Formation of Ozone in the Los Angeles Atmosphere

Littman, F.E.; Ford, H. W.; Endow, N.

doi:10.1021/ie51400a035

Cited by 20 publications

(6 citation statements)

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“…In the early 1950s, air pollution and automobiles were rst correlated by Californian scientists who established that a huge amount of traffic was to blame for the smoggy skies over the Los Angeles area. [103][104][105][106][107] Over the years, international concern about environmental pollution caused by polluting sources has been increasing as it becomes a global environmental issue. Consequently, several developed and developing countries have enacted legislation for the control of pollutant gases in the exhaust stream of automobiles.…”

Section: Exhaust Catalysismentioning

confidence: 99%

Noble metal ions in CeO₂and TiO₂: synthesis, structure and catalytic properties

Bera

Hegde

2015

RSC Adv.

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In past four decades, CeO 2 has been recognized as an attractive material in the area of auto exhaust catalysis because of its unique redox properties. In presence of CeO 2 , catalytic activity of noble metals supported on Al 2 O 3 gets enhanced due to higher dispersion of noble metals in their ionic form. In last several years, we have been exploring an entirely new approach of dispersing noble metal ions on CeO 2 and TiO 2 matrices for redox catalysis. In this article, dispersing of noble metal ions by solution combustion as well as other methods over CeO 2 and TiO 2 resulting mainly in −δ (M = Pd, Pt, Rh and Ru) catalysts, structure of these materials, their catalytic properties toward different types of catalysis, structure−property relation and mechanism of catalytic reactions are reviewed. In these catalysts, noble metal ions are incorporated into substrate matrix to a certain limit in a solid solution form. Lower valent noble metal ion substitution in CeO 2 and TiO 2 creates noble metal ionic sites and oxide ion vacancies that act as adsorption sites for redox catalysis. It has been demonstrated that these new generation noble metal ionic catalysts (NMIC) have been found to be catalytically more active than conventional respective nano crystalline noble metal catalysts dispersed on oxide supports. 5 at.% and hence, substitution of only 1−2 at.% noble metal ion in CeO 2 is sufficient to develop a catalyst. The underlying principle of doping aliovalent metal ions into CeO 2 or TiO 2 lattice is to retain their parent structures. In this sense, new-age advanced catalysts such as Ce 1−x M x O 2−δ (M = Pd, Pt, Rh, Cu, Ag and Au), Ce 1−x−y A x M y O 2−δ (A = Ti, Zr, Sn and Fe; M = Pt and Pd) and Ti 1−x M x O 2−δ (M = Pd, Pt, Rh and Ru) retaining their parent fluorite and anatase structures have been prepared in our laboratory employing solution combustion method. 20−23 Thus, synthesis of these single phase oxides is a new conceptwhich is the basis of metal ion catalysts. In these catalysts, noble metal ions and corresponding oxide ion vacancies are supposed to be the active sites. Since, the adsorption sites in these catalysts are noble metal ions such as Pd 2+ , Pt 2+ , Rh 3+ and Ru 4+ , we have named these materials as noble metal ionic catalysts (NMIC). In last several years, we have been studying several exhaust catalytic reactions such as NO reduction, CO and hydrocarbon oxidation, selective catalytic reduction of NO, three-way catalytic reaction, water gas shift (WGS) reaction, preferential oxidation of CO (CO−PROX), H 2 + O 2 recombination reaction, hydrogenation and Heck reaction over these noble metal ionic catalysts and it has been demonstrated that these catalysts are much more active for several catalytic reactions compared to other conventional supported metal catalysts. In this review, at first, we mainly discuss about background, synthesis and characterization of these noble metal ionic catalysts (NMIC). Then we emphasize on our detailed work related to exhaust catalysis comparing activities with t...

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Section: Exhaust Catalysismentioning

confidence: 99%

Noble metal ions in CeO₂and TiO₂: synthesis, structure and catalytic properties

Bera

Hegde

2015

RSC Adv.

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“…Papers such as those by Thomas (156) and Byran and Romanovsky (50) dealt 1%-ith air pollution measurement. The latter paper is a thorough review of the air-monitoring program of the Los Angeles air pollution control district, including monitoring and recording instruments for sulfur dioxide, oxidants, carbon monoxide, nitric oxide, nitrogen dioxide, particulate sampling, and ozone.…”

Section: General Trendsmentioning

confidence: 99%

“…Cummings and Redfearn (46) encountered the old difficulty of calibration at extremely low concentrations, R hich was overcome by using a method in which the sulfur dioxide and air were flowing continuously to eliminate varying adsorption and desorption of sulfur dioxide on the Fvalls of vessels. Littman et al (156) described the use of a continuous oxidant recorder for measuring ozone in the atmosphere. Holmes and Johnson (113) reviewed briefly the special problems of probing the upper atmosphere.…”

Section: General Trendsmentioning

confidence: 99%

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Automatic Operations

Patterson¹

1959

Anal. Chem.

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“…This consideration is important in terms of the photochemical nature of smog formation and in terms of some of the present hypotheses concerning atmospheric reactions (18) < 25) .…”

Section: Recent Work On Atmospheric Mechanismsmentioning

confidence: 99%

Considerations of The Feasibility of Control of Oxides of Nitrogen

Tow

1957

Journal of the Air Pollution Control Association

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Formation of Ozone in the Los Angeles Atmosphere

Cited by 20 publications

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Noble metal ions in CeO₂and TiO₂: synthesis, structure and catalytic properties

Noble metal ions in CeO₂and TiO₂: synthesis, structure and catalytic properties

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Considerations of The Feasibility of Control of Oxides of Nitrogen

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Formation of Ozone in the Los Angeles Atmosphere

Cited by 20 publications

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Noble metal ions in CeO2and TiO2: synthesis, structure and catalytic properties

Noble metal ions in CeO2and TiO2: synthesis, structure and catalytic properties

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Considerations of The Feasibility of Control of Oxides of Nitrogen

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Noble metal ions in CeO₂and TiO₂: synthesis, structure and catalytic properties

Noble metal ions in CeO₂and TiO₂: synthesis, structure and catalytic properties