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To better understand the benzene alkylation with chloroaluminate ionic liquids (ILs) as catalyst, the interfacial properties between the benzene/butene binary reactants and chloroaluminate ILs with varying cation alky chain length and different anions were investigated using molecular dynamics (MD) simulations. The results indicate that ILs can obviously improve the interfacial width, solubility and diffusion of reactants compared to H2SO4. The longer alkyl chains of cations present a density enrichment at the interface and protrude into the binary reactants phase. Furthermore, the ILs consisting of 1-octyl-3-methylimidazolium cations ([Omim]+) and the stronger acidity heptachlorodialuminateanions ([Al2Cl7]–) are more beneficial to promote the interfacial width and facilitate the dissolution and diffusion of benzene in both the IL bulk and the interfacial region in comparison to the ones with shorter alkyl chains cations and weaker acidity anions. The information gives us a better guideline for the design of ILs for benzene alkylation.

Lanthanum-containing (LaX) and cerium-containing X zeolites (CeX) were prepared by a double-exchange, double-calcination method. By changing the calcination atmospheres between nitrogen and air, the CeIV contents in CeX zeolites were adjusted and their impacts on physicochemical properties and catalytic performance in isobutane alkylation were established. The crystallinity of CeX zeolite was found to be negative correlated with the CeIV content. This is believed to be due to the water formed during the oxidation of CeIII, which facilitates the framework dealumination. As a consequence, calcining in air results in a great elimination of strong Bronsted acid sites while under nitrogen protection, this phenomenon was mostly hindered and the sample's acidity was preserved. When tested in a continuously flowed slurry reactor, the catalyst lifetime for isobutane alkylation was found to be linearly related with the strong Bronsted acid concentration. In addition, Ce3+ was found more benefit for the hydride transfer compared with La3+, which is ascribed to the stronger polarization effect on the C-H bond of isobutane. Moreover, the decline of hydride transfer activity can be slowed down by the catalytic cracking of the bulky molecules. Based on the product distribution, a new catalytic cycle of dimethylhexanes (DMHs) involving a direct formation of isobutene rather than tert-butyl carbocation was proposed in isobutane alkylation.

Hydrodesulfurization (HDS) reaction can significantly reduce the viscosity and sulfur content of heavy oil, while the HDS reaction mechanism of tetrahydrothiophene as the main sulfide in heavy oil is still unclear. The HDS experiment of tetrahydrothiophene catalyzed by nickel phosphide (Ni2P) is carried out at 200–300 °C. The results indicate that the H2S production under the catalysis of Ni2P increases obviously within 200–250 °C. The main gas products of HDS reaction are butane, butene and H2S. Meanwhile, the mechanism of tetrahydrothiophene catalyzed by Ni2P is analyzed based on Density Functional Theory (DFT). It is revealed that the adsorption model is most stable when tetrahydrothiophene is vertically adsorbed on the V–Ni-Hcp1 site of Ni2P (001). The C–S bond is elongated and the C–C bond is shortened after adsorption. Hydrogenation (HYD) is the most possible reaction route of tetrahydrothiophene on Ni2P (001) surface. There are two routes with the lowest activation energy, which are C4H8S→C4H8SH∗→C4H9SH∗→C4H10+H2S and C4H8S→C4H9S∗→C4H9∗+SH∗→C4H10+H2S. Butane and H2S are produced in the reaction, corresponding to the experimental results. This study provides a basis for understanding of the HDS mechanism of tetrahydrothiophene catalyzed by Ni2P.

Copper nanoparticles on silica support are cheap and effective catalysts for dehydrogenation of n-butanol, a biomass-derived building block which is increasingly used. Ultrasonically assisted Cu catalysts are prepared, characterized, and tested for the conversion of n-butanol to n-butanal. The best performance in terms of overall conversion of n-butanol and selectivity to butanal was offered by ultrasound-prepared process of the Cu nanoparticles. In conventional wet impregnation method, Cu nanoparticles on the surface of support tend to aggregate in some sort of cubic aggregates with the size of 4–5 µm and because of this, the percentage of the centers of silica (on which intermolecular dehydration reactions occur) is higher compared to Cu metallic centers (that promotes the dehydrogenation reaction). The ultrasound reduction stage used in the preparation of catalysts provides a better coverage of the catalyst surface by Cu nanoparticles that have a more uniform dimension, which offers a greater selectivity to butanal (more than 95%) and a negligible selectivity to butene.

With the development of coal chemical industry, large amounts of naphthalene and n-butene are produced, and converting them into high value-added products through alkylation has gained particular importance and interest. In this work, liquid coordination complexes (LCCs) were used as acid catalysts for the first time in the naphthalene alkylation reaction under mild conditions to obtain multi-butylnaphthalenes with high yield. Various reaction conditions were thoroughly investigated. The LCC consisting of urea and AlCl3 showed excellent catalytic performance under optimal reaction conditions, giving 100% conversion of naphthalene and 99.66% selectivity towards multi-butylnaphthalenes. Combining the catalyst properties and catalytic results, a plausible reaction mechanism was proposed. The lubricating properties of the synthesized products were investigated for their potential application as lubricating base oils. The synthesized multi-butylnaphthalenes showed comparable physicochemical properties and tribological performances as the commercial cycloalkyl base oil.

The main object of this research is modeling, sensitivity analysis, and multi-objective optimization of the ethylene dimerization process at the presence of a homogenous catalyst. Industrially, the ethylene dimerization occurs in a bubble column reactor equipped with an external cooler to prevent temperature runaway. In the first step, the considered bubble column reactor is heterogeneously simulated considering a two-phase flow regime by coupling the kinetic and equilibrium based models. To validate the accuracy of developed model, the simulation results are compared with the plant data. The simulation results show that the mass transfer from gas to liquid phase controls the ethylene dimerization rate in the considered plant. In the second step, the effects of operating pressure and temperature on the ethylene conversion and butene selectivity are investigated by the developed model. The simulation results show that pressure has an insignificant effect on the conversion and selectivity due to the high contact time of gas and liquid medium, low gas to liquid flow rate, and high mass transfer area. In the third step, a multi-objective optimization problem is programmed and the optimal temperature of reactor is calculated by the TOPSIS decision-making method.

The structure-performance evolution of Co/N-AC catalyst during ethylene oligomerization was investigated in detail. It was found that the catalytic activity sharply decreased in the first 30 h with the ethylene conversion decreasing from 64 to 4%. Butene selectivity increased gradually in the first 10 h then remained about 74%, while the selectivity for hexene and octene exhibited an opposite trend. The ratio of α-olefin to isomers for butene increased greatly with time on stream and most of the generated butene was 1-butene. Based on the structure characterization at different reaction stages, CoOx was suggested to be major active phase and the coverage of long-chain hydrocarbons as well as the loss of surface CoOx active sites due to size growth of Co3O4 nanoparticles were the main reasons for catalytic deactivation. The structure-performance evolution of Co/N-AC catalyst during ethylene oligomerization was investigated and the coverage of long-chain hydrocarbons as well as the loss of surface CoOx active sites due to size growth of Co3O4 nanoparticles were the main reasons for catalytic deactivation

Ethylene-butene copolymer (EBC)/carbon-fiber (CF) composites can be utilized as an electromechanical material due to their ability to change electric resistance with mechanical strain. The electro-mechanical properties and thermal conductivity of ethylene butene copolymer (EBC) composites with carbon fibers were studied. Carbon fibers were introduced to EBC with various concentrations (5 to 25 wt%). The results showed that carbon fibers’ addition to EBC improves the electric conductivity up to 10 times. Increasing the load up to 2.9 MPa will raise the electric resistance change by 4 500% for a 25% fiber sample. It is also noted that the EBC/CF composites’ electric resistance underwent a dramatic increase in raising the strain. For example, the resistance change was around 13 times higher at 15% strain compared to 5% strain. The thermal conductivity tests showed that the addition of carbon fibers increases the thermal conductivity by 40%, from 0.19 to 0.27 Wm–1K–1.

We report the kinetics of ethylene oligomerization over the Ni-H-Beta for temperatures ranging between 50 and 100 °C and pressures ranging between 5 and 28 atm. According to our results, the apparent activation energies involved in the formation of butene, hexene, and octene are 44, 78, and 60 kJ.mol−1, respectively. The measured lower apparent activation energy for butene formation relative to hexene and octene is a likely result of the fact that the measured butene formation is not the true (forward) rate of formation of butene but it the net rate because of the consumption of butene in secondary reactions. Analysis of the reaction order indicates that participation of butene in chain-growth reactions takes place via desorption followed by re-adsorption of butene on the catalyst. The results also indicate that hexene undergoes a similar process. In the present paper, we refer to the pathway involving co-oligomerization of butene and hexene as “cascade co-oligomerization”. Based on these findings, we proposed a reaction network and modeled reaction rate expressions for ethylene consumption and butene, hexene, and octene formation based on the construction of a micro-kinetic model. We calculated the kinetic parameters involved in the reaction network proposed and found evidence that the formation of octene proceeds mainly via the “cascade co-oligomerization” of re-adsorbed butene with ethylene.

The effects of steaming at varying times and temperatures on ZSM-5 pore structures, framework Al distribution, acid properties and ethanol to propene (ETP) catalytic performance were systematically studied in this study. The results show that the crystallinity and specific surface areas of steam treated ZSM-5 samples decrease with the increase treatment time and temperature. 27Al MAS NMR and Co(II) exchange-ICP results show that the isolated framework Al species (Alsingle) can be preferentially removed from the zeolite framework, while the paired Al sites (Alpairs) remain relatively stable after steam treatment. The characterization of Py-IR reveals that the concentration of B acid sites and the acid strength are all declined with the steaming time or temperature increase. The catalytic results of ETP at 450°C show that the sample after steaming gives improved selectivities to propene and butene at the expense of ethene conversion and alkanes selectivity relative to the unmodified zeolite. Besides, a good positive correlation between ethylene conversion and Alsingle concentration is found, whereas the propene formation is influenced by the combination effect of Alsingle and Alpairs sites.

The isomerization and hydroformylation of butene under the catalysis of Rh-BIPHEPHOS were investigated by varying the butene feed and reaction temperature. The results indicate that in the presence of syngas, with 1-butene as feed, more isomerization product (i.e. 2-butene) is detected in comparison with the hydroformylation products, whereas with 2-butene as the feed, the hydroformylation is superior to isomerization. Due to the equilibrium limit between 1-butene and 2-butene, the increase of temperature shows a great positive effect on the isomerization reaction. Furthermore, under the catalysis of Rh-BIPHEPHOS, more n-pentanal is always formed than i-pentanal, as the larger bite angle of BIPHEPHOS restricts the intermediate rearrangement in the formation of i-pentanal.

The regional montmorillonite clay from Santo Amaro da Purification, the region of Reconcavo Baiano, was subjected to chemical treatment for the destruction of organic matter, after which the pillarization technique was applied using the hydroxyacetatoferro precursor (III) in order to generate a isomerization of butane 1. The solids were characterized by conventional techniques such as: DRX, TG/DTA, specific surface area measurement, MEV and RTP, in order to evaluate their importance as a clay-resercible that can be restructured chemical composition and crystallographic.. The results indicated that the pillarization resulted in the formation of thermally stable iron oxide. The Bronsted acid sites, detected by absorbed pyridine FTIR, were active in the geometric isomerization of butenes, with 22% selectivity to the cis isomer and 47% to the trans isomer.

Octanes in alkylation products obtained from industrial alkylation were studied by batch experiments. More than eight octane isomers were identified and quantified by gas chromatography-mass spectrometry. Based on a classic carbenium ion mechanism, the carbocation transition states in concentrated sulfuric acid catalyzed alkylation were investigated using quantum-chemical simulations and predicted the concentration and octane isomerization products including trimethylpentane and dimethylhexane as well as the formation of heavier compounds that resulted from the oligomerization of octane and butene. The agreement between model calculations and experimental data was quite satisfactory. Calculation results indicated that composition and content of trimethylpentanes in the alkylation products were 2,2,4-trimethylpentane > 2,3,3-trimethylpentane > 2,3,4-trimethylpentane > 2,2,3-trimethylpentane whether the 2-butene or i-butene acts as olefin. Heavier compounds in the alkylate were primarily formed by the oligomerization of dimethylhexane with 1-butene. Hopefully, the carbocation transition state models developed in this work will be useful for understanding the product distributions of octane in alkylation products.

Catalytic dimerization of ethylene (C2H4) to butene (C4H8) utilizes homogenous catalysts composed of transition metal molecular complexes in the presence of a co-catalyst or Ni, Rh or Cr supported heterogeneous catalysts. Recently, a heterogeneous cobalt catalyst supported on NH4OH-treated carbon (Co/N C) has gained attention. However, the structure of the active site, the identity of the active phase, the role of NH4OH treatment and the effect of thermal activation have remained elusive. Herein, in situ Raman spectroscopy showed the absence of crystalline cobalt oxide phases, such as CoO or Co3O4, in the working catalyst. An intense Raman band at 810 cm−1 was detected in the as-synthesized catalyst, which corresponds to μCo-peroxo species formed via auto-oxidation of the [Co(NH3)x]2+ sites during the drying step. UV–vis DRS absorbance bands at ∼286, 340 and 560 nm indicated that a mixture of octahedral Co3+ and Co2+ is present in the as-synthesized catalyst. During thermal treatment in inert atmosphere, the 265 and 810 cm−1 Raman bands diminished signifying the reduction of μCo-peroxo sites, with the oxidation of some NH3 ligands to N2O(g), indicated by an IR doublet at ∼2225 cm−1. UV–vis DRS during thermal treatment corroborated the reduction of Co3+ to Co2+, with Co2+ sites coordinated in a tetrahedral fashion, as indicated by a new absorbance band at ∼600−700 nm. The presence of the immobilized pseudo-tetrahedral [Co(NH3)x]2+ molecular complexes active for dimerization is proposed as an alternative to previous reports that attribute olefin dimerization activity to crystalline cobalt oxide phase in this catalyst. Steady-state catalytic test results at 1 bar, 80 °C, 5.0 % C2H4 at 10 sccm, 0.3 g catalyst show that model catalyst containing crystalline cobalt oxides (Co/C) exhibited similar initial butene productivity to the [Co(NH3)x]2+ containing Co/N C catalyst, but suffered sharper deactivation due to the irreversible olefin deposition on Co3+ sites.

The oxidative dehydrogenation (ODH) of 1-butene to 1,3-butadiene was studied over a series of AFe2O4 catalysts, where A = Zn, Mn, Ni, Cu, Mg and Fe. The catalysts were characterised by XPS, EPR spectroscopy, BET surface area analysis, Raman spectroscopy and XRD. All the ferrites were active for ODH and gave an order of activity after 80 h on-stream of ZnFe2O4 > NiFe2O4 > MnFe2O4 > MgFe2O4 > CuFe2O4 > FeFe2O4. All catalysts lost significant surface area (up to ~ 80%) under reaction conditions of 0.75:1:15 oxygen:1-butene:steam with an overall GHSV of 10,050 h−1 at 693 K. Fe3O4 was unstable under reaction conditions and was converted to Fe2O3, which showed very low activity. Nickel ferrite was the only material that gave carbon dioxide as a significant product, all others were selective to 1,3-butadiene. Zinc ferrite gave a steady-state yield of 1,3-butadiene of ~ 80%. Inversion parameters were determined for the ferrites from XPS and a correlation was obtained between 1,3-butadiene yield and inversion parameter, indicating that Fe3+ in an octahedral hole is a key species in the mechanism of oxidative dehydrogenation. Butene isomerisation and ODH were shown to occur on different sites.

The polymers/copolymers blending has been investigated to improve the ductility of PLA. The rubbery or flexible polymers are keys to success in enhancing the ductility of PLA blends. However, the interfacial interaction between copolymers and PLA needs to be concerned. Here, we synthesized the copolymer of poly(butene succinate) (PBTS) and polylactide (PBTS-PLA), which consisted of C=C on the main chain. The PBTS-PLA aimed to increase the ductility of the PLA blend and the interfacial interaction between PBTS-PLA and PLA by thermal crosslink. The elongation at break of the blend films increased when added PBTS-PLA at 1 phr, and it was two times higher than neat PLA. The tensile strength and Young’s modulus decreased as PBTS-PLA was increased. The crosslinked films showed the highest elongation at break when added PBTS-PLA at 5 phr, and it has 2.4 times higher than neat PLA. These might have been due to the synergistic effect of ductility and crosslink reaction. The crosslink reaction improved interfacial adhesion between PBTS-PLA and PLA as PBTS-PLA particles on the film surface were diminished.

The adsorption and diffusion behaviors of isobutane, 2-butene, and trimethylpentane (TMP) on the silica surface with various surface groups were investigated using molecular dynamics (MD) simulatio...

1,3-BD production process from lignin consisting of four unit operations such as gasification, dimethyl ether (DME) synthesis, n-butene synthesis, and isomerization/dehydrogenation, was simulated. This process could be designed as a renewable energy system that can not only produce 1,3-BD but also self-supply almost all the heat and power for the operation. The balance of payment (BP), which is the income incurred from processing a unit weight of lignin, was employed as the economic efficiency of the process. The effect of the reaction conditions in the DME to n-butene synthesis step (the third step) on the BP was investigated. Since few catalysts have been reported for synthesizing n-butene from DME, realistic reaction conditions and catalytic performance were set. An increase in the DME content of the feed gas and a decrease in the reaction pressure led to an increase in the n-butene yield and a decrease in the power, followed by an increase in the 1,3-BD yield and BP. Considering the expected power selling price after the termination of the Feed-in-Tariff scheme, the 1,3-BD production process could have comparable BPs with gasification power generation as a representative competitive process.

Direct conversion of greenhouse gas carbon dioxide (CO2) into lower olefins (ethylene, propylene and butene) provides an appealing approach to tackle CO2 emission challenges. Admixed catalysts composed of metal/metal oxides and SAPO-34 have been widely used for catalytic CO2 hydrogenation to lower olefins. However, interactions between metal/metal oxides and SAPO-34 remain obscure. Here, a novel family of admixed catalysts composed of Fe–Cu–K and SAPO-34 (Fe–Cu–K/SAPO) is developed for efficient catalytic CO2 hydrogenation to lower olefins, which can achieve 49.7% CO2 conversion and 62.9% selectivity of lower olefins, with CO selectivity

Dehydration of n-butanol (nB) to corresponding olefins (butene) is an important reaction route to realize efficient utilization of bulk bio-alcohols. In this work, novel phosphate modified oxidized multi-walled carbon nanotubes (P-oCNT) were prepared via a simple impregnation process, and the proposed solid acid catalyst exhibited superior catalytic activity and stability in nB dehydration reactions with 94% nB conversion and 99% butene selectivity under gentle reaction conditions (260 °C). In situ titration results revealed that the Bronsted and Lewis acid sites are all active sites, and the Lewis acid sites contribute to over 88% of the activity in nB dehydration reactions. The polyphosphate species (POx) were identified as the key Lewis acid active sites, which were covalently linked onto the oCNT surface via C–O–P bonds, and the carbon matrix played a vital role in enhancing and stabilizing the catalytic activity of the POx species. The basic kinetic analysis results indicated that the nB dehydration reaction on P-oCNT catalysts followed the E1 mechanism, while the reaction route would shift to E2 with the reaction temperature increasing. The relatively high catalytic efficiency and sustainable nature of the whole non-metallic system show the potential of the proposed reaction system in modern chemical industries.

The acidic properties of a selected SiO2–Al2O3 support material have been modified by steam-treating to study the influence on the formation of active nickel sites for butene oligomerization. For this purpose, the steam-treated supports were impregnated in situ with Ni (Cp)2. FTIR spectroscopy of pyridine adsorption revealed that the steaming procedure provokes changes of Bronsted as well as Lewis acid sites. In dependence on intensity of the steam-treatment, the amount of Bronsted acid sites decreases and weaker Al3+ Lewis acidic sites are created possibly in alumina-like agglomerates. Changes of the Al coordination sphere by steam-treatment was also confirmed by 27Al MAS NMR spectroscopy. The decrease of Bronsted acidity of the SiO2–Al2O3 support lowers its catalytic activity for the proton-catalyzed butene oligomerization, but the formation of active nickel sites on the differently treated supports under reaction conditions is not affected, as reflected by comparable activity of the respective Ni catalysts. As demonstrated by pyridine adsorption studies, mainly the weak Al3+ Lewis acidic sites (fivefold coordinated Al) created by steam-treatment were covered by Ni(Cp)2 impregnation, resulting in the formation of new, medium strong Ni2+ Lewis acidic sites which are active in coordinative catalysis. Although the Bronsted sites are only partly replaced by Ni, the remaining Bronsted sites have no influence on octene isomer distribution. It seems that the coordinative mechanism of oligomerization is generally preferred on Ni-impregnated samples.

Herein, we report a comparative study of ethylene activation and 1-hexene isomerization carried out with isomeric neutral and cationic methallyl nickel complexes L1Ni(η3-C3H5) and [L1Ni(η3-C3H5)][B(ArF)4] in the presence of borane co-catalysts. To understand the reactivity of nickel complexes with NacNac ligands, we used chemometric methods to classify different catalysts reported to date. The mechanism of interaction of [L1Ni(η3-C3H5)][B(ArF)4]/B(C6F5)3 with 1-hexene was studied by ESI-MS and allowed to detect cationic species formed in situ. Moreover, there is a very small difference in reactivities from combination of nickel complexes and borane co-catalysts used to alkene isomerization, while the reactivity with ethylene of both systems is very different, [L1Ni(η3-C3H5)][B(ArF)4]/B(C6F5)3 produce butene, while L1Ni(η3-C3H5)/B(C6F5)3 form polyethylene. Furthermore, DFT studies revealed that the origin of the catalytic activity in cationic and neutral methallyl nickel complexes co-activated by B(C6F5)3 is mainly due to direct steric effects of the ligand-nickel center where the conformation of the chelate ring is affected by the catalyst symmetry. This work demonstrates how the cationic or neutral nature of the same system affects its catalytic and structural properties.

AEI-type aluminosilicate zeolites with sheet-like morphology were successfully synthesized by the crystal growth inhibitor (CGI)-assisted method, where cetyltrimethylammonium bromide (CTAB) worked as a CGI. The obtained sheet-like AEI-type aluminosilicates showed a higher yield of butenes and longer catalytic lifetime in the direct conversion of propene to butenes than the conventional sample. The improvement of catalytic performance originated from tuning the molecular diffusion in the zeolite particles. The sheet-like morphology gave a higher molecular diffusivity, and consecutive reactions were suppressed. Moreover, there was a significant difference in the product distribution of butene isomers; linear butenes and iso-butene were the dominant product over the typical AEI-type aluminosilicate with cubic particles induced by the shape selectivity into zeolitic micropores, while the sheet-like one yielded a higher selectivity for iso-butene. It was revealed that the distribution of Bronsted acid sites between internal and external surfaces could be controlled by increasing the external surface area coming from the sheet-like particles.

In order to better understand the low-temperature oxidation chemistry of alkenes, 1-butene and i-butene oxidation experiments triggered by dimethyl ether (DME) were conducted in a jet-stirred reactor at 790 Torr, 500–725 K and the equivalence ratio of 0.35. Low-temperature oxidation intermediates involved in alcoholic radical chemistry and allylic radical chemistry were detected by using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). To better interpret the experimental data, a kinetic model was proposed based on our low-temperature oxidation model of DME and comprehensive oxidation models of 1-butene and i-butene in literature. Based on present experimental results and modeling analysis, alcoholic radical chemistry initiated by OH addition is mainly responsible for the low-temperature chain propagation of butenes, since the Waddington mechanism plays a dominant role compared with the chain-branching pathways through the second O2 addition. Allylic radical+HO2 reactions producing alkenyl hydroperoxides and fuel+O2 serve as the major chain-branching and chain-termination pathways, respectively, and they are competitive in the negative temperature coefficient (NTC) region. In contrast, chain-branching pathways originating from allylic radical+O2 and alkyl-like radical+O2 reactions have little contribution to the OH formation. Comparison with the simulation results of butane/DME mixtures demonstrates that butenes can largely inhibit the reactivity of DME at low temperatures due to its reduced low-temperature chain-branching process. However, in the NTC region, butenes may not be good OH absorbents since the allylic radicals can convert HO2 to OH and consequently enhance the oxidation reactivity.

Previously, 3D printing of porous materials and metal oxides was limited to low loading metal loadings, as increasing the nitrate salt concentrations, which are used to generate the oxide component, gave rise to poor rheological properties beyond 10 wt %. In this study, we addressed this problem by directly printing insoluble oxides alongside H-ZSM-5 zeolite, which allowed for increased oxide loadings. Various metal oxides such as V2O5, ZrO2, Cr2O3, and Ga2O3 were doped onto H-ZSM-5 through the additive manufacturing method. Characterization and correlation between the X-ray diffraction, NH3-temperature-programmed desorption, O2-temperature programmed oxidation, temperature-programmed reduction, scanning electron microscopy-energy dispersive spectroscopy, and in situ CO2 DRIFTS experiments revealed that directly 3D printing metal oxides/H-ZSM-5 inks leads to significant modification in the surface properties and oxide bulk dispersion, thereby enhancing the composites' reducibility and giving rise to widely differing product distributions in n-hexane cracking reaction. The obtained metal oxide/zeolite structured materials were used as bifunctional structured catalysts for the selective formation of light olefins from hexane at 550-600 °C and GHSV = 9000 mL/gcatalst·h in a packed-bed reactor. Among the various compositions of metal oxides/H-ZSM-5 examined (i.e., 15 wt % Ga2O3, 15 wt % ZrO2, 15 wt % V2O5, 15 wt % Cr2O3, or 5 wt % Cr/10 wt % ZrO2/10 wt % V2O5/10 wt % Ga2O3 balanced with H-ZSM-5), the 15 wt % Cr/ZSM-5 monolith displayed the best n-hexane cracking performance, as it achieved 80-85% conversion of hexane with a 40% selectivity toward propylene, 30% selectivity toward ethylene, and 10% selectivity toward butene at 550 °C. The sample also showed zero benzene/toluene/xylene selectivity and no deactivation after 6 h. This study represents a proof-of-concept for tailoring customizable heterogeneous structured catalysts by directly 3D printing high loading of metal oxides/porous zeolite and is a breakthrough in material science.

Zirconium-based metal–organic frameworks (Zr-MOFs) have been increasingly studied over the past two decades as heterogeneous catalysts due to their synthetic tunability, well-defined nature, and ch...

The continuous development of a core C-0 - C-4 kinetic mechanism generally involves updating it using reliable kinetics and thermodynamics and may also involve the inclusion of missing reaction pathways to improve the integrity, prediction accuracy and applicability of the mechanism over a wider range of combustion relevant conditions. Accurate kinetic descriptions of the core mechanism can have a substantial influence on accurate predictions of higher hydrocarbon combustion models as the consumption of these larger species rely heavily on the core mechanism. This study is motivated by a severe under prediction in the reactivity of the high temperature experimental targets of di-isobutylene (DIB), an important component used in surrogate fuel formulations. It is worth noting that isobutene (iC(4)H(8)) laminar burning velocities are also severely under-predicted in the recent publication of Zhou et al. [1], which is regarded as a critical fragment formed in the decomposition of DIB, that dictates its fate. We discuss the latest developments to the isobutene kinetics and illustrate the influence that these updates have on the oxidation of higher order hydrocarbons, such as DIB and iso-octane (iC 8H 18). Improving the kinetic accuracy of the C-0 - C-4 core mechanism improved not only the iC 4 H 8 predictions but also the predictions of higher hydrocarbons which hierarchically rely on it, for instance, the peak flame speeds for specific cases of iso-octane, iso-butene and di-isobutylene have improved by 3, 6, 12 cm s(-1), respectively. In addition, the new iC(4)H(8) model is in excellent agreement with the new laminar burning velocity measurements taken in this study at 1 atm and 428 K. The contribution of the new iC(4)H(8) kinetics alone for the improvement in the LBV predictions is significant, in particular the (C)over dot(3)H(5-)t +(C)over dotH(3) = i(C)over dot(4)H(7) +(H)over dot and i(C)over dot(4)H(8) = i(C)over dot(4)H(7) + (C)over dot reactions are very sensitive at high temperatures. In addition, the new isobutene model is in very good agreement with experimental ignition delay times and species profiles measured during pyrolysis and oxidation conditions. (C) 2020 The Author(s). Published by Elsevier Inc. on behalf of The Combustion Institute. The authors at NUI Galway recognize funding support from Science Foundation Ireland (SFI) via their Principal Investigator Program through project number 15/IA/3177. UCF's effort is based upon work supported by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under Award Number DE-EE0007984 (Co-Optima). This work at LLNL was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 as part of the Co-Optimization of Fuels & Engines (Co-Optima) project sponsored by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies and Vehicle Technologies Offices. peer-reviewed

Although research in renewables is growing at a tremendous rate, the world will still be greatly dependent on fossil fuels for at least the first half of this century. In the quest for more efficie...

Polymorphism is determined by the intrinsic molecular architecture designed via chemical synthesis and the external flow stimuli applied in practical processing. In this work, flow-induced crystall...

Abstract One of the main challenges in the field of heterogeneous catalysis is the involvement of thin solid films and membranes and their application in flow systems. In this regard, we report here the application of self-supported bacterial cellulose (BC) reinforced nanosized platinum (Pt)/N-doped bamboo-like carbon nanotube (NBCNT) hybrid catalyst membrane with a thickness of 35 ± 5 µm in the hydrogenation of n-butene. To synthetized the BC-NBCNT/Pt nanohybrid membrane catalyst a simple impregnation route was applied in a two-step process. As-prepared material was tested in a continuous flow system and the conversion was followed directly by using Fourier transform infrared spectroscopy. Furthermore, the fabricated films were characterized by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and specific surface area measurement (Brunauer–Emmett–Teller). Hydrogenation performance was studied on both single and double films. Results revealed that 97% conversion of n-butene can be achieved using these bacterial cellulose reinforced hybrid membranes. Graphic abstract

The reaction mechanism of the direct conversion of ethylene to propene over Ni-containing catalysts is assumed in literature to comprise (i) ethylene dimerization to 1-butene, (ii) butene isomerization and (iii) metathesis of 2-butene with ethylene to propene. To elucidate if the third step of this reaction is really metathesis, the reaction of 13C-labelled ethylene with 12C-trans-2-butene was studied and the distribution of 12C and 13C atoms in propene and the other reaction products was measured by a gas chromatograph with mass spectrometer detector. Since only traces of propene containing one 13C atom were observed, metathesis cannot play a substantial role in propene formation. This conclusion was confirmed by the lack of other products that would have been formed in secondary reactions by metathesis. The observed reaction products and the distribution of 12C and 13C atoms therein strongly suggest a reaction mechanism involving C-C olefin coupling reactions at Ni2+ surface sites and cracking reactions of the formed higher olefins at acidic sites of the catalysts. The proposed mechanistic pathway explains also the differences in the distribution of 12C and 13C atoms in propene formed over the two catalysts differing in their nature of Ni2+ surface species and acidic sites.

Bimetallic nanoparticle (NP)-supported catalysts for use in the hydrogenation reaction has received growing attention on account their excellent catalytic performance. In the present work, bimetallic Au–Pt and monometallic Pt/Au NPs were supported on the Zr-based metal–organic framework UiO-67 via a simple impregnation–reduction method. The catalytic performance of the catalysts for selective 1,3-butadiene (1,3-BD) hydrogenation was influenced by the space velocity, reaction temperature and Au/Pt molar ratio. Whilst bimetallic AuPt/UiO-67-3 displayed catalytic activity similar to that of Pt/UiO-67 for selective 1,3-BD hydrogenation, the former also exhibited much higher selectivity toward total butenes than the latter. The AuPt/UiO-67-3 catalyst with a 1.1:1.0 Au/Pt molar ratio exhibited the best catalytic activity and butene selectivity for selective 1,3-BD hydrogenation at 100 °C with a space velocity of 117 L/(h gcat). This work provides a practical example of novel and efficient bimetallic supported catalysts.

Ethanol is a promising platform molecule for production of a variety of fuels and chemicals. Of particular interest is producing middle distillate fuels (i.e., jet and diesel blendstock) from renew...

A kinetics theory of catalyst deactivation is presented of the solid acid-catalyzed alkylation reaction of isobutane with propylene or butene that gives alkylate, a high octane fuel, as product. The intimate relation between the kinetics network of the reaction, catalyst deactivation kinetics, and residence time distribution is analyzed. The question is addressed why the deactivation of the alkylation reaction in a continuously stirred tank reactor (CSTR) is slow compared to that in a tubular plug flow reactor (PFR). Conditions are derived where such differences will be minimum and maximum. In the reaction regime of high alkylate selectivity, linear and quadratic power law kinetics equations in propylene concentration can be deduced from microkinetics. They are used to derive analytical expressions of deactivation times for CSTR and PFR. The theoretical power law kinetics equations can be related to previously established empirical rate equations of catalyst deactivation. We show that, in the CSTR, the self-alkylation reaction path contributes substantially to the deactivation time. In the self-alkylation reaction, alkylate is formed by reaction of the isobutene reaction intermediate and isobutane. Catalysts of high proton strength can benefit catalyst deactivation times by suppressing the carbenium ion deprotonation reaction that produces alkenes as isobutene. In the PFR, selective alkylate formation occurs only when the reaction occurs in a reaction zone of the catalyst bed. Deactivation is faster than in CSTR because of the reactant profile in the reaction zone. This reaction zone has restricted mobility due to the fast deactivation of reactive protons located behind the reaction zone by alkenes formed by nonselective reactions in the reaction zone. In PFR, as long as the reaction is limited to an immobile reaction zone, deactivation time is independent of reaction site density and contact time. Contact time dependence arises when the reaction zone is mobile. Overall deactivation time then depends strongly on the degree of deactivation of the protons behind the reaction zone.

The capacity of HZSM-5 zeolite (SiO2/Al2O3 ratio = 30–280) based catalysts with a hierarchical porous structure has been explored for the oligomerization of 1-butene at low pressure. Catalysts were characterized (structural, physical and acid properties) and tested in a fixed bed reactor under the following conditions: 1.5 bar; 175–325 °C; space time, 0.5–10 gcatalyst h (molC)−1; butene partial pressure, 0.375–1.5 bar; time on stream, 10 h. Results were evaluated with the aim of boosting naphtha (C5-C12=) fraction. A good compromise between conversion (62% in C units contained) and naphtha yield (42%) was achieved by using a HZSM-5 zeolite with SiO2/Al2O3 = 30 at 275 °C and 6 gcatalyst h (molC)−1, where 23% corresponds to C8-C12= and 19% to C5-C7=, respectively. Furthermore, the hierarchical porous structure facilitated catalysts to tend to a pseudo-stationary deactivation state after 2–3 h time on stream, which could be interesting for process scale up.

The Waddington mechanism, or the Waddington-type reaction pathway, is crucial for low-temperature oxidation of both alkenes and alcohols. In this study, the Waddington mechanism in the oxidation chemistry of butene and butanol isomers was systematically investigated. Fundamental quantum chemical calculations were conducted for the rate constants and thermodynamic properties of the reactions and species in this mechanism. Calculations were performed using two different ab initio solvers: Gaussian 09 and Orca 4.0.0, and two different kinetic solvers: PAPR and MultiWell, comprehensively. Temperature- and pressure-dependent rate constants were performed based on the transition state theory, associated with the Rice Ramsperger Kassel Marcus and master equation theories. Temperature-dependent thermochemistry (enthalpies of formation, entropy, and heat capacity) of all major species was also conducted, based on the statistical thermodynamics. Of the two types of reaction, dissociation reactions were significantly faster than isomerization reactions, while the rate constants of both reactions converged toward higher temperatures. In comparison, between two ab initio solvers, the barrier height difference among all isomerization and dissociation reactions was about 2 and 0.5 kcal/mol, respectively, resulting in less than 50%, and a factor of 2-10 differences for the predicted rate coefficients of the two reaction types, respectively. Comparing the two kinetic solvers, the rate constants of the isomerization reactions showed less than a 32% difference, while the rate of one dissociation reaction (P1 ↔ WDT12) exhibited 1-2 orders of magnitude discrepancy. Compared with results from the literature, both reaction rate coefficients (R4 and R5 reaction systems) and species' thermochemistry (all closed shell molecules and open shell radicals R4 and R5) showed good agreement with the corresponding values obtained from the literature. All calculated results can be directly used for the chemical kinetic model development of butene and butanol isomer oxidation.

—A two-stage method was developed for the synthesis of 1,3-butadiene by dehydration of 1-butanol to a mixture of butenes on γ-Al2O3 granules prepared by self-propagating high-temperature synthesis (SHS) followed by dehydrogenation of the butene fraction to 1,3-butadiene using a porous ceramic catalytic SHS converter [Fe,Cr]/γ-Al2O3(K,Ce)/α-Al2O3. The dehydration of 1-butanol to the butene mixture proceeded almost completely at ~100% selectivity on γ-Al2O3 granules obtained by SHS at 300°C, which is 50 degrees lower than on industrial gamma-alumina granules. The use of an original hybrid catalytic membrane reactor (HCMR) with selective removal of hydrogen from the reaction zone led to a ~1.3-fold increase in the yield of 1,3-butadiene at ultrapure hydrogen extraction of up to 16 mol % of the total amount of the hydrogen product. The catalytic activity of the system did not decrease after 20 h of experiment, in contrast to its activity in the industrial process, where catalyst regeneration is performed every 8–15 min.

Two kinds of soft-bridged iminopyridyl ligands and their metal (iron and cobalt) complexes were synthesized. All soft-bridged iminopyridyl ligands and metal complexes were fully characterized by FT-IR, 1H NMR, UV–Vis, ESI-MS, and ICP-MS. Upon activation with methylaluminoxane (MAO), these metal complexes exhibited moderate catalytic activity up to the range of 105 g/(mol Me h) for ethylene oligomerization, and butene was the major product, while for the cobalt complexes, activation with EtAlCl2 in toluene produced Friedel–Crafts toluene alkylation products. In the catalytic systems, cobalt complexes exhibited better catalytic activity and selectivity towards higher carbon number olefins (≥C8) than their iron analogues. The correlations between metal complexes and their catalytic activities and product distribution were investigated in detail under various reaction parameters such as reaction temperature, ethylene pressure and amount of co-catalyst. Under optimized conditions ([Co] = 7 μmol, 35°C, 1.0 MPa, MAO-to-Co = 500), soft-bridged iminopyridyl cobalt catalyst Co1 led to catalytic activity of 6.18 × 105 g/(mol Co h) and 29.97% selectivity for higher carbon number olefins. However, under optimized conditions ([Fe] = 7 μmol, 25°C, 1.0 MPa, MAO-to-Fe = 500), soft-bridged iminopyridyl iron catalyst Fe1 led to catalytic activity of 4.73 × 105 g/(mol Fe h) and 22.60% selectivity for higher carbon number olefins.

Wax deposition in production tubing and pipelines is very critical in Nigeria petroleum industry. It can lead to a reduction in production, shut-in of wells, choking of flow lines, failure of downhole equipment, increased power requirement and loss in revenue. In the bid to address this issue, a Niger Delta crude oil sample was characterized in this study to know its wax deposition tendency and other chemical properties. The effect of temperature on the viscosity of the crude oil sample was studied, and the degree of viscosity reduction (DVR) of the crude oil sample in the presence of poly (ethylene-butene) (PEB) and nano-aluminium oxide (Al2O3) blend at different temperatures was evaluated. 100 ppm of nano-Al2O3 blend with 1000 ppm, 2000 ppm and 5000 ppm of PEB, respectively, was added to the crude oil sample at different temperatures, and the degree of viscosity reduction (DVR) in each blend at 10 °C, 15 °C, 20 °C, 30 °C and 35 °C was evaluated. The blend with 2000 ppm of PEB with 100 ppm nano-Al2O3 is the best for offshore application as it gave the highest DVR of 77.9% and 73.7% at 10 °C and 15 °C, respectively, while the other blends gave a DVR of about 70% at 10 °C and 15 °C. As the crude sample temperature approached the wax appearance temperature of 29 °C, the DVR of PEB/Al2O3 blend drastically reduced. PEB/Al2O3 blend inhibited wax precipitation, and at low temperatures, a significant reduction in the viscosity of the crude oil sample was observed, which makes it a good recommendation for offshore application.

Lignocellulosic waste is a potential feedstock for the generation of fuels and commodity chemicals, but existing conversion methods are too cost-intensive to be viable long-term solutions. Electrochemical reductions are promising for decentralized biomass valorization due to their modular scaling and capacity to run intermittently and without high temperatures or pressures. Using crotonaldehyde as a multi-functional model compound for the many partially unsaturated oxygenates found in processed biomass, we here demonstrate the production of butanal, butanol, butene, and butane (variously useful as commodity chemicals and major components of liquified petroleum gas) under ambient conditions by reductive bulk electrolysis with a copper mesh working electrode. We identify an optimum potential for reduced organic production under the reaction conditions and compare product distributions from reductions of intermediate species to further propose branching reaction pathways. Though butanal is typically the most abundant product from crotonaldehyde reduction, most of the butene and butane appear to result from a pathway involving initial reduction of the aldehyde group. We discuss evidence that selectivity is driven by interplay between crotonaldehyde reduction, local pH shifts due to the hydrogen evolution reaction, and changes in site reactivity and availability due to electrode fouling. This demonstration of model electrochemical biomass valorization also serves to inform further exploration into reduction of multi-functional molecules and electrochemical biomass processing in general.

The intrinsic coupling effect between the multiscale microstructure and macroscopic performance is a fundamental issue in polymer engineering and polymer physics. Combing the tensile testing and in...

The partial hydrogenation of but-1-yne and but-2-yne was studied with a view to probing the difference between external and internal alkynes. Catalysts with Pd and Pd4S active phases were prepared on a carbon nanofiber support. Over the simple Pd catalyst over-hydrogenation was common which restricted alkene selectivity greatly – 25–35% depending on temperature. In contrast, the Pd4S active phase offered exceptional alkene selectivity (maximum of 92–93% alkene selectivity for both the external and internal alkyne). DFT calculations were subsequently used to rationalise this difference in product selectivity – sulfur appears to change the geometry of the active site in Pd4S and create a surface which favours alkene desorption relative to over-hydrogenation. This work further emphases the potential of palladium sulfide phases as an alternative to purely metallic palladium catalysts for partial alkyne hydrogenation.

We show that under relevant processing conditions, isotactic poly(butene-1) (iPB-1) directly crystallizes into the thermodynamically stable form I and III from the melt state when it is confined in...

Al2O3 binders of various particle sizes were used to formulate a zeolite Y-based catalyst, and the acidity of catalysts increases with decreasing Al2O3 particle size. Characterization results showe...

In the present study, alumina-supported palladium catalysts were prepared by modified electroless deposition (ED) method in presence of surfactants and their performance was significantly improved compared to that prepared in absence of surfactants. Depending on the type and concentration of surfactant, loading and morphology of deposited palladium varied. Both anionic (sodium dodecyl sulphate) and non-ionic (Tween 20) surfactants were observed to be the most effective in dispersing the metals in the precursor solution. Average metal cluster sizes obtained for catalysts prepared by wetness impregnation, modified electroless deposition and surfactant-assisted deposition method were 11.89, 4.6 and 1.18 nm, respectively. The conversion of butane and selectivity to butene was observed to be function of size of deposited Pd cluster. The conversion and selectivity towards butenes increased with the decreasing particle size. The SDS surfactant-assisted prepared catalyst, having the lowest metal cluster size (1.18 nm), showed the highest activity (33% conversion at 600 °C) and over 99% selectivity for butenes.