Nonmethane hydrocarbons NMHCs

Many GTL-derived fuels are being considered for blending with gasoline and diesel to achieve emission reductions of particulate matter (PM), carbon monoxide (CO), nitrogen compounds (NOx) and nonmethane hydrocarbons (NMHC). The most promising fuels converted from natural gas are methanol and ethers such as dimethyl ether (DME) and mcthyl-t-bntyl ether (MTBE). 

Methane and the Nonmethane Hydrocarbons. It is traditional to distinguish CH4 from all other atmospheric hydrocarbons. Methane is by far the most abundant atmospheric hydrocarbon and has very large natural emissions. Its abundance in auto exhaust but low atmospheric reactivity has led air pollution scientists to enact controls on nonmethane hydrocarbons NMHC (also called VOC for volatile organic compounds, which include oxygenated hydrocarbons). 

S02 and nonmethane hydrocarbons (NMHC) were removed, 67-78% and 17-20%, respectively, by the windowed panels. For NMHC, it is assumed that the fractions of lower aldehydes and olefins are removed, since Ti02 degrades such fractions much more rapidly than saturated and aromatic hydrocarbons. 

In reality, the situation is somewhat more complicated owing to the presence at high concentrations of NO , of increased levels of nonmethane hydrocarbons (NMHCs), especially in places such as the urban... 

In addition to these compounds, the photochemical production of small amounts of nonmethane hydrocarbons (NMHC) such as ethene, propene, ethane, and propane has also been reported. Production of these compounds appears to result from the photolysis of the CDOM, with O values of the order of 10 -10 . The overall... 

Figure 2 Simplified scheme of marine nonmethane hydrocarbon (NMHC) production. In the marine troposphere NMHC acts as a sink for hydroxyl (OH) radicals and thereby plays a key role in ozone chemistry.

Chan LY, Chu KW, Zou SC, Chan CY. Wang XM, Barletta B, Blake DR. Guo H. Tsai WY (2006) Characteristics of nonmethane hydrocarbons (NMHCs) in industrial, industrial-urban, and industrial-suburban atmospheres of the Pearl River Delta (PRD) region of south China. J Geophys Res Atmos 111 011304... 

For the purpose of EKMA modeling, hydrocarbons include only nonmethane hydrocarbons (NMHC), or nonmeihane organic carbon (NMOC) methane is excluded due to its comparatively low reactivity. The concentration of NMHC in an air sample is usually expressed in terms of the moles of carbon per mole of air, denoted ppmC or ppbC (parts per million carbon or parts per billion carbon). For any hydrocarbon, its air concentration in ppm(v) or ppb(v) can be converted to ppmC or ppbC by... 

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