Mobae Afeworki

The new concept of supported ionic liquid catalysis involves the surface of a support material that is modified with a monolayer of covalently attached ionic liquid fragments. Treatment of this surface with additional ionic liquid results in the formation of a multiple layer of free ionic liquid on the support. These layers serve as the reaction phase in which a homogeneous hydroformylation catalyst was dissolved. Supported ionic liquid catalysis combines the advantages of ionic liquid media with solid support materials which enables the application of fixed-bed technology and the usage of significantly reduced amounts of the ionic liquid. The concept of supported ionic liquid catalysis has successfully been used for hydroformylation reactions and can be further expanded into other areas of catalysis.

A combination of solid-state 13C NMR, X-ray photoelectron spectroscopy (XPS) and sulfur X-ray absorption near edge structure (S-XANES) techniques are used to characterize organic oxygen, nitrogen, and sulfur species and carbon chemical/structural features in kerogens. The kerogens studied represent a wide range of organic matter types and maturities. A van Krevelen plot based on elemental H/C data and XPS derived O/C data shows the well established pattern for type I, type II, and type III kerogens. The anticipated relationship between the Rock−Eval hydrogen index and H/C is independent of organic matter type. Carbon structural and lattice parameters are derived from solid-state 13C NMR analysis. As expected, the amount of aromatic carbon, measured by both 13C NMR and XPS, increases with decreasing H/C. The correlation between aromatic carbon and Rock−Eval Tmax, an indicator of maturity, is linear for types II and IIIC kerogens, but each organic matter type follows a different relationship. The average aliphatic carbon chain length (Cn‘) decreases with an increasing amount of aromatic carbon in a similar manner across all organic matter types. The fraction of aromatic carbons with attachments (FAA) decreases, while the average number of aromatic carbons per cluster (C) increases with an increasing amount of aromatic carbon. FAA values range from 0.2 to 0.4, and C values range from 12 to 20 indicating that kerogens possess on average 2- to 5-ring aromatic carbon units that are highly substituted. There is basic agreement between XPS and 13C NMR results for the amount and speciation of organic oxygen. XPS results show that the amount of carbon oxygen single bonded species increases and carbonyl−carboxyl species decrease with an increasing amount of aromatic carbon. Patterns for the relative abundances of nitrogen and sulfur species exist regardless of the large differences in the total amount of organic nitrogen and sulfur seen in the kerogens. XPS and S-XANES results indicate that the relative level of aromatic sulfur increases with an increasing amount of aromatic carbon for all kerogens. XPS show that the majority of nitrogen exists as pyrrolic forms in comparable relative abundances in all kerogens studied. The direct characterization results using X-ray and NMR methods for nitrogen, sulfur, oxygen, and carbon chemical structures provide a basis for developing both specific and general average chemical structural models for different organic matter type kerogens.

A combination of XPS and solid-state 15N NMR have been used to characterize the nitrogen forms in a variety of different carbonaceous samples having high natural nitrogen abundance. It is currently difficult to unequivocally interpret and quantify individual 15N NMR and XPS spectra. The advantages of using a multiple technique approach for nitrogen speciation as well as the limitation of XPS nitrogen (1s) and 15N NMR spectroscopy are discussed. XPS and 15N NMR results show that pyridinic and pyrrolic nitrogen are present in quinoline and isoquinoline pyrolysis chars. Pyridinic nitrogen is the most abundant form in quinoline pitch while isoquinoline pitch produced the most pyrrolic nitrogen. A small amount of quaternary nitrogen (∼10 mol %) appeared in the XPS spectrum of the chars, however, no additional nitrogen forms were identified above the noise level in the 15N NMR spectra. The 15N NMR spectrum of Green River kerogen shows a single broad feature centered around −245 ppm in the 15N NMR, consistent with the position of pyrrolic nitrogen forms. XPS spectra of Green River kerogen show a large peak at 400.2 eV and the peak at this position in the curve-resolved nitrogen (1s) spectrum is consistent with pyrrolic nitrogen forms. Other XPS peaks were consistent with and attributed to pyridinic quaternary and amine nitrogen species. Acid treatment of Green River kerogen resulted in an increase in the quaternary nitrogen feature in both the XPS and 15N NMR spectra with a concomitant decline in the XPS pyridinic and amine nitrogen features. Pyrolysis of kerogen resulted in the appearance of a peak near −80 ppm in the 15N NMR spectrum attributed to pyridinic nitrogen forms. XPS spectra also show an increase in pyridinic nitrogen upon pyrolysis. XPS results show that the major peak in the curve-resolved nitrogen (1s) spectrum of both fresh and pyrolyzed peats appears at 400.2 eV. Both amide and pyrrolic nitrogen appear at this energy position and it is impossible to distinguish between these two species based on XPS data alone. For fresh peat, the major peak in the 15N NMR spectrum occurs at chemical shift positions consistent with the presence amide nitrogen forms. The main peak in the 15N NMR spectrum of pyrolyzed peats broadens and shifts toward higher field. This change is associated with the loss of amide forms and the appearance of pyrrolic nitrogen forms

A combination of XPS and solid-state 13C NMR techniques have been used to characterize organic oxygen species and carbon chemical/structural features in peats, pyrolyzed peats, lignites, and other coals. Both the 13C NMR and XPS results show the same ordering for the amount of aromatic carbon, higher ranking coals > lignites > peats. In general the value for H/C decreases as the percent of aromatic carbon increases. For pyrolyzed peats, the H/C level is higher than lignites and other coals of comparable levels of aromatic carbon. This is likely due to significant differences in the carbon structural framework of these materials. A van Krevelen plot, based on elemental H/C data and XPS derived O/C data, shows the well-established pattern for peats, lignites, and other coals. In general, O/C decreases as the percent of aromatic carbon increases, with the expected magnitude ordering, peats > lignites > higher ranking coals. Most of the H/C values of pyrolyzed peats are higher than coals at comparable O/C. A range of O/C levels (0.23−0.13) were produced from pyrolysis of peats; however, these data, when plotted versus the percent aromatic carbon, fall below the values for lignites and other coals. These results indicate that simple pyrolysis does not appear to fully capture the chemical transformations encountered during the natural formation of coals. Both XPS and 13C NMR results are sensitive to the basic difference in the kinds of organic oxygen species found in peats and coals. The advantages of using a combination of XPS and 13C NMR along with the pitfalls of using a single technique for organic oxygen speciation are discussed. For peats, pyrolyzed peats, lignites, and other coals, XPS results for the total amount of organic oxygen fall between upper and lower limit estimates based on 13C NMR derived parameters associated with different oxygen species. For lignites and other coals, there is a sharp drop in the number of carbonyl and carboxyl groups near 60% aromatic carbon. The amount of carbon− oxygen single-bonded species reflected in the NMR parameters falO and faOCH3 and the XPS parameter C−O oxygen, decrease as the percent aromatic carbon increases. The highest levels of phenolic and phenoxy oxygen are found near 60% aromatic carbon. NMR results show that the amount of phenolic and phenoxy carbon (faP) and aliphatic carbon−oxygen single-bonded species (falO) are very similar for pyrolyzed peats, lignites, and other coals at comparable levels of aromatic carbon. These results indicate that thermal decarboxylation/decarbonylation and demethoxylation pathways exist for peat and suggest that similar pathways occur during natural coalification processes.

The first zeolite structure (ITQ-40) that contains double four (D4) and double three (D3) member ring secondary building units has been synthesized by introducing Ge and NH(4)F and working in concentrated synthesis gels. It is the first time that D3-Rs have been observed in a zeolite structure. As was previously analyzed [Brunner GO, Meier, WM (1989) Nature 337:146-147], such a structure has a very low framework density (10.1 T/1,000 A(3)). Indeed, ITQ-40 has the lowest framework density ever achieved in oxygen-containing zeolites. Furthermore, it contains large pore openings, i.e., 15-member rings parallel to the [001] hexagonal axis and 16-member ring channels perpendicular to this axis. The results presented here push ahead the possibilities of zeolites for uses in electronics, control delivery of drugs and chemicals, as well as for catalysis.