CO2 Capture by the Amine-modified Mesoporous Materials
ABSTRACT Novel CO2 adsorbents were prepared by grafting two different aminosilanes on mesoporous silica MCM-41 and SBA-15. The properties of the mesoporous materials before and after surface modification were investigated by powder X-ray diffraction (XRD) pattern, solid-state 29Si nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectra, and measurements of N2 adsorption and desorption isothermal, which confirmed that aminosilanes were grafted on the surface of the channels in the mesoporous materials. Thermogravimetry analysis (TGA) evaluated the amount of grafted amine to be about 1.5–2.9 mmol·g−1. The CO2 adsorption capacity of MCM-41 increased from 0.67 mmol·g−1 to 2.20 mmol·g−1 after AEAPMDS (N-β-(aminoethyl)-γ-aminopropyl dimethoxy methylsilane) modification (p=101 kPa) at room temperature. The studies of the mechanism of CO2 adsorption suggested that there were two main contributions to the increase: the chemical adsorption based on the active sites of amine groups and the capillary condensation caused by the nano-scale channels of the mesoporous materials.
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ABSTRACT: To improve the working and living environment of submarine crews, an integrated system of CO2 removal and O2 regeneration was designed to work under experimental conditions for 50 people in a submarine cabin during prolonged voyages. The integrated system comprises a solid amine water desorption (SAWD) unit for CO2 collection and concentration, a Sabatier reactor for CO2 reduction and a solid polymer electrolyte (SPE) unit for O2 regeneration by electrolysis. The performances of the SAWD-Sabatier-SPE integrated system were investigated. The experimental results from the SAWD unit showed that the average CO2 concentration in the CO2 storage tank was more than 96% and the outlet CO2 concentration was nearly zero in the first 45 min, and less than 1/10 of inlet CO2 after 60 min when input CO2 was 0.5% (1000 L). About 950 L of CO2 was recovered with a recovery rate of 92%∼97%. The output CO2 concentration was less than 0.2%, which showed that the adsorption-desorption performance of this unit was excellent. In the CO2 reduction unit we investigated mainly the start-up and reaction performance of the Sabatier reactor. The start-up time of the Sabatier reactor was 6, 8 and 10 min when the start-up temperature was 187.3, 179.5 and 168 °C, respectively. The product water was colorless, transparent, and had a pH of 6.9∼7.5, and an electrical conductivity of 80 µs/cm. The sum of the concentration of metal ions (Ru3+, Al3+, Pb2+) was 0.028% and that of nonmetal ions (Cl−, SO4 2−) was 0.05%. In the O2 regeneration unit, the O2 generation rate was 0.48 m3/d and the quantity was 2400 L, sufficient to meet the submariners’ basic oxygen demands. These results may be useful as a basis for establishing CO2-level limits and O2 regeneration systems in submarines or similar enclosed compartments during prolonged voyages.Journal of Zhejiang University - Science A: Applied Physics & Engineering 11/2009; 10(11):1642-1650. DOI:10.1631/jzus.A0920017 · 0.61 Impact Factor
Conference Paper: Low-noise, high-speed avalanche photodiodes[Show abstract] [Hide abstract]
ABSTRACT: Describes materials and structural modifications to the thin multiplication regions that have yielded ultra low multiplication noise. In the low gain regime, these APDs have achieved excess noise factors lower than that of Si APDs. Very high gain-bandwidth products can be achieved by proper design of the multiplication region and the use of a waveguide structure.Device Research Conference, 2001; 02/2001