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Fischer-Tropsch synthesis was carried out with a ruthenium catalyst by using H2/D2 switching and competitive methods. The results showed that there is an inverse isotope effect during ruthenium-catalyzed Fischer-Tropsch reactions with the hydrocarbon production rate increasing when syngas was switched to D2/CO. When the ruthenium-catalyzed Fischer-Tropsch synthesis was conducted using a mixture of H2/D2/CO (1:1:1) as the syngas, the H/D ratios in hydrocarbons produced by the reaction are less than 1, indicating that the deuterium was enriched in these hydrocarbons. Also, the deuterium enrichment is a function of carbon number with more deuterium enriched in larger hydrocarbons. These results are similar to the results of cobalt and iron catalyzed Fischer-Tropsch reactions we have reported earlier. To explain these results and other experimental facts accumulated over the years about Fischer-Tropsch synthesis, we proposed the alkylidene mechanism for this important reaction, in which MCH is the monomer of this polymerization-like reaction and M=CHR is the growing chain. Based on this mechanism, we developed mathematic equations for each step of propagations to calculate the deuterium enrichment. The theoretic deuterium enrichment results calculated based on the Alkylidene mechanism are very close to the experimental results of deuterium enrichment of ruthenium-catalyzed Fischer-Tropsch reactions.

The detailed investigation of heavy oil catalytic upgrading is important because heteroatom-containing compounds are detrimental to refining processes and the environment. Atmospheric residues (ARs) with different compositions were hydrotreated in two plug-flow reactors in series to study the reactivity of various species over the commercial catalysts at the molecular level. A 15-T Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with atmospheric pressure photoionization (APPI) was applied to determine the molecular composition without chemical derivatization. Here, we examined the changes in bulk and molecular composition of two different ARs. The catalytic reactivity of the ARs was determined with respect to the relative abundance of the double bond equivalent (DBE) distribution dependent on carbon number for each class, such as hydrocarbon, sulfur, and nitrogen species. Reactivities and reaction routes of hydrocarbon, sulfur, and nitrogen species were discussed in detail at the molecular level.

Copper (Cu) provides a cost-effective means of producing value-added fuels through the electrochemical reduction of carbon dioxide (CO2RR). However, we observed the production of hydrocarbons via CO2RR on commercial Cu films is less efficient because of the surface impurities, i.e., Fe. Carbon monoxide (CO), a reaction intermediate of CO2RR to hydrocarbons, binds strongly to the Fe sites and interrupts the production of hydrocarbons, resulting in an active hydrogen evolution reaction (HER). Herein, we report a method of blocking the effect of Fe impurities on the Cu surface through the preferential growth of nano-sized metal-organic frameworks (MOFs) on Fe site. When zirconium (Zr)-based MOFs (UiO-66) forms a compensating layer on Cu film via the terephthalic acid (TPA)-Fe coordination bond, the UiO-66 coated Cu film (UiO-66@Cu) presents significantly improved hydrocarbon Faradaic efficiency (FE) of 37.59% compared to 14.68% FE on commercial Cu film (99.9% purity) by suppressing HER. According to X-ray photoelectron spectroscopy (XPS) analysis, the UiO-66 ligand binds to entire metallic Fe site on the Cu surface, while metallic Cu is retained. Thus, UiO-66@Cu provides active sites of Cu for CO2RR and leads to highly efficient and selective production of hydrocarbons.

Catalytic hydrodeoxygenation (HDO) of biomass-derived oxy-compounds to advanced hydrocarbon fuels usually requires bifunctional catalysts containing metals and acidic sites. The appropriate tuning of metal and/or acidic active sites at interfaces of bifunctional catalysts can significantly improve catalyst activity and product selectivity. Here, 4-trifuoromethyl salicylic acid (TFMSA), as a hydrothermal stable organic acid, was employed to tailor the bifunctional interface of Ru/γ-Al2O3 to enhance the catalytic performance on converting lignin-derived phenols to jet fuel range cycloalkanes. More than 80% phenol was converted into cyclohexane at 230 °C for 1 h over Ru/γ-Al2O3 modified by TFMSA, which was about three times higher than that over unmodified Ru/γ-Al2O3. X-ray diffraction (XRD), Transmission electron microscope (TEM), H2 chemisorption, and energy dispersive X-ray spectroscopy (EDS) elemental mapping results indicated that Ru nanoparticles and TFMSA were well distributed on γ-Al2O3, and a nanoscale intimacy between Ru and TFMSA was reached. Meanwhile, Fourier transform infrared spectroscopy after pyridine adsorption (Py-FT-IR) analysis proved that Bronsted acidic sites on the catalytic interfaces of TFMSA modified Ru/γ-Al2O3 had been improved. Moreover, the kinetic and density functional theory (DFT) results suggested that the synergistic effects of adjacent Ru nanoparticles and acidic sites were crutial for promoting the rate-limiting conversion step of phenol HDO to cyclohexane.

Titanium undergoes biological aging, represented by increased hydrophobicity and surface accumulation of organic molecules over time, which compromises the osseointegration of dental and orthopedic implants. Here, we evaluated the efficacy of a novel UV light source, 172 nm wavelength vacuum UV (VUV), in decomposing organic molecules around titanium. Methylene blue solution used as a model organic molecule placed in a quartz ampoule with and without titanium specimens was treated with four different UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed over 90% of methylene blue, while there was 3-, 3-, and 8-fold more methylene blue after the HUVC, PUV, and UVC treatments, respectively. In dose-dependency experiments, maximal methylene blue decomposition occurred after one minute of VUV treatment and after 20–30 min of UVC treatment. Rapid and effective VUV-mediated organic decomposition was not influenced by the surface topography of titanium or its alloy and even occurred in the absence of titanium, indicating only a minimal photocatalytic contribution of titanium dioxide to organic decomposition. VUV-mediated but not other light source-mediated methylene blue decomposition was proportional to its concentration. Plastic tubes significantly reduced methylene blue decomposition for all light sources. These results suggest that VUV, in synergy with quartz ampoules, mediates rapid and effective organic decomposition compared with other UV sources. This proof-of-concept study paves the way for rapid and effective VUV-powered photofunctionalization of titanium to overcome biological aging.

Catalytic steam reforming of propylene, benzene and toluene was investigated over Mn-Cr-O spinel oxides with different stoichiometry. The catalysts were structurally stable during reforming conditions except for Mn3O4, which reduced in situ to MnO. The Cr2O3 catalyst showed the highest initial rate for propylene reforming, whereas the Mn-rich Mn1.5Cr1.5O4 spinel was the most active and stable catalyst for aromatic reforming. Reforming rates of olefins and aromatics were comparable under 0.05 bar hydrocarbon and 0.40 bar steam at 873 K. The reforming rate of olefins and aromatics was first order in hydrocarbon and slightly inhibited by H2O, which is consistent with a Mars-van Krevelen type mechanism. Of the hydrocarbons investigated, only the rate of toluene reforming was negative first order in excess H2. Results from diffuse reflectance infrared Fourier transform spectroscopy of adsorbed toluene on a spinel catalyst suggest that H2 inhibits the rapid oxidation of the methyl group of toluene.

Implementation of lanthanide-organic frameworks (LOFs) as solid adsorbents has been frequently handicapped by their permanent porosity being difficult to establish owing to the remarkable flexibility and diversity of lanthanide ions in terms of coordination number and geometry. Construction of robust LOFs with permanent porosity for industrially important hydrocarbon separation will greatly expand their application potential. In this work, by distributing N and O donors into an

Gas-phase cationic ternary complexes of group 10 metals of the formula [(phen)M(X)]+, where phen = 1,10-phenanthroline (M = Ni, Pd, or Pt; and X = H or CH3), react with cyclohexane via C–H activation, forming the respective cyclohexyl species [(phen)M(c-C6H11)]+. Upon collisional activation, these species undergo two key competing processes: (i) ring opening followed by "cracking" of the hydrocarbon chain leading to extrusion of propylene and ethylene as major products among other hydrocarbons; and (ii) dehydrogenation of the cyclohexyl ring leading to the loss of one, two, or three hydrogen molecules, with subsequent loss of cyclohexenes or benzene. The relative prevalence of these two pathways strongly depends on the metal ion, with Pt preferring dehydrogenation over ring opening. The multiple catalytic cycles operating within both pathways are described. Density functional theory (DFT) calculations are used to shed light on mechanistic aspects associated with the experimental results.

[Nb(η6-C6H3Me3)2] reacts with ethylenediamine (en) solutions of K4Ge9 in the presence of 18-crown-6 to give [(η6-C6H3Me3)NbHGe6]2- (1) and [(η6-C6H3Me3)NbGe6Nb(η6-C6H3Me3)]2- (2) as their corresponding [K(18-crown-6)]+ salts. The crystalline solids are dark brown, air-sensitive, and sparingly soluble or insoluble in most solvents. The [K(18-crown-6)]+ salts of cluster ions 1 and 2 have been characterized by energy-dispersive X-ray (EDX) analysis, NMR studies, single-crystal X-ray diffraction, and electrospray ionization time-of-flight (ESI-TOF) mass spectrometry studies. Cluster ions 1 and 2 have markedly different [Ge6] moieties: an electron-deficient carborane-like subunit in 1 and a two-center, two-electron cyclohexane-like subunit in 2.

The development of porous materials for ethylene (C2H4) separation and purification, a very important separation process in the chemical industry, is urgently needed but quite challenging. In particular, the realization of selectivity-reversed adsorption (namely, C2H4 is not preferentially adsorbed) and the simultaneous capture of multinary coexisting impurities such as ethane (C2H6) and acetylene (C2H2) will significantly simplify process design and reduce energy and cost consumption, but such porous materials are quite difficult to design and have not yet been fully explored. In this work, by employing an aromatic-rich bithiophene-based tetraisophthalate ligand, we solvothermally fabricated an anionic In(III)-based framework termed ZJNU-115 featuring In(COO)4 as an inorganic secondary building unit as well as one-dimensional channels. Due to the absence of unsaturated metallic sites, together with aromatic-rich channel surface decorated with abundant hydrogen-bonding acceptors of carboxylate oxygen and thiophene sulfur atoms, desolvated ZJNU-115 exhibited an unusual adsorption relationship with respect to C2 hydrocarbons, namely, simultaneous and preferable capture of C2H6 and C2H2 over C2H4 at the temperatures investigated, thus representing a rare metal-organic framework (MOF) with the promising potential for one-step adsorption-phase purification of C2H4 from a trinary C2 hydrocarbon mixture. Compared to a few of the MOFs reported for such an application, ZJNU-115 displayed simultaneously good adsorption selectivities of both C2H2 and C2H6 over C2H4. Furthermore, its separation potential can be postsynthetically tailored by substituting dimethylammonium (Me2NH2+) counterions with tetraalkyl ammonium ions (NR4+; R = Me, Et, or n-Pr). More importantly, ZJNU-115 was stable in various organic solvents as well as aqueous solutions with pH values ranging from 5 to 9, thus laying a solid foundation for its practical applications. The design principle and the performance regulation strategy adopted in this work will offer valuable guidance for the contrapuntal construction of porous MOFs employed for direct multicomponent purification of C2H4 with improved performance.

A method for obtaining perchlorinated di-S,S-substituted derivatives of the closo-decaborate anion with various alkyl groups has been developed: [B10Cl9SR2]- (R= i-C3H7, n-C3H7, n-C4H9, n-C8H17, n-C12H25, n-C18H37, CH2Ph, and cyclo-S(CH2)4). The method is based on the preparation of the sulfonium-substituted anion [B10H9SR2]- by alkylation of the anion [B10H9SH]2- with bromoalkanes (i-C3H7Br, n-C3H7Br, n-C4H9Br, n-C8H17Br, n-C12H25Br, n-C18H37Br, PhCH2Br, and BrCH2(CH2)2CH2Br) followed by the cluster chlorination with sulfuryl chloride SO2Cl2 in acetonitrile. The process proceeds until the hydrogen atoms in the boron cluster are completely replaced with chlorine and completes within 60 h. It has been found that the melting point of salts ((C4H9)4N)[B10Cl9SR2] (R= i-C3H7, n-C3H7, n-C4H9, n-C8H17, n-C12H25, and n-C18H37) strongly depends on the length of the hydrocarbon chain of the substituent R.

Electrochemical CO2 reduction reaction (CO2 RR) to multicarbon hydrocarbon and oxygenate (C2+ ) products with high energy density and wide availability is of great importance, as it provides a promising way to achieve the renewable energy storage and close the carbon cycle. Herein we design a Cu-CuI composite catalyst with abundant Cu0 /Cu+ interfaces by physically mixing Cu nanoparticles and CuI powders. The composite catalyst achieves a remarkable C2+ partial current density of 591 mA cm-2 at -1.0 V vs. reversible hydrogen electrode in a flow cell, substantially higher than Cu (329 mA cm-2 ) and CuI (96 mA cm-2 ) counterparts. Induced by alkaline electrolyte and applied potential, the Cu-CuI composite catalyst undergoes significant reconstruction under CO2 RR conditions. The high-rate C2+ production over Cu-CuI is ascribed to the presence of residual Cu+ and adsorbed iodine species which improve CO adsorption and facilitate C-C coupling.

Proton exchange membranes (PEMs) play a critical role in many electrochemical devices that could solve the shortcomings of current energy storage and conversion systems. Hydrocarbon-based PEMs are an attractive alternative for replacing the state-of-the-art perfluorosulfonic acid PEMs; however, synthetic routes are generally limited to sulfonation of aromatic units (pre- or postpolymerization functionalization). Here we disclose a facile and scalable one-pot synthetic method of converting an alkyl halide functionality to a sulfonate in polymer systems. With this method, sulfonated hydrocarbon PEMs can be conveniently prepared from a precursor polymer of anion exchange membranes which have recently experienced significant advances. Polyphenylene type PEMs (BPSA and

We report the synthesis of polymethylene waxes, a surrogate of PE waxes, by a controlled polymerization reaction in water at or near r.t. and under atmospheric pressure. The monomer, dimethylsulfoxonium methylide, is generated in situ from a salt, trimethylsulfoxonium halide. The carbon sources for the polymerizations are C1 molecules, which can be derived from nonpetroleum feedstock. DMSO serves as the C1 carrier and is not consumed. The reaction is initiated and catalyzed by trialkylboranes, compounds that are stable in water. A certain degree of molecular weight control is achieved by adjusting the stoichiometry of “salt” to organoborane. Polymethylene, the simplest hydrocarbon polymer, is a semicrystalline material. The room temperature polymerization produces a linear polymer approximately 100 °C below its melting temperature (Tm). The supercooled polymers rapidly crystallize into flat nanoparticles comprised of stacked lamellae.

Hydrophilic–hydrophobic block copolymer ionomers based on polyphenylenes with controlled the block lengths were synthesized for the first time by a catalyst-transfer polycondensation of a dibromo phenylene derivative having a neopentyl ester protected sulfonic acid group, followed by the polycondensation of hydrophobic dibromo hexyloxybenzene. The diblock copolymer ionomers were obtained by the removal of neopentyl groups, resulting in clear phase separation dependent on the block lengths. The well-developed microphase separation provided controlled water uptake and sufficiently high proton conductivity, especially at low relative humidity conditions. The fine block copolymerization by using catalyst transfer polycondensation is a promising strategy for the development of hydrocarbon ionomers having well-defined ordered structures with reasonable proton conductivity for fuel cell applications.

Adsorptive desulfurization is a promising alternative to hydrodesulfurization for minimizing harmful sulfur emissions from hydrocarbon fuels. Cu in Y zeolite (CuY) has shown effective sulfur adsorp...

The shale of the seventh member of the Triassic Yanchang Formation in the Ordos Basin (abbreviated as Chang 7 shale) is the most prospective shale for in situ conversion process. In our previous study, a series of artificial maturation experiments were conducted to simulate the hydrocarbon generation–retention–expulsion process. However, during the experiments, a large amount of hydrogen sulfide (H₂S) was generated along with hydrocarbon products. Therefore, in this study, a combination of X-ray photoelectron spectroscopy, X-ray diffraction, and elemental analysis was used to reveal the thermal transformation of sulfur species and the formation process of H₂S. The results showed that kerogen decomposition and the corresponding products exert a strong influence on the transformation of organic sulfur and pyritic sulfur and, thus, on H₂S formation. Before the peak hydrocarbon-generating stage (

Methane dehydroaromatization (MDA) on Mo/ZSM-5 zeolite catalyst provides a promising route for the direct transformation of natural gas into high-valued chemicals. Understanding the nature of active sites on Mo/ZSM-5 represents one of the challenges to be resolved for technical application of this process. Herein, by using (1)H{(95)Mo} double-resonance solid-state NMR spectroscopy, we identify proximate dual active sites on Mo/ZSM-5 catalyst by direct observation of internuclear spatial interaction between Brønsted acid site and Mo species in zeolite channels. The acidic proton-Mo spatial interaction is correlated with methane conversion and aromatics formation in the MDA process, which is demonstrated to be an important factor in determining the catalyst activity and lifetime. The evolution of olefins and aromatics in Mo/ZSM-5 channels is monitored by detecting their host-guest interactions with both active Mo sites and Brønsted acid sites via (1)H{(95)Mo} double-resonance and two-dimensional (1)H-(1)H correlation NMR spectroscopy, which reveals the intermediate role of olefins in hydrocarbon pool process during the MDA reaction.

In recent years, bifunctional catalysts for the syngas-to-olefins (STO) reaction via the oxide-zeolite (OX-ZEO) strategy has been intensively investigated. However, the bifunctional catalyst containing H-SSZ-13 with a 100% H+-exchanging degree for the STO reaction has not been developed because of the high selectivity to paraffin. Here, we report a ZnCrO x + H-SSZ-13 bifunctional catalyst, which contains the submicron H-SSZ-13 with adequate acidic strength. Light olefins in hydrocarbon reached 70.8% at a CO conversion of 20.9% over the ZnCrO x + H-SSZ-13(23S) bifunctional catalyst at 653 K, 1.0 MPa, and GHSV = 6000 mL·g-1·h-1 after 800 min of STO reaction. The effect of CO and H2 on the C-C coupling was discussed by carrying out the methanol-to-olefins (MTO) reaction under a similar atmosphere as that of the STO reaction. H2 and CO should play a more dominant role than the conventional hydrogen transfer reaction on the undesired high selectivity of paraffins. These findings provide new insight into the design of the bifunctional catalyst for the STO process via the OX-ZEO strategy.

Dibenzobismepines may be described as bismuth heterocycles containing two arene functional groups (see the graphic). The coordination chemistry of mono- and dinuclear bismepines has been investigat...

An analysis is performed of results from works performed with the active participation of V.V. Lunin on the selective catalytic reduction of nitrogen oxides by hydrocarbons in the presence of an excess of oxygen. The main characteristics of the mechanism of the reactions, which includes the key step of interaction between nitrite–nitrate complexes and hydrocarbons, are determined using a unique set of spectral and kinetic means. This forms the basis for designing active components of catalysts of these processes that ensure high surface coverages by nitrite–nitrate complexes under actual conditions of catalysis, high rates of hydrocarbon activation on such sites, and their effective interaction with the nitrite–nitrate complexes. This is achieved by changing the transition metal cation on the surface of the support, its nearest coordination environment, its degree of clustering, and the basicity of the support. This approach ensures high activity, selectivity, and stability in desirable reactions under actual conditions for active components based on cations of copper, cobalt, nickel, and iron, along with such supports as high-silica zeolites, partially stabilized zirconia, zirconia-pillared natural clays, and framework zirconium phosphates, including ones promoted with silver or platinum. For the practical use of these active components, procedures are developed to deposit them on cellular honeycomb substrates using binders, creating efficient catalysts protected by RF patents.

International journal of chemical kinetics (2020). doi:10.1002/kin.21453, Published by Wiley, New York, NY

Diesel oxidation catalysts (DOC) were investigated for oxidation activity, NO conversion stability, and sulfur poisoning/regeneration on Pd/Al2O3, Pt/Al2O3, and Pd-Pt/Al2O3 catalysts. The Pd/Al2O3 catalyst was more active for CO and hydrocarbon (C3H6 and C3H8) oxidation, while the Pt/Al2O3 catalyst efficiently oxidized NO. The formation of a Pd-Pt alloy in the Pd-Pt/Al2O3 catalyst maintained Pd in a more reduced phase, resulting in the superior activity of this catalyst for the oxidation of CO, C3H6, and NO in comparison with its monometallic counterparts. The Pd-Pt alloy not only provided more low-temperature activity but also retained the stability of NO oxidation. The Pd-Pt alloy also favored the spillover of SO2 to the alumina support, resulting in significantly higher adsorption capacity of the Pd-Pt/Al2O3 catalyst, extensively prolonging its lifetime. However, the stable sulfates on Pd-Pt/Al2O3 made it difficult to completely regenerate the catalyst. The bimetallic sample showed higher activity for CO, C3H8, and C3H6 after sulfur poisoning and regeneration.

It is proposed to use a spent cracking catalyst of petroleum hydrocarbons containing 1 wt.% of rare earth element (REE) oxides as an alternative REE feed source. The study covers the process of removing silicon in the form of ammonium hexafluorosilicate (NH4)2SiF6 by sintering an oil cracking catalyst sample with NH4F and subsequent (NH4)2SiF6 sublimation to produce an aluminum-containing concentrate of rare earth elements. The orthogonal central compositional planning of the experiment was used to study the effect of three factors: sublimation temperature (350 to 400 °С), duration (40 to 80 min), and weight of the catalyst fluorinated sintered mass (5 to 10 g) on the (NH4)2SiF6 sublimation completeness. Results obtained in the experiment were used to build a second-order model, which correlate with experimental data. The dynamics of (NH4)2SiF6 sublimation removal was determined for sublimation durations of τ = 10, 20, 40 and 80 min at processing temperatures of 350, 375 and 400 °C. The (NH4)2SiF6 removal degree values calculated based on the second-order model for τ = 44, 48, 52, 56, 60, 64, 68, 72, and 76 min fit well the experimental curves. Spectra of fluorinated catalyst samples before and after sublimation were studied using X-ray phase analysis and IR spectroscopy. The data of IR spectroscopy and X-ray phase analysis are in good agreement and show that (NH4)2SiF6, (NH4)3AlF6 and unreacted NH4F are present in the catalyst with NH4F sintered mass, and only aluminum compounds are detected – NH4AlF4 and AlF3 after sublimation. These data indicate the completeness of the sublimation removal of silicon from the catalyst and NH4F sintered mass with NH4AlF4 and AlF3 aluminum compounds only observed after sublimation. REE concentration is 15 % due to silicon removal.

Cationic dyes of various natures have been investigated in order to select a dye that is stable under strongly alkaline conditions and applicable for the quantitative extraction-photometric determination of higher carboxylic acids. The nature of the dye, solvent, the length of the hydrocarbon radical of carboxylic acids and the pH of the aqueous phase for the extraction of ionic associates of higher carboxylic acids with cationic dye with pyronin G were experimentally studied. The study substantiates the practical application of the cationic dye pyronin G as an effective reagent for the quantitative extraction-photometric determination of higher carboxylic acids.

The ternary Pd complexes [(phen)Pd(H)]+ (1-Pd) and [(phen)Pd(CH3)]+ (5-Pd) (where phen = 1,10-phenanthroline) both react with hexane in a linear ion trap mass spectrometer, forming the C–H activation product [(phen)Pd(C6H11)]+ (3-Pd) and releasing H2 and CH4, respectively. Density functional theory (DFT) calculations agree well with the experiments in predicting low barriers for these reactions proceeding via a metathesis mechanism. Species 3-Pd undergoes extensive fragmentation, or "cracking", of the hydrocarbon chain when sufficient energy is supplied via collision-induced dissociation (CID), resulting in the extrusion of a mixture of alkenes, methane, and hydrogen. DFT calculations show that Pd "chain-walking" from α (terminal carbon) to β and from β to γ positions can proceed with barriers sufficiently below those required for chain "cracking". The fragmentation reactions can be made catalytic if 1-Pd and 5-Pd produced by CID of 3-Pd are allowed to react with hexane again. Ni complexes largely mirrored the chemistry observed for Pd. Both 1-Ni and 5-Ni reacted with hexane, forming 3-Ni, which fragmented under CID conditions in a fashion similar to 3-Pd. In contrast, only 5-Pt reacted with hexane to form 3-Pt, which fragmented predominantly via sequential losses of H2.

Recently, metal-organic frameworks (MOFs) have been investigated as potential materials for CO2 capture and light hydrocarbon storage/separation due to their high porosity, large surface area, and tunable skeleton structures. In this work, the six cobalt-based MOFs 1-6 were successfully synthesized under solvothermal conditions by a mixed-ligand strategy. 1 and 2 have the same framework structure with a topology of {42·5}2{44·510·67·76·8}, while the structures of the 3-6 frameworks are the same with a topology of {42·5}2{44·510·69·74·8}. The adsorption properties of these MOFs for CO2 and C2 hydrocarbons were then investigated, and the effect of the functional groups was discussed. The results revealed that the introduction of amino and bromo groups could effectively strengthen the adsorption performance.

The coal system of the Taiyuan Formation in the Dongpu Sag is a good source rock. In this paper, the representative hydrogen-rich coal of the Taiyuan Formation is selected for pyrolysis experiments. We used high-resolution transmission electron microscopy and Fourier transform infrared spectroscopy to characterize the structural evolution of coal during thermal simulation, combined with the characteristics of gas and liquid products from low-maturity coal pyrolysis to comprehensively reveal the process of coal of the Taiyuan Formation to hydrocarbon. The results show that the evolution of a hydrogen-rich coal structure is mainly divided into five stages: (1) Before 350 °C: The content of aromatic hydrogen and the distance between aromatic layers are almost unchanged. The aromatic structure is mainly composed of naphthalene and 2 × 2 aromatic rings, indicating that polycondensation does not clearly occur. Liquid hydrocarbons reach their maximum amount due to liptinite cracking. (2) 350-400 °C: The aromatic layer distance rapidly decreases, indicating that considerable polycondensation occurs. The fatty acid hydrogen in vitrinite is gradually reduced, which is caused by cracking of the side chain of the vitrinite fat to generate gaseous hydrocarbons. The rapid decline in liquid hydrocarbons and total hydrocarbons and the rapid increase in the aromatic hydrogen content of vitrinite may be caused by the cyclization and aromatization of the long-chain fatty acid structure, which converts the liquid hydrocarbons back to a solid. (3) 400-450 °C: The aromatic layer distance is almost unchanged. The fatty acid hydrogen in vitrinite slowly decreases, and the aromatic hydrogen in vitrinite gradually increases. The large amount of gaseous hydrocarbon generated at this stage is partly due to the continued cleavage of the fatty acid side chains in vitrinite and partly from the cleavage of the fatty acid side chains from the solid formed by aromatization. (4) 450-550 °C: The aromatic layer distance rapidly decreases to the minimum, and aromatic rings with sizes above 4 × 4 increase rapidly. Aromatic hydrogen rapidly decreases to the minimum, and the fatty acid hydrogen of vitrinite quickly decreases to 0. Considerable polycondensation and demethylation reactions occur in the vitrinite to produce a large amount of gaseous hydrocarbon. (5) 550-600 °C: The aromatic layer distance and contents of fatty acid hydrogen and aromatic hydrogen in vitrinite change slowly. Additionally, the yields of gas and liquid do not change significantly, indicating that the polycondensation intensity decreases and that the vitrinite and liptinite are cracked without producing hydrocarbons.

Low temperature combustion (LTC) diesel engines are more fuel efficient and have coincident lower temperature exhaust gas and higher CO and hydrocarbon exhaust gas concentrations than today’s standard diesel engine. To meet regulations, diesel oxidation catalysts (DOCs) will need to be improved and optimized to handle these higher CO and hydrocarbon concentrations emitted and the simultaneous lower exhaust temperatures. Pt-Pd bimetallic catalysts are often used as oxidation catalysts. Here, the mechanistic effects of water on CO and C3H6 oxidation were studied over model monometallic Pt and Pd catalysts, and a bimetallic 1:1 Pt-Pd/ γ-Al2O3 catalyst. Water in the reaction mixture improved CO oxidation light-off for the monometallic Pd and Pt-Pd catalysts and had a negative impact on light-off over the monometallic Pt catalyst. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed that more CO adsorbed on the Pd and Pt-Pd catalysts when water was present, particularly at the particle/support interface, while the opposite occurred on the Pt catalyst. For C3H6 oxidation, water in the reaction showed a negative impact on the light-off temperature for the Pd catalyst and a positive effect for the Pt catalyst. The Pt-Pd catalyst showed intermediate light-off behavior between the two monometallic catalysts. In terms of selectivity, slightly more CO and acetic acid were formed over the Pd and Pt-Pd catalysts when water was in the reaction mixture, while less CO was formed over the Pt catalyst, but overall, the selectivity towards certain partial oxidation products was not greatly affected with the addition of water to the reaction mixture.

Periodic density functional theory (DFT) calculations are employed to understand the origin of structure sensitivity in hydrodechlorination (HDC) of trichloroethylene (TCE) over different facets of a palladium catalyst. The HDC reaction is simulated on the terrace (Pd (111) and Pd (100)) and undercoordinated (Pd (211) and Pd (110)) sites of the Pd catalyst. The most stable binding configuration of TCE on the Pd surfaces is observed to be through the di-σ mode of binding, wherein each carbon atom of the TCE molecule is adsorbed atop of the Pd atom. On comparing TCE adsorption over different facets of Pd, a maximum binding energy of −178 kJ mol−1 is calculated over the Pd (110) surface. TCE, upon adsorption on Pd catalyst, undergoes dechlorination followed by hydrogenation of the hydrocarbon intermediates. The activation energies for C–Cl bond dissociation steps are significantly low when compared to the hydrogenation steps. The chlorine released from dechlorination tends to block the active sites, thereby poisoning the surface with high binding energies (B.E > −160 kJ mol−1) on all the surfaces. The trend in chlorine binding energies on Pd facets follows: Pd (110) > Pd (211) > Pd (100) > Pd (111). The removal of surface chlorine is facilitated by its reaction with surface hydrogen to form hydrogen chloride. The activation energy for hydrogen chloride formation is calculated to be 90 kJ mol−1 and 88 kJ mol−1 on Pd (111) and Pd (100) terrace sites, respectively and 109 kJ mol−1 and 118 kJ mol−1 on the step Pd (211) and corrugated Pd (110) facets, respectively. This suggests the ease of removal of Cl as HCl from the terrace sites as compared to the step and corrugated sites. The structure sensitivity in the TCE HDC reaction could possibly arise due to the differences in the energetics of Cl removal on different Pd facets. This mechanistic understanding could provide a rationale for designing suitable catalysts for the HDC of TCE.

CeO2 nanorods with a mean width of 11.9 nm were synthesized via a facile hydrothermal method. Subsequently, Fe/CeO2 and Fe/CeO2@xMnO2 catalysts were prepared from the CeO2 nanorods and applied in the high-temperature Fischer–Tropsch synthesis of light olefins. Results show that the CeO2 support donates electrons to Fe species, which promotes the dissociation of CO while suppressing the hydrogenation reaction, and then improves the selectivity to light olefins. The synergistic effect between Mn and Ce can improve the oxygen mobility on the catalyst surface and promote the electron-donating ability of Ce, thereby promoting the formation of χ-Fe5C2 and further improving the selectivity to light olefins. However, excess Mn hinders the contact between CeO2 and Fe species and the migration of O atoms, and electron transfer from Ce to Fe can be blocked. Additionally, the reduction of iron oxides was suppressed and subsequently the CO conversion was reduced. The best hydrocarbon distribution for light olefins was 40.4% at a CO conversion of 39.9% over the Fe/CeO2@0.2MnO2 catalyst.

The combination of a methanol synthesis catalyst and a solid acid catalyst opens the possibility to obtain olefins or paraffins directly from CO2 and H2 in one step. In this work several PdZn/TiO2-ZSM-5 hybrid catalysts were employed under CO2 hydrogenation conditions (240-360 °C, 20 bar, CO2/N2/H2 = 1/1/3) for the synthesis of CH3OH, consecutive dehydration to dimethyl ether and further oxygenate conversion to hydrocarbons. No significant changes after 36 h reaction on the methanol synthesis catalyst (PdZn/TiO2) were observed by XRD, XAS or XPS. No olefins were observed, indicating that light olefins undergo further hydrogenation under reaction conditions, yielding the corresponding alkanes. Increasing the aluminium sites in the zeolites (Si:Al ratio 80:1, 50:1 and 23:1) lead to a higher concentration of mild Brønstead acid sites promoting hydrocarbon chain growth.

Modifying VNU-18 (a MOF with a partial cone-sql layer pillared by the chains of pillars decorated with OH-) by substitution of OH- with Cl-, a new isoreticular structure, [Cu6(L)5·(Cl-)2·H2O·4DMF]·4DMF·6(H2O) (SNNU-Bai67, SNNU-Bai = Shaanxi Normal University Bai's group), has been successfully synthesized. Furthermore, we deeply investigated the selective C2 hydrocarbon separation properties of SNNU-Bai67 and VNU-18 by single-component gas adsorption experiments, breakthrough experiments and simulation studies. They exhibit highly selective adsorption for C2 hydrocarbons over CH4 compared to many reported MOFs for the separation of C2 hydrocarbons from CH4, due to the suitable pore sizes of the partial corn sql-layer built from the isophthalic acid analogy and Cu-paddlewheel units. Interestingly, with the counterion of OH- in VNU-18 tuned by Cl- in SNNU-Bai67, the adsorption uptake values of C2 hydrocarbons were apparently improved by 15.0% for C2H2, 20.4% for C2H4 and 25.3% for C2H6, respectively, while the IAST selectivities of C2 hydrocarbons/CH4 were still nearly the same, which may be because the synergistic effect of interactions of HC2/1OCOO, HC2/1N/CPy, HPyCC2, ππ or HC2CC2 between the gas molecules and the framework is enhanced by the weaker polarity of Cl- decorating the framework.

The trapping of paraffins is beneficial compared to selective olefin adsorption for adsorptive olefin purification from a process engineering point of view. Here we demonstrate the use of a series of Zn2(X-bdc)2(dabco) (where X-bdc2- is bdc2- = 1,4-benzenedicarboxylate with substituting groups X, DM-bdc2- = 2,5-dimethyl-1,4-benzenedicarboxylate or TM-bdc2- = 2,3,5,6-tetramethyl-1,4-benzenedicarboxylate and dabco = diazabicyclo[2.2.2.]octane) metal-organic frameworks (MOFs) for the adsorptive removal of ethane from ethylene streams. The best performing material from this series is Zn2(TM-bdc)2(dabco) (DMOF-TM), which shows a high ethane uptake of 5.31 mmol g-1 at 110 kPa, with a good IAST selectivity of 1.88 towards ethane over ethylene. Through breakthrough measurements a high productivity of 13.1 L kg-1 per breakthrough is revealed with good reproducibility over five consecutive cycles. Molecular simulations show that the methyl groups of DMOF-TM are forming a van der Waals trap with the methylene groups from dabco, snuggly fitting the ethane. Further, rarely used high pressure coadsorption measurements, in pressure regimes that most scientific studies on hydrocarbon separation on MOFs ignore, reveal an increase in ethane capacity and selectivity for binary mixtures with increased pressures. The coadsorption measurements reveal good selectivity of 1.96 at 1000 kPa, which is verified also through IAST calculations up to 3000 kPa. This study overall showcases the opportunities that pore engineering by alkyl group incorporation and pressure increase offer to improve hydrocarbon separation in reticular materials.

To activate methane at low or medium temperatures is a difficult task and a pre-requisite for the conversion of this light alkane into high value chemicals. Herein, we report the preparation and characterizations of novel SnOx/Cu2O/Cu(111) interfaces that enable low-temperature methane activation. Scanning tunneling microscopy identified small, well-dispersed SnOx nanoclusters on the Cu2O/Cu(111) substrate with an average size of 8 A, and such morphology was sustained up to 450 K in UHV annealing. Ambient pressure X-ray photoelectron spectroscopy showed that hydrocarbon species (CHx groups), the product of methane activation, were formed on SnOx/Cu2O/Cu(111) at a temperature as low as 300 K. An essential role of the SnOx–Cu2O interface was evinced by the SnOx coverage dependence. Systems with a small amount of tin oxide, 0.1–0.2 ML coverage, produced the highest concentration of adsorbed CHx groups. Calculations based on density functional theory showed a drastic reduction in the activation barrier for C–H bond cleavage when going from Cu2O/Cu(111) to SnOx/Cu2O/Cu(111). On the supported SnOx, the dissociation of methane was highly exothermic (ΔE ∼ −35 kcal mol−1) and the calculated barrier for activation (∼20 kcal mol−1) could be overcome at 300–500 K, target temperatures for the conversion of methane to high value chemicals.

Catalytic oxidation is the most efficient method of minimizing the emissions of harmful pollutants and greenhouse gases. In this study, ZrO2-supported Pd catalysts are investigated for the catalytic oxidation of methane and ethylene. Pd/Y2O3-stabilized ZrO2 (Pd/YSZ) catalysts show attractive catalytic activity for methane and ethylene oxidation. The ZrO2 support containing up to 8 mol% Y2O3 improves the water resistance and hydrothermal stability of the catalyst. All catalysts are characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), O2-temperature-programmed desorption (O2-TPD), and CO-chemisorption techniques. It shows that high Pd dispersion and Pd–PdO reciprocation on the Pd/YSZ catalyst results in relatively high stability. In situ diffuse reflectance infrared Fourier-transform (DRIFT) experiments are performed to study the reaction over the surface of the catalyst. Compared with bimetallic catalysts (Pd : Pt), the same amounts of Pd and Pt supported on ZrO2 and Y2O3-stabilized ZrO2 catalysts show enhanced activity for methane and ethylene oxidation, respectively. A mixed hydrocarbon feed, containing methane and ethylene, lowers the CH4 light-off temperature by approximately 80 °C. This shows that ethylene addition has a promotional effect on the light-off temperature of methane.

Owing to the chemical inertness and thermodynamic stability of CO2, efficiently regulating product selectivity during CO2 hydrogenation is still a big challenge. Without impairing the CO2 reactivity and stability, outstanding selectivity values, where 73.2% of the total hydrocarbon products were alkenes (CO free) and 97.9% of the total alcohol products were C2+ alcohols (87.4% ethanol), were achieved using a Na-promoted Fe3O4 microsphere catalyst. Significantly, compared to the literature results relating to CO2 hydrogenation, the highest yields of alkenes (22.03%) and ethanol (11.23%) were achieved in this work. Multiple characterization results demonstrate that the Na promoter contributes to tuning the composition of the iron oxides and iron carbides. In situ CO2-DRIFTS and NAP-XPS results revealed that the key step in ethanol formation is considered to be the bonding of adsorbed CHO* and *CHx. Synergistically utilizing the distinct catalytic roles of iron carbides and iron oxides can guide the design of effective catalysts and provide fundamental understanding relating to CO2 hydrogenation.

Hydrocarbon and perfluorinated polymers display distinct thermodynamic partitioning characteristics. These differences enable perfluoropolymers to outperform hydrocarbon polymers for many membrane-...

The nano-sized HZSM-5 zeolites with different Si/Al ratios were pretreated, characterized, and tested in ethylene oligomerization performed in a fixed-bed reactor under relatively mild conditions. The effects of catalyst acidity and reaction temperature on the activity, selectivity and stability were investigated, and a possible reaction route of ethylene over acidic sites of nano-sized HZSM-5 catalyst was proposed. In comparison with micro-sized HZSM-5 zeolite, nano-sized HZSM-5 zeolites exhibited higher activity and better resistance to deactivation. Under optimal conditions (T = 275–300 °C, P = 3.0 MPa, WHSV = 1.0 h−1), The average ethylene conversion was 62.5% over the nano-sized HZSM-5 with an Si/Al ratio of 80, while the selectivity to C4+ olefins and α-olefins was 64.3% and 13.3%, respectively. Furthermore, the products of ethylene oligomerization were a complex hydrocarbon mixture due to the acid-catalyzed secondary reactions, for which the distribution of even and odd numbered carbon atoms formed a continuous volcanic shape mainly centered on C6–C10. Furthermore, these tests demonstrate that the activity and selectivity of ethylene oligomerization depend on the operating conditions and the acidity of the catalysts. These results indicate that the Bronsted acid sites may be mainly responsible for secondary reactions and deactivation of the catalyst, whereas the Lewis acid sites may be more advantageous for ethylene oligomerization.

Experimental justification has been provided for the possibility of extractive isolation of technetium from raffinate of technical process of affinage of uranium–plutonium product resulting from hydrometallurgical reprocessing of spent nuclear fuel (SNF). Technetium (VII) from aqueous solution of Zr(IV) (10 g/L) and 4 mol/L HNO3 with small content of ZrOb+ and $${\text{Z}}{{{\text{r}}}_{{\text{2}}}}{\text{O}}_{{\text{3}}}^{{b + }}$$ oxocations is recovered by 80% in 30% TBP in hydrocarbon diluent over seven stages of counter-current continuous cascade at ratio O : A = 1 : 1. Variation in phase flow ratio for cascade part leads to virtually complete Tc(VII) extraction in organic phase over ten stages. Technetium(VII) is selectively back extracted from loaded organic phase with water virtually completely over eleven stages of counter-current continuous cascade. Technological extraction scheme for technetium isolation from SNF solutions has been proposed.

Chemical kinetic models of gasoline, jet, and diesel fuels and their mixtures with bioderived fuels are needed to assess fuel property effects on efficiency, emissions, and other performance metrics in internal combustion and gas turbine engines. As these real fuels have too many fuel components to be included in a chemical kinetic model, surrogate fuels containing fewer components are used to represent them. These surrogate fuels mimic the chemical classes or molecular structures contained in the real fuel. One of the important chemical classes in gasoline, jet, and diesel fuels comprises cyclohexanes. Cyclohexanes comprise about 30% or more by weight in diesel fuel. Also, Mueller et al (Energy Fuels. 2012;26(6):3284-3303) proposed n-butylcyclohexane (nBCH) as a component in a nine-component surrogate palette to represent the ignition properties, distillation curve, density, and molecular structures of a diesel certification fuel. In this work, experimental measurements of the ignition delay times (IDTs) of nBCH in a shock tube and in a rapid compression machine are reported over a wide range of temperature, pressure, and equivalence ratio important for enabling the validation of a chemical kinetic model for nBCH for combustion in diesel engines. The range of conditions are temperatures of 630-1420 K, pressures of 10, 30, and 50 bar, and equivalence ratios of 0.3, 0.5, 1.0, and 2.0 in 'air'. A detailed chemical model is developed for nBCH to simulate its ignition at both low and high-temperature conditions and at relevant elevated pressures. The experimentally measured IDTs are used to improve and validate the chemical kinetic model. The work at LLNL was supported by the U.S. Department of Energy, Vehicle Technologies Office (program managers Mike Weismiller and Gurpreet Singh) and performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. NUIG acknowledges the financial support of Saudi Aramco, the Irish Research Council and Science Foundation Ireland under grant numbers 15/IA/3177 and 16/SP/3829. Jinhu Liang acknowledges the International Scientific Cooperation Projects of Key R＆D Programs in Shanxi Province via project number 201803D421101. peer-reviewed 2021-11-26

A novel metal-organic framework (MOF), [Zn2(tdca)2(bppd)2]·2DMF, has been synthesized solvothermally using the ligand thiophene-2,5-dicarboxylic acid (H2tdca), coligand N,N'-bis(4-pyridylmethylene)-1,4-benzenediamine (bppd), and Zn(NO3)2. Single crystal X-ray crystallography reveals that the titled MOF is a three-dimensional pillared-layered MOF. A layer is constituted by a Zn(tdca) unit, and the layers are stabilized by the long hydrocarbon coligand, bppd, which acts as a pillar. A rectangular pore size of 11.42 × 8.12 A2 is found in the framework. The porous framework is found to be an excellent fluorescence sensor for the detection of toxic Cd2+ ion. The sensor shows high selectivity and sensitivity and a quick response toward Cd2+. The synthesized MOF is able to not only detect cadmium ions but also adsorb iodine in the gas phase. The MOF can adsorb ∼66% iodine, verified by thiosulfate-iodine titration and TG analysis. Adsorbed iodine can also be removed easily in acetonitrile as well as in n-hexane, which shows that iodine can be reversibly loaded as well as unloaded into the framework.

Selective adsorption of CO2 from flue gas is extremely significant because of its increasing concentration in air and its deleterious effect on the environment. In this work, we have explored metal-ion-bound prismane molecules for selective CO2 adsorption from the flue gas mixture. The Ca2+-bound prismane complex exhibits superior CO2 selectivity and adsorption capacity. The calculated binding energy and molecular electrostatic potential (MESP) analysis showed that the rectangular face of prismane binds strongly with metal ions as compared to its triangular face. The CBS-QB3 and density functional theory-based functional M06-2X/6-311+G(d) calculations show that the prismane molecule can bind to one Li+, K+, Mg2+, and Ca2+ ion with favorable binding energy. The metal-ion-bound prismane complexes have been examined for their CO2, N2, and CH4 adsorption capacity. Prismane-Ca2+ can bind with six CO2 molecules strongly with an average binding energy of -18.1 kcal/mole as compared to six N2 (-12.6) and five CH4 (-13.4) gas molecules. The gravimetric density calculated for the CO2-adsorbed prismane-Ca2+ complex has been found to be 69.1 wt %. The discrete hydrocarbon structure for selective separation of CO2 is rare in the literature and can have potential applications for cost-effective CO2 capture from the flue gas mixture.

Steamed zeolites have improved catalytic properties for hydrocarbon activation (alkane cracking reaction as well as alkane dehydrogenation). The nature of this practically important phenomenon has remained a mystery for the last six decades and was speculated to be related to increased Bronsted acidity during dealumination. We now prove that during steaming aluminum oxide clusters evolve (due to hydrolysis of Al out of framework positions with the following clustering) in the zeolitic micropores with properties very similar to (nano)facets of hydroxylated transition-alumina surfaces. Bronsted acidity of zeolite does not increase and the total number of Bronsted acid sites decreases during steaming. O5Al(VI)-OH surface sites of alumina clusters dehydroxylate at elevated temperatures to form penta-coordinate Al1O5 sites that are capable of initiating alkane cracking by breaking the first C-H bond very effectively, with the following reaction steps catalyzed by nearby zeolitic Bronsted acid sites. This explains the underlying reason behind the improved alkane cracking and alkane dehydrogenation activity of steamed zeolites: heterolytic C-H bond breaking occurs on penta Al(V)1O5 sites of aluminum oxide clusters confined in zeolitic pores. Furthermore, slightly decreased number of adjacent Al framework sites (due to Al dislodgement from the framework) decreases the coking activity, prolonging catalyst lifetime. Our findings explain the origin of enhanced activity of steamed zeolites at the molecular level and provide the missing understanding of the nature of extra-framework Al species formed in steamed/dealuminated zeolites. Furthermore, our findings suggest that similar La2O3 clusters exist for La-containing zeolites and the origin of their cracking activity promotion should be similar.

application/pdf, Journal of Solid State Chemistry. 2020, 290 (121545), P.1-6

The surface structure of copper (Cu) electrodes is a key factor determining product selectivity during electrochemical reduction reaction of carbon dioxide (CO2ERR). We investigated the influence o...