Benzene Cyclohexane Research Articles

Reversible hydrogenation and dehydrogenation of benzene for hydrogen storage on highly dispersed Pd/γ-Al2O3 catalyst

The research and development of efficient catalyst is the key to achieving high-capacity hydrogen storage in liquid organic hydrogen carriers (LOHCs). The highly dispersed Pd/γ-Al2O3 catalysts with few-atom Pd were prepared by impregnation method using HNO3 as promoter. The hydrogen storage capacity of the benzene/cyclohexane hydrogen carriers was further investigated by vapor phase benzene hydrogenation and cyclohexane dehydrogenation reactions over the studied Pd/γ-Al2O3 catalysts. The results showed that the metal Pd was the active centers for the benzene hydrogenation/cyclohexane dehydrogenation reactions. The addition of HNO3 can effectively promote the metal Pd to be highly dispersed, thus improving the Pd atoms utilization and reducing the Pd dosage. Meanwhile, the strongly electronic effects between the highly dispersed Pd species and the Al2O3 support promoted the electron-deficient Pdδ+ sites to be formed, which enhanced the adsorption and activation ability for the reactants molecules. The benzene conversion on the Pd/γ-Al2O3 catalyst with a metallic Pd loading of 1.0 wt% reached 97.51 % at 200 °C. While the cyclohexane conversion reached 90.94 % at 400 °C with the actual hydrogen storage capacity of 6.54 wt%, which provided an effective idea for large-scale storage and transportation of H2 based on LOHCs.

Design method of extractant for liquid–liquid extraction based on elements and chemical bonds

In the petrochemical industry process, the relative volatility between the components to be separated is close to 1 or the azeotrope that systems are difficult to separate. Liquid–liquid extraction is a common and effective separation method, and selecting an extraction agent is the key to extraction technology research. In this paper, a design method of extractants based on elements and chemical bonds was proposed. A knowledge-based molecular design method was adopted to pre-select elements and chemical bond groups. The molecules were automatically synthesized according to specific combination rules to avoid the problem of "combination explosion" of molecules. The target properties of the extractant were set, and the extractant meeting the requirements was selected by predicting the correlation physical properties of the generated molecules. Based on the separation performance of the extractant in liquid–liquid extraction and the relative importance of each index, the fuzzy comprehensive evaluation membership function was established, the analytic hierarchy process determined the weight ratio of each index, and the consistency test results were passed. The results of case study based on quantum chemical analysis demonstrated that effective determination of extractants for the analysis of benzene–cyclohexane systems. The results unanimously prove that the method has important theoretical significance and application value.

Control of the pore chemistry in metal-organic frameworks for efficient adsorption of benzene and separation of benzene/cyclohexane

Control of the pore chemistry in metal-organic frameworks for efficient adsorption of benzene and separation of benzene/cyclohexane

Mechanistic insight into separation of benzene and cyclohexane by extractive distillation using deep eutectic solvent as entrainer

In this work, a technical scheme for separation of benzene and cyclohexane by extractive distillation using deep eutectic solvent (DESs) as entrainer was proposed. Acetic acid (AA) was selected as hydrogen bond donor (HBD), tetraethylammonium bromide (TEAB) and tetraethylammonium chloride (TEAC) were selected as hydrogen bond acceptors (HBA), and two kinds of DESs were successfully prepared (i.e., DES1 is TEAC : AA = 1:3, DES2 is TEAB : AA = 1:3). Vapor liquid equilibrium experiments show that the relative volatility of benzene cyclohexane system can be significantly improved by using DESs as an entrainer, so that the separation of the target system can be achieved by extractive distillation. Further, quantitative calculations and molecular dynamics simulations were performed to explore the separation mechanism at the molecular level. The interaction sites between molecules were revealed by ESP analysis, and the interaction types between molecules were further elaborated by IGMH analysis. The results show that the Br atom of TEAB and the Cl atom of TEAC have hydrogen bonding with benzene, while there is π - π interaction between AA and benzene. The intermolecular interaction energy and spatial distribution function (SDF) further proved that the interaction between DES and benzene was stronger than that with cyclohexane. In conclusion, DES as entrainer for azeotrope separation has broad industrial application prospects.

SBA-15 and carbon supported nickel, heteropoly acid catalysts for the hydrodeoxygenation of lignin derived trans-anethole to sustainable aviation fuel

Catalyst is the key for the hydrodeoxygenation (HDO) of lignin derivatives to produce alkyl aromatics and alkyl cycloalkanes, key components of 100% sustainable aviation fuels (SAF). Mono and bi-functional catalysts of nickel (Ni) and heterophosphotungstic acid (HPW) supported on SBA-15 and carbons were prepared, characterized and evaluated for the HDO of lignin derived trans-anethole. The SBA-15 structure was intact but its surface area and pore volume decreased with the incorporation of Ni and HPW. UV–Visible DRS and XPS confirmed the presence of Nio and Ni2+ in the bi-functional catalysts. FTIR spectra of pyridine adsorbed Ni(10)-HPW(10)/SBA-15 catalyst showed the presence of both Brønsted and Lewis acid (Ni2+) sites and hence its acidity was higher than mono functional HPW/SBA-15 catalyst as indicated by the ammonia TPD studies. The synergy between them might be the possible reason for the higher and stable conversion, higher HDO selectivity, and more importantly higher selectivity for propyl benzene and propyl cyclohexane over bi-functional catalysts. Among the bi-functional catalysts, the highest conversion and HDO selectivity were observed over Ni(10)-HPW(10)/SBA-15. Its highest selectivity for propyl cyclohexane was due to its mean Ni particle size of 31.02 nm, large enough for the co-adsorption of hydrogen and benzene ring of propyl benzene, thus led to its saturation. Optimum temperature for the maximum conversion and HDO selectivity was found to be 400 °C for the bi-functional catalysts. Comparing carbon and SBA-15 supported Ni-HPW catalysts, later have shown higher HDO selectivity owing to strong metal-support interaction.

Study of the Dynamic Modes of the Operation of Flowsheets for the Extractive Distillation of a Benzene–Cyclohexane–Toluene Mixture

Study of the Dynamic Modes of the Operation of Flowsheets for the Extractive Distillation of a Benzene–Cyclohexane–Toluene Mixture

Evaluation of the adequacy of phase equilibria modeling based on various sets of experimental data

Objectives. The purpose of the paper is to compare the adequacy of mathematical models of vapor–liquid equilibrium (VLE) and their ability to reproduce the phase behavior of the ternary system benzene–cyclohexane–chlorobenzene using different experimental data sets to evaluate binary interaction parameters.Methods. The research methodologies were mathematical modeling of VLE in the Aspen Plus V.10.0 software package using activity coefficient models (Non-Random Two-Liquid (NRTL), Wilson) and the Universal quasichemical Functional-group Activity Coefficients (UNIFAC) group model, which allows for independent information. For the benzene–cyclohexane–chlorobenzene ternary system, the use of the NRTL equation is warranted because it provides a better description of the VLE experimental data.Results. The diagram construction of the constant volatility of cyclohexane relative to benzene lines revealed three topological structures. Only one of them can be considered reliable because it corresponds to the experimental data and coincides with the UNIFAC model diagram constructed based on independent UNIFAC model data. The results indicate that to study systems containing components with similar properties, it is necessary to improve the description quality of the available data sets (the relative error should not exceed 1.5%).Conclusions. The reproduction of the thermodynamic features of various manifolds in the composition simplex obtained by processing direct VLE data can be used to supplement the adequacy of the model. For the cyclohexane–benzene–chlorobenzene system, the best NRTL equation parameters are those regressed from the extensive experimental VLE data available in the literature for the ternary system as a whole.

Beyond Beer's Law: Quasi-Ideal Binary Liquid Mixtures.

We have recorded attenuated total reflection infrared spectra of binary mixtures in the (quasi-)ideal systems benzene-toluene, benzene-carbon tetrachloride, and benzene-cyclohexane. We used two-dimensional correlation spectroscopy, principal component analysis, and multivariate curve resolution to analyze the data. The 2D correlation proves nonlinearities, also in spectral ranges with no obvious deviations from Beer's approximation. The number of principal components is much higher than two and multivariate curve resolution carried out under the assumption of the presence of a third component, results in spectra which only show bands of the original components. The results negate the presence of third components, since any complex should have lower symmetry than the individual molecules and thus more and/or different infrared-active bands in the spectra. Based on Lorentz-Lorenz theory and literature values of the optical constants, we show that the nonlinearities and additional principal components are consequences of local field effects and the polarization of matter by light. Lorentz-Lorenz theory is, however, not able to explain, for example, the different blueshifts of the strong A2u band of benzene in the three mixtures. Obviously, infrared spectroscopy is sensitive to the short-range order around the molecules, which changes with content, their shapes, and their anisotropy.

Anaerobic phenanthrene biodegradation by a newly isolated sulfate-reducer, strain PheS1, and exploration of the biotransformation pathway

Phenanthrene is a widespread and harmful polycyclic aromatic hydrocarbon that is difficult to anaerobically biodegrade. Current challenges in anaerobic phenanthrene bioremediation are a lack of degrading cultures and limited knowledge of biotransformation pathways. Under sulfate-reducing conditions, pure-cultures and biotransformation processes for anaerobic phenanthrene biodegradation are poorly understood. In this study, strain PheS1, which is phylogenetically closely related to Desulfotomaculum, was found to be a sulfate-reducing phenanthrene-degrading bacterium. Anaerobic phenanthrene biodegradation using PheS1 was proposed based on metabolite and genome analyses, and the initial step was identified as carboxylation based on the detection of 2-phenanthroic acid, [13C]-2-phenanthroic acid, and [D9]-2- phenanthroic acid when phenanthrene+HCO3−, phenanthrene+H13CO3−, and [D10]-phenanthrene+HCO3− were used as the substrate, respectively. PheS1 genome ubiD gene encoding of carboxylase putatively involved in the biodegradation was performed. Next, benzene ring reduction and cleavage that produced benzene compounds and cyclohexane derivative were reported to occur in the downstream biotransformation processes. Additionally, benzene, naphthalene, benz[a]anthracene, and anthracene can be utilised by PheS1, whereas pyrene and benz[a]pyrene cannot. We discovered a new phenanthrene-degrading sulfate-reducer and provided the anaerobic phenanthrene biotransformation pathway under sulfate-reducing conditions, which can act as a reference for practical applications in bioremediation and for studying the molecular mechanisms of phenanthrene in anaerobic zones.

Advances in adsorptive separation of benzene and cyclohexane by metal-organic framework adsorbents

• Industrial separation of azeotropic benzene-cyclohexane incurs high energy footprint. • MOFs for benzene (Bz) over cyclohexane (Cy), Bz/Cy or the reverse, Cy/Bz selectivity. • Potential Bz/Cy and Cy/Bz separation performances analyzed by established methods. • Supramolecular interactions guided binding pockets enable Bz or Cy selectivity. • Future outlook on MOFs targeted at supramolecular Bz or Cy selective scaffolds. The chemical industry represents ca. 7% of the global GDP and 40% of its immense energy footprint stems from the separation/purification processes of commodity chemicals, particularly downstream processing of hydrocarbons. Of critical importance is the separation of C6 cyclic hydrocarbons benzene (C 6 H 6 ) and cyclohexane (C 6 H 12 ). Supplanting thermally driven distillation protocols such as azeotropic and extractive distillation methods by recyclable adsorbents, such as metal-organic framework (MOF) physisorbents, holds great promise for the reduction of this energy footprint. Whilst MOFs have come of age as physisorbents, they have been studied as benzene or cyclohexane selective adsorbents only rarely. Thanks to their amenability to crystal engineering, intensive research efforts have enabled metal-organic chemists to offer tunable coordination nanospaces in MOF sorbents in an adsorbate-specific manner, including aromatic benzene or aliphatic cyclohexane molecules. Despite the ever-expanding library of MOFs that often features families or isoreticular platforms of high surface-area materials with electron-rich or electron-deficient local pore environments, this research topic is underexplored and represents a niche area with a high upside potential. This review captures the progress made in MOF adsorbents to accomplish adsorption selectivity guided separation of the foregoing pair of C6 azeotropic hydrocarbons, which is crucial to the production of high-grade cyclohexane and benzene -important feedstock chemicals for further conversion into more useable commodity products, or as liquid organic hydrogen carriers. We also critically interrogate these examples to understand key structural and compositional approaches in order to efficiently design MOFs to extract benchmark selectivities and consequent high separation performances.

Nano-Pd/CeO2 catalysts for hydrogen storage by reversible benzene hydrogenation/dehydrogenation reactions

Nano-CeO2 supports, which have different structure from different preparation methods, were used to prepare nano-Pd/CeO2 catalysts. The hydrogen storage capacity of prepared nano-Pd/CeO2 catalysts were studied via vapor phase benzene hydrogenation and cyclohexane dehydrogenation reactions. Results show that the prepared Pd/CeO2 catalysts exhibit excellent benzene hydrogenation and cyclohexane dehydrogenation performances. The catalytic performance of the Pd/CeO2 catalysts is related to the dispersion of metallic Pd, hydrogen adsorption-desorption ability and structure of Pd/CeO2 catalysts and so on. And those properties are also directly affected by the morphology and mesoporous structure of the prepared nano-Pd/CeO2 catalysts that can be regulated by CeO2 support preparation methods. The synergistic effect between metal Pd, CeO2 support and their structures can effectively promote benzene hydrogenation and cyclohexane dehydrogenation, thus promoting hydrogen storage capacity. The prepared Pd/CeO2-HT catalyst, which has high specific surface area, developed pore structure and highly dispersed metal Pd species, exhibits superior catalytic performances. And, the Pd/CeO2-HT catalyst exhibits superior catalytic hydrogen storage performances. The benzene conversion over it at 200 °C reaches 99.5%. Whereas the cyclohexane conversion at 450 °C is 65.3%, and the H2 production capacity is 73.77 g/h.

Dual Emissive Gold(I)–Sulfido Cluster Framework Capable of Benzene–Cyclohexane Separation in the Solid State Accompanied by Luminescence Color Changes

A decanuclear gold(I)-sulfido complex, [(LH)4Au10S4]Cl2 (LH-Au10S4-Cl, where LH = 4,5-bis(diphenylphosphanyl)-2H-1,2,3-triazole), assembled from the reaction of H2S with the chlorogold(I) precursor obtained from the click reaction of [dppa(AuCl)2] (where dppa = 1,2-bis(diphenylphosphino)acetylene) with NaN3, is shown to display a bright dual green and red emission in the solid state. Single crystal X-ray diffraction (SCXRD) studies indicate a gold(I) cluster-based framework assembled through intermolecular halogen···hydrogen bonds as well as other weak interactions. The framework of LH-Au10S4-Cl is found to display high stability toward solvent molecules, with capability to encapsulate solvent molecules, such as benzene and cyclohexane, inside the crystal lattice voids via a single-crystal-to-single-crystal (SCSC) transformation. With different degrees of influence on the dual green and red emission, crystalline solids of LH-Au10S4-Cl exhibit remarkable solvatochromic luminescence in the presence of benzene and cyclohexane. Notably, due to the size confinement of the lattice cavities, the LH-Au10S4-Cl solids exhibit a high selectivity (>95%) toward benzene in a mixture of equimolar concentration of benzene and cyclohexane. This work has demonstrated the promising capability of gold(I)-sulfido cluster frameworks to serve as luminescent functional materials for the separation of benzene and cyclohexane.

Mechanisms of Caromatic-C bonds cleavage in lignin over NbOx-supported Ru catalyst

Efficient and selective cleavage of Caromatic-C linkages in lignin to enhance the productivity of monocyclic aromatic hydrocarbons is an extremely challenging and attractive task. Previously, we reported a Ru/NbOPO4 catalyst that realized the catalytic cleavage of both interunit C-C and C-O bonds in one-pot lignin conversions [Chem, 2019, 5, 1521–1536]. However, the roles of NbOx species in the selective Caromatic-C cleavage are not clear and need to be extensively studied. Herein, we focus on the exploration of the catalytic mechanisms of Caromatic-C bond cleavage over NbOx-supported Ru catalyst, by comparing with those of Ru/TiO2, Ru/ZrO2, and Ru/Al2O3 catalysts. It shows that the Ru/Nb2O5 catalyst exhibits high activity and remarkable selectivity to monocyclic hydrocarbons. A combined diffuse reflectance infrared Fourier Transform spectra (DRIFTS) and density functional theory (DFT) calculation analysis unambiguously confirmed that (i) NbOx not only can strongly adsorb phenylcyclohexane via benzene ring, but also selectively activate Caromatic-C bond between benzene ring and cyclohexane; (ii) NbOx can promote the protonation of phenylcyclohexane with the assistance of H3PO4; and (iii) NbOx can significantly reduce the barrier of Caromatic-C bonds cleavage of the carbocation intermediate (C6H5(H)C6H11+). A detail underlying mechanism has been established, which would have further implications to promote the design of new, high efficient catalysts.

Investigation of anaerobic biodegradation of phenanthrene by a sulfate-dependent Geobacter sulfurreducens strain PheS2

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous and harmful contaminants, which can be degraded aerobically. However, the persistence of PAHs in anoxic environments indicates that anaerobic biodegradation of PAHs should also be investigated. Pure-culture and biotransformation processes for anaerobic phenanthrene biodegradation with sulfate as a terminal electron acceptor remains in its infancy. In this study, we investigated anaerobic biodegradation of PAHs by PheS2, an isolated phenanthrene-utilizing sulfate-reducer, using phenanthrene as a model compound. PheS2 was phylogenetically closely related to Geobacter sulfurreducens and reduced sulfate to sulfide during anaerobic phenanthrene biodegradation. Phenanthrene biodegradation processes were detected using gas chromatography-mass spectrometry, genome, and reverse transcription quantitative PCR analyses. Carboxylation was the initial step of anaerobic phenanthrene biodegradation based upon detection of 2- and 4-phenanthroic acid, its isotopically labeled analogs when using 13C-labeled bicarbonate and fully deuterated-phenanthrene (C14D10), and genes encoding enzymes putatively involved in the biodegradation. Further, ring-system reducing and cleavage occurred, and substituted benzene series and cyclohexane derivatives were detected in downstream biotransformation metabolites. Additionally, PheS2 can degrade benzene, naphthalene, anthracene, and benz[a]anthracene, but not pyrene and benz[a]pyrene. This study describes the isolation of an anaerobic phenanthrene-degrading sulfate-reducer, the first pure-culture evidence of phenanthrene biotransformation processes with sulfate as an electron acceptor.

Anaerobic biodegradation of phenanthrene by a newly isolated nitrate-dependent Achromobacter denitrificans strain PheN1 and exploration of the biotransformation processes by metabolite and genome analyses.

Polycyclic aromatic hydrocarbons (PAHs) are widespread and harmful contaminants and are more persistent under anaerobic conditions. The bioremediation of PAHs in anaerobic zones has been enhanced by treating the contamination with nitrate, which is thermodynamically favourable, cost-effective, and highly soluble. However, anaerobic PAHs biotransformation processes that employ nitrate as an electron acceptor have not been fully explored. In this study, we investigated the anaerobic biotransformation of PAHs by strain PheN1, a newly isolated phenanthrene-degrading denitrifier, using phenanthrene as a model compound. PheN1 is phylogenetically closely related to Achromobacter denitrificans and reduces nitrate to nitrite (not N2 ) during the anaerobic phenanthrene degradation process. Phenanthrene biotransformation processes were detected using gas chromatography-mass spectrometry and were further examined by reverse transcription-quantitative PCR and genome analyses. Carboxylation and methylation were both found to be the initial steps in the phenanthrene degradation process. Downstream biotransformation processed benzene compounds and cyclohexane derivatives. This study describes the isolation of an anaerobic phenanthrene-degrading bacterium along with the pure-culture evidence of phenanthrene biotransformation processes with nitrate as an electron acceptor. The findings in this study can improve our understanding of anaerobic PAHs biodegradation processes and guide PAHs bioremediation by adding nitrate to anaerobic environments.

Thermochemistry of Solutions of Alkanes in Binary Mixtures: Azeotropes

This work is devoted to the study of azeotropes by the method of solvation thermodynamics. In the present work the thermochemistry of alkane solutions in binary mixtures was studied. The infinite dilution solution enthalpies of n-hexane, n-octane, and n-dodecane in binary mixtures were measured at 298.15 K. Alkanes were used as solutes since they are not capable of specific interactions with solvents. It should be noted that the differences in the solution of alkanes in a series of solvents are caused by differences in the interactions between the solvent molecules. Binary mixtures (benzene–cyclohexane) and (n-hexane–acetone) at different molar ratios, including the compositions corresponding to azeotropes, were used. The composition of both azeotropes obtained by distillation was determined by means of densimetry, and was found to be in good agreement with published data. The compositions of chosen azeotropes insignificantly change with temperature. The excess solution enthalpies of n-alkanes in binary solvents were calculated. It was found that the extremum value of the excess solution enthalpy corresponds to their azeotrope composition.

Chalcogen Bonding and Hydrophobic Effects Force Molecules into Small Spaces.

Supramolecular capsules are desirable containers for the study of molecular behavior in small spaces and offer applications in transport, catalysis, and material science. We report here the use of chalcogen bonding to form container assemblies that are stable in water. Cavitands 1-3 functionalized with 2,1,3-benzoselenadiazole walls were synthesized in good yield from resorcin[4]arenes. The solid-state single-crystal X-ray structure of 3 showed a dimeric assembly cemented together through multiple Se···N chalcogen bonds. Binding of hydrophobic and amphiphilic guests in D2O was investigated by 1H NMR methods and revealed host-guest assemblies of 1:1, 2:1, and 2:2 stoichiometries. Small guests such as n-hexane or cyclohexane assembled as 2:2 capsular complexes, larger guests like cyclohexane carboxylic acid or cyclodecane formed 1:1 cavitand complexes, and longer linear guests like n-dodecane, cyclohexane carboxylic acid anhydride, and amides created 2:1 capsular complexes. The 2:1 complex of the capsule with cyclohexane carboxylic acid anhydride was stable over 2 weeks, showing that the seam of chalcogen bonds is "waterproof". Selective uptake of cyclohexane over benzene and methyl cyclohexane over toluene was observed in aqueous solution with the capsule. Hydrophobic forces and hydrogen-bonding attractions between guest molecules such as 3-methylbutanoic acid stabilized the assemblies in the presence of the competing effects of water. The high polarizability and modest electronegativity of Se provide a capsule lining complementary to guest C-H bonds. The 2,1,3-benzoselenadiazole walls impart an unusually high magnetic anisotropy to the capsule environment, which is supported by density functional theory calculations.

Investigation of anaerobic phenanthrene biodegradation by a highly enriched co-culture, PheN9, with nitrate as an electron acceptor

In this study, we developed a highly enriched phenanthrene-degrading co-culture, PheN9, which uses nitrate as an electron acceptor under anaerobic conditions, and the processes mediating biodegradation were proposed. The dominant bacteria populations included Pseudomonas stutzeri (91.7% relative abundance), which shared 98% 16S rRNA-sequence similarity with the naphthalene-degrading, nitrate-reducing strain NAP-3-1, and Candidatus_Kuenenia (2.3% relative abundance), which is a type of anammox bacteria. Enrichment transformed 54% of the added phenanthrene, reduced nitrate, and generated significant amounts of nitrite. Enrichment also result in partial consumption of the produced nitrite by the anammox bacteria. The key initial steps of anaerobic phenanthrene biodegradation by PheN9 were methylation and carboxylation, which were identified for detection of metabolic products, as well as carboxylase and methyltransferase activities. The methylation product was then oxidized to 2-naphthoic acid and then underwent sequential biodegradation steps. Then, ring-system reducing occurred, and the metabolic products were identified as dihydro-, tetrahydro-, hexahydro-, and octahydro-2-phenanthroic acid. Downstream degradation proceeded via a substituted benzene series and cyclohexane derivatives. This study employed anaerobic phenanthrene-biodegradation processes with nitrate as an electron acceptor. These findings can improve our understanding of anaerobic polycyclic aromatic hydrocarbon (PAH) biodegradation processes and guide PAH bioremediation by adding nitrate to anaerobic environments.

Liquid–Liquid Extraction of Benzene and Cyclohexane Using Sulfolane-Based Low Transition Temperature Mixtures as Solvents: Experiments and Simulation

The separation of benzene and cyclohexane is considered to be one of the most challenging processes in the petrochemical industry. In this paper, low transition temperature mixtures (LTTMs) were used as solvents for the separation of benzene and cyclohexane. The selected LTTMs were sulfolane–tetrabutylammonium bromide 5:1 and ethylene glycol–trimethylamine hydrochloride 5:1, and liquid–liquid equilibrium (LLE) data of benzene–cyclohexane–LTTMs were experimentally determined at 40 °C under a normal atmosphere. Moreover, the effects of the mole ratio of hydrogen bond donor (HBD) sulfolane and hydrogen bond acceptor (HBA) tetrabutylammonium bromide on extraction performance were also observed based on the LLE data. It is found that, when the mole ratio of sulfolane to tetrabutylammonium bromide is 5:1, LTTM has the best extraction performance. In addition, the LLE data of the benzene–cyclohexane–LTTMs ternary system were used to fit parameters of the NRTL activity coefficient model. Based on the NRTL model the continuous extraction process was simulated and the operating parameters were obtained, and high product purity (cyclohexane 0.997) and high recovery efficiency (cyclohexane 93.28% and benzene 98.25%) can be achieved. In conclusion, the LTTM sulfolane–tetrabutylammonium bromide 5:1 is a promising solvent for the extractive separation of benzene–cyclohexane mixtures.

Effect of the morphology on the vapor phase benzene catalytic hydrogenation over Pd/CeO2 catalyst

CeO2 nanorods and nanocubes, which were used as supports to Pd (3.0 wt.%)/CeO2 catalysts, which were prepared by hydrothermal method. TEM, HRTEM, XRD, and H2-TPD were used to study the physic-chemical properties of the Pd/CeO2 catalysts. The Pd/CeO2 catalysts were applied to investigate the vapor phase benzene catalytic hydrogenation reaction under atmospheric pressure at the temperature of 100–200 °C. Results show that the Pd/CeO2 catalysts exhibit morphology-dependent catalytic activity. The Pd/CeO2 nanorod catalyst (PC100) has a superior vapor phase benzene catalytic hydrogenation performance. The benzene catalytic hydrogenation conversion and cyclohexane selectivity are 96.4% and 100% at 200 °C, respectively.