Showing papers on "NOx published in 1969"

Exhaust gas purification

Abstract: This invention is concerned with a process for the effective removal of carbon monoxide hydrocarbons and the oxides of nitrogen from the exhaust stream of mobile internal combustion engines. This purification is accomplished by passing the exhaust gas from an engine operating at near the stoichiometric fuel-air ratio through a high-temperature catalyst. This catalyst is normally a noble metal catalyst. The exhaust gas is then cooled to a temperature in the vicinity of 700* F., ammonia is added and the ammoniated stream is passed over a second catalyst which can be either a base metal catalyst or a noble metal catalyst.

In vitro alveolar macrophage viability. Effect of gases.

Abstract: A simple, rapid method was developed for the determination of in vitro alveolar macrophage viability after exposure to gases. Air pollutants such as ozone, sulfur dioxide, and oxides of nitrogen killed alveolar macrophages, as determined by the dye exclusion test. Ozone (O3) was effective at very low concentrations. Other gases such as carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), methyl chloride (CH3Cl), acrolein, acetaldehyde, acetone, isoprene, benzene, and hydrocyanic acid (HCN) had no effect on cell viability.

Chemistry of Atmospheric Oxidants

Abstract: All of the important oxidants in polluted air are formed there by chemical reactions which occur among the primary pollutants. The most abundant of these oxidants is ozone which is formed in a cycle involving nitric oxide, nitrogen dioxide, atmospheric oxygen, and hydrocarbons. This ozone is best understood, not as a reaction product, but as an intermediate in steady-state concentration between formation and disappearance reactions. Hydrocarbons permit accumulation of ozone by reacting to scavenge the nitric oxide which would otherwise remove the ozone. The amount of ozone which can be formed in ambient polluted air is limited to about 1 ppm because these scavenging reactions become less effective when the nitric oxide concentration becomes very small. The peroxyacyl nitrates are a group of oxidants which result from reactions between oxides of nitrogen and organic pollutants. Olefinic and aromatic hydrocarbons make the largest contribution to PAN formation; saturates contribute little if any. The role of...

Treatment of exhaust gases containing nitrogen oxides and other noxious compounds

Abstract: A METHOD OF TREATING GASES CONTAINING NOXIOUS OXIDES, PARTICULARLY OXIDES OF NITROGEN, WITHOUT SUBJECTING SAID GASES TO CATALYTIC ACTION, WHEREIN THE GASES ARE INTIMATELY CONTACTED WITH A POROUS BODY COMPOSED OF FIBERS PLATED WITH GOLD, THE POROUS BODY BEING NEGATIAVELY CHARGED

Air pollution and the compression-ignition engine

Abstract: The compression-ignition engine, popularly known as the diesel, is examined as a contributor to metropolitan air pollution. Smoke and odor are recognized as the primary targets of public objection to the diesel, and factors relevant to the smoke and odor problem are discussed. Problems that involve diesel smoke are seen by the author as readily manageable but a satisfactory solution to the diesel odor problem is not yet evident. Other pollutants—unburned hydrocarbon, partially burned hydrocarbon, oxides of nitrogen, and in lesser degree, carbon monoxide—are significant in the products of diesel combustion. Of these, only oxides of nitrogen and possibly the aldehydes typically are discharged in quantities that in equivalent volumes of combustion product may exceed the quantities discharged by spark-ignition reciprocating internal combustion engines. Features both inherent and unique to the diesel combustion process are discussed as factors relevant to generation or avoidance of objectionable pollutants. In this context the high temperatures and oxygen availability in diesel combustion are seen as serious impediments to satisfactory reduction of the yield of oxides of nitrogen in the diesel process, but they are favorable in holding concentrations of pollutants in other categories to acceptably low levels. Except for the problem of odor and of oxides of nitrogen, it would appear that the combustion processes of the compression-ignition engine inherently are favorable toward engine design and operation for reduction in pollutants to meet environmental needs.

Nitric oxide analysis

Abstract: Method and apparatus for determining the nitric oxide content of a sample gas stream. The nitric oxide in the gas stream is reacted with an excess amount of ozone so as to completely convert the nitric oxide into nitrogen dioxide. The resulting gas containing nitrogen dioxide and residual ozone is passed through a scrubber which removes the ozone and does not affect the nitrogen dioxide content of the gas. The resulting gas is then analyzed for its NO2 content, which is a function of the nitric oxide content of the sample gas. The method and apparatus may also be utilized for determining the total amount of nitrogen dioxide and nitric oxide in a sample gas. The invention is particularly applicable to the monitoring of air for air pollution control.

Method and system for reducing oxides of nitrogen and other pollutants from internal combustion engines

Abstract: Oxides of nitrogen (NOx) in the exhaust gas emissions of an internal combustion engine are reduced, as measured on a standard 7-mode driving cycle, by utilizing natural gas as a fuel and operating with an equivalence ratio from about 1.25 to about 1.35. The 1.25 value corresponds to the maximum permissible amounts of NOx as measured in parts per million. The 1.35 value corresponds to the value where unacceptable power loss would result if exceeded. A gas-air mixer having a metering pin modified to operate with a natural gas inlet pressure of from -0.5 inches of H2O to +0.5 inches of H2O and within the specified range of equivalence ratios is employed. A modulator produces a fuel-rich condition at full throttle to increase power.

Treatment of off-gases from nitric acid oxidation of anolone

Abstract: Off-gases, obtained from the nitric acid oxidation of an organic feed comprising cyclohexanol and cyclohexanone and mixtures thereof by contact in a reactor with nitric acid at an elevated temperature whereby adipic acid is produced, the mixture of offgases comprising nitric oxide, nitrogen dioxide, other oxides of nitrogen, carbon dioxide, nitrogen and carbon monoxide, are mixed with an oxygen-containing gas and the resultant mixture is passed through the organic feed being passed to the nitric acid reactor. This results in utilizing all reactive oxidizing agents in the off-gases and transferring a portion of the highly exothermic reaction from the main reactor to the off-gas scrubber.

The question of the formation of oxides of nitrogen in the determination of carbon and hydrogen by the flash combustion of aromatic nitro compounds in a current of oxygen

Abstract: 1. In the combustion of aromatic nitro compounds by the “flash” method, about 13% of oxides of nitrogen is formed, which is somewhat less than on combustion in a tube. 2. The presence of chlorine in nitrogen-containing substances or in a mixture of substances leads to an increase in the amount of oxides of nitrogen in the combustion gases. 3. The formation of NO2 in the combustion of substances containing no nitrogen under high-temperature conditions has been confirmed.