No description available.

No description available.

No description available.

Dimethyl ether (DME), as a solution to environmental pollution and diminishing energy supplies, can be synthesized more efficiently, compared to conventional methods, using a catalytic distillation column for methanol dehydration to DME over an active and selective catalyst. In current work, using an autoclave batch reactor, a variety of commercial catalysts are investigated to find a proper catalyst for this reaction at 110-135 C and 900 kPa. Among the -Alumina, Zeolites (HY, HZSM-5 and HM) and ion exchange resins (Amberlyst 15, Amberlyst 35, Amberlyst 36 and Amberlyst 70), Amberlyst 35 and 36 demonstrate good activity for the studied reaction at the desired temperature and pressure. Then, the kinetics of the reaction over Amberlyst 35 is determined. The experimental data are described well by Langmuir-Hinshelwood kinetic expression, for which the surface reaction is the rate determining step. The calculated apparent activation energy for this study is 98 kJ/mol. / Chemical Engineering

Thesis (M.S.)--Oregon State University, 1987. / Typescript (photocopy). Includes bibliographical references (leaves 135-139). Also available on the World Wide Web.

No description available.

As a byproduct of incomplete combustion, soot attracts increasing attentions as extensive researches exploring serious health and environmental effects from soot particles. Soot emission reduction requires a comprehensive understanding of the mechanism for polycyclic aromatic hydrocarbons and of soot formation and aging processes. Therefore, advanced experimental techniques and numerical simulations have been conducted to investigate this procedure. In order to investigate the effects of dimethyl ether (DME) mixing on soot particle size distribution functions (PSDFs), DME was mixed in premixed ethylene/oxygen/argon at flames at the equivalence ratio of 2.0 with a range of mixing ratio from 0% to 30% of the total carbon fed. Two series of atmospheric pressure flames were tested in which cold gas velocity was varied to obtain different flame temperatures. The evolution of PSDFs along the centerline of the flame was determined by burner stabilized stagnation probe and scanning mobility particle sizer (SMPS) techniques, yielding the PSDFs for various separation distances above the burner surface. Meanwhile, the flame temperature profiles were carefully measured by a thermocouple and the comparison to that of simulated laminar premixed burner-stabilized stagnation flame was satisfactory. Additionally, to understand the chemical role of DME mixing in soot properties, characterization measurements were conducted on soot samples using thermo-gravimetric analysis (TGA) and elemental analysis (EA). Results of the evolution of PSDFs and soot volume fraction showed that adding DME into ethylene flame could reduce soot yield significantly. The addition of DME led to the decrease of both the soot nucleation rate and the particle mass growth rate. To explain the possible mechanism for the observation, numerical simulations were performed. Although DME addition resulted in the slight increase of methyl radicals from pyrolysis, the decrease in acetylene and propargyl radicals inhibited the production of polycyclic aromatic hydrocarbons. At the same time, the addition of DME gave rise to the increase of the flame temperatures, which favored the production of OH radicals. The incremental concentration of OH radicals promoted the oxidation rate of soot particles. Additionally, soot samples from flames with higher DME mixing ratios showed higher O/C, H/C mass ratios and thus better oxidation characteristics. In summary, the addition of DME reduces soot emission in two ways: on the one hand, it inhibits soot nucleation and mass/size growth, then the production of soot particles decreases; on the other hand, it promotes soot oxidation process by increasing the concentration of OH radicals and improving the oxidation behavior of the soot particles, then more particles are oxidized. Both of them are responsible for the reduction of soot emissions at the presence of DME.

The study of the reaction of cadmium and sulfur in dimethylsulfoxide (DMSO) is presented. Specifically, the reaction of dissolved molecular sulfur in DMSO at temperatures greater than 90°C with freshly precipitated metallic cadmium is followed by UV-visible spectrometry, atomic absorption spectrometry, and Raman spectrometry. Evidence for the formation of a new cadmium-sulfur species and S3- is discussed. In a second reaction, an equilibrium sodium polysulfide solution in DMSO is titrated with a solution of cadmium ion at room temperature and the reaction progress is followed by means of UV-visible spectrometry. A calculation of the average number of polysulfide charges reacting with each cadmium ion, n̄Q, was made using literature values of the molar absorptivities of the ions S3-, S8- 2, and S6- 2 and Beer's law. Likewise, the average number of sulfur atoms, n̄M, reacting with each cadmium ion was determined. A value of 4.8 polysulfide charges per cadmium ion was determined for n̄Q and a value of 18 sulfur atoms per cadmium ion was determined for n̄M. The significance of the possible formation of cadmium polysulfide complexes is discussed briefly in conjunction with the reaction mechanisms involved in the electrodeposition of CdS from a DMSO solution of CdCl2 and S8.

published_or_final_version / abstract / Ecology and Biodiversity / Master / Master of Philosophy

The reaction of dimethylcopper lithium and di-n-butylcopper lithium with 3-bromo-2-(2-phenylacetamido) acrylic acid, mp 174 - 175°, produced as major products 3-methyl-2-(2-phenylacetamido) acrylic acid and 3-n-butyl-2-(2-phenylacetamido) acrylic acid, respectively. The dimethylcopper lithium reaction was stereospecific for the E geometrical isomer, mp 198 - 199°, and produced 3-methyl-2-(2-phenylacetamido) acrylic acid and 2-(2-phenylacetamido) acrylic acid in a 3:1 molar ratio, respectively. The di-n-butylcopper lithium reaction produced as the main products 3-n-butyl-2-(2-phenylacetamido) acrylic acid and 2-(2- phenylacetamido) acrylic acid in a 7:1 molar ratio, respectively, with the 3-n-butylacrylic acid comprising 83% of the product. The reaction produced the E isomer, mp 205 - 206°, and the Z isomer, mp 164 - 165°, in the approximate ratio of 2:1, respectively. The configuration of the products of both reactions was determined by the comparison of the nuclear magnetic resonance spectra with spectra of model compounds of known configuration. Nuclear magnetic resonance evidence relating to the stereochemistry of 3-bromo-2-(2-phenylacetamido) acrylic acid based on the single isomers of this acid and the corresponding methyl ester reported in the literature was inconclusive. In order that a comparison of the properties of both isomers could be made, an attempt was made to prepare the uncommon isomer of methyl 3-bromo-2-(2-phenylacetamido) acrylate from (a) the common isomer by hydrobromination-dehydrobromination with triethylamine and (b) from methyl 2-(2-phenylacetamido) acrylate by bromination-dehydrobromination with triethylamine. Both attempts were unsuccessful.