Reactions Of Hydrocarbons Research Articles

Olefin methylation over iron zeolites and the methanol to hydrocarbons reaction

The effect of olefin addition to a stream of dimethyl ether on the methanol homologation reaction is investigated using iron-substituted zeolites Fe-beta and Fe-ZSM-5. The reaction was investigated using plug-flow microreactors in the temperature range of 240–400 °C, at a total pressure of 0.239 MPa and a WHSV of 6.12 (g DME/gcat-hr). For Fe-beta (Si/Fe= 9.2) catalysts, isobutene co-feeding almost doubles dimethyl ether (DME) consumption rate and shifts selectivity towards larger olefins with carbon numbers from 5 to 7. Addition of isobutene above 6.3%, however, resulted in a reduction of DME consumption rates, an effect assigned to the replacement of surface methoxy groups for adsorbed olefins in the zeolite pores. Below a temperature of 340 °C hydride-transfer rates are negligible; reaction rates are stable for over 5.5 h and the products consist almost exclusively of olefins and a small amount of methane. Above 360 °C the onset of catalytic hydride transfer processes is observed leading to fast catalyst deactivation rates and an increase in the concentration of aromatic species. Iron ZSM-5 (Si/Fe = 21.4) catalysts under similar reaction conditions consumes methanol faster than Fe-beta at approximately three times the TOF (on a per iron basis). The Fe-ZSM-5 catalyst was selective to a distribution of products (C5 to C8) as compared to Fe-beta which was selective to primarily C5 and C7. Co-feeding larger olefins (2-methyl-2-butene, 2,3-dimethyl-2-butene, 2,3,3-trimethyl-1-butene, and 2,4,4-trimethyl-2-pentene) at a 3.9% olefin concentration over Fe-beta changed selectivity towards cracking products (C4 compounds such as isobutene). As the size of the olefin increases, a reduction of DME consumption rate is also observed. These results show that co-feeding olefins with DME over Fe-zeolites is a promising route to increase methylation rates at relatively low temperatures producing larger branched olefins and that the product distribution is highly dependent on the zeolite pore size and structure of the olefin.

Aqueous Mediated Heterogeneous Catalysis

Pyrolysis atmosphere has significant effect on yield and composition of coal tar. A pyrolysis and gasification integrated reactor in laboratory was used to investigate effects of gasification syngas on yield and composition of coal tar. The results show that tar yield of Naomaohu coal reaches the maximum at 600 °C, and gasification syngas (G-gas) is more beneficial to improve the tar yield at low temperature (550−600 °C). Especially, 550 °C tar yield increases by 4.4% compared with that under N2. With the introduction of G-gas, the yield of tar obtained at high temperature (650−800 °C) decreases, but the quality of tar obtained at 650−700 °C is improved obviously due to the increase of light components. The cracking reaction of aliphatic hydrocarbons and oxygen-containing compounds in volatiles from pyrolysis at 550 and 600 °C is intensified by G-gas, thus substituted benzene and naphthalene compounds in coal tar increase. For the volatiles obtained above 650 °C, the secondary cracking reaction of phenolic compounds is enhanced with the introduction of G-gas, which results in a decrease of phenolic compounds in tar. G-gas is also favorable for the secondary cracking reaction of polycyclic aromatic hydrocarbons in volatiles from pyrolysis at 800 °C, but more favorable for generation of which in the tar obtained below 700 °C

Turbulent transport and reactions of plant-emitted hydrocarbons in an Amazonian rain forest

The processes governing the temporal and spatial patterns of isoprene and monoterpenes emitted by a rainforest in the central Amazon region of Brazil is investigated using a combination of field experiments and numerical simulations. Specifically, Large Eddy Simulations (LES) were used to resolve emissions of isoprene and monoterpenes, turbulent transport, and air chemistry. The coupled chemistry-transport LES included the effects of isoprene and monoterpenes reactivity due to reactions with hydroxyl radical and ozone. The LES results are used to compute vertically resolved budgets of isoprene and monoterpenes in the rainforest canopy in response to emissions, turbulent transport, surface deposition, and air chemistry. Results indicated that emission and dispersion dominated the isoprene budget as the gases were transported out of the canopy space. In a region limited by nitrogen oxides (with prevailing nitric oxide levels of < 0.5 parts per billion), the in-canopy chemical destruction removed approximately 10% of locally emitted monoterpenes. Hydroxyl radical production rates from the ozonolysis of monoterpenes amounted to ≈2×106radicalscm−3s−1 and had similar magnitude to the light-dependent hydroxyl radical formation. One key conclusion was that the Amazonia rainforest abundantly emitted monoterpenes whose in-canopy ozonolysis yielded hydroxyl radicals in amounts similar to the magnitude of light-dependent formation. Reactions of monoterpenes and isoprene with hydroxyl radical and ozone were necessary for the maintenance of the Amazon rainforest canopy as a photochemically active environment suitable to generate oxidants and secondary organic aerosols.

Experimental and chemical kinetic behaviors at the explosion reaction of typical C6 hydrocarbons

This research is aimed at exploring the influence of the vapor molecular structure of hydrocarbons on vapor explosion. To achieve this aim, the overpressure and flame propagation images of typical C6 hydrocarbons (benzene, cyclohexane and n-hexane) at equivalence ratios (φ = 0.6, 0.8, 1, 1.2 and 1.4) were studied in a closed visual explosion experimental pipeline (initial temperature 22–25 °C and initial pressure 1 atm), and the chemical kinetic behaviors were analyzed through the JetSurF2.0 mechanism. The results reveal that different molecular structures of fuels lead to great differences in the activities of their reaction intermediates. Many stable resonance groups such as C5H5 and C3H3 are generated in the reaction system of benzene vapor as a result of the special benzene ring structure. Cyclohexane decomposes into more highly active intermediates, i.e., 1,3-butadiene (SAXC4H7), and fewer chain terminators, i.e., propylene, due to its ring structure. N-hexane decomposes into more small-molecule substances as a result of its linear structure. The difference in the activity of the intermediates greatly affects the production of the key free radical OH, and further influences the intensity of the branched chain reaction. Hence, the explosion intensities of the three kinds of hydrocarbon vapors follow the order: cyclohexane > n-hexane ≈ benzene. In addition, as their C/H ratios differ, the equivalence ratio variation exerts varying influences on the reaction H+O2=O+OH. This study is of theoretical significance for the prevention and control of hydrocarbon vapor explosion.

Systematic study on dynamic pyrolysis behaviors, products, and mechanisms of weathered petroleum-contaminated soil with Fe2O3

Weathered petroleum-contaminated soil (WPCS) with a high proportion of heavy hydrocarbons is difficult to remediate. Our previous research demonstrated that Fe2O3-assisted pyrolysis was a cost-effective technology for the remediation of WPCS. However, the pyrolysis behaviors, products, and mechanisms of the WPCS with Fe2O3 are still unclear. In this study, a combination of Thermogravimetric–Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) techniques were used to explore these pyrolysis characteristics. The thermal desorption/degradation of light and heavy hydrocarbons in the WPCS mainly occurred at 200–400 °C and 400–550 °C, respectively. The activation energy of thermal reaction of heavy hydrocarbons was decreased in the presence of Fe2O3 during the WPCS pyrolysis processes. In the process, the released inorganic gaseous products were mainly H2O and CO2, while the released organic gaseous compounds were primarily cycloalkanes, alkanes, acids/esters, alcohols, and aldehydes. Compared with the WPCS pyrolysis without Fe2O3, the yields of gaseous products released during the WPCS pyrolysis with Fe2O3 were reduced significantly, and some gaseous products were even not detected. This phenomenon was contributed by the following two reasons: 1) heavy hydrocarbons in the WPCS were more easily transformed into coke in the presence of Fe2O3 during pyrolysis; 2) some released gaseous products were reacted with Fe2O3 and fixed on the soil particles. Therefore, the WPCS pyrolysis with Fe2O3 can effectively reduce the burden of tail gas treatment. Criado method analysis results suggested that the reaction mechanism of heavy hydrocarbons during the WPCS pyrolysis with Fe2O3 was rendered as the synergic effects of diffusion, order-based, and random nucleation and growth reactions.

Effects of syngas from semi-coke in situ gasification on yield and quality of tar from pyrolysis of Naomaohu coal

Pyrolysis atmosphere has significant effect on yield and composition of coal tar. A pyrolysis and gasification integrated reactor in laboratory was used to investigate effects of gasification syngas on yield and composition of coal tar. The results show that tar yield of Naomaohu coal reaches the maximum at 600 °C, and gasification syngas (G-gas) is more beneficial to improve the tar yield at low temperature (550−600 °C). Especially, 550 °C tar yield increases by 4.4% compared with that under N2. With the introduction of G-gas, the yield of tar obtained at high temperature (650−800 °C) decreases, but the quality of tar obtained at 650−700 °C is improved obviously due to the increase of light components. The cracking reaction of aliphatic hydrocarbons and oxygen-containing compounds in volatiles from pyrolysis at 550 and 600 °C is intensified by G-gas, thus substituted benzene and naphthalene compounds in coal tar increase. For the volatiles obtained above 650 °C, the secondary cracking reaction of phenolic compounds is enhanced with the introduction of G-gas, which results in a decrease of phenolic compounds in tar. G-gas is also favorable for the secondary cracking reaction of polycyclic aromatic hydrocarbons in volatiles from pyrolysis at 800 °C, but more favorable for generation of which in the tar obtained below 700 °C

Transformation mechanism of polycyclic aromatic hydrocarbons and hydrogen production during the gasification of coking sludge in supercritical water

In this study, the characteristic of hydrogen production and polycyclic aromatic hydrocarbons (PAHs) transformation during supercritical water gasification (SCWG) of coking sludge (400 °C - 450 °C, 1 min–30 min) were explored. The total gas yield was between 0.62 mol/kg OM and 1.05 mol/kg OM (on dry basis), and the proportion of CH4 and H2 was only between 5.41% and 6.44%. PAH content were increased from 194.92 mg/kg to 326.04 mg/kg, and mainly high molecular weight PAHs, which were formed from the Diels-Adler reaction of single aromatic hydrocarbon and the addition reaction of low molecular weight PAHs. High reaction temperature favored more active PAH formation than reaction time. The possible control methods for PAH formation during SCWG of coking sludge was proposed. H2O2 and KOH addition effectively reduce PAHs amount in solid residues by 46.67% and 38.33%, and KOH performed positive effect on hydrogen production. The work revealed that the inhibition of PAHs and hydrogen production were achieved from SCWG of coking sludge with KOH addition.

Photochemical evolution of the 2013 California Rim Fire: synergistic impacts of reactive hydrocarbons and enhanced oxidants

Abstract. Large wildfires influence regional atmospheric composition, but chemical complexity challenges model predictions of downwind impacts. Here, we elucidate key connections within gas-phase photochemistry and assess novel chemical processes via a case study of the 2013 California Rim Fire plume. Airborne in situ observations, acquired during the NASA Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) mission, illustrate the evolution of volatile organic compounds (VOCs), oxidants, and reactive nitrogen over 12 h of atmospheric aging. Measurements show rapid formation of ozone and peroxyacyl nitrates (PNs), sustained peroxide production, and prolonged enhancements in oxygenated VOCs and nitrogen oxides (NOx). Observations and Lagrangian trajectories constrain a 0-D puff model that approximates plume photochemical history and provides a framework for evaluating process interactions. Simulations examine the effects of (1) previously unmeasured reactive VOCs identified in recent laboratory studies and (2) emissions and secondary production of nitrous acid (HONO). Inclusion of estimated unmeasured VOCs leads to a 250 % increase in OH reactivity and a 70 % increase in radical production via oxygenated VOC photolysis. HONO amplifies radical cycling and serves as a downwind NOx source, although impacts depend on how HONO is introduced. The addition of initial HONO (representing primary emissions) or particulate nitrate photolysis amplifies ozone production, while heterogeneous conversion of NO2 suppresses ozone formation. Analysis of radical initiation rates suggests that oxygenated VOC photolysis is a major radical source, exceeding HONO photolysis when averaged over the first 2 h of aging. Ozone production chemistry transitions from VOC sensitive to NOx sensitive within the first hour of plume aging, with both peroxide and organic nitrate formation contributing significantly to radical termination. To simulate smoke plume chemistry accurately, models should simultaneously account for the full reactive VOC pool and all relevant oxidant sources.

Radiation-induced D/H Exchange Rate Constants in Aliphatics Embedded in Water Ice

Gas-phase and solid-state chemistry in low-temperature interstellar clouds and cores leads to a D/H enhancement in interstellar ices, which is eventually inherited by comets, meteorites, and even planetary satellites. Hence, the D/H ratio has been widely used as a tracer for the origins of extraterrestrial chemistry. However, the D/H ratio can also be influenced by cosmic rays, which are ubiquitous and can penetrate even dense interstellar molecular cores. The effects of such high-energy radiation on deuterium fractionation have not been studied in a quantitative manner. In this study, we present rate constants for radiation-induced D-to-H exchange for fully deuterated small (1–2 C) hydrocarbons embedded in H2O ice at 20 K and H-to-D exchange for the protiated forms of these molecules in D2O ice at 20 K. We observed larger rate constants for H-to-D exchange in the D2O ice versus D-to-H exchange in H2O ice, which we have attributed to the greater bond strength of C–D versus C–H. We find that the H-to-D exchange rate constants are smaller for protiated methane than ethane, in agreement with bond energies from the literature. We are unable to obtain rate constants for the unsaturated and reactive hydrocarbons ethylene and acetylene. Interpretation of the rate constants suggest that D/H exchange products are formed in abundance alongside radiolysis products. We discuss how our quantitative and qualitative data can be used to interpret the D/H ratios of aliphatic compounds observed throughout space.

Impact characteristics of post injection on exhaust temperature and hydrocarbon emissions of a diesel engine

Increasing exhaust gas temperature (EGT) and providing hydrocarbon (HC) reactants by in-cylinder post injection are effective measures to assist diesel engine exhaust aftertreatment operation for efficient pollution control. The aim of this study is to explore calibration guidance of post injection for base engine performance and aftertreatment requirements. Therefore, the effect of start of post injection (SOPI) timing on engine performance and emissions, especially the relationship between the variations of the EGT and HC emissions caused by different post injection timings were experimentally studied with a 2.0 L high-pressure common-rail diesel engine at different loads. The results showed that the maximum torque contribution was produced by post injection at the earliest SOPI timing at all load levels. When the post injection timing was retarded, the engine brake torque decreased gradually, and more energy of the post injected fuel raised the EGT. The EGT decreased and the HC emissions increased significantly as the SOPI timing was further retarded. At the 20%, 50%, and 80% loads, the maximum EGTs were 357.7, 465.4, and 615.8 °C, increased by 11.6%, 8.6%, and 7%, respectively. The maximum HC emissions were 4932, 3929, and 2746 ppm, increased by 12.44, 1.8, and 5.18 times, respectively. Moreover, a tradeoff relationship between the EGT and the HC emissions was observed at different SOPI timings by a normalized analysis. However, no clear tradeoff relationship between the soot and the NOx emissions was found in the SOPI timing sweep. Consequently, the appropriate SOPI timing range should be determined based on the needs of the aftertreatment system, and multiple post injections may be required to simultaneously increase the EGT and provide the HC reactants for aftertreatment. The optimal SOPI timing also needs to be selected based on impacts on soot and NOx at different loads.

Synthesis of Nanocrystalline Mordenite Zeolite with Improved Performance in Benzene Alkylation and n‐Paraffins Hydroconversion

AbstractNanocrystalline mordenite (MOR) zeolites were hydrothermally synthesized in a single step with commercial cetyltrimethylammonium (CTA) hydroxide as the sole organic template, while the aluminum source was varied in a typical synthesis gel. CTA can effectively reduce the crystal growth of MOR zeolites, in some cases selectively in the a‐ and b‐directions of the unit cell. These nanocrystalline MOR zeolites do not only have a larger external surface area than their bulk counterparts prepared without CTA, but the Brønsted acid sites in the side‐pockets are also more accessible. The combination of the use of CTA and AlCl3 ⋅ 6H2O afforded the best‐performing catalyst with much improved activity in benzene alkylation and hydroconversion of n‐hexadecane (n‐C16). Modifying MOR synthesis with CTA hydroxide is a cheap and effective method to open up the one‐dimensional micropore system of mordenite, increasing the catalytic performance in hydrocarbon reactions.

Effects of inherent minerals on oily sludge pyrolysis: Kinetics, products, and secondary pollutants

Considerable inherent minerals in oily sludge (OS) caused intricate effects on OS pyrolysis behaviors. This work investigated the effects of individual mineral on pyrolytic products and secondary pollutants by pyrolysis of artificial OS, which was prepared by assembling pure mineral chemicals (SiO2, CaO, MgO, Fe2O3, and Al2O3) with petroleum oil. Results showed that the effects of inherent minerals on OS pyrolysis tightly depended on pyrolysis temperature, where the thermal cracking and secondary reactions of heavy hydrocarbons were promoted at high temperature. Their effects also varied with inherent mineral species. The existence of SiO2 in OS had negligible influences on OS pyrolysis. CaO and MgO were favored for almost invariant quality of liquid product and the lowest total petroleum hydrocarbons (TPHs) content in solid residues. Because CaO and MgO weakened the stabilities of hydrogen bonds and hydroxyls groups and thus accelerating devolatilization of TPHs from OS. Fe2O3 and Al2O3 helped in the lower TPHs content in solid residues as well. Moreover, they were favored for more pyrolytic gases and long chain liquid product though the yield of liquid product decreased. It may attribute to the enhanced deoxidation and polymerization of Fe2O3 and Al2O3. Along with OS pyrolysis, inherent minerals tended to inhibit N/S/Cl-containing pollutants at the stage of dehydration and devolatilization (<358 °C), but promote their releasing at the stage of thermal cracking and secondary reactions (>358 °C). This work might provide inspiration for getting insight into the OS pyrolysis behaviors and proposing clean fuel production strategies.

Fabrication of three dimensional SiC@C hybrid for efficient direct dehydrogenation of ethylbenzene to styrene

• The 3D carbon decorated SiC hybrid (core-shell structure) is first prepared by a simple template method as a potential robust metal free ethylbenzene DDH catalyst. • The SiC@C catalyst exhibits a large specific area (410.30 m 2 g −1 ) and high catalytic activity (11.58 mmol g −1 carbon h −1 ) in DDH of EB, nearly 4 times that of nanodiamond. • The extraordinary catalytic performance is attributed to the abundant surface carbonyl groups on the carbon layers. • The unique 3D core shell structure can inhibit the aggregation of SiC@C nanocrystals and is benefit for the heat and mass transfer during the dehydrogenation reaction. Synthesis of hybrid carbon materials with core-shell structure and robust catalytic performance is of great research interest, and remains a great challenge in catalytic dehydrogenation of hydrocarbons reaction. In this paper, few-layer sp 2 carbon decorated SiC nanocrystals with core-shell structure (SiC@C) were fabricated through a dual-confined magnesiothermic method by employing glucose and SiO 2 as precursors. The SiC@C nanocrystals were further crosslinked to be a three dimensional (3D) mesoporous hybrid by the in situ generated carbon as binders and exhibiting a 410.30 m 2 g −1 large surface area. The as-prepared SiC@C hybrid materials as metal-free catalysts were evaluated in the steam-free direct dehydrogenation of ethylbenzene to styrene. Benefiting from the abundant surface carbonyl groups on the graphite carbon layers, the optimized yield rate of styrene normalized by carbon mass was as high as 11.58 mmol g −1 carbon h −1 , nearly 4 times that of nanodiamonds. Considering the low cost and excellent catalytic activity, the hybrid 3D SiC@C material may be a promising candidate for direct dehydrogenation of hydrocarbons.

Facile and selective approach towards synthesis of a series ZSM-5/ZSM-12 catalysts for methanol to hydrocarbons reactions: Applying different synthesis driving force and conditions

The use of ultrasonic waves was developed for synthesis of zeolites at shorter crystallization time with improving their desirable properties. A series of nanostructured ZSM-5/ZSM-12 composite zeolites with different Si/Al ratios and alkalinity using organic templates were prepared by hydrothermal and sonochemical synthesis methods. The physicochemical properties of synthesized nanocatalysts such as structure, morphology, textural, and acidity were characterized via XRD, FESEM, N2 physisorption, FTIR, TPD-NH3, TGA-DTG techniques. The results revealed that increasing the Si/Al ratio and alkalinity in the hydrothermal samples enhanced the crystallization, formation of amorphous microcrystals, and dominant phase of MFI with decreasing MTW competitive phase. Zeolites synthesized by high-temperature and short-time sonochemical method had higher crystallinity, less dominant phase of ZSM-5, smaller crystals, greater surface areas, higher concentration of Brønsted acid sites, and stronger strength of moderate/strong acid sites. The catalytic performance of the zeolites for MTH conversion was evaluated under a reaction temperature of 450 °C at different times on stream. The results showed that the sonochemical zeolite had a higher methanol conversion (100%), higher selectivity toward olefins (28% vs. 19%) with more C3=/C2= ratio (0.79 vs. 0.58), and lower alkanes selectivity (66% vs. 72%) after 240 min TOS.

Spectro-kinetics of the methanol to hydrocarbons reaction combining online product analysis with UV–vis and FTIR spectroscopies throughout the space time evolution

The well-studied methanol to hydrocarbons reaction over a ZSM-5 zeolite catalyst has been used to develop a spectro-kinetic approach to obtain an overall reaction mechanism involving both retained species and gas-phase products. We combined two in situ spectroscopic techniques (ultraviolet–visible and Fourier-transform infrared spectroscopies) with online product analysis to obtain the time- and space time-resolved evolution of the entire reaction media. A ZSM-5 zeolite catalyst was tested in two commercial spectroscopic cells at 400 °C using different space times (different inlet flow rates). Specifically, our work focusses on the effect of the space time (key parameter in any kinetic study) and how to tune other parameters such as partial pressure of methanol to resolve, from the spectroscopic and gas-phase points of view, the mechanisms of reaction and deactivation. Our approach reinforces the previous interpretation of these two combined networks in the selected reaction, thus, proving that the spectro-kinetic approach is a robust methodology to simultaneously build overall reaction and deactivation mechanisms.

Induced Near-Infrared Emission and Controlled Photooxidation based on Sulfonated Crown Ether in Water.

Regulation of physio-chemical properties and reaction activities via noncovalent methodology has become one of increasingly significant topics in supramolecular chemistry and showed inventive applications in miscellaneous fields. Herein, we demonstrate that sulfonated crown ether can form very stable host-guest complexes with a series of push-pull-type photosensitizers, eventually leading to the dramatic fluorescence enhancement in visible and near-infrared regions. Meanwhile, severe suppression in singlet oxygen (1 O2 ) production is found, mainly due to the higher energy barriers between the excited single and triple states upon host-guest complexation. Moreover, such complexation-induced tuneable 1 O2 generation systems has been utilized in adjusting the photochemical oxidation reactions of polycyclic aromatic hydrocarbons (anthracene) and sulfides ((methylthio)benzene) in water. This supramolecularly controlled photooxidation based on the selective molecular binding of crown ether with photosensitizers may provide a feasible and applicable strategy for monitoring and modulating many photocatalysis processes in aqueous phase.

High-crystallinity single-walled carbon nanotube aerogel growth: Understanding the real-time catalytic decomposition reaction through floating catalyst chemical vapor deposition

In this study, high-purity single-walled carbon nanotubes (SWCNTs) are synthesized with additional carrier gas through floating catalyst chemical vapor deposition. The presence of Ar during the SWCNT aerogel formation affects to the precursor decomposition and to the formation of different reactive hydrocarbons. Furthermore, the concentration of produced various carbon species is sensitive to the carrier gas compositions. The in-situ sampling methods prove the thermodynamic pathway for the hydrocarbon cracking during carbon nanotube (CNT) aerogel formation process. The addition of Ar promoted the formation of reactive hydrocarbon species, such as CH3, CH4, and C2H4/CO, to improve CNT morphology and graphitization. Ar has improved purity of CNTs compared to when only H2 is used. The synthesized CNTs were narrow in size, and the diameter decreased from 1.8 to 1.2 nm with the carrier gas composition (Rx) according to Ar addition. The IG/ID ratio of the CNTs changed from 78 to 3 at R0.1 and R0.57, respectively. Furthermore, the purity also increased to approximately 10% from 78% to 91% depending on Rx.

Diamond and methane formation from the chemical decomposition of polyethylene at high pressures and temperatures

Polyethylene (C2H4)n was compressed to pressures between 10 and 30 GPa in a diamond anvil cell (DAC) and laser heated above 2500 K for approximately one second. This resulted in the chemical decomposition of the polymer into carbon and hydrocarbon reaction products. After quenching to ambient temperature, the decomposition products were measured in the DAC at pressures ranging from ambient to 29 GPa using a combination of x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). XRD identified cubic diamond and methane as the predominant product species with their pressure–volume relationships exhibiting strong correlations to the diamond and methane equations of state. Length scales associated with the diamond products, obtained from SAXS measurements, indicate the formation of nanodiamonds with a radius of gyration between 12 and 35 nm consistent with 32–90 nm diameter spherical particles. These results are in good agreement with the predicted product composition under thermodynamic and chemical equilibrium.

Углеводородный состав продуктов крекинга мальтенов нафтеновой нефти с добавкой WC/Ni–Cr

Using GCMS the composition of hydrocarbons in maltenes from heavy naphthenic crude oil (Usa oilfield) after cracking in the presence of WC/Ni–Cr additive and without it has been studied. Cracking of maltenes carried out at 450°С within 2 hours in isothermal mode. Using WC/Ni–Cr additive during cracking contributes to the deepening of the destruction reactions in hydrocarbons and resins. It is shown, the content of low-molecular alkanes С11–С19, alkylbenzenes С9–С10 increases essentially in the maltenes cracked with the additive while that of cyclohexanes and bicyclanes decreases, tri-, tetra- and pentacyclic saturated hydrocarbons destruct completely as compared with maltenes cracked without the additive. There are changes in the composition of naphthenic hydrocarbons. The reactions of condensation occur along with destruction reactions, leading to the formation of polyaromatic hydrocarbon.

SCF3 Radical Initiated Cascade Reaction of Unsaturated Hydrocarbon

SCF₃ Radical Initiated Cascade Reaction of Unsaturated Hydrocarbon