Dinitrogen surfaces

A. Ozaki and K. Aika. Catalytic Activation of dinitrogen, ibid. pp. 87-158, Volume 7 B.E. Koel and G.A. Somorjai. Surface stmctural chemistiy, pp. 159-218. 

Calculate the solubility of dinitrogen in blood that is in contact with air (78% N2 ) at atmospheric pressure and at 4.0 atm, the pressure at a sea depth of 100 feet. Determine the volume of N2 that will be released from 1 L of blood if a deep-sea diver surfaces quickly from this depth. If this escape of N2 occurs in the form of gas bubbles that are 1 mm in diameter, how many bubbles per liter is this ... 

The readsorption and incorporation of reaction products such as 1-alkenes, alcohols, and aldehydes followed by subsequent chain growth is a remarkable property of Fischer-Tropsch (FT) synthesis. Therefore, a large number of co-feeding experiments are discussed in detail in order to contribute to the elucidation of the reaction mechanism. Great interest was focused on co-feeding CH2N2, which on the catalyst surface dissociates to CH2 and dinitrogen. Furthermore, interest was focused on the selectivity of branched hydrocarbons and on the promoter effect of alkali on product distribution. All these effects are discussed in detail on the basis... 

Reacting dinitrogen with dihydrogen on a catalytic iron surface (the Haber-Bosch process)... 

Currently, almost all industrial dinitrogen fixation is due to the old Haber-Bosch [2] process. This operates at high temperature and pressure, and uses a promoted metallic-Fe catalyst. The reaction assumed to occur by coordination of both dinitrogen and dihydrogen on the catalyst surface, followed by stepwise assembly of ammonia from these molecules. 

Since the first step of all of these reactions is dinitrogen coordination to either the surface of the catalyst or transition metal center of the complex, let us briefly discuss the nature and importance of the M-N2 interaction, and the possible coordination modes ofN2 to transition metal centers. These issues were the subjects of many discussions in the literature [10, 11] and it is commonly agreed that the interaction of the N2 molecule with transition metal centers facilitates the activation of the N=N triple bond the stronger the M-N2 interaction, the easier to break the N=N triple bond. 

The direct use of ammonia or dinitrogen and hydrogen to synthesize imido amido complexes is essentially pioneers territory [58, 59]. Recently, we have formed, by surface organometaUic chemistry, a well-defined Ta amido imido species by reaction with either ammonia [9] or with dinitrogen and dihydrogen at subatmospheric pressure [60]. 

The starting tantalum hydride(s) also cleave the dinitrogen triple bond at low pressure of hydrogen and at 250 °C to yield the surface Ta amido imido complex [(=SiO)2Ta(=NH)(NH2)] (Scheme 2.22) [60]. 

The capacity of isolated Ta hydrides to fully cleave the NsN bond is thus original with respect to surface science [the dissociative chemisorption of dinitrogen on... 

However, over the past decade, advances in, and in particular the availability of sophisticated instrumentation, and in the understanding of the instrumental techniques and the hosts and guests to which they are applied, mean that this need no longer be the case. A recent example in which a gamut of carefully chosen techniques, including such basic but essential measurements as elemental analyses, has led to the same precise characterization of surface species as has been the mainstay of molecular compounds is the study of the synthesis, characterization and reactivity of tantalum hydrides on silica, and their involvement in the dissociation of dinitrogen [203]. 

Koch, T. G., S. F. Banham, J. R. Sodeau, A. B. Horn, M. R. S. McCoustra, and M. A. Chesters, Mechanisms for the Heterogeneous Hydrolysis of Hydrogen Chloride, Chlorine Nitrate and Dinitrogen Pentoxide on Water-Rich Atmospheric Particle Surfaces, J. Geophys. Res., 102, 1513-1522 (1997). 

The compound [ (T -CsHs TiCH CiCHg) ] has been characterized (337). Its homologs are well known. Surface anchoring of titanium complexes to Si02 in order to produce heterogeneous, supported dinitrogen complexes has not been successful (202). 

It is clear that charge separation is the primary event, followed by electron bombardment of dinitrogen in the air near the charged (presumably new) surface. The emission is accompanied by the expected radio signals, and electron and positive ion release (12), and thus will be called "lightning" throughout this paper. 

Miessner, H., Surface-chemistry in a zeolite matrix—Well-defined dinitrogen complexes of rhodium supported on dealuminated Y-zeolite. J. Am. Chem. Soc. 116,11522 (1994). 

A concise review of data relative to the photofixation of dinitrogen on transition metal oxides is presented. Analysis of data is focussed upon the nature and potential efectivenes of a process which can occur in nature on the surface of particular inorganic materials when exposed to direct sunlight. The significance of this process is discussed. Finally, some new and selected results are presented which outline particular mechanistic aspects of the photoassisted nitrogen process. 

In addition to reduction, oxidations reactions of adsorbed dinitrogen seems to be promoted on irradiated Ti02 surfaces, despite the reaction being thermodynamic not very unfavorable. 

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