Low Molecular Weight Alkanes Research Articles

Alternative Production of Hydrocarbons from Natural Gas (Methane) via Synthesis Gas and Methanol

Abstract As a result of research, it has been found that DME from natural gas (methane), oil production and oil refinery wastes and low molecular weight olefins based on it are studied. Therefore, methanol and DME, along with synthesis gas, are relevant for the improvement of the production technology of environmentally friendly motor fuels. The most active and selective catalysts for the dehydration of methanol in DME have a texture that allows the resulting DME to desorb from the surface without steric hindrance. Such “open surface” catalysts of acidic nature include mesoporous γ - Al2O3 and large-pore zeolite HU, whose promotion with H3PO4 achieves 100 % selectivity for DME formation at 88-90 % conversion of methanol. Experiments were performed by varying the amount of methanol in the CH3OH : (CO + H2) reaction mixture from 25 to 100 % by volume. In the main experiments with CO : H2 = 1:1 ratio, the linear speed of the reaction gas flow was kept constant at 3.8 ÷ 0.2 cm3 min−1, that is, the contact time was kept constant for 15.5-16 s. The reaction products were analyzed by gas chromatography.

Cationic Tantalum Hydrides Catalyze Hydrogenolysis and Alkane Metathesis Reactions of Paraffins and Polyethylene.

Sulfated aluminum oxide (SAO), a high surface area material containing sulfate anions that behave like weakly coordinating anions, reacts with Ta(═CHtBu)(CH2tBu)3 to form [Ta(CH2tBu)2(O-)2][SAO] (1). Subsequent treatment with H2 forms Ta-H+ sites supported on SAO that are active in hydrogenolysis and alkane metathesis reactions. In both reactions Ta-H+ is more active than related neutral Ta-H sites supported on silica. This reaction chemistry extends to melts of high-density polyethylene (HDPE), where Ta-H+ converts 30% of a low molecular weight HDPE (Mn = 2.5 kg mol-1; Đ = 3.6) to low molecular weight paraffins under hydrogenolysis conditions. Under alkane metathesis conditions Ta-H+ converts this HDPE to a high MW fraction (Mn = 6.2 kDa; Đ = 2.3) and low molecular weight alkane products (C13-C32). These results show that incorporating charge as a design element in supported d0 metal hydrides is a viable strategy to increase the reaction rate in challenging reactions involving reorganization of C-C bonds in alkanes.

New insights into the pyrolysis of n-tetradecane using ReaxFF molecular dynamics simulations: Implications for understanding the thermal cracking of subsurface crude oil

The fragmentation of normal alkanes during the cracking of oil under geochemical conditions with high thermal stress is important for the preservation of crude oils in reservoirs and the formation of gaseous hydrocarbons. In this study, the kinetics behavior, cracking mechanisms, and products of n-tetradecane pyrolysis were investigated using reactive molecular dynamics (ReaxFF MD) simulations at high temperatures (2000K∼3000 K). The pyrolysis process itself, its main products and intermediates, and kinetic behavior were analyzed at an atomic/molecular level. Low molecular weight (C1–C5) alkanes and olefins, together with H2, were the predominant intermediates and products of the simulations. Three distinct stages—a stable stage, initial decomposition, and secondary pyrolysis—can be distinguished during the decomposition process. The reactant n-tetradecane was exhausted when the simulation temperature reaches ∼2250 K, accompanied by a rapid increase in hydrocarbons with molecular numbers C1–C5. The yield of C2–C5 peaked at ∼2500 K and then decreased. The number of CH4 molecules increased continuously throughout the entire simulation process because of the contribution of secondary pyrolysis. The Arrhenius parameters obtained from ReaxFF MD simulations, on the basis of first-order kinetic analysis of n-tetradecane, were reasonably consistent with experimental data and generally in agreement with results from pyrolysis experiments on crude oils in the laboratory. The pyrolysis process and reaction mechanism of n-tetradecane were also reasonably consistent with laboratory pyrolysis experiments on whole oils and their individual components. ReaxFF molecular dynamics simulation is therefore considered to be a valid approach for the study of thermal cracking of subsurface crude oils.

Cell-like microparticles with tunable acoustic properties for calibrating devices

Mechanophenotype of biological cells has demonstrated correlation with biomolecular states and cell function. Hence, new methods to measure mechanophenotype at high throughput are of growing interest. Acoustophoretic microdevices can characterize cell mechanical features; however, calibration particles with physiologically relevant properties are needed to quantify and optimize device performance. Currently, conventional polymer microspheres are rigid and do not replicate cell deformation and compressibility. To address this, we developed monodisperse, tunable, cell-like microparticles (MPs) from polyacrylamide hydrogel, fabricated with a microfluidic droplet generator. Size and compressibility are adjusted by fabrication parameters, and density is adjusted by incorporation of nanoparticles (NPs). Here, we present for the first time microparticles of reduced density and acoustic contrast (lower than unloaded MPs) achieved by loading MPs with nanoparticles of low molecular weight alkanes. We produced the NPs by sonication and photopolymerization before addition to the MP precursor. NP-loaded MPs were less dense than unloaded MPs at 1005.9 and 1013.6kg/m3, respectively, and they exhibited negative acoustic contrast by acoustophoresis in aqueous medium while that of unloaded MPs was positive. These new particles extend the tunable range of acoustic contrast, mimicking and exceeding that of most biological cells and could also aid cell separation when conjugated to cells.

Geochemical Properties of Heavy Oil in Central Sumatra Basin

Heavyoilcommonly occurs due to biodegradation, whichmade the lighter fractiondisappears and then leaves the heavier fraction. Heavy oil is characterized by asphaltic, solid, and viscous because it contains asphalthene. Chemically, heavy oils contain fewer hydrogen atoms than light oils. Bulk properties ofheavy oil in addition to having a specific gravity of less than 25° API gravity, high viscosity, and often contain (concentration) of heavy metals (vanadium, nickel) which is higher than light oil (normal oil). Geochemical analysis based on the gas chromatography (GC) chromatogram of heavy oil in the Central Sumatra Basin shows a different pattern. The chromatogram pattern eliminates the light molecular fractions of the compounds in biodegraded oil and tar sand/bitumen. According to their geochemical properties, there are 4 (four) types of heavy oil in the Central Sumatra Basin namely: Type l come from shallow reservoir, water wash, and full biodegradation/all alkane depleted); Type 2 come from shallow reservoir, meteoric water, and light biodegradation, only low molecular weight alkane depleted); Type 3 come from deep reservoir, vertical gravity segregation, decreased weight fraction, can be caused by oil conditions in thick reservoirs, covered by impermeable lithology and usually located on the edge of the field (flank). Type 4 which contains medium-heavy oil (27°API) and is difficult to produce.

Перспективы использования попутного нефтяного газа в России и за рубежом

The article analyzes the current state and prospects of utilization of associated petroleum gas (APG), the main components of which are methane and other low molecular weight alkanes. When separated from crude oil, APG contains hydrocarbons such as ethane, propane, butane, and pentane, as well as water vapor, hydrogen sulfide (H2S), carbon dioxide (CO2), nitrogen (N2) and other components. Associated petroleum gas containing such impurities cannot be used without purification. The authors noted that the shortage of APG processing capacities both in the Russian Federation and in the world is one of the reasons for the high level of gas flaring in oil fields. In 2022, oil production decreased by 8% (from 82 million barrels per day in 2021 to 76 million barrels per day), while global gas flaring decreased by 5% (from 150 billion cubic meters in 2021 to 142 billion cubic meters). Russia, Iraq, Iran, the United States of America, Algeria, Venezuela, and Nigeria have remained the top seven countries in gas flaring for nine consecutive years since the first of two satellites to monitor gas flares from space was launched in 2012. These seven countries produce 40% of the world's oil annually, but they account for about two-thirds (65%) of the world's gas flaring. Rational methods of utilization of associated petroleum gas were determined, which depend on the conditions of oil production, such as the characteristics of the field, the oil/gas ratio (gas-oil factor), as well as market opportunities for the extracted gas. An algorithm for choosing the technology of rational use of APG in oil and gas companies is proposed. An overview of all APG utilization methods is given, which focuses on unit costs, economic benefits, and the nature of the environmental impact. The innovative experience of the effective use of APG in the USA and Canada is analyzed. Particular attention is paid to the need to solve the problem of the effective use of APG in the world, especially to reduce the volume of flaring.

Catalysts for the Conversion of CO2 to Low Molecular Weight Olefins-A Review.

There is a large worldwide demand for light olefins (C2=–C4=), which are needed for the production of high value-added chemicals and plastics. Light olefins can be produced by petroleum processing, direct/indirect conversion of synthesis gas (CO + H2) and hydrogenation of CO2. Among these methods, catalytic hydrogenation of CO2 is the most recently studied because it could contribute to alleviating CO2 emissions into the atmosphere. However, due to thermodynamic reasons, the design of catalysts for the selective production of light olefins from CO2 presents different challenges. In this regard, the recent progress in the synthesis of nanomaterials with well-controlled morphologies and active phase dispersion has opened new perspectives for the production of light olefins. In this review, recent advances in catalyst design are presented, with emphasis on catalysts operating through the modified Fischer–Tropsch pathway. The advantages and disadvantages of olefin production from CO2 via CO or methanol-mediated reaction routes were analyzed, as well as the prospects for the design of a single catalyst for direct olefin production. Conclusions were drawn on the prospect of a new catalyst design for the production of light olefins from CO2.

Geochemical Characterization of Some Biodegraded Oils from the Niger Delta Basin, Nigeria

This study aimed to examine the compositional changes resulting from biodegradation, fathom the extent of degradation, and provide clues for interpreting the evolution and the overall effects on the quality of the oils. Ten oil samples from onshore-offshore fields were analyzed using gas chromatography (GC) and GC-mass spectrometry (GC-MS) methods. GC results indicate variable loss of low molecular weight (LMW) alkanes, besides the presence of unresolved complex mixture (UCM). Saturated, aromatic, resins, and asphaltenes (SARA) compositions and low saturate/aromatic ratio confirmed evidence of biodegradation. Biodegradation levels of the considered oils range from light to moderate, based on Peters and Moldowan scale. This influenced shifts in the ‘primary compositions’ of oils probably from paraffinic or paraffinic-naphthenic oils to aromatic-naphthenic oils. Total ion chromatograms of well 1 and 2 from Northern depobelt, show presence of LMW alkanes, co-existing side by side with UCM, suggesting multiple charges. However, biomarker fingerprints of the oils lack evidence of in-reservoir mixing of biodegraded and non-biodegraded oils. Nevertheless, the possibility of oil mixing cannot be excluded, because biodegradation is progressive and is ongoing. This study, shows the process has dramatically impacted the fluid properties, commercial worth, and economic producibility of the investigated oil accumulations in the basin.

Influence of oil types on the formation and stability of nano-emulsions by D phase emulsification

The effect of oil types on the formation and stability of nano-emulsions by D phase emulsification method was investigated comprehensively in this paper. Three kind of oils (straight-chain alkanes, branched alkanes, and esters oils) were used and the formation of the nano-emulsions was studied. The stability of prepared nano-emulsions was characterized by the variation curve of the droplet mean diameter within 28 days. It has been found that for alkane oils, the molecular weight was important to the formation and stability of nano-emulsions. Low molecular weight alkane oil (7# mineral oil, Isododecane) formed smaller nano-emulsions (157.3 nm, 125.1 nm), but the emulsions have poor stability. For ester oils containing heteroatoms in the structure, nano-emulsions with bigger particles tended to be formed due to the better affinity of oils to glycerin. In addition, it was found that the formation and stability of nano-emulsions should be discussed separately. Temperature had different effects at different preparation processes.

Effect of dissolution, evaporation, and photooxidation on crude oil chemical composition, dielectric properties and its radar signature in the Arctic environment.

Accidental release of petroleum in the Arctic is of growing concern owing to increases in ship traffic and possible future oil exploration. A crude oil-in-sea ice mesocosm experiment was conducted to identify oil-partitioning trends in sea ice and determine the effect of weathering on crude oil permittivity. The dissolution of the lighter fractions increased with decreasing bulk oil-concentration because of greater oil-brine interface area. Movement of the oil towards the ice surface predominated over dissolution process when oil concentrations exceeded 1 mg/mL. Evaporation decreased oil permittivity due to losses of low molecular weight alkanes and increased asphaltene-resin interactions. Photooxidation increased the permittivity of the crude oil due to the transformation of branched aromatics to esters and ketones. Overall, the weathering processes influenced crude oil permittivity by up to 15%, which may produce sufficient quantifiable differences in the measured normalized radar cross-section of the ice.

Comparative study of a vitrinite-rich and an inertinite-rich Witbank coal (South Africa) using pyrolysis-gas chromatography

This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry. A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample. The vitrinite-rich sample has 83 vol% total vitrinite (mineral-matter-free basis), whereas the inertinite-rich counterpart has 66 vol% total inertinite. The vitrinite-rich sample is dominated by collotelinite and collodetrinite. Fusinite, semifusinite, and inertodetrinite are the main macerals of the inertinite-rich sample. Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR). The pyrolysis products of the coal samples are generally similar, comprised of low and high molecular weight alkanes, alkylbenzenes, alkylphenols, and alkyl-subtituted polycyclic aromatic hydrocarbons, although the vitrinite-rich sample is chemically more diverse. The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history. Based on the 13C CP-MAS SS NMR analysis, the inertinite-rich sample has a greater fraction of phenolics, reflected in the py-GC/MS results as substituted and unsubstituted derivatives. The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample. The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples, though more abundant in the former. The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite macerals.

Detoxification of oil-contaminated soils by using humic acids

The paper deals with the study of the effect of peat mechanoactivation on the structure and biostimulating and detoxifying properties of isolated humic acids (HA) in of oil-contaminated soil. It is shown that the mechanical activation of peat leads to an increase in the HA yield by a factor of 2-3. In this case, the changes in the fragment composition of HA are observed. Hence, the percentage of aromatic and oxidized alkyl fragments increases, while the amount of oxygen-containing functional groups decreases. The binding of petroleum organic compounds occurs due to the presence of an aromatic skeleton in the structure of HA. The increase in the proportion of aromatic fragments in the structure of mechanically activated HAs increases their affinity for hydrophobic oil compounds, thereby providing them a detoxifying ability. The maximum detoxifying ability of mechanically activated HA determines their biostimulating properties in the wheat seed germination experiment. The biostimulating effect from the use of mechanically activated HA samples is manifested itself to a greater degree in the increase in the height of the sprout stem and the dry mass of the aerial part of the plant. The processes of biodegradation of oil in the soil in the presence of HA are investigated. It is shown that the amount of bitumoids extracted from the soil in the presence of HA is reduced by 30%. The content of hydrocarbons in bitumoids decreases by 50% due to the biodegradation of low molecular weight alkanes. At the same time, the degree of branching of hydrocarbon chains increases, which suggests a microbiological activity. An increase in alcohol-benzene resins in the composition of bitumoids indicates the stimulation of hydrocarbon-oxidizing bacteria by humic acids. According to the data of IR spectroscopy, the content of paraffin hydrocarbons has decreased during the destruction of oil by soil microflora.

Hydrotreatment of pyrolysis liquids derived from second-generation bioethanol production residues over NiMo and CoMo catalysts

Lignin-rich digested stillage from second-generation bioethanol production is a unique biomass-derived feedstock, not only because it contains high amounts of lignin but also due to its residual amounts of cellulose and hemicellulose. In this study, catalytic hydrotreatment experiments were conducted on pyrolysis liquids obtained from the lignin-rich feedstock using sulphided NiMo/Al2O3 and CoMo/Al2O3 catalysts. The aim was to obtain a high conversion of the initial pyrolysis feed into a hydrotreated oil with a high phenolics and aromatics fractions. Experiments were carried out in a stirred batch reactor at 350 °C and 10 MPa of H2 (initial pressure). Product oils were obtained in about 60–65% w/w, the remainder being an aqueous phase (12–14% w/w), solids (7–8% w/w) and gas phase components (all on initial pyrolysis oil feed basis). The product oils were characterised in detail using various techniques (elemental composition, GCxGC-FID, GPC, and 2D HSQC NMR). The oxygen content was reduced from 23% w/w in the pyrolysis oils to 7.5–11.5% in the hydrotreated oils, indicative of the occurrence of hydrodeoxygenation reactions. This was also evident from the chemical composition, showing an increase in the amounts of low molecular weight aromatics, alkylphenolics, alkanes and cycloalkanes in hydrotreated oils. Performance of the two catalysts was compared, and a higher degree of deoxygenation was observed for the NiMo catalyst. The implications of the findings for the valorisation of second-generation bioethanol residues are also discussed.

Combining electrokinetic transport and bioremediation for enhanced removal of crude oil from contaminated marine sediments: Results of a long-term, mesocosm-scale experiment

Marine sediments represent an important sink of harmful petroleum hydrocarbons after an accidental oil spill. Electrobioremediation techniques, which combine electrokinetic transport and biodegradation processes, represent an emerging technological platform for a sustainable remediation of contaminated sediments. Here, we describe the results of a long-term mesocosm-scale electrobioremediation experiment for the treatment of marine sediments contaminated by crude oil. A dimensionally stable anode and a stainless-steel mesh cathode were employed to drive seawater electrolysis at a fixed current density of 11 A/m2. This approach allowed establishing conditions conducive to contaminants biodegradation, as confirmed by the enrichment of Alcanivorax borkumensis cells harboring the alkB-gene and other aerobic hydrocarbonoclastic bacteria. Oil chemistry analyses indicated that aromatic hydrocarbons were primarily removed from the sediment via electroosmosis and low molecular weight alkanes (nC6 to nC10) via biodegradation.

ВЛИЯНИЕ ТЕХНОЛОГИЧЕСКОГО РЕЖИМА УСТАНОВКИ ТЕРМИЧЕСКОГО ПИРОЛИЗА УГЛЕВОДОРОДОВ НА КАЧЕСТВЕННЫЙ СОСТАВ ТЯЖЁЛОЙ СМОЛЫ


 
 
 
 The dependence of the yield and composition of the heavy pyrolysis resin on the initial hydrocarbon feedstock and the process conditions is investigated. The variation of technological parameters within certain limits leads to a change in the content of low molecular weight olefins in the gaseous pyrolysis products, as well as the qualitative and quantitative composition of by-product liquid products. As a result of the research, the optimum process conditions for the pyrolysis of straight-run gasoline were determined, which, with the maximum conversion of hydrocarbons to low-molecular-weight olefins, significantly increases the yield of heavy resin containing a wide fraction of naphthalene, biphenyl, indene and their alkyl derivatives. It is shown that when treating by-products containing valuable hydrocarbons as target products and combining the technological mode of pyrolysis and their composition, it is possible to achieve along with the maximum yield of low molecular weight olefins, a significant yield of heavy pyrolysis resin and qualitative changes in its composition.
 
 
 

Alternatives for Conventional Alkane Solvents.

The studies described in this paper show that hydrocarbon oligomers are alternatives for low molecular weight alkane solvents. These oligomeric solvents are nontoxic, nonvolatile, and recyclable alternatives to heptane in thermomorphic solvent mixtures that use a polar solvent such as methanol, aqueous ethanol, or DMF or in biphasic mixtures that use acetonitrile. Regardless of which polar solvent is used, hydrocarbon oligomers like poly(α-olefin)s (PAOs) exhibit very low leaching into the polar phase. UV-visible spectroscopy studies show that these solvents have the solubility properties of heptane. For example, PAOs dissolve heptane soluble dyes and quantitatively separate them from polar phases in thermomorphic solvent mixtures. PAOs either as pure solvents or as additives in heptane act as antileaching agents, decreasing the already low leaching of such dyes into a polar phase in heptane/polar solvent mixtures. These oligomeric hydrocarbon solvents were also compared to heptane in studies of azo dye isomerization. The results show that thermal isomerization of an azo dye occurs at the same rate in heptane and a PAO. Further studies of carboxylic acid promoted dye isomerization in heptane and a PAO show that low molecular weight and oligomeric carboxylic acids are kinetically equivalent at accelerating this isomerization. The results suggest that these and other hydrocarbon oligomers behave as solvents like their low molecular weight nonpolar hydrocarbon solvents and that they can be substituted successfully for conventional solvents like heptane.

High Performance Liquid Chromatography at −196 °C

Ultralow temperature high-performance liquid chromatography (HPLC) was developed using a liquefied gas as the mobile phase. HPLC separation of low molecular weight alkanes at -196 °C with liquid nitrogen mobile phase was successfully achieved, whereas their GC separation at -196 °C using helium gas mobile phase failed to elute the analytes due to strong adsorption. Prior to the further study of HPLC at -196 °C, the effect of column temperature on the chromatographic behavior was investigated, and it was found that the retention of analytes drastically increased when the column temperature was over the boiling point of the mobile phase. As the study of retention control in HPLC at -196 °C, the mobile phases of nitrogen and methane mixtures were investigated. The addition of methane to the nitrogen mobile phase suppressed the retention of the analytes (tetra-deuterated methane, ethane, and propane), that is, the retention on HPLC at ultralow temperature could be controlled by the mobile phase composition, akin to the typical retention in HPLC. The selectivity toward the n- and iso-alkane in HPLC at -196 °C was altered compared with that in GC separation at room temperature. A significant enhancement of retention of alkanes compared with alkanes were observed in HPLC at -196 °C.

Liquid chromatography/mass spectrometry identification of intermediates and vulcanization products by using squalene as vulcanization model compound.

Sulfur-vulcanized rubber is a three-dimensional polymer network, insoluble in all organic solvents. For this reason, vulcanization products are difficult to study and identify by conventional analytical techniques. To simplify this task, low molecular weight olefins have been used as model compounds (MCs) in place of rubber in vulcanization experiments. In this work, the vulcanization process was investigated using squalene (SQ) as MC. By-products, intermediates and products were separated by semipreparative reversed-phase liquid chromatography (RPLC) with UV detection. Each fraction was collected, concentrated and characterized by flow injection analysis (FIA) and non-aqueous reversed-phase (NARP) LC coupled to positive atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Under the latter conditions, an Information-Dependent Acquisition (IDA) was performed on a linear ion trap mass spectrometer to obtain structural information. Several vulcanized compounds containing up to three SQ molecules, cross-linked with chains involving up to 14 sulfur atoms overall, have been identified along with some of their oxidized products (epoxides and hydroperoxides). The FIA-MS spectra showed peak clusters, each of which included two-three subclusters; the interpretation was complicated by the occurrence of more ion species per product, by the unsaturation grade and by the characteristic isotopic distribution of sulfur. The enhanced product ion scan (EPI) spectra, acquired during the IDA experiments, supported the FIA-MS identification allowing one to count the number of sulfur atoms. The sensitivity of the developed analytical strategy was due to the enrichment factor achieved via semipreparative chromatography and the very good response of the APCI detection. Pattern fragmentation and chromatographic behavior simplified the identification of the cured compounds and their oxidized products, whose occurrence was related to the grade of oxidation of SQ used as reagent. Copyright © 2016 John Wiley & Sons, Ltd.

Construction of Asymmetric Graphene Sandwiches: Decoration Using Semiconductor and Metal Nanostructures

The low-dimensional carbon materials, i.e. graphene-based metal and metal oxide nanocomposites fabrication procedure at the polarizable organic/water interface opens an alternative way to prepare catalyst materials.1-2 These graphene-based nanostructures could be useful substrates for catalytic processes, such as the hydrogen evolution or the oxidation of low molecular weight alkanes to liquid alcohol fuels. The polarizable organic/water interface offers the possibility of incorporating, as well as constructing in situ at the interface, highly complex catalytic centers and supports, including photoactive semiconductors, metallic nanostructures.3 Chemical vapor deposition (CVD) on copper foil was employed to grow macroscopic (cm scale) graphene and the high purity CVD GR monolayers assembled at an polarizable organic/water interface.1-2 The semiconductors, titanium oxide (TiO2) and molybdenum disulfide (MoS2) were exfoliated in an organic solvent, and assembled at the interface, then the top of CVD GR was decorated by fishing out either the TiO2 or MoS2 layer. The top-side of CVD GR was also decorated by metal and metal oxide nanoparticles (NPs), i.e. Au, Pd, Pt and PdO, PtO, respectively, using a solution chemistry-based galvanic displacement.1 In situ electrochemical and spontaneous, electroless metal deposition of Pd, Pt, Au and Ag NPs at the interface-assembled previously top-side decorated CVD GR was studied.1-2 We have fabricated a range of different dual-decorated CVD GR-based nanostructures, including semiconductors, metals and metal oxides on top, and metal NPs on bottom-side, respectively. Either the same nanostructures (symmetric decoration), or different ones (asymmetric decoration) were used for the preparation of bi-functionalized graphene sandwiches, which are adsorbed at the organic/water interface. The successful fabrication of such dual-decorated graphene-based metal nanocomposites was confirmed using various microscopic techniques (scanning electron and atomic force microscopies) and several spectroscopic methods (X-ray photoelectron, 3D energy dispersive X-ray tomography, mapping mode Raman spectroscopy and electron energy loss spectroscopy). Taken together it is inferred from these techniques that the location of deposited nanoparticles is on opposite sides of the graphene monolayer. 1. Toth, P. S.; Velický, M.; Ramasse, Q. M.; Kepaptsoglou, D. M.; Dryfe, R. A. W., Advanced Functional Materials, 2015, DOI: 10.1002/adfm.201500277.2. Toth, P. S.; Ramasse, Q. M.; Velický, M.; Dryfe, R. A. W., Chemical Science, 2015, 6, 1316-1323.3. Rodgers, A. N. J.; Booth, S. G.; Dryfe, R. A. W., Electrochemistry Communications, 2014, 47, 17-20.

Effect of high-temperature pre-reduction in Fischer–Tropsch synthesis on Fe/ZrO2 catalysts

Fischer–Tropsch synthesis of low molecular weight (C2C4) olefins is a valuable alternative process for the production of key chemicals from non-petroleum precursors such as a renewable C source like biomass. The influence of the H2 treatment temperature of zirconia-supported iron catalysts on the conversion of synthesis gas has been investigated. The CO conversion rate, based on steady-state, increased with the pretreatment temperature up to a maximum and then decreased at higher temperatures. Moreover, methane selectivity was found to decrease slightly from the lowest H2 treatment temperatures (46%) to the highest ones (34%), while C2C4 and C5+ hydrocarbons followed an opposite trend. Presumably, methane formation takes place at highly active low coordination sites residing at corners and edges, which are more abundant on small iron carbide particles. Lower hydrocarbons are mainly produced at terrace sites that are available and active, quite independent of the iron crystallite size.