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Objectives/Scope: Presently, high capital and operating costs are preventing monetization of high-pressure natural gas containing substantial quantities of CO2. The objective of the paper is to highlight an advancement in the removal of CO2 from high-pressure natural gas, such as the Natuna and Llaird fields. In particular, the paper will show how the Verdis Process dramatically reduces the operating costs and energy demand of CO2 removal, and how the Process integrates with pipelining or deep well disposal of the CO2 while producing market-ready natural gas. Methods, Procedures, Process: The presentation will be structured in 3 parts. The first part will briefly outline the current state of the art in CO2 removal from high-pressure natural gas, the second part will explain the Verdis CO2 Process, which uses a solid-state absorbent, and the economic and environmental benefits it can bring, and the third part will explain the applicability over a wide range of gas compositions, including the presence of hydrogen sulfide. Results, observations, Conclusions: High-pressure gas (over 1100 psi) containing elevated levels of CO2 is difficult to monetize because of the high cost of CO2 removal. Although un-economical, cryogenic processes have been the leading technologies for treating this difficult gas because a liquid CO2 product facilitates deep well disposal of the CO2 without compression. However, the process is very energy-intensive. Verdis has now developed an energy-efficient solid state CO2 absorbent that can be stripped with dry gas at 90-130 ºC and at pressures higher than those of the feed gas. By using warm CO2 at over 1100 psi as the stripping gas, the stripped CO2 can be returned to the liquid state just by cooling to below 30 ºC ready for disposal downhole or pipelining. No compressors are needed. Even for lower-pressure natural gas, while a liquid CO2 is not produced directly, the CO2 compression costs for liquifying are substantially reduced. Novel/Additive Information: The Process is entirely novel. The Presentation will enhance the understanding of the audience members of CO2 recovery in general and the Verdis Process in particular, and provide a new alternative for treating high-pressure natural gas and other difficult gases containing CO2.

Recently, iron 2-ethylhexanoate (Fe-eh, 1) in combination with ascorbic acid 6-palmitate (AsA6p) has been reported as a good catalytic system for the oxidation of ethyl linoleate (EL), an unsaturated lipid. In response to the fascinating chemistry of this bio-inspired iron-based catalyst the structure of Fe-eh, and the effect of AsA6p on it, have been studied. Fe-eh was found to be a trinuclear oxido-centered iron(III) cluster of general formula [ Fe 3 III ( μ 3 -O ) ( eh ) 6 ( acetone ) 3 ] ( eh ) . The Mossbauer spectra of 1 indicate that the trinuclear iron core is not symmetric as the spectra exhibit two equivalent iron(III) sites and one unique iron(III) site. Variable temperature magnetic measurements indicate that the three iron centers are antiferromagnetically coupled. Upon the addition of AsA6p to complex 1 a new species (2), which has not yet been completely identified, is formed. Mossbauer spectroscopy indicates, however, that 2 is a mixed-valence cluster which probably has an iron-core that differs in symmetry from 1. The reduction of 1 to 2 was also monitored in time by electrospray ionization mass spectrometry, revealing that the reduction reaction is kinetically dependent on the molar ratio AsA6p/Fe-eh. Based on these results and other available information, a general mechanism for the oxidation of EL under the effect of the combination of AsA6p/Fe-eh is proposed.

Several well-defined diiron siloxide complexes have been synthesized, isolated, characterized, and used as molecular precursors for the grafting of well-defined isolated iron species on the surface of mesoporous silica SBA-15. The precursors have bridging siloxide ligands, a diamine linker, or a μ –oxo diiron core, and their binuclear structures have been confirmed by elemental analysis, solution molecular weight measurements, and nuclear magnetic resonance spectroscopy. All precursors react with SBA-15 to immobilize the iron centers and produce silanol; the various stoichiometries and structural implications of these grafting reactions are discussed. Calcination of the grafted iron complexes yields materials largely devoid of organic components, and these calcined catalysts are active in the oxidation of hydrocarbons by hydrogen peroxide . The catalytic activities and selectivities of these materials are compared with each other and with those of other Fe/SiO 2 catalysts. Issues including iron-loading dependence and grafting conditions are discussed. Characterization of the catalysts by diffuse–reflectance ultraviolet–visible, X-band electron paramagnetic resonance, Mossbauer, and extended X-ray absorption fine structure spectroscopies indicates that although the diiron structures of the precursors are usually maintained during the initial grafting process, calcination results in their conversion to monoiron centers on the support. This theory is also consistent with the generally similar catalytic behaviors of materials prepared from diiron and monoiron precursors. The implications of these findings for the generality of molecular precursor techniques are discussed.

Cerium oxide solid samples were prepared via precipitation from aqueous solution of hydrous cerium(III) nitrate in the presence of different percentages of hydrogen peroxide (H2O2) as model corrosion inhibiting coatings materials for aluminum alloys. X-ray absorption spectroscopy at the Ce LIII-edge was applied for the characterization of crystalline anhydrous CeO2, nanocrystalline hydrous CeO2, nanocrystalline CeO2 sample I precipitated in the presence of H2O2, and an amorphous CeO2 sample II precipitated at a higher H2O2 concentration. An analysis by X-ray absorption near-edge structure (XANES) for cerium oxides did not indicate a broad variation in cerium valence state in the precipitated samples as compared to anhydrous CeO2. Furthermore, XANES analysis revealed a decrease in the intensity of the white line peaks for the precipitated samples relative to those in anhydrous CeO2. The EXAFS spectra of the oxides showed that H2O2 reduced the precipitate's particle diameter and bulk crystallinity. Growth i...

The synthesis and characterization of a mononuclear iron(III) complex [Fe(Hphpz)Cl(CH3OH)] (1) and a tetranuclear assembly of a bis(μ-hydroxo)-bridged dinuclear iron(III) complex [{Fe(Hphpz)2(OH)}2][Fe(Hphpz)3]2 (2) with the ligand 3(5)-methyl-5(3)-(2-hydroxyphenyl)pyrazole (H2phpz) is reported. Compound 1 is converted into 2 in a methanol solution and in the presence of a base. The asymmetric unit of 2 consists of two independent [Fe(Hphpz)3] molecules and one dinuclear complex [Fe(Hphpz)2(OH)]2 containing two crystallographically non-equivalent iron(III) ions; the three units are linked by N−H···O and O−H···O hydrogen bonding and stacking interactions to form a cluster with an approximate C2-symmetry. The Mossbauer spectra of [{Fe(Hphpz)2(OH)}2][Fe(phpz)3]2 have been measured at 295 and 78 K and indicate the presence of four crystallographically distinct, but chemically similar iron(III) sites. The magnetic properties of this compound originate from the weak antiferromagnetic interaction between the FeIII ions of the [Fe(phpz)2(OH)]2 dimer (J = −2.8 cm−1). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Here we demonstrate that magnetic susceptibility (MS) data from Scladina Cave, Belgium, provide a time–depth–climate relationship that is correlated to the marine oxygen isotopic record and thus yields a high-resolution relative dating method for sediments recovered from many archaeological sites. This methodology will help resolve one of the major problems facing archaeologists, namely the difficulty of acquiring absolute dates with reasonable precision for the period from 40,000 to 400,000 years or so. The problem is that dating techniques applicable to most materials within this age range are subject to significant errors. Relative dating techniques, such as magnetic secular variation or stable isotope methods, offer the potential to improve this precision, but both methods suffer from problems that make broad application to many sites impossible. However, for most archaeological cave sites, MS measurements of cave sediments offers the potential for intra-site correlation and paleoclimate estimation. This is possible in protected cave environments because the MS of cave sediments results from climate processes active outside caves, which cause variations in magnetic properties of the sediments that ultimately accumulate inside caves. Once deposited, these materials are often preserved and their stratigraphy provides a time–depth–climate signal that can be identified. Therefore MS data can be used as an independent methodology, alongside conventional methods such as sedimentology and palynology, for relative age dates, and correlation within and between sites by tracing evidence of paleoclimatic change. This correlation has been used to infer an age of 90,000±7000 years for Neanderthal skeletal remains recovered from Scladina Cave, an important Middle Paleolithic archaeological site in Belgium.

1,1′-Bis-silylferrocenylenes ( p -XC 6 H 4 SiMe 2 -C 5 H 4 ) 2 Fe, X=Br ( 1 ), CHO ( 2 ), CHC(CN) 2 ( 3 ) have been synthesized and characterized by NMR and Mossbauer spectroscopy, single crystal X-ray diffraction and electrochemistry. Complex 1 crystallizes in the centrosymmetric space group P 2 1 / n whereas 3 forms in the non-centrosymmetric group Cc . The latter complex exhibits a chain-like structure in the solid state via CH⋯N intermolecular hydrogen bonding. The hyperpolarizability of 3 is significantly greater than the related mono-silylferrocene complex (C 5 H 5 )Fe(C 5 H 4 SiMe 2 C 6 H 4 CHC(CN) 2 ) while Mossbauer spectroscopy exhibits negligible charge transfer between the cyano groups and the ferrocenylene iron center.

Fe/Au nanoparticles have been chemically synthesized through a reverse micelle reaction and investigated by both conventional and synchrotron based x-ray diffraction and by magnetic and Moessbauer spectral studies. The powder x-ray diffraction patterns reveal both the presence of crystalline alpha-iron and gold and the absence of any crystalline iron oxides or other crystalline products. First-order reversal curves, along with the major hysteresis loops of the Fe/Au nanoparticles have been measured as a function of time in order to investigate the evolution of their magnetic properties. The iron-57 Moessbauer spectra of both uncoated iron nanoparticles and the Fe/Au nanoparticles have been measured at 78 and 295 K and indicate that two major iron containing components are present, namely the expected alpha-iron and the unexpected amorphous Fe1-xBx alloy; several poorly crystallized ordered iron(III) oxide components as well as paramagnetic iron(II) and iron(III) components are also observed. These results indicate that the Fe-core/Au-shell nanoparticles synthesized through reverse micelles are far more complex that had been believed., 31 pages, 1 table, 8 figures, to appear in Chemistry of Materials

The new ligands Na[(p-IC6H4)B(3-Rpz)3] (R = H, Me) have been prepared by converting I2C6H4 to IC6H4SiMe3 with Li(t)Bu and SiMe3Cl, and then to IC6H4BBr2 with BBr3 and subsequent reaction with 3 equiv of (un)substituted pyrazole and 1 equiv of NaO(t)Bu. These new ligands react with FeBr2 to give either purple, low-spin Fe[(p-IC6H4)B(pz)3]2 or colorless, high-spin Fe[(p-IC6H4)B(3-Mepz)3]2. Depending upon the crystallization conditions, Fe[(p-IC6H4)B(3-Mepz)3]2 can exist both as two polymorphs and as a methylene chloride solvate. An examination of these polymorphs by variable-temperature X-ray crystallography, magnetic susceptibility, and Mossbauer spectroscopy has revealed different electronic spin-state crossover properties for each polymorph and yields insight into the influence of crystal packing, independent of other electronic perturbations, on the spin-state crossover. The first polymorph of Fe[(p-IC6H4)B(3-Mepz)3]2 has a highly organized three-dimensional supramolecular structure and does not undergo a spin-state crossover upon cooling to 4 K. The second polymorph of Fe[(p-IC6H4)B(3-Mepz)3]2 has a stacked two-dimensional supramolecular structure, a structure that is clearly less well organized than that of the first polymorph, and undergoes an abrupt iron(II) spin-state crossover from high spin to low spin upon cooling below ca. 130 K. The crystal structure of the methylene chloride solvate of Fe[(p-IC6H4)B(3-Mepz)3]2 has a similar stacked two-dimensional supramolecular structure, but the crystals readily lose the solvate. The resulting desolvate undergoes a gradual spin-state crossover to the low-spin state upon cooling below ca. 235 K. It is clear from a comparison of the structures that the long-range solid-state organization of the molecules, which is controlled by noncovalent supramolecular interactions, has a strong impact upon the spin-state crossover, with the more highly organized structures having lower spin-crossover temperatures and more abrupt spin-crossover behavior.

Sonogashira coupling reactions of terminal alkynes with Fe[(p-IC6H4)B(3-Mepz)3]2 (pz = pyrazolyl ring) yield Fe[(p-PhC2C6H4)B(3-Mepz)3]2 (2), Fe[(p-Me3SiC2C6H4)B(3-Rpz)3]2 (R = H, 3a, R = Me, 3b), and Fe[(p-HC2C6H4)B(3-Mepz)3]2 (R = H, 4a, R = Me, 4b), a series of new complexes containing "third generation" poly(pyrazolyl)borate ligands. Complex 2 undergoes a fairly gradual iron(II) electronic spin-state crossover with a 30 K hysteresis, whereas complex 3b is an unusual example of a complex with equivalent iron(II) sites in the high-spin form that shows an abrupt 50% spin crossover. For complex 4b, 50% of the iron(II) sites undergo a gradual spin-state transition between 185 and 350 K with an activation energy of 1590 +/- 30 cm(-1) and a T(1/2) = 280 K and, for the remaining iron(II) sites, an abrupt cooperative spin-state crossover between 106 and 114 K. The crystal structures of 4b obtained for each of the three distinct electronic spin states reveal two crystallographically different iron(II) sites, and analysis of the molecular/supramolecular structures indicates that the difference in the degree of pyrazolyl ring tilting in the ligands between the two sites, rather than the strength of the intermolecular forces, play a prominent role in determining the temperature of the spin-state crossover.

The synthesis and characterization of two new bis(l-alkoxo)-bridged dinuclear iron(III) complexes with the ligands 1-(2hydroxyethyl)-pyrazole (Hnhep) and 1-(2-hydroxyethyl)-3,5-dimethylpyrazole (Hnhed), [Fe(nhep)Cl2(EtOH)]2 (1) and [Fe(nhed)Cl2]2 (2) are reported. The crystal structures of both complexes reveal the presence of centrosymmetric dinuclear units. In compound 1, the iron(III) center has a coordination number of six, with a slightly distorted octahedral geometry. In compound 2, the bulkier nhed ligand, with methyl groups at the 3- and 5-positions of the pyrazole ring, leads to a coordination number of five at the iron(III) center in a distorted square pyramidal geometry. The magnetic properties of both complexes have been investigated in the range 2–300 K and indicate the presence of fairly weak antiferromagnetic exchange interactions between iron(III) ions (J1 = � 10.04 cm � 1 for 1 and J2 = � 12.5 cm � 1 for 2). The inactivity of both complexes in the cyclohexane hydroxylation appears to be partly due to the presence of the strong iron(III)–chloride bond that does not allow exchange with the reactant molecules. � 2004 Published by Elsevier Ltd.