Presence Of Light Hydrocarbons Research Articles

Inhibiting the Formation of Toxic HCN Induced by C3H6 Coexistence and Enhancing C3H6 Resistance of Cu-Zeolite in the NH3-SCR Reaction.

The presence of light hydrocarbons (HCs) in diesel exhaust, specifically C3H6, significantly affects the performance of the state-of-the-art Cu-SSZ-13 zeolite NH3-SCR catalysts. It also leads to the formation of highly toxic HCN, posing risks to the environment and human health. In this work, the highly toxic HCN formation is inhibited, and the C3H6 resistance of Cu-SSZ-13 is improved by secondary metal modification via doping with rare earth/transition metal elements. Upon introduction of C3H6, the activity of Cu-SSZ-13 significantly decreases at medium-high temperatures. This is primarily due to the competitive reaction between C3H6 and NH3, which compete for the NH3 reductant required in the NH3-SCR reaction, resulting in the production of HCN. The unfavorable effect is alleviated on the modified catalysts due to their enhanced oxidation capabilities toward C3H6 and the HCHO intermediate, facilitating the complete oxidation of C3H6 to COx. This inhibits the undesirable partial oxidation reaction between C3H6 and NH3, thereby improving the activity of Cu-SSZ-13 at medium to high temperatures and significantly reducing the formation of highly toxic HCN.

Solar oil refinery: Solar-driven hybrid chemical cracking of residual oil towards efficiently upgrading fuel and abundantly generating hydrogen

There is an urgent need to shift away from the present heavy dependence on fossil fuels and embrace renewable energy sources, particularly in the context of the energy-intensive oil refining process. Built on the Solar Reactive Utilization framework, this study presents an innovative concept called the Solar Oil Refinery, applying solar energy in the energy-demanding oil refining. Herein, a solar multi-energies-driven hybrid chemical oil refining system, exemplified by residual oil cracking, has been successfully developed and formulated in solar-driven thermo-electrochemical cracking of residual oil. This integrated solar oil refining system, coupled with solar pyrolysis and electrolysis - synergistic thermo- and electrochemistry, can greatly promote the “cracking” of residual oil. Owing to the simultaneous applications of solar heat, solar electricity, and the relevant chemical reactions, the system can significantly improve solar utilization efficiency, the cracking rate and the hydrogen yield. In the operation, solar energy, co-functioning with oil, is converted into light hydrocarbon fuel with the advantage of excess hydrogen energy storage. Notably, the temperature required for solar oil cracking is considerably reduced compared with that of conventional pyrolysis, with a cracking rate of 11.2% at the initial temperature of 230 ℃. As the temperature rises, the cracking rate is elevated, reaching 45.22% at 275 ℃ and an impressive 89.85% at the typical temperature of 425 ℃, in contrast to the 44.25% achieved in conventional pyrolysis. In the conventional pyrolysis, the gas, liquid, solid products and unreacted residual oil are accounted for 3.98%, 24.57%, 15.57%, and 55.75%, respectively, but, in the solar oil cracking, the gas, liquid, solid products and residual oil improve to 13.2%, 75.1%, 1.65%, and 10.05%, respectively. This process is characterized by a substantial increase of gas and liquid phase products, coupled with a significant reduction of solid phase products and unreacted residual oil. At 425 ℃, a noteworthy increase of 10.7% in gasoline, 21.7% in diesel, and 18.13% in vacuum gas oil occurs in solar oil cracking compared to conventional pyrolysis. The presence of light hydrocarbons and oxygen-containing organic compounds are detected in both gas-phase and liquid-phase products. In solar oil cracking, the hydrogen yield has been significantly boosted to 63.0% in the combined action of the hydrolysis and electrolysis, surpassing the hydrogen yield achieved through the conventional pyrolysis. The simultaneous utilization of both solar heat and solar electricity which substantially enhances total solar utilization efficiency and the oil conversion rate, can effectively reduce the consumption of the fossil energy in petroleum industry.

Reflectance spectroscopy and ASTER imagery applied to unravel mineral assemblage as surface indicators of hydrocarbon micro-seepage in the region of Khuzestan oilfields, Iran

The present study makes an attempt to describe spectral characteristics of the surface features in some parts of the Khuzestan region, using reflectance spectroscopy and ASTER data related to the hydrocarbon micro-seepage in Maroun and Mansouri oil fields. The study involves surface sediment sampling with appropriate dispersion of the samples, and laboratory analysis in terms of sediment and mineralogy through spectroscopy analysis and geological map. Soil samples were collected from 45 and 20 locations points for Maroun and Mansouri oilfields, respectively. ASD-Fieldspec3 spectroradiometer and The Spectral Geologist (TSG) software were used to determine the hydrocarbon absorptions and their mineral constituents. Four classes were identified as hydrocarbon absorption ranges, i.e.: 1220–1320 and 1350–1550 nm indicating presence of light hydrocarbons; 1700–1750 and 2290–2360 nm pertaining to heavy hydrocarbons. Results suggest that Maroun oilfield samples have stronger absorptions in heavy hydrocarbons absorption but weaker for the Mansouri oilfield samples. The Mansouri samples have an acceptable absorption in light hydrocarbons absorption (1175 nm). Furthermore, these spectra were used as ground truth for creating mineral zonation maps using Spectral Angle Mapper (SAM) classification applied to ASTER data. The results also suggest that surface indicators of hydrocarbon are associated with alteration minerals such as kaolinite, siderite and goethite for the Maroun oilfield whereas Mansouri oilfield exhibits only kaolinite group of minerals. In addition, a comparison by reflectance between the contaminated and uncontaminated soil samples was also carried out.

Prediction of liquid propane hydrate formation conditions in the presence of light hydrocarbons (C2-C5): Experimental investigation and thermodynamic modeling

In this investigation, the equilibrium conditions of liquid propane hydrate formation in the presence of light hydrocarbons (C2-C5) are presented. The central composite design (CCD) as a method of the response surface methodology (RSM) was applied to minimize the number of experiments (47 runs) and to determine the optimum operating conditions for the highest equilibrium pressure. The effect of five independent variables involving temperature and gas mixture component concentration on the pressure of propane hydrate formation was studied. The thermodynamic model is based on the van der Waals-Platteeuw (vdW-P) combined with the Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) Equations of State (EoS) and Parrish and Prausnitz approach. For the first time, simultaneously statistical and thermodynamic models were studied, and it indicates that the statistical model (Design Expert) has a perfect correlation (R2 = 0.9999) with the experiment and the thermodynamic modeling by PVTsim (E = 0.56%) had a better predictor than MATLAB (E = 2.79%).

Effect of Manganese on the Selective Catalytic Hydrogenation of COx in the Presence of Light Hydrocarbons Over Ni/Al2O3: An Experimental and Computational Study

The promoting effect of manganese on the Ni/Al2O3 catalyst for the hydrogenation of carbon oxides, in the presence of light hydrocarbons, was studied. Ni/Al2O3 displayed a high activity for the com...

A FLUORESCENCE CONTRIBUTION TO THE RECOGNITION OF FLUIDS TRAPPED IN MINERALS IN THE CARPATHIAN OUTCROPS

Based on the assumption that fluorescence studies are an important tool in search and characterization of hydrocarbons, samples of rocks, minerals and the organic matter were collected in the Western Carpathian area spreading from the Mszana Górna region in the west to the Bieszczady Mts. in the east, and continuously, towards SE outside the Polish frontier, in Ukraine and Slovakia. Analytical procedures comprised preparation, microscopic observation of the material (organic matter and minerals) from the point of view of inclusions and fluorescence followed by detailed luminescence studies. Those steps have been followed by the microthermometric determinations. The application of the fluid inclusion methods, which are one of the newest analytical tools in the last two decades have led to the characteristics of fluids trapped in the inclusions in the area. The fluorescence studies showed some diversity of hydrocarbons both in compositions and in distribution. The analyses were performed in double-sided polished thin sections prepared based on cold techniques. Fluorescence of inclusions in two minerals, quartz and calcite, was checked in those specific thin sections either in glued wafers, or loose (single) crystals. The fluid inclusion studies were accompanied later on by solid organic matter inclusion studies. Those point to the presence of the following minerals: quartz, dolomite, calcite, clay minerals, gypsum with anhydrite admixture, traces of pyrite and siderite, feldspars. General distribution of fluorescing and not fluorescing inclusions suggests the presence of light hydrocarbons (methane) in the west and south of the area, being enriched in higher hydrocarbons (oil) towards the east.

Manganese‐containing redox catalysts for selective hydrogen combustion under a cyclic redox scheme

Selective hydrogen combustion (SHC) in the presence of light hydrocarbons was demonstrated with a series of Mn‐containing mixed oxide redox catalysts in the context of a chemical looping‐oxidative dehydrogenation scheme. Unpromoted and 20 wt % Na2WO4‐promoted Mg6MnO8, SrMnO3, and CaMnO3 exhibited varying SHC capabilities at temperatures between 550 and 850°C. Reduction temperature of unpromoted redox catalysts increased in the order Mg6MnO8 < SrMnO3 < CaMnO3. Promotion with 20 wt % Na2WO4 resulted in more selective redox catalysts capable of high‐temperature SHC. XPS analysis revealed a correlation between suppression of near‐surface Mn and SHC selectivity. Na2WO4/CaMnO3 showed steady SHC performance (89% H2 conversion, 88% selectivity) at 850°C over 50 redox cycles. In series with a Cr2O3/Al2O3 ethane dehydrogenation catalyst, Na2WO4/CaMnO3 combusted 84% of H2 produced while limiting COx yield below 2%. The redox catalysts reported can be suitable for SHC in a cyclic redox scheme for the production of light olefins from alkanes. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3141–3150, 2018

Identification of endogenous and anthropogenic hydrocarbons in bottom deposits of peat lakes and evaluation of their contribution to the “hydrocarbon index”

Gas chromatography with mass spectrometric detection was used to analyze bitumens isolated from bottom sediments of peat lakes contaminated with petroleum products. Endogenous hydrocarbons are characterized by the presence of n-alkanes with an odd number of carbon atoms in the molecule in the characteristic region of C23–C33, the absence of a “hump” characteristic of oil products in the chromatogram, and the presence of light hydrocarbons, eluting in the initial part of the chromatogram (light hydrocarbons are usually lost when the sample is dried). The distribution profile of odd n-alkanes is used to assess the contribution of endogenous hydrocarbons to the “hydrocarbon index” with the help of the pattern recognition method. The concentration of light hydrocarbons is from 50 and 300–400 to 3500–5000 mg/kg for a number of samples and even up to 26000 mg/kg in some samples. The concentration of petroleum hydrocarbons and heteroatomic compounds varies from the lowest values of 30–80 mg/kg up to 20000 mg/kg and higher.

Equilibrium prediction of CO2 reforming of coke oven gas: Suitability for methanol production

A thermodynamic study of the equilibrium of the CO2 reforming of coke oven gas (COG) was carried out with the aid of Aspen Plus® software. The influence of various operation conditions (temperature, pressure, COG composition and CO2/CH4 ratio) upon different parameters (conversions, yields, outlet composition, carbon production, by-products) was studied in order to evaluate the suitability of the process for producing a synthesis gas appropriate for methanol production. It was established that it is necessary to work at temperatures higher than 800°C, at the lowest possible pressures and in stoichiometric conditions of CH4 and CO2. It was also found that the presence of light hydrocarbons in the COG gives rise to a syngas that is more suitable for methanol production than when they are absent. However, they were also observed to promote deactivation of the catalyst.

Selective combustion of hydrogen in the presence of hydrocarbons: Part 2. Metal oxide based catalysts

The selective hydrogen combustion (SHC) properties of some metal-oxide catalysts have been investigated at 500 and 550 °C and atmospheric pressure. This reaction is of importance in the development of new dehydrogenation technology based on partial combustion of hydrogen to provide in situ heat generation to the endothermic dehydrogenation processes. Selective hydrogen combustion in the presence of light hydrocarbons is possible under certain reaction conditions for some catalysts. In 2O 3/SiO 2 and unsupported Bi 2O 3 are able to selectively combust hydrogen in a gas mixture with propane and oxygen, In 2O 3/SiO 2 being the most active catalyst. Bi 2O 3/SiO 2 and PbO x /SiO 2 show moderate properties as selective hydrogen combustion catalysts in the presence of propane. When propene is added to the gas mixture, Bi 2O 3/SiO 2 and PbO x /SiO 2 are no longer able to selectively combust hydrogen. In 2O 3/SiO 2, on the other hand, shows a higher activity and combusts hydrogen with 90% selectivity at low oxygen flows, and with 80% selectivity at stoichiometric amounts (to water) of oxygen. The explanation as to why certain oxides are selective is not known, but differences in electronic structure of the oxides can be linked with different SHC properties.

Selective combustion of hydrogen in the presence of hydrocarbons: 1. Pt-based catalysts

In this communication we present experimental results showing that under certain reaction conditions the selective combustion of hydrogen in the presence of light hydrocarbons is possible over a PtSn/SiO 2 catalyst. This reaction is of importance in the development of new dehydrogenation technology based on partial combustion of hydrogen to generate heat in situ to the endothermic dehydrogenation processes. Both Sn/SiO 2 and PtSn/SiO 2 seem to be able to selectively combust hydrogen in a gas mixture with propane and oxygen, whereas Pt/SiO 2 alone is less selective. If propene is added to the gas mixture, Sn/SiO 2 is no longer able to selectively combust hydrogen. PtSn/SiO 2, on the other hand, can combust hydrogen with about 80% selectivity at 550 °C and 90% selectivity at 500 °C as long as the oxygen flow is less than half the amount of hydrogen (stoichiometry to water formation). As soon as the oxygen flow exceeds half the amount of hydrogen, the selectivity to CO x increases at the expense of water. The results show that surface reactions are involved.

Pitfalls and Caveats in Surface Light Hydrocarbon Surveying

The credible application of light hydrocarbon surveying in petroleum exploration requires an appreciation of the genesis, mobility, and alteration of light hydrocarbons in subsurface and surface environments. In this context, case studies and experimental work are discussed in this paper illustrating some of the pitfalls that beset light hydrocarbon surveying. These examples document a variety of spurious or false' light hydrocarbon anomalies that are genetically related to soil and sediment properties (e.g., mineralogy, parent material, indigenous organic material, biological activity) rather than to seepage phenomena. Also discussed are instances in which the natural alteration of biogenically produced light hydrocarbons in surface environments has yielded hydrocarbons that mimic thermogenically produced hydrocarbons. In addition, examples are shown in which light hydrocarbons produced during shale diagenesis (and that can be expelled via shale compaction) resemble thermogenically produced light hydrocarbons. Finally, data are presented that indicate that acid extraction, a popular analytical technique, can itself produce hydrocarbons from soil and sediment samples containing particular clay and organic constituents. Thus, the challenge in light hydrocarbon surveying is to critically evaluate the presence of light hydrocarbons in surface materials in terms of a number of possible origins, not all of which imply the existence of subsurfacemore » reservoired hydrocarbons.« less