The objective of the work presented here is to develop a nanoporous solid adsorbent which can serve as a "molecular basket" for CO 2 in the condensed form. Polyethylenimine (PEI)-modified mesoporous molecular sieve of MCM-41 type (MCM-41-PEI) has been prepared and tested as a CO 2 adsorbent. The physical properties of the adsorbents were characterized by X-ray powder diffraction (XRD), N 2 adsorption/desorption, and thermogravimetric analysis (TGA). The characterizations indicated that the structure of the MCM-41 was preserved after loading the PEI, and the PEI was uniformly dispersed into the channels of the molecular sieve. The CO 2 adsorption/desorption performance was tested in a flow system using a microbalance to track the weight change. The mesoporous molecular sieve had a synergetic effect on the adsorption of CO 2 by PEI. A CO 2 adsorption capacity as high as 215 mg-CO 2 /g-PEI was obtained with MCM-41-PEI-50 at 75 °C, which is 24 times higher than that of the MCM-41 and is even 2 times that of the pure PEI. With an increase in the CO 2 concentration in the CO 2 /N 2 gas mixture, the CO 2 adsorption capacity increased. The cyclic adsorption/desorption operation indicated that the performance of the adsorbent was stable.

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Adsorption separation of CO2 from simulated flue gas containing CO2, O2, and N2 with and without moisture was investigated using a novel nanoporous adsorbent based on polyethylenimine (PEI)-modified mesoporous molecular sieve MCM-41 in a flow system. The CO2 adsorption capacity and CO2 separation selectivity of MCM-41 were greatly improved by loading PEI into its nanosized pore channels, which made the resulting adsorbent operating like a “molecular basket” for CO2. CO2 adsorption capacity of the MCM-41-PEI adsorbent for the simulated moist flue gas was higher than that for the simulated dry flue gas. CO2 separation selectivity of the MCM-41-PEI adsorbent was also improved in the presence of moisture when compared with those in the dry gas condition. The influence of moisture concentrations in the simulated flue gas on the CO2 adsorption separation performance was also examined. The results of adsorption/desorption separation cycles showed that the MCM-41-PEI adsorbent was stable over 10 cycles of adsorption/desorption operations. The hydrothermal stability of the “molecular basket” adsorbent was better than that of the MCM-41 support alone.

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Because Foster Wheeler North America Corp. (hereinafter “Foster Wheeler”) is supplying and supporting pulverized fuel (PF) boilers producing steam with higher temperatures and pressures, increasing emphasis must be given to potential sources of corrosion and deposition. Further, because Foster Wheeler is developing projects involving cofiring of biomass fuels (e.g., wood waste, agricultural materials) with coals from a variety of sources, again corrosion and deposition must be thoroughly investigated. Chlorine frequently is identified as a significant source of corrosion and deposition, both from coal and from biomass, and in PF boilers. Given the pressures to advance to higher steam pressures and temperatures, an investigation of the consequences of chlorine was undertaken. This investigation was designed to highlight the potential for corrosion risks associated with once-through units and advanced cycles. This research took the form of a detailed literature investigation to evaluate chlorine in solid fuels: coals of various ranks and origins, biomass fuels of a variety of types, petroleum cokes, and blends of the above. The investigation focused upon an extensive literature review for papers, book chapters, and other documents dating back largely to 1991. The issues addressed focused upon depositionslagging and foulingand corrosion. Issues such as mercury control facilitation, or HCl emissions, are not considered in this review. It is recognized that chlorine can facilitate mercury capture by influencing the oxidation state of mercury (see, e.g., Pavlish et al., Fuel Process. Technol. 82 (2/3), 89−165; Senior et al., Fuel Process. Technol. 63 (2/3), 187−213; and Senior, Sadler, and Sarofim, Preprints: Division of Fuel Chemistry, American Chemical Society 50 (1), 295−298). This, however, is outside the focus of this analysis. Municipal solid waste, and its derivatives, are also not included in this review. Issues with municipal waste tend to focus on formation of polychlorinated dioxins and furans (see, e.g., Everaert, Chemosphere 46, 439−448), again outside the considerations of this review. The focus is strictly corrosion and deposition. To address the deposition and corrosion issues, this review evaluates the following considerations: concentrations of chlorine in available solid fuels including various coals and biomass fuels, forms of chlorine in those fuels, and reactionsincluding reactivitiesof chlorine in such fuels. The assessment includes consideration of alkali metals and alkali earth elements as they react with, and to, the chlorine and other elements (e.g., sulfur) in the fuel and in the gaseous products of combustion. The assessment also includes other factors of combustion: for example, combustion conditions including excess O2 and combustion temperatures. It also considers analyses conducted at all levels: theoretical calculations, bench scale laboratory data and experiments, pilot plant experiments, and full scale plant experience. Case studies and plant surveys form a significant considerat...

It is demonstrated that bitumen can be separated from "water-wet" Alberta oil sands and "oil-wet" Utah oil sands using a so-called analogue ionic liquid (IL) based on deep eutectic mixtures of choline chloride and urea (ChCl/U) together with a diluent such as naphtha. Unlike conventional ILs, these eutectics are relatively cheap and environmentally friendly. The process is straightforward and involves simply mixing the components at ambient temperatures followed by standard solid/liquid and liquid/liquid separation steps. The ChCl/U mixture appears to reduce the adhesion of bitumen to sand, facilitating separation. It is also immiscible with hydrocarbons such as bitumen or oil. Coupled with a large density difference, this results in a sharp phase separation of hydrocarbons from the ChCl/U mixture. The ChCl/U deep eutectic essentially acts as a separating fluid, keeping the naphtha-diluted bitumen and extracted sand apart, facilitating subsequent separations and solvent recovery steps. However, ChCl/U mixtures are highly viscous at ambient temperatures, but high concentrations of this deep eutectic in water also work well. Initial scale-up work suggests that this approach may form the basis for a viable large-scale process.

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