C2 Hydrocarbons Research Articles

Light-Driven Depolymerization of Cellulosic Biomass into Hydrocarbons.

Cellulose and hemicellulose are the main constituents of lignocellulosic biomass. Chemical derivatization of lignocellulosic biomass leads to a range of C5 and C6 organic compounds. These C5 and C6 compounds are valuable precursors (or fine chemicals) for developing sustainable chemical processes. Therefore, depolymerization of cellulose and hemicellulose is essential, leading to the development of various materials that have applications in biomaterial industries. However, most depolymerized processes for cellulose have limited success because of its structural quality: crystallinity, high hydrogen-bond networking, and mild solubility in organic and water. As a result, various chemical treatments, acidic (mineral or solid acids) and photocatalysis, have developed. One of the significant shortcomings of acidic treatment is that the requirement for high temperatures increases the commercial end cost (energy) and hampers product selectivity. For example, a catalyst with prolonged exposure to high temperatures damages the catalyst surface over time; therefore, it cannot be used for iterative cycles. Photocatalysts provide ample application to overcome such flaws as they do not require high temperatures to perform efficient catalysis. Various photocatalysts have shown efficient cellulosic biomass conversion into its C6 and C5 hydrocarbons and the production of hydrogen (as a green energy component). For example, TiO2-based photocatalysts are the most studied for biomass valorization. Herein, we discussed the feasibility of a photocatalyst with application to cellulosic biomass hydrolysis.

Guest molecule engineered pore aperture of a yttrium-based metal–organic framework for efficient 1,3-butadiene separation from C4 hydrocarbons

Molecular sieving separation of 1,3-butadiene (C4H6) from C4 hydrocarbons is a highly desired method for C4H6 purification while it is still a challenge to finely tune the pore aperture size of metal–organic framework (MOF) adsorbent. To develop molecular-sieving MOFs for gas separation, most efforts mainly focus on the precise control of intrinsic window size of MOF framework while little effort has focused on regulating the pore size of MOF by guest molecule. In this work, we report the guest molecule engineered pore aperture strategy of MOF for molecular-sieving separation of C4H6 from other C4 hydrocarbons. As a proof-of-concept experiment, the aperture pore structure of a robust yttrium-based Y-abtc (abtc = 3, 3′, 5, 5′-azobenzene-tetracarboxylate) was adjusted by the controlled decomposition of the trapped dimethylamine cations in the pores. The optimal Y-abtc-160, which was obtained by treating the as-synthesized Y-abtc sample at 160 °C, exhibits typical type I adsorption isotherm for C4H6 at 298 K while other C4 components are excluded by size exclusion effect even at 1 bar. The C4H6 uptake in Y-abtc-160 is up to 49.5 cm3 g−1 at 1 bar, which exceeds all the reported adsorbents with ideal molecular-sieving effect. The column breakthrough experiments verify the efficient separation of C4H6/n-C4H8, C4H6/iso-C4H8, C4H6/n-C4H10, and C4H6/iso-C4H10 binary mixtures. In addition, Y-abtc-160 MOF has good regeneration ability and excellent chemical stability, implying great potential for the practical separation of C4H6 from other C4 hydrocarbons.

Production of jet fuel range hydrocarbons using a magnetic Ni–Fe/SAPO-11 catalyst for solvent-free hydrodeoxygenation of jatropha oil

A novel, multifunctional Nix–Fe/SAPO-11 catalyst was synthesized and characterized, and its activity was evaluated for the solvent-free hydrodeoxygenation of jatropha oil. The catalyst has a spherical structure and moderate acid strength, and exhibited excellent cyclization and deoxidation activity. The inclusion of iron facilitated the dispersion of active components. Consequently, the iron-nickel alloy particle size remained small, resulting in an optimal distribution of the product. The composition of the products is linear alkanes (59.83%), isoparaffins (4.16%), aromatics (8.41%), and naphthenes (12.03%), where jet fuel components are relatively high, accounting for 55.04% of C8–C16 hydrocarbons. Interestingly, the iron present in the catalyst allowed the use of an external magnetic field for the rapid separation and recycling of the catalyst. Despite multiple uses, the recycled catalyst maintained high activity following five cycles, with hydrocarbon content consistently above 85%. The synergic effect of the metallic and acid sites of the catalyst, let to realize one-pot hydrodeoxygenation, isomerization, aromatization, and cracking of substrate forming bio-jet fuel range hydrocarbons.

Modification of Detailed Kinetic Mechanism for Aromatic Hydrocarbon Formation during C3–C4 Hydrocarbon Pyrolysis

Modification of Detailed Kinetic Mechanism for Aromatic Hydrocarbon Formation during C3–C4 Hydrocarbon Pyrolysis

Delaminated and Pit-rich Nano-kaolinites obtained via an Intercalation-etching Method and their Application to Fischer–Tropsch Synthesis

AbstractModified kaolinites possess excellent adsorption properties and, therefore, are regarded widely as potential catalytic components. The use of modified kaolinites as a catalytic component for Fischer–Tropsch synthesis (FTS) has remained unexplored, however. In the current study, delaminated and pit-rich nano-kaolinite was prepared via acid treatment of N-methylformamide (NMF)-intercalated kaolinite (intercalation-etching strategy), and was used as a support to prepare a cobalt-based FTS catalyst (denoted as 15%-Co-HNKln). Compared with other FTS catalysts, the supports for which were raw kaolinite or directly acid-treated kaolinite, the 15%-Co-HNKln showed several advantages such as large specific surface area, dispersed Co particles with small particle size, more new active sites, and significant surface acidity. Given the aforementioned advantages, the 15%-Co-HNKln catalyst demonstrated very good FTS performance. Compared with that of the raw kaolinite-supported FTS catalyst, the CO conversion rate and C5–C12 hydrocarbon selectivity of 15%-Co-HNKln increased by 20% and 15%, respectively.

CALCULATION OF THERMODYNAMIC AND KINETIC PARAMETERS OF CATALYTIC CRACKING REACTIONS ON LEWIS AND BRØNSTED ACID SITES

Link for citation: Nazarova G.Y., Ivashkina E.N., Maltsev V.V. Calculation of thermodynamic and kinetic parameters of catalytic cracking reactions on Lewis and Brønsted acid sites. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 214-225. In Rus. The relevance of the research is caused by the emerging necessity of developing a mathematical model to optimize the heterogeneous process of catalytic cracking. This tools should take into account both the chemical transformations of a wide range of hydrocarbon groups (different feedstock types), as well as the stages of adsorption, reactants diffusion, conversion of hydrocarbons on the catalyst surface, acid characteristics and pore size of the catalysts. The study of the hydrocarbon conversion patterns on Lewis or Brønsted acid sites using quantum-chemical modeling methods allow us to quantify the thermodynamic parameters of reactants adsorption, the kinetic parameters of carbocations formation and cracking on acid sites. These results are necessary to develop a mathematical model based on the of heterogeneous catalytic reaction mechanism. The aim of this work is to identify the level of quantum chemical theory and to determine the thermodynamic and kinetic parameters of reactants adsorption, carbenium ions formationand hydrocarbons cracking on Lewis and Brønsted acid sites. Methods: quantum-chemical modeling methods to optimize the molecular geometry of reactants and products of catalytic cracking reactions, calculate vibrational frequencies, thermodynamic parameters of adsorption and catalytic cracking of hydrocarbons and heteroatomic compounds with the participation of Bronsted and Lewis acid sites. Results. The chosen level of quantum-chemical theory allowed obtaining the results that are consistent with the laws of the process and the experimental reactivity of hydrocarbons in cracking reactions on acid catalysts. The thermodynamic parameters of the adsorption of C6–C16 hydrocarbons and thiophenes on Lewis and Brønsted acid sites were identified. We found that during the cracking of n-hexane on the Lewis acid site, the reaction is limited by the carbenium ion formation stage.The activation energy of this stage was 281,3 kJ/mol whereas the value for the cracking stage was 277,2 kJ/mol. Further study shows that the activation energy of carbenium ion formation from izohexane and C8–C10 alkanes with normal structure on the Lewis acid site was 257,6 and 279,2…277,9 kJ/mol. The most energetically favorable is the formation of carbocation from hexene at Brønsted acid sites (76,59 kJ/mol). The results of the work will be used to create a mathematical model of a heterogeneous process based on the Langmuir–Hinshelwood equations.

Insight into performance over IM-5, ZSM-5 and ZSM-11 zeolites for n-heptane cracking to light olefins in the absence & presence of steam

The three dimension (3D) 10-membered ring channels zeolite has a unique advantage in increasing light olefins for catalytic cracking reaction. Herein, zeolites IM-5, ZSM-5 and ZSM-11 were synthesized hydrothermally to achieve comparable texture properties and SiO2/Al2O3 ratios. The acid content and acid strength of the three zeolites were as follows: IM-5 > ZSM-5 > ZSM-11. Meanwhile, 1H DQ MAS NMR confirmed that there was a synergistic effect between Brønsted and Lewis acids in IM-5 zeolite. However, IM-5 zeolite with lots of strong BAS had an unexpected low TOF in n-heptane cracking. Furthermore, the light olefins selectivity was as follows: IM-5 > ZSM-11 > ZSM-5 at 550–650 ℃ in the absence of steam. IM-5 zeolite had the particular advantage in ethylene, and its selectivity was up to 44.9 %. After steam was introduced, the monomolecular cracking reaction, the aromatization of propylene and the deep cracking of C3 and C4 hydrocarbons were inhibited over the three zeolites. Steam could prolong the activity of IM-5 zeolite, but accelerate the deactivation of ZSM-5 and ZSM-11 zeolites. The primary cause for the rapid deactivation of ZSM-5 and ZSM-11 zeolites was dealuminization in steam, whereas for the IM-5 zeolite, it was the rapid formation of coke on its surface, thereby blocking its micropore channels.

A new approach to determining the blending octane number of gaseous components of motor gasolines

The octane number for gaseous components (GC) is currently determined using the calculation method proceeding from the hydrocarbon composition. The method provides determination of the research octane number (RON) only. A discrepancy between the actual and predicted values of the octane number thus determined leads to an overestimated introduction of these components into the fuel which results in the reduced fuel performance and economic indicators of the production. In this regard, the development of a new approach to the determination of the blending octane number of low-boiling components is extremely important for designing optimal formulations of motor fuels. A method for determining the blending octane numbers (both RON and MON) of motor gasoline gaseous components has been improved due to preliminary sample preparation by bubbling which provided taking into account the proportion of involving fractions of C4 hydrocarbon and pentane-amylene along with the chemical nature of the base fuel components. It is shown that the value of the blending octane number for gaseous components depends on the hydrocarbon composition of the base component. Application of the developed method to determining the blending octane number of gaseous components of motor fuels allowed us to obtain optimal formulations of gasoline with the involvement of low-boiling by-products and increased the accuracy of forecasting the composition of fuels thus improving the economic performance of the production.

Mid-infrared cross-sections and pseudoline parameters for trans-2-butene (2-C4H8)

We measured cross-sections for trans-2-butene (trans-2-C4H8: CH3-CHCHCH3) in the mid-infrared (800–1533 cm−1) in support of remote sensing of Titan’s atmosphere. Trans-2-butene is one of many C4 hydrocarbons that is predicted to be present in Titan’s atmosphere in detectable abundance, but it has also eluded detection thus far. We collected 20 pure and N2-mixture spectra at temperatures between 180–297 K using a high-resolution Fourier transform spectrometer (Bruker IFS 125 HR) at the Jet Propulsion Laboratory. Spectral resolutions were selected between 0.0039 and 0.062 cm−1, depending on sample pressures. We observed several fundamental modes of vibration and compared their updated band centers against those previously reported in the literature. Our observations span the 800–1533 cm−1 range, which contains multiple vibrational bands and hot band features, and we report temperature-dependent cross-sections in this spectral range. To ensure that our cross-section results are reliable measures of band intensities, we also collected an additional set of 8 room temperature N2-mixture spectra, investigating the linearity between integrated absorbance and optical burden. We fit all of the observed spectra simultaneously to derive a single set of pseudoline parameters, which include intensities and lower-state energies at separate frequency bins, which are considered as pseudoline positions. The pseudolines are observed to be able to reproduce the observed spectra via line-by-line radiative transfer calculations to within a few percent across the spectral region. The pseudoline list is compiled in HITRAN database format, making it readily integrable in existing radiative transfer codes. The absorption cross-sections represented by the pseudolines provide important laboratory input to the search for elusive molecules in future observations with JWST/MIRI or ground-based observatories such as NASA’s Infrared Telescope Facility, as well as in the Cassini/CIRS data archive.

New reaction path for long-chain hydrocarbons by electrochemical CO2 and CO reduction over Au/stainless steel

The Fischer-Tropsch (F-T) synthesis is recognized for its ability to produce long-chain hydrocarbons. In this study, we aimed to replicate F-T synthesis using electrochemical CO2 reduction and CO reduction reactions on a stainless steel (SS) support with a gold (Au) overlayer. Under CO2-saturated conditions, the presence of Au on the SS surface led to the formation of CH4 and a range of hydrocarbons (CnH2n and CnH2n+2, n = 2–7), while bare SS primarily produced hydrogen. The Au(10 nm)/SS exhibited the highest hydrocarbon production in CO2-saturated phosphate, indicating a synergistic effect at the Au-SS interface. In CO-saturated conditions, bare SS also produced long-chain hydrocarbons, but increasing Au thickness resulted in decreased production due to poor CO adsorption. Hydrocarbons were formed through both direct and indirect CO adsorption pathways. Anderson-Schulz-Flory analysis confirmed surface CO hydrogenation and C–C coupling polymerization following conventional F-T synthesis. The C2 hydrocarbons exhibited distinct behavior compared to C3-5 hydrocarbons, suggesting different reaction pathways. Despite low reduction product levels, our EC method successfully replicated F-T synthesis using the Au/SS electrode, providing valuable insights into C–C coupling mechanisms and electrochemical production of long-chain hydrocarbons. Depth-profiling X-ray photoelectron spectroscopy revealed significant changes in surface elemental compositions before and after EC reduction.

Shale oil resource evaluation with an improved understanding of free hydrocarbons: Insights from three-step hydrocarbon thermal desorption

The pyrolysis parameter S1, which indicates the amount of free hydrocarbons present in shale, is often underestimated due to hydrocarbon loss during sample handling and measurement processes. To remedy this issue, we strongly recommend an immediate three-step hydrocarbon thermal desorption (HTD) approach to be conducted on oil shale at the drilling site. This approach measures Sg, S0, and S1*, which refer to gaseous, light, and free hydrocarbons, respectively. The new shale oil content value, calculated from the total of these three parameters, is far more precise and reliable than traditional pyrolysis S1. Moreover, we thoroughly investigated the components and microscopic occurrence features of hydrocarbons thermally desorbed at three temperature stages using gas chromatography (GC) and X-ray microcomputed tomography (CT). For example, we selected Chang 73 mud shale. Our experimental results irrefutably indicate that the ultimate shale oil content of poor resource rocks is significantly impacted by evaporative loss, with this effect being greater when the total organic carbon (TOC) is lower. Additionally, C1-5 and C1-7 hydrocarbons constitute almost all of Sg and S0, respectively. Sg and S0 are predominantly composed of C1-3 gaseous hydrocarbons, with a maximum proportion of 42.93%. In contrast, S1* contains a substantial amount of C16-31 hydrocarbons. A three-dimensional reconstruction model of an X-ray micro-CT scan shows that while the amount of shale organic matter greatly decreases from the frozen state to 300 °C, the pore volume significantly increases, particularly between 90 and 300 °C. The increased pore volume is mainly due to macropores and fractures. It is imperative to note that the shale oil triple-division boundaries must be adjusted based on more accurate oil content, although this would not affect the resource zones to which the samples already belong (ineffective, low-efficient, and enriched resources). In conclusion, we strongly advise conducting an immediate well-site analysis or utilizing preservation procedures, such as deep freezing or plastic film wrapping followed by core waxing, to minimize volatile loss.

Enhanced biodegradation of crude oil contamination by indigenous bacterial consortium under real conditions

This study was performed to evaluate the efficiency of using locally isolated bacteria to degrade crude oil in sea water-based medium. The bacteria were isolated from water samples taken from different sea environments (Mediterranean, Aegean, Marmara, and Black Sea). The experiments for crude oil degradation were carried out in small volume (100 mL sea water medium in 250 mL shaking flasks) or large volume (14 L sea water-based medium in a plastic container). Furthermore, the media were not sterilized and remained open to the environment (non-sterile conditions). On the other hand, the media were shaken at a low speed of 50 rpm to mimic sea conditions. Of twelve bacterial isolates, four isolates (PB1, PB4, PB6, and PB7) having higher oil degradation potential were selected. According to 16S rRNA analysis, the isolates PB4 and PB6 were identified as, respectively, Rhodococcus qingshengii and Alcanivorax venustensis, and the other two isolates (PB1 and PB7) as Pseudomonas sabulinigri. When the usability of four isolates alone or as a co-culture for crude oil degradation was tested, co-cultures were found to cause more crude oil degradation than individual bacterial cultures. Among the co-cultures, the maximum degradation of crude oil was achieved with the association of PB6 + PB4. During the experiments, carbon sources and minerals were not supplemented to the sea water medium, and even the supplementation of only nitrogen source (especially ammonium sulphate) was determined to significantly enhance the crude oil degradation potential of the bacterial consortium (PB6 + PB4). Spectrophotometric analyses (OD225) demonstrated that crude oil degradation continued up to 12th day in small volume but 16th day in large volume. GC-MS analyses revealed that co-culture of PB6 and PB4 degraded 100% of C9–C12 and C16–C29 hydrocarbons and 85% of C13–C15 hydrocarbons.

Adsorption mechanisms of ethane, ethene and ethyne on calcium exchanged LTA and FAU zeolites

The aim of this study is to unravel the influence of single, double and triple bonds in hydrocarbons on the mechanisms of adsorption on zeolites. Therefore, the adsorption of the C2 hydrocarbons ethane, ethene and ethyne on different adsorbents is studied by adsorption calorimetry. As adsorbents pure sodium LTA (NaA) and FAU (NaX) zeolites and calcium exchanged CaNaA and CaNaX zeolites are used. Based on experimental loadings and heat of adsorption, the influence of the number and distribution of cations on different cation positions are discussed in detail. With increasing degree of exchange the increasing number of Ca2+-cations introduce energetically more valuable adsorption sites into the zeolites. On the other hand, the decreasing total number of cations has a negative effect on saturation loading. The impact of these opposing effects and the different occupation of cation positions on the interactions and mechanisms occurring are discussed. The loading increases from ethane to ethene to ethyne and shows higher values on FAU compared to LTA. In terms of interactions, due to the single bond, in ethane only dispersion and induction interactions are formed. In ethene and ethyne due to the double and triple bonds, respectively, additional quadrupole cation and π-interactions occur. In this study, for the first time the formation of a π-complex with Ca2+-cations at position I in LTA and at positions II, III, and III’ in FAU is demonstrated. For ethyne, additional π-complex formation with Na+-cations on the identical positions is also detected, which was previously unknown in literature.

Discovering a Single‐Atom Catalyst for CO2 Electroreduction to C1 Hydrocarbons: Thermodynamics and Kinetics on Aluminum‐Doped Copper

AbstractThe electrochemical reduction of carbon dioxide (CO2) to hydrocarbons is a potential option to achieve carbon neutrality. Although copper (Cu) shows the highest activity for the CO2 reduction reaction (CO2RR) to hydrocarbons among metals, high reaction overpotentials and significant H2 production limit its use. We investigate single‐atom alloys (SAAs) of ten metals (Ag, Au, Fe, Ir, Ni, Pd, Pt, Rh, Ru, Al) on Cu(111), which is the most‐favored facet on Cu for methane production, using density functional theory. We examined the dopants’ ability to lower the free energy of the elementary reaction, *CO to *CHO, which is the potential‐determining step (PDS). Out of the SAAs studied, only Al‐doped Cu demonstrated a lowering of the PDS free energy. Additionally, weaker adsorption energies of *CO and *H on Al−Cu(111) suggest a preference for C1 hydrocarbons and inhibition of H2 evolution. Finally, activation barrier calculations for the PDS on Al−Cu(111) involving an explicitly hydrated proton indicated better intrinsic activity for C1 hydrocarbons compared to pure Cu(111). We also confirmed the stability of Al−Cu SAA compared to small Al clusters. Through a comprehensive study of both thermodynamics and kinetics, our study presents Al−Cu SAA as a promising catalyst for CO2 electroreduction to C1 hydrocarbons.

PH-Regulated Refinement of Pore Size in Carbon Spheres for Size-Sieving of Gaseous C8 , C6 and C3 Hydrocarbon Pairs.

Selective separation of industrial important C8 , C6 and C3 hydrocarbon pairs by physisorbents can greatly reduce the energy intensity related to the currently used cryogenic distillation techniques. The achievement of size-sieving based on carbonaceous materials is desirable, but commonly hindered by the random structure of carbons often with a broad pore size distribution. Herein, a pH-regulated pre-condensation strategy was introduced to control the carbon pore architecture by the sp2 /sp3 hybridization of precursor. The lower pH value during pre-condensation of glucose facilitates the growth of aromatic nanodomains, rearrangement of stacked layers and a concomitant transition from sp3 -C to sp2 -C. The subsequent pyrolysis endows the pore size manipulated from 6.8 to 4.8 Å and narrowly distributed over a range of 0.2 Å. The refined pores enable effective size-sieving of C8 , C6 and C3 hydrocarbon pairs with high separation factor of 1.9 and 4.9 for C8 xylene (X) isomers para-X/meta-X and para-X/ortho-X, respectively, 5.1 for C6 alkane isomers n-hexane/3-methylpentane, and 22.0 for C3 H6 /C3 H8 . The excellent separation performance based-on size exclusion effect is validated by static adsorption isotherms and dynamic breakthrough experiments. This synthesis strategy provides a means of exploring advanced carbonaceous materials with controlled hybridized structure and pore sizes for challenging separation needs.

Suspension oligomerization of C9 hydrocarbon fraction initiated by aliphatic N-substituted aminoperoxides

We investigated the production of petroleum resins by suspension oligomerization of С9 hydrocarbon fraction initiated by aliphatic aminoperoxides. The reaction mixture consisted of a dispersion medium (water), a dispersed phase (C9 fraction), an initiator, which is soluble in the dispersed phase, and a suspension stabilizer. In the range of variables studied, reaction temperature (313–353 K) and initiator concentration (0.032–0.096 mol/l) do not have a significant effect on the oligomers yield. The process conditions most influencing the course of suspension oligomerization of the С9 fraction are as follows: stirring intensity (Re=2290–13450) with the correlation index of 0.88, reaction time (30–240 min) with the correlation index of 0.87 and the ratio of dispersed phase to dispersed medium (1:1–1:4) with the correlation index of –0.91. The correlation between the yield and bromine number (correlation index of –0.82) confirmed the passage of oligomerization reaction via the unsaturated bonds of the monomer. The hydrocarbon resins obtained by low-temperature suspension oligomerization were mainly cooligomers of styrene and its derivatives. As a result of suspension oligomerization at low temperatures, products were obtained which were characterized by a light color (color index of 10–20 mg I2/100 ml), a molecular weight of 505–530 and a softening point of 347–354 K.

Rheology, mechanical properties and peel adhesion of hot-melt adhesive based on thermoplastic polyurethane/nanosilica

A series of thermoplastic polyurethane hot-melt adhesive formulations have been synthesized by melt blending of polyether-based thermoplastic polyurethane and different nanosilica, C5, and C9 hydrocarbon loadings. Different analyses, including FESEM, tensile strength, rotational rheometry, T-peel strength with polyester fabric, and nitrogen gas permeability, are conducted to examine the properties of the prepared adhesive formulations. The results show that the addition of 0.25 wt% of nanosilica increased the tensile properties of the polyurethane slightly and improved the T-peel strength with the polyester fabric. On the other hand, adding 5 wt% of C5 hydrocarbon tackifier reduced the tensile properties a bit, reduced the storage and loss modulus, and increased the T-peel strength with the polyester fabric. On the other hand, adding the C9 tackifier reduced the tensile strength more than the counterpart formulation including C5, reduced the storage and loss modulus and increased the T-peel strength. A noteworthy result was that the addition of nanosilica in the presence of C5 or C9 tackifiers lowered the loss and storage modulus and complex viscosity Adhesive formulation with 5 wt% of C5 tackifier has the highest average and maximum peel strength with about 20 and 35% higher strength than neat TPU.

Customized hourglass-shaped channels in a copper(II)-organic framework for one-step ethylene purification from ethylene/ethane/acetylene ternary mixtures with high adsorption capacity

One-step purification of C2H4 from C2H2/C2H4/C2H6 ternary mixtures represents an important yet challenging task in chemical industry. Favored adsorption of C2H2 and C2H6 over C2H4 has stringent requirements on pore size and surface chemistry of the adsorbents. We report a Cu-MOF (Cu–L), [Cu0.5(L)0.5]·2DMF (H2L = 4′-(1H-1,2,4-triazol-1-yl)-[1,1ꞌ-biphenyl]-3,5-dicarboxyl)) with one-dimensional hourglass-shaped channels decorated by phenyl rings and triazole units. Suitable pore structure and customized pore surface have endowed Cu–L with high adsorption capacities toward C2 hydrocarbons, and preferential adsorption of C2H2 and C2H6 over C2H4. Separation capability of Cu–L has been confirmed by multicomponent breakthrough experiments and polymer-grade C2H4 can be directly obtained from C2H2/C2H6/C2H4 (1/1/1 and 1/9/90, v/v/v) mixtures. The underlying mechanism of preferential adsorption was revealed by Grand Canonical Monte Carlo simulations and DFT calculations.

Pillar-layered metal-organic frameworks with benchmark C2H2/C2H4 and C2H6/C2H4 selectivity for one-step C2H4 production

Energy-efficient adsorptive separation shows great potential for the one-step production of high-purity ethylene (C2H4) from ternary C2 hydrocarbons. However, it remains a formidable challenge to fabricate high-performance adsorbents that exhibit simultaneous high selectivity (>2) towards acetylene/ethylene (C2H2/C2H4) and ethane/ethylene (C2H6/C2H4). Herein, we report a pillar-layered metal–organic framework, Ni(sdba)(dabco)0.5 (H2sdba = 4,4′-sulfonyldibenzoic acid; dabco = 1,4-diazabicyclo [2.2.2] octane), for preferential trapping of C2H6 and C2H2 over C2H4. The abundant accessible binding sites endow Ni(sdba)(dabco)0.5 with outstanding C2H2/C2H4 (2.28) and C2H6/C2H4 (2.47) selectivity with high C2H6 (3.15 mmol g−1) and C2H2 (4.41 mmol g−1) uptake among porous materials reported for one-step C2H4 purification. Dynamic breakthrough experiments demonstrated the feasibility of producing high-purity C2H4 (>99.9%) from C2H2/C2H6/C2H4 gas-mixtures (1/1/1 and 1/9/90, v/v/v) in a single step. Computational simulations reveal that the aromatic-rich pore spaces, which decorated with accessible interlayer uncoordinated oxygen atoms of sulfonyl groups and alkyl functionalities, can provide multiple C-H···O, C-H···π, and C-H···H interactions for selectively recognizing C2H6 and C2H2 over C2H4.

Effect of Molecular Structure of C10 Hydrocarbons on Production of Light Olefins in Catalytic Cracking

The effect of the molecular structure of feedstock on the cracking reaction of C10 hydrocarbons to ethylene and propylene over H-ZSM-5 zeolite was investigated. To better compare the effect of decane on the production of light olefins, the thermal cracking and catalytic cracking performance of decane were first investigated. As a comparison, the thermal cracking and catalytic cracking of decane were studied by cracking over quartz sand and H-ZSM-5. Compared with the thermal cracking reaction over quartz sand, the catalytic cracking reaction of decane over H-ZSM-5 has a significantly higher conversion and light olefins selectivity, especially when the reaction temperature was lower than 600 °C. On this basis, the catalytic cracking reactions of decane and decene over H-ZSM-5 were further compared. It was found that decene with a double bond structure had high reactivity over H-ZSM-5 and was almost completely converted, and the product was mainly olefin. Compared with decane as feedstock, it has a lower methane yield and higher selectivity of light olefins. Therefore, decene was more suitable for the production of light olefins than decane. To this end, we designed a new light olefin production process. Through olefin cracking, the yield of light olefins in the product can be effectively improved, and the proportion of different light olefins such as ethylene, propylene and butene can be flexibly adjusted.