carbon nanotubes was examined by means of photoemission, X‐ray photoelectron, X‐ray emission and X‐ray absorption spectroscopy. Field electron emission characteristics of samples produced were correlated with nitrogen content. The experimental data was interpreted using results of quantum‐chemical semiempirical AM1 calculations on models of nitrogen‐containing carbon tubes. Incorporation of three‐coordinated nitrogen was found from calculation of the models using the transfer matrix approximation to improve the current‐voltage characteristics of carbon nanotubes.