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Different opinions on the oil-source correlation and migration of the Moxizhuang-Yongjin block in the Junggar Basin, NW China, have seriously affected oil and gas exploration in this area. This research is based on the results of biomarker analysis and carbon isotope of monomer hydrocarbon on crude oil and source rock samples from different blocks. Two oil families (A1, A2, and B) are classified by cluster analysis on nine typical biomarker ratios. Typically, sub-family A1 oils are distributed in the Zhuang 102 well block of the Moxizhuang block, and their gammacerane index is the highest. The abundance of C

The catalytic partial oxidation of methane is achieved at low temperatures (90% at ∼35% methane conversion at approximately 6 turnovers. Under our catalytic methane oxidation reaction conditions, MeTFA is stable against overoxidation, which explains the likely high selectivity at conversions >15%. Using combined experimental studies and DFT calculations, a mechanism involving soluble and molecular Mn species in the catalytic cycle is proposed. The proposed reaction pathway involves initial activation of Mnᴵᴵ by dioxygen, cleavage of a methane C–H bond by a Mnᴵᴵᴵ hydroxo intermediate, rebound of the methyl radical to generate MeTFA, and finally regeneration of the starting MnII complex. Also, this process is shown to be applicable to the oxidation of ethane, favoring the mono-oxidized product ethyl trifluoroacetate (EtTFA) and reaching ∼46% conversion.

Ceria has been used as a hydrogenation catalyst especially in selective alkyne hydrogenation, but the reaction mechanism regarding the role of different surface hydrogen species remains unclear. In...

Two unusual tricyclic terpanes (compounds X and Y) and four tetracyclic terpanes (compounds X1, Y1, Z, and Z1) have been detected in crude oils from the Pearl River Mouth, Beibuwan, and Liaohe basi...

Metal oxides with high porosity usually exhibit better performance in many applications, as compared with the corresponding bulk materials. Template-assisted method is generally employed to prepare porous metal oxides. However, the template-assisted method is commonly operated in wet conditions, which requires solvents, soluble metal oxide precursors, and a long time for drying. To overwhelm those drawbacks of the wet procedure, a mechanochemical nanocasting method is developed in the current work. Inspired by solid-state synthesis, this strategy proceeds without solvents, and the ball milling process can enable pores replicated in a shorter time (60 min). By this method, a series of highly porous metal oxides were obtained, with several cases approaching the corresponding surface area records (e.g., ZrO2, 293 m2 g–1; Fe2O3, 163 m2 g–1; CeO2, 211 m2 g–1; CuOx-CeOy catalyst, 237 m2 g–1; CuOx-CoOy-CeOz catalyst, 203 m2 g–1). Abundant nanopores with clear lattice fringes in metal oxide products were witnesse...

Reservoir geochemistry has a practical application in petroleum exploration. A typical Paleozoic carbonate oilfield was selected from the Tabei Uplift of the Tarim Basin (northwestern China) to exhibit the method, application, and exploration implications of reservoir geochemistry. Oil–oil correlation indicates that all oils analyzed in this study belong to one single oil group. The overall oil migration direction traced by selected organic molecular markers is from the southern to the northern regions of the Halahatang region. The source kitchen for current oil accumulations in the carbonate reservoir is predicted to locate to the south of this oilfield, most likely between the Awati and Manjiaer depressions. Based on the characteristics of hydrocarbon-bearing inclusions and the histograms of the homogenization temperatures (Th) and ice-melting temperatures of associated aqueous inclusions, the oil charging temperatures were obtained. The stratigraphic-burial and geothermal histories for representative i...

The effect of surface structure of TiO2 nanocrystals on the structure, amount, and strength of adsorbed CO2 and resistance to SO2 was investigated using in situ IR spectroscopy and mass spectrometric techniques along with first-principles density functional theory (DFT) calculations. TiO2 nanoshapes, including rods {(010) + (101) + (001)}, disks {(001) + (101)}, and truncated octahedra {(101) + (001)}, were used to represent different TiO2 structures. Upon CO2 adsorption, carboxylates and carbonates (bridged, monodentate) are formed on TiO2 rods and disks, whereas only bidentate and monodentate carbonates are formed on TiO2 truncated octahedra. In general, the order of thermal stability of the adsorbed CO2 species is carboxylates ≈ monodentate carbonates > bridged carbonates > bidentate carbonates ≈ bicarbonates. TiO2 rods and disks adsorb CO2 more strongly than TiO2 truncated octahedra, which is explained by the larger number of low coordinated surface oxygen and oxygen vacancies on the rods and disks th...

The kinetics and mechanism of methanol dehydration, redox, and oxidative coupling were investigated at 300 °C under dilute oxygen concentration over anatase TiO2 nanoplates and truncated-bipyramidal nanocrystals in order to understand the surface structure effect of TiO2. The two TiO2 nanoshapes displayed both (001) and (101) facets, with a higher fraction of the (001) facet exposed on the nanoplates, while truncated-bipyramidal nanocrystals were dominated by the (101) facet. A kinetic study using in situ titration with ammonia shows that the active sites for methanol dehydration are acidic and nonequivalent in comparison to redox and oxidative coupling. In situ FTIR spectroscopy reveals that adsorbed methoxy is the dominant surface species for all reactions, while the observed methanol dimer is found to be a spectator species through isotopic methanol exchange, supporting the dissociative mechanism for methanol dehydration via surface methoxy over TiO2 surfaces. Density functional theory calculations sho...

An ultrastable Au nanocatalyst based on a heterostructured perovskite support with high surface area and uniform LaFeO3 nanocoatings was successfully synthesized and tested for CO oxidation. Strikingly, small Au nanoparticles (4–6 nm) are obtained after calcination in air at 700 °C and under reaction conditions. The designed Au catalyst not only possessed extreme sintering resistance but also showed high catalytic activity and stability because of the strong interfacial interaction between Au and the heterostructured perovskite support.

1H nuclear magnetic resonance (NMR) spectroscopy was used to study hydroxylic surface species on ceria nanocubes, a crystalline, high-surface-area CeO2 that presents mostly (100) facets. Water adsorption and desorption experiments in combination with fast magic angle spinning (MAS, 20–40 kHz) 1H NMR provide high-resolution 1H spectra that allow the observation of ten resonance bands (water or hydroxyl) on or under the (100) surface. Assignments were made using a combination of adsorption and temperature-programmed desorption, quantitative spin counting, deuterium exchange, spin–lattice (T1) and spin–spin (T2) relaxation, and DFT calculations. In air, the (100) surface exists as a fully hydroxylated surface. Water adsorption and dissociation on dry ceria surfaces occur first at oxygen vacancies, but Ce3+ centers are not required since water dissociation is barrier-less on the fully oxidized surface. Surface −OH functionality occurs in two resolved bands representing isolated −OH (1 ppm) and hydrogen-bonded...

The distribution of phenyldibenzofurans (PhDBFs) and methyldibenzofurans (MDBFs) and their potential implications in petroleum organic geochemistry have been investigated for sediment extracts and crude oils derived from lacustrine shale, marine shale, marine carbonate, and terrestrial (fluvial/deltaic/fresh water) mudstone. PhDBF isomers in a set of lacustrine shales from the Liaohe Basin (East China) are identified in the m/z 244 mass chromatograms of the aromatic fraction by coinjection of internal synthetic standards on a high resolution capillary column (HP-5MS). The results show that the relative abundance of 4-PhDBF/2-PhDBF and 4-PhDBF/(2-PhDBF+3-PhDBF) increase gradually with increasing burial depth and maturity (R0 ≥ 0.6%), and have a good correlation with vitrinite reflectance in lacustrine shales from wells S202 and SG1 in the Liaohe Basin. These two ratios, defined as phenyldibenzofuran ratio-1 and -2 (PhFR-1 and PhFR-2), may be potential maturity indicators for mature sediments in this study....

Mango proposed a significant invariance of four isoheptanes, in which a ratio of sums (K1) remains at approximately 1, regardless of the absolute concentrations. Gas chromatographic analyses of 70 oils from the Tarim Basin demonstrated that most of these oils share invariant K1 values close to 1.0, even if they are derived from different sources and have varying degrees of maturity and biodegradation. However, a few unexpectedly high K1 values occurred in certain oils from the Tazhong-4 Oilfield in the Tazhong Uplift, and these oils are characterized by abnormally high contents of dibenzothiophenes (DBTs). An excellent positive correlation between the elevated K1 values and the abnormally high DBT contents indicated that the thermochemical sulfate reduction (TSR) alteration, which contributed to the increased DBT contents, likely resulted in the elevated K1 values. Methylhexanes (MHs) are assumed to be more susceptible to TSR than dimethylpentanes (DMPs), and the terminal methyl groups of C7 compounds are...

A total of 32 oils and condensates were collected from four gas/oil fields (Dalaoba, Luntai, Kuqa, and Yakela) in the Yakela Faulted Uplift (Tarim Basin, northwest China). The composition of biomarkers and a previous study show that oils and condensates in the Dalaoba, Luntai, and Kuqa gas/oil fields originated from lacustrine mudstone/shale source rocks deposited in an oxic environment. Oils and condensates from the Yakela gas/oil field are of typical marine carbonate origin. Some phenyl-substituted polycyclic aromatic hydrocarbons, including phenylnaphthalenes (PhNs) and terphenyls (TrPs), were unequivocally detected in most of these oils and condensates. They are present in significant abundance in oils and condensates from the Dalaoba, Luntai, and Kuqa gas/oil fields. However, the concentrations of PhNs and TrPs are relatively lower or below the detection limit in oils and condensates from the Yakela gas/oil field. The ratios of 2-PhN/2-MN and m-TrP/3-MBP are used in this study to describe the abundan...

The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly(vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligands (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in ...

Seawater contains a large amount of uranium (∼4.5 billion tons) which can serve as a nearly limitless supply for an energy source. However, to make the recovery of uranium from seawater economically feasible, lower manufacturing and deployment costs are desirable, and good solid adsorbents must have high uranium uptake, reusability, and high selectivity toward uranium. In this study, atom-transfer radical polymerization (ATRP), without the high-cost radiation-induced graft polymerization, was used for grafting acrylonitrile and tert-butyl acrylate from a new class of trunk fibers, forming adsorbents in a readily deployable form. The new class of trunk fibers was prepared by the chlorination of polypropylene (PP) round fiber, hollow-gear PP fiber, and hollow-gear polyethylene fiber. During ATRP, degrees of grafting (d.g.) varied according to the structure of active chlorine sites on trunk fibers and ATRP conditions, and the d.g. as high as 2570% was obtained. Resulting adsorbent fibers were evaluated in U-...

The effects of the surface structure of ceria (CeO2) on the nature, strength, and amount of species resulting from SO2 adsorption were studied using in situ IR and Raman spectroscopies coupled with mass spectrometry, along with first-principles calculations based on density functional theory (DFT). CeO2 nanocrystals with different morphologies, namely, rods (representing a defective structure), cubes (100 facet), and octahedra (111 facet), were used to represent different CeO2 surface structures. IR and Raman spectroscopic studies showed that the structure and binding strength of adsorbed species from SO2 depend on the shape of the CeO2 nanocrystals. SO2 adsorbs mainly as surface sulfites and sulfates at room temperature on CeO2 rods, cubes, and octahedra that were either oxidatively or reductively pretreated. The formation of sulfites is more evident on CeO2 octahedra, whereas surface sulfates are more prominent on CeO2 rods and cubes. This is explained by the increasing reducibility of the surface oxyge...

In addition to their well-known redox character, the acid–base property is another interesting aspect of ceria-based catalysts. Herein, the effect of surface structure on the acid–base property of ceria was studied in detail by utilizing ceria nanocrystals with different morphologies (cubes, octahedra, and rods) that exhibit crystallographically well-defined surface facets. The nature, type, strength, and amount of acid and base sites on these ceria nanoshapes were investigated via in situ IR spectroscopy combined with various probe molecules. Pyridine adsorption shows the presence of Lewis acid sites (Ce cations) on the ceria nanoshapes. These Lewis acid sites are relatively weak and similar in strength among the three nanoshapes according to the probing by both pyridine and acetonitrile. Two types of basic sites, hydroxyl groups and surface lattice oxygen are present on the ceria nanoshapes, as probed by CO2 adsorption. CO2 and chloroform adsorption indicate that the strength and amount of the Lewis bas...

Dibenzofuran (DBF), its alkylated homologues, and benzo[b]naphthofurans (BNFs) are common oxygen-heterocyclic aromatic compounds in crude oils and source rock extracts. A series of positional isomers of alkyldibenzofuran and benzo[b]naphthofuran were identified in mass chromatograms by comparison with internal standards and standard retention indices. The response factors of dibenzofuran in relation to internal standards were obtained by gas chromatography–mass spectrometry analyses of a set of mixed solutions with different concentration ratios. Perdeuterated dibenzofuran and dibenzothiophene are optimal internal standards for quantitative analyses of furan compounds in crude oils and source rock extracts. The average concentration of the total DBFs in oils derived from siliciclastic lacustrine rock extracts from the Beibuwan Basin, South China Sea, was 518 μg/g, which is about 5 times that observed in the oils from carbonate source rocks in the Tarim Basin, Northwest China. The BNFs occur ubiquitously in source rock extracts and related oils of various origins. The results of this work suggest that the relative abundance of benzo[b]naphthofuran isomers, that is, the benzo[b]naphtho[2,1-d]furan/{benzo[b]naphtho[2,1-d]furan + benzo[b]naphtho[1,2-d]furan} ratio, may be a potential molecular geochemical parameter to indicate oil migration pathways and distances.

Methanol has been considered as a “smart” molecule in studying the surface sites of metal oxide catalysts. In this work, methanol was utilized to probe the nature of surface sites of ceria nanocrystals with defined surface planes (nanoshapes), including rods (containing {110}), cubes ({100}), and octahedra ({111}). The adsorption and desorption of methanol were followed by in situ IR and Raman spectroscopy as well as mass spectrometry. Upon methanol adsorption at room temperature, on-top, bridging and three-coordinate methoxy species are formed on the surface of rods and cubes, whereas only on-top methoxy is present on the octahedra surface. The distribution of the methoxy species is believed to be determined not only by the coordination status of surface Ce cations but also by the number of defect sites on the three nanoshapes. During the desorption process, the methoxy species are gradually dehydrogenated into H2 and CO via formate species as intermediates on the three ceria surfaces. A second intermedi...

The support effect has long been an intriguing topic in catalysis research. With the advancement of nanomaterial synthesis, the availability of faceted oxide nanocrystals provides the opportunity to gain unprecedented insights into the support effect by employing these well-structured nanocrystals. In this Letter, we show by utilizing ceria nanoshapes as supports for vanadium oxide that the shape of the support poses a profound effect on the catalytic performance of metal oxide catalysts. Specifically, the activation energy of VOx/CeO2 catalysts in oxidative dehydrogenation of isobutane was found to be dependent on the shape of ceria support, rods < octahedra, closely related to the surface oxygen vacancy formation energy and the numbe of defects of the two ceria supports with different crystallographic surface planes.

This paper reports the synthesis of 2.5 nm gold clusters on the oxygen free and chemically labile support carbon nitride (C3N4). Despite having small particle sizes and high enough water partial pressure these Au/C3N4 catalysts are inactive for the gas phase and liquid phase oxidation of carbon monoxide. The reason for the lack of activity is attributed to the lack of surface −OH groups on the C3N4. These OH groups are argued to be responsible for the activation of CO in the oxidation of CO. The importance of basic −OH groups explains the well documented dependence of support isoelectric point versus catalytic activity.

The mechanism of the size-dependent outer/inner phase transformation in ultrafine TiO2 particles with narrowed size distribution was intensively investigated using UV Raman spectroscopy, X-ray diffraction, and transmission electron microscopy. Particle size is found to be the critical parameter determining the onset transition temperature and nucleation performance. The transformation temperature was decreased with the decrease of initial particle size. Rutile nucleates at interfaces of the contacting anatase grains (

Phase transformation of TiO2 from anatase to rutile is studied by UV Raman spectroscopy excited by 325 and 244 nm lasers, visible Raman spectroscopy excited by 532 nm laser, X-ray diffraction (XRD), and transmission electron microscopy (TEM). UV Raman spectroscopy is found to be more sensitive to the surface region of TiO2 than visible Raman spectroscopy and XRD because TiO2 strongly absorbs UV light. The anatase phase is detected by UV Raman spectroscopy for the sample calcined at higher temperatures than when it is detected by visible Raman spectroscopy and XRD. The inconsistency in the results from the above three techniques suggests that the anatase phase of TiO2 at the surface region can remain at relatively higher calcination temperatures than that in the bulk during the phase transformation. The TEM results show that small particles agglomerate into big particles when the TiO2 sample is calcined at elevated temperatures and the agglomeration of the TiO2 particles is along with the phase transformation from anatase to rutile. It is suggested that the rutile phase starts to form at the interfaces between the anatase particles in the agglomerated TiO2 particles; namely, the anatase phase in the inner region of the agglomerated TiO2 particles turns out to change into the rutile phase more easily than that in the outer surface region of the agglomerated TiO2 particles. When the anatase particles of TiO2 are covered with highly dispersed La2O3, the phase transformation in both the bulk and surface regions is significantly retarded, owing to avoiding direct contact of the anatase particles and occupying the surface defect sites of the anatase particles by La2O3.

By using XRD, TG-DTA, NMR, and UV resonance Raman spectroscopy, the nature and location of vanadium species between VAPO-5 and VAPSO-5 molecular sieves were comparatively studied. It was found that different vanadium species exist in VAPO-5 and VAPSO-5 molecular sieves. Polymerized vanadium oxides and bulk V2O5 crystallites are the main vanadium species in VAPO-5 molecular sieves. However, in VAPSO-5 molecular sieves, tetrahedrally coordinated vanadium species are dominant. Namely, most of the vanadium species in VAPO-5 exist outside the framework, whereas most of the vanadium species in VAPSO-5 are incorporated into the framework. The formation of framework vanadium in VAPSO-5 molecular sieves is found to be associated essentially with the presence of framework silicon atoms.

Ti-substituted mesoporous SBA-15 (Ti−SBA-15) materials have been synthesized by using a new approach in which the hydrolysis of the silicon precursor (tetramethoxysilane, TMOS) is accelerated by fluoride. These materials were characterized by powder X-ray diffraction patterns (XRD), X-ray fluorescence spectroscopy (XRF), N2 sorption isotherms, diffuse-reflectance UV−visible (UV−vis) and UV−Raman spectroscopy, 29Si MAS NMR, and the catalytic epoxidation reaction of styrene. Experiments show that Ti−SBA-15 samples of high quality can be obtained under the following conditions: F/Si ≥ 0.03 (molar ratio), pH ≤ 1.0, aging temperature ≤ 80 °C, and Ti/Si ≤ 0.01. It was found that the hydrolysis rate of TMOS was remarkably accelerated by fluoride, which was suggested to play the main role in the formation of Ti−SBA-15 materials of high quality. There is no stoichiometric incorporation of Ti, and the Ti contents that are obtained are quite low in the case of the approach that is proposed. The calcined Ti−SBA-15 m...

The phase transformation of zirconia from tetragonal to monoclinic is characterized by UV Raman spectroscopy, visible Raman spectroscopy, and XRD. Electronic absorption of ZrO2 in the UV region makes UV Raman spectroscopy more sensitive at the surface region than XRD or visible Raman spectroscopy. Zirconia changes from the tetragonal phase to the monoclinic phase with calcination temperatures elevated and monoclinic phase is always detected first by UV Raman spectroscopy for the samples calcined at lower temperatures than that by XRD and visible Raman spectroscopy. When the phase of zirconia changes from tetragonal to monoclinic, the slight changes of the phase at very beginning can be detected by UV Raman spectroscopy. UV Raman spectra clearly indicate that the phase transition takes place initially at the surface regions. It is found that the phase change from tetragonal to monoclinic is significantly retarded when amorphous Zr(OH)4 was agglomerated to bigger particles and the particle agglomeration of ...

Titanium-containing mesoporous molecular sieve Ti−MCM-41 has been synthesized using colloidal silica as the silicon source and TiCl3 solution as the titanium source and was characterized by X-ray diffraction, N2 adsorption, UV−vis, and UV−Raman spectroscopies. The formation of anatase TiO2 can be avoided during the synthesis and the crystallization of the molecular sieve because of the relatively low hydrolysis rate of an inorganic TiCl3 solution. The characterization results confirm that most Ti4+ ions are isolated and tetrahedrally coordinated in the framework of MCM-41. Different auxiliary templates, tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrabutylammonium hydroxide, and NH3·H2O were used to synthesize the Ti−MCM-41 molecular sieve. Among them, TMAOH and TEAOH were found to be the most effective auxiliary templates to improve the long-ranged order of the molecular sieves.