Prepared under National Science Foundation Grant no. OEP 76-00284. / National Science Foundation Grant no. OEP 76-00284.

Sol-gel production of catalyst supports has been investigated in order to produce homogeneous, high surface area alumina/zirconia materials. A novel microwave method of preparing colloidal Pd has been developed and a range of alumina/zirconia supported Pd catalysts has been produced. These have been tested for activity in terms of temperature programmed three way catalysis (simultaneous removal of NO, CO and C3H8 from a simulated car exhaust stream) and from the array of catalysts produced a suitable catalyst was chosen for further investigation. This catalyst had a 3% zirconia / 97% alumina support and contained ~1% Pd by weight and was examined for activity in the NO + CO + O2 system at temperatures below 500°C. Temperature programmed catalytic experiments revealed the reactions to be chemically controlled below ~400°C but diffusion controlled above this. CO temperature programmed reduction was used to examine the oxidation state of the Pd and revealed a complex Pd/PdO system to be present involving bulk PdO and surface oxide. Further kinetic studies showed that the reactions between NO, CO and O2 to have positive orders in all components. The reaction rates were stable over a wide range of conditions and the NO + CO reaction proved to have a low selectivity towards N2O. In-situ DBIFTS experiments alongside transient pulse work were used to illustrate low CO adsorption which indicated that these reactions proceeded via a redox mechanism in which Pd is oxidised by NO or O2 before being reduced by CO. The support material was examined by XRD following extended heating regimes and then compared to an identically treated sol-gel alumina. The zirconia doped alumina was found to possess a far greater thermal resistance to sintering than the pure alumina material and this was attributed to Zr4+ ions preventing the diffusion of Al3+ to form a-alumina.

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Introduction: Diesel fuel (D) is used in a variety of applications for several industries, including transportation, agriculture, railroads, construction, and mining. In addition to being non-renewable, combustion of diesel fuel (D) leads to negative occupational health outcomes in mining. Currently the Mine Safety and Health Administration (MSHA) regulates diesel exhaust exposure with an 8-hour, time-weighted average permissible exposure limit (PEL) of 160 µg/m3 respirable (<1.0 µm in size) diesel particulate matter (rDPM). Alternative fuels such as biodiesel (B) and a natural gas/diesel blend (GDiesel® [G]) are considered promising alternatives. While the former fuel has been extensively investigated, the latter has not. Objectives: The aims of this dissertation were: (1) to evaluate and compare D and G exhaust exposures from operation of a Wagner and a (2) JCI load-haul-dump (LHD) at the University of Arizona San Xavier Underground Mining Laboratory (SX); and (3) to synthesize existing peer-reviewed literature comparing D emission exposures to those of B and/or G. Methods: For Aims 1 and 2, operator-location and area exposure samples were collected for 200 minutes in an underground mining laboratory while an LHD with oxidation catalyst was operated with D and then G fuel. Analytes of interest included total diesel particulate matter (tDPM) and rDPM, total and respirable elemental and organic carbon (tEC, rEC, tOC, rOC, respectively), as well as the carbonyl compound (CC) formaldehyde (CH2O), nitric oxide (NO), and nitrogen dioxide (NO2). Exposure assessment was conducted within the guidelines of the National Institute of Occupational Safety and Health’s (NIOSH) Manual of Analytical Methods. Specifically, methods #5040 (tDPM, tEC, tOC, rDPM, rEC, rOC), #6014 (NO, NO2), and #2016 (CH2O). Reported laboratory results were time-weighted over an 8-hour period. Between-fuel comparisons were performed using Wilcoxon rank sum testing. Results: For Aim 1, twenty-three D and 12 G samples were collected. Use of G in the Wagner LHD showed statistically and practically significant reductions in rDPM, tDPM, elemental and organic carbons, NO, NO2, and CH2O. For Aim 2, twenty D and 16 G samples were collected. Use of G in the JCI LHD was associated with a significant decrease in NO2 (p=0.012), and significant increase in rEC (p=0.024). After removing outliers, tEC also showed significant increase (p=0.023). Most of the 20 scholarly works reviewed utilized a laboratory setting (75%), while just 15% were conducted in the field, and 10% simulated field conditions. Twenty percent (4) of studies specifically focused on the mining industry. In addition, most evaluated soy-based B (56%) but did not utilize pollution controls (70%) on equipment. Generally, literature showed that use of B decreased DPM and increased oxides of nitrogen (NOx) emission exposures. While more studies (5) showed increases in CCs, two showed decreases. Discussion: Our studies show that: 1) the use of G has potential for statistically and practically significant reductions in several D exhaust contaminants regulated by MSHA; and 2) variability in exposure and emission concentrations across engine, pollution control and operation configurations exists for B and likely exists for G. Differences observed across fuels and studies are also likely due to fuel composition and characteristics, and combustion temperatures. Further occupational health research is needed to evaluate G emissions under controlled conditions with various equipment configurations, as well as in-field settings to determine whether G exhaust exposures are reduced and actually less toxic than those of D. The impact of this work is substantial and timely. Recent increases in respiratory disease prevalence among miners, including young miners, concerns occupational health and industrial hygiene professionals. In addition, MSHA has requested information regarding diesel exhaust controls and is considering future revisions to the rDPM standard. Efforts to reduce D exhaust emissions will also impact occupational and environmental health worldwide.

The NOx health and environmental problems make necessary to reduce this gaseous emission from different sources. Furthermore, its increase in the last years and the difficulties to remove it with after-treatment systems already in the market make more urgent the development of new techniques. The purpose of this investigation is to study the low temperature catalytic oxidation of NO to NO2 and its adsorption over a renewable activated carbon (AC) from coconut shell. The present research presents the results of experimental work carried out using a laboratory scale reactor to investigate the low temperature catalytic oxidation of NO. Activated carbon was housed in the reactor and tests were carried out with different reactor sizes, different activated carbon forms and shapes, different gas mixtures at different temperatures and different levels of humidity to simulate dry and wet particulate-free diesel engine exhaust gas. The effects of addition of ozone in the gas on the NO oxidation were also explored. Gas analysis upstream and downstream of the catalytic reactor was carried out in all cases during the charge and regeneration of the AC. An extensive literature review in conjunction with measurement of some properties of the activated carbon helped to understand better its characteristics and behaviour. The results of this study indicate that in the case of dry gas, the activated carbon initially acts as an adsorber and only after operation of several hours, the NO oxidation that takes place in the reactor results in increased NO2 levels in the product gas. The NO conversion is affected by the activated carbon form and reaction conditions including temperature, humidity, oxygen, NO, CO2 content in the inlet gas, temperature, space velocity, linear gas velocity, residence time, reactor shape, AC pretreatment and lifespan. Water vapour has a detrimental effect on the conversion of NO to NO2 before the AC reaches the steady-state conditions. On the other hand, ozone is effective in converting NO to NO2 at room temperature. This research has developed some findings not studied or reported by other researches before and confirms and/or complements results reported in the literature review by other groups, which will benefit the development of a renewable after-treatment system of NOx emissions.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xv, 111 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 89-91).

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains viii, 167 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 128-130).

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xiii, 147 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 120-124).

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 115 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 101-102).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains ix, 69 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 59-64).