John L. Gossage

Sustainability assessment of polygeneration processes based on syngas derived from coal and natural gas

Abstract Polygeneration systems produce chemicals, electricity, fuel, hydrogen, etc., from one or more type of feedstock. Considering their promise to provide high material and energy conversion from natural resources, polygeneration systems are recognized as promising technologies for future chemical and power industries. Sustainability assessment of these systems can provide valuable information to designers. Embedding exergy analysis and inherent safety score that quantify the efficiency and societal aspect, respectively, to complement the widely accepted economic assessment and environmental impacts assessment in a decision tree evaluation framework provides a more comprehensive, yet fast methodology to compare related processes in terms of sustainability. In this paper two different polygeneration systems, which use coal and natural gas as feed to produce di-methyl ether and power, are compared using a comprehensive sustainability assessment methodology. The results of the assessment are used to identify the more sustainable process, taking into account the economic, environmental, societal and efficiency factors.

Water-related matrix isolation phenomena during NO2 photolysis in argon matrix.

Photolysis (350–450 nm) of NO2 molecules trapped in argon matrices at 10 K has been studied using Fourier transform infrared (FT-IR) spectroscopy to examine the mobility of the photolysis products, O(3P) and NO, and their subsequent reactions. The formation of N2O5 and N2O3 from reactions of these mobile species with immobilized NO2 and N2O4 is confirmed. Water molecules from the background gases in the vacuum have been found to be isolated in the argon matrix during deposition of diluted NO2 in Ar. The entrapped water molecules along with some of their NO2 adducts have been characterized. Exposure of the matrix to photons to photolyze NO2 resulted in not only internal matrix reactions, but also an enhanced deposition of ice over the surface of the argon matrix. This is caused by photodesorption of water molecules from the walls of the matrix isolation chamber and their subsequent condensation on the matrix surface. This ice overlayer has been found to give a very significant dangling OH band and a substantial librational band in the FT-IR spectra, indicating substantial surface area and internal porosity, respectively. The potential of using photodesorbed water to establish high surface area ice interfaces with dangling OH groups for heterogeneous photoreaction studies is discussed.

Fourier Transform Infrared-Probed O(3P) Microreactor: Demonstration with Ethylene Reactions in Argon Matrix

To demonstrate the development of an oxygen atom microreactor in the form of liquid-helium-cooled solid argon matrix deposited on an infrared (IR) window, the oxidation of ethylene by mobile O atoms has been investigated. O atom diffusion through the argon matrix is confirmed and used to examine ethylene–oxygen atom reactions. In a bench-scale matrix isolation system probed with a Fourier transform infrared (FT-IR) spectrometer, matrices of solid Ar at 8–10 K doped with NO2 and ethylene have been prepared on a ZnSe window within an evacuated cryostat. The matrices have been photolyzed using 350–450 nm photons, and the reaction products resulting from the reaction of O(3P), one of the photolysis products of NO2, with ethylene have been identified using FT-IR and a Gaussian 98W simulation program. These products include oxirane, acetaldehyde, ethyl nitrite radical, and ketene. The temperature effect in the range of 10–30 K on the products formed has also been investigated. The reaction mechanisms are discussed and the viability of the solid Ar matrix being a low temperature microreactor to examine reaction mechanisms of mobile oxygen atoms is elaborated.

Characterization of Copper-Manganese-Aluminum-Magnesium Mixed Oxyhydroxide and Oxide Catalysts for Redox Reactions

Complex multi-metal catalysts require several stages in their preparation. These are: co-mixing, co-precipitation, milling and sol-gel, drying, dehydroxylation, and calcination and sometimes regeneration of the hydroxide by rehydration. These processes require thermal analysis (DTA, TGA, DSC) and accompanying off gas analysis, plus one or more of these: XRD, XPS, SEMEDS, FTIR and UV-VIS. In this study, hydrotalcite, hopcalite and mixed systems were prepared and guided by the above characterization techniques. The systems were initiated by mixing the chlorides or nitrates followed by hydrothermal treatments to produce the hydroxides which were further treated by washing, drying, and calcination. The thermal analysis was critical to guide the preparation through these stages and when combined with structural determination methods considerable understanding of their chemical and physical changes was obtained. The correlations between preparation and characterization will be discussed.