Hydrogenation Of 1-octene Research Articles

Electrocatalytic Transfer Hydrogenation of 1-Octene with [(tBuPCP)Ir(H)(Cl)] and Water.

Electrocatalytic hydrogenation of 1-octene as non-activated model substrate with neutral water as H-donor is reported, using [(tBuPCP)Ir(H)(Cl)] (1) as the catalyst, to form octane with high faradaic efficiency (FE) of 96 % and a kobs of 87 s-1. Cyclic voltammetry with 1 revealed that two subsequent reductions trigger the elimination of Cl- and afford the highly reactive anionic Ir(I) hydride complex [(tBuPCP)Ir(H)]- (2), a previously merely proposed intermediate for which we now report first experimental data by mass spectrometry. In absence of alkene, the stoichiometric electrolysis of 1 in THF with water selectively affords the Ir(III) dihydride complex [(tBuPCP)Ir(H)2] (3) in 88 % FE from the reaction of 2 with H2O. Complex 3 then hydrogenates the alkene in classical fashion. The presented electro-hydrogenation works with extremely high FE, because the iridium hydrides are water stable, which prevents H2 formation. Even in strongly alkaline conditions (Bu4NOH added), the electro-hydrogenation of 1-octene with 1 also proceeds cleanly (89 % FE), suggesting a highly robust process that may rely on H2O activation, reminiscent to transfer hydrogenation pathways, instead of classical H+ reduction. DFT calculations confirmed oxidative addition of H2O as a key step in this context.

An Insight into the Role of Reactant Structure Effect in Pd/C Catalysed Aldehyde Hydrogenation.

The different activity of a 1% Pd/carbon catalyst towards aromatic and aliphatic aldehydes hydrogenation has been explored by 13C NMR relaxation. The ratio between T1 relaxation times of adsorbed (ads) and free diffusing (bulk) molecules (T1ads/T1bulk) can be used as an indicator of the relative strength of interaction between the reactant and the catalytic surface, where the lower the T1ads/T1bulk, the higher the adsorption strength. It can be seen that 1% Pd/carbon showed a reverse catalytic behaviour towards benzaldehyde and octanal hydrogenation, which can be explained by analysing the T1 relaxation times related to each substrate in the presence of the catalyst. Comparing and correlating the different T1ads/T1bulk values, we were able to prove that the different catalytic results mainly depend on the contrasting adsorption behaviour of substrates on the catalyst. Moreover, the role of the solvent has been disclosed, as NMR results revealed that the adsorption of the reactants was strongly affected by the choice of solvent, which is revealed to be critical in modulating catalytic activity. As a consequence, T1ads/T1bulk measurements can provide a guide to the selection of appropriate reaction conditions for improving catalytic activity.

Effects of lipid bilayer encapsulation and lipid composition on the catalytic activity and colloidal stability of hydrophobic palladium nanoparticles in water.

This article shows the preparation of a lipid-nanoparticle assembly (LNA) which contains hydrophobic palladium nanoparticles (PdNPs) within the hydrophobic regions of the liposomal micelles. To understand the colloidal stability and catalytic activity of LNAs, the structure–property relationships of LNAs are investigated by manipulating the lipid composition and reaction temperature. The studies of LNAs using dynamic light scattering (DLS), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM) show decreased colloidal stability with the incorporation of PdNPs compared to their counterpart 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) liposomes without PdNPs. LNAs with PdNPs catalyze the hydrogenation of 1-octene and its isomers to octane under one atm hydrogen gas and at room temperature within 24 h. The kinetic studies show that the isomerization of 1-octene to 2-octene occurs more favorably in the early stage of the reactions, which is followed by the subsequent hydrogenation of all octene isomers. The studies on temperature effects indicate that there is a significant increase in conversion yield of substrates when the reaction temperature increases from 22 to 37 °C, which correspond to room temperature and biological temperature, respectively. Phase transition of DSPC-PdNP LNAs from gel to liquid crystalline phase changing the fluidity of the bilayer is proposed to be the main reason for dramatic increases in the catalytic activity of the LNAs. It is also found that the rate of hydrogenation is dependent on the lipid composition of LNAs with the presence of cholesterol having a negative influence on the catalytic activity of LNAs while increasing their colloidal stability.

Impact of the impregnation sequence on the surface characteristics on Cu-Ag supported on γ-Alumina towards the liquid phase competitive hydrogenation of octanal in the presence of octene

Bimetallic Cu-Ag/Al2O3 catalysts were prepared for competitive hydrogenation of octanal to octanol, with octene as a competing reactant. These catalysts were prepared using simultaneous and sequential impregnation to determine the promotional effect of silver on the copper catalysts. The increased catalytic performance of the simultaneous impregnated 4.5Cu-0.5Ag/γ-Al2O3 (4.5 wt% Cu and 0.5 wt% Ag) catalyst included a higher octene conversion compared to the sequential catalysts which was due to the differences in synergistic copper-silver interaction. The catalysts yielded selectively high octanal and low octene conversions. It was found that under the same operating conditions at 140°C and 50 bar H2, the sequentially impregnated catalyst, S-0.5Ag-4.5Cu/γ-Al2O3 gave a high conversion of 83 %, while maintaining a low octene conversion of 4 mol%, compared to its monometallic counterpart 5Cu (5 wt% Cu/γ-Al2O3) which gave 69 % octanal conversion and 3 % octene conversion. Silver, initially used as a reduction promoter, showed to have also played a role as a structural promoter in some catalysts, which improved carbonyl adsorption as shown from the improved preferential selectivity towards octanal conversion compared to the undesired octene conversion.

A Facile and In-situ Methanol-mediated Fabrication of Low Pd Loading, High-efficiency and Size-selectivity Pd@ZIF-8 Hydrogenation Catalyst.

In-situ encapsulation of tiny and well-dispersed Pd nanoparticles (Pd NPs) in zeolitic imidazolate frameworks (ZIFs) was firstly achieved using a one-pot and facile methanol-mediated growth approach, in which methanol served as both solvent and a mild reductant. The microstructure, morphology, crystallinity, porosity as well as evolution process of the catalysts were determined by TEM, XRD, N2 adsorption and UV-vis spectra. Due to the complete encapsulation of such Pd NPs combined with ultrahigh surface area and uniform microporous structure of ZIF-8, the resulting Pd@ZIF-8-60 min nanocomposite exhibited more superior catalytic activity for olefins hydrogenation with TOF of 7436 h-1 and excellent size selectivity than previously reported catalysts. Furthermore, the catalyst displays excellent recyclability for 1-octene hydrogenation and without any loss of the Pd active species.

Applicability of CNT as support candidate for thiophene hydrodesulfurization and 1-octene hydrogenation catalyst

The application of carbon nanotubes (CNT) as a support candidate for hydrotreating catalysts for FCC (fluid catalytic cracking) gasoline was researched in the microreactor with a fixed bed at experimental conditions. The CNT synthesized using the AC arc discharge method was functionalized by chemical treatment with nitric acid. Scanning electron spectroscopy (SEM), X-ray diffraction (XRD) and X-photoelectron spectroscopy (XPS) of the functionalized CNT show that during the functionalization of it, HNO3 impurities unwanted for further application were removed and carbon nanostructures haveoxidized, and therefore they have oxide functional groups attached to those walls. At all the conditions observed, the Ni-Mo/CNT catalysts and Co-Mo-0.25 catalyst showed better hydrodesulfurization activities in comparison with the conventional Ni-Mo/γ-Al2O3. As shown in the XRD analysis, the Ni–W/CNT catalysts showed lowest thiophene hydrodesulfurization activity in the temperature range observed, but they showed very good hydrogenation activity on model compounds used.Catalytic performance tests of different catalysts showed that good applicability of the CNT as support candidate for the hydrotreating catalysts. It also was experimentally demonstrated that the Ni-Mo/CNT and Co-Mo/CNT can be the best hydrotreating catalysts.

The Continuous Flow Ag/γ-Al2O3 Catalysed Preferential Hydrogenation of Octanal in an Octanal/Octene Mixture

Ag/γ-Al2O3 catalysts, containing 5 and 25 wt% Ag, were synthesized by the slurry phase impregnation method. They were tested for the liquid phase continuous flow preferential hydrogenation of octanal in a mixture with octene. The catalysts were characterised by XRD, IR, BET, SEM, TEM and NH3-TPD. These catalysts showed strong preference for octanal hydrogenation, irrespective of reaction temperature or silver loading. A maximum octanal conversion of 90% with selectivity towards octanol of 94% was achieved over 25 wt% Ag/γ-Al2O3 at 180 °C with minimal octene conversion (< 3%).

Water: Friend or Foe in Catalytic Hydrogenation? A Case Study Using Copper Catalysts

Copper oxide supported on alumina and copper chromite were synthesized, characterized, and subsequently tested for their catalytic activity toward the hydrogenation of octanal. Thereafter, the impact of water addition on the conversion and selectivity of the catalysts were investigated. The fresh catalysts were characterized using X-ray diffraction (XRD), BET surface area and pore volume, SEM, TEM, TGA-DSC, ICP, TPR, and TPD. An initial catalytic testing study was carried out using the catalysts to optimize the temperature and the hydrogen-to-aldehyde ratio—which were found to be 160 °C and 2, respectively—to obtain the best conversion and selectivity to octanol prior to water addition. Water impact studies were carried out under the same conditions. The copper chromite catalyst showed no deactivation or change in octanol selectivity when water was added to the feed. The alumina-supported catalyst showed no change in conversion, but the octanol selectivity improved marginally when water was added.

Regeneration of a 15% Ni/SiO2 phosphorus poisoned catalyst and subsequent effects of the support on recovery of the catalytic activity

The deactivation of a 15 wt.% Ni supported on SiO2 (15 NiSi) catalyst by triphenylphosphine during the hydrogenation of octanal to octanol, and subsequent regeneration, was studied. Characterization of the catalyst by hydrogen chemisorption, TPR, powder XRD, ICP-OES, BET surface area analysis, and TEM showed the presence of large nickel clusters with a poor metal dispersion for the fresh catalyst prior to deactivation. This, however, had a positive effect, since the catalyst was very active and highly tolerant of the triphenylphosphine poison, taking significantly longer on stream to deactivate compared to a 15% Ni supported on alumina catalyst (15 NiA). The 15 NiSi catalyst was also effectively regenerated using a tandem octanol wash-hydrogen treatment regeneration protocol, which restored the conversion to 76%, after deactivation to 20%, and restored the octanol selectivity to that observed for the non-poisoned 15 NiSi catalyst, which was 86%. The present catalyst was also shown to be more effectively regenerated when compared to the 15 NiA catalyst. Regeneration of the poisoned catalyst did not remove phosphorus, but restored large nickel particles and resulted in the formation of Ni2P, which is active for octanal hydrogenation.

Continuous Flow Preferential Hydrogenation of an Octanal/Octene Mixture Using Cu/Al2O3 Catalysts.

γ-Alumina-supported catalysts with varying copper loadings (5–25 wt %) were prepared by incipient wet impregnation and characterized by various characterization techniques. These catalysts were tested for the selective hydrogenation of octanal in a mixture containing 10 wt % octanal and 2 wt % octene diluted in octanol. The reactions were carried out in a continuous flow fixed-bed reactor in a down flow mode with varying pressures, liquid hourly space velocities, and hydrogen (H2)-to-aldehyde molar ratios. The catalyst activities were assessed over a temperature range between 100 and 180 °C using hydrogen gas as the hydrogen source. The results obtained showed that under these experimental conditions, copper preferentially hydrogenates the aldehyde and the copper content exhibited no significant influence on the catalyst activity or product selectivity. Kinetic modeling revealed that both octanal and octene hydrogenation were first-order reactions, although octene conversion was very low until octanal conversion had reached a significant level. The activation energy for octanal hydrogenation is higher than the octene hydrogenation. A maximum octanal conversion of >99% was obtained at 160 °C, and the best selectivity toward octanol of 99% was achieved at 100 °C (53% conversion). The pressure played a small role with regards to octanal conversion and selectivity toward octanol, whereas it exhibited a significant influence on the octene conversion. Increasing the hydrogen-to-aldehyde ratio was found to have a direct influence on both octanal and octene conversion.

Silica-bonded DABCO hydrogen sulfate ((SB-DABCO)HSO4): a new dual-interphase catalyst for the diversity-oriented pseudo-five-component synthesis of bis(pyrazolyl)methanes and novel 4-[bis(pyrazolyl)methane]phenylmethylene-bis(indole)s

Silica bonded n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane hydrogen sulfate ((SB-DABCO)HSO4) was prepared as a new interphase dual-catalyst and was successfully applied for the diversity-oriented synthesis of bis(pyrazolyl)methanes via a one-pot pseudo-five-component condensation reaction. This approach provides a versatile range of available substrates and high diversity of desired products. Moreover, ((SB-DABCO)HSO4) was successfully applied for the synthesis of some novel [bis(pyrazolyl)methane]-bis(indole)s as more complex molecules.

The effect of ionic liquid on alumina supported copper catalysts for the competitive hydrogenation of octanal in the presence of octene

The influence of 1-butyl-3-methylimidazolium bis(trifluromethanesulfonyl)imide ([BMIM][NTf2]) on Cu/γ-Al2O3 was investigated for the competitive hydrogenation of octanal in the presence of octene in a continuous flow reactor. The role of the solid catalyst was investigated by comparing the activities of one-step (N15Cu) vs two step (2N15Cu) wet impregnated catalyst. Characterization techniques included nitrogen physisorption, temperature programmed studies, electron microscopy and X-Ray Photoelectron Spectroscopy which were used to determine the catalyst properties and metal-ionic liquid interaction of the uncoated and IL coated catalysts. The Cu SCILL catalyst (solid catalyst with an ionic liquid layer) showed enhanced catalytic performance as compared to the uncoated catalyst. Under optimized conditions, the 2N15Cu SCILL catalyst favoured the desired hydrogenation of the octanal, whilst minimizing the undesired octene hydrogenation. The octene conversion decreased from 26% to 6% over the SCILL catalyst. The presence of the ionic liquid also increased the selectivity towards the desired product, 1-octanol, from 93.5% over the uncoated catalyst to 99.8% over the SCILL catalyst. Investigation into the interaction between the copper and the ionic liquid revealed that the ionic liquid is physically adsorbed onto the catalyst’s surface, and induced changes in the SCILL catalysts surface acidity, BET surface area and hydrogen-metal interaction. It seems likely that the thermal and chemical properties of the ionic liquid also contributed to the SCILL catalyst behaviour, for example, the polar nature of the ionic liquid favours the diffusion of octanal as opposed to octene within the ionic liquid layer. This results in a greater selectivity towards CO hydrogenation which is desired.

New Insights into the Kinetics of Structural Transformation and Hydrogenation Activity of Nano-crystalline Molybdenum Carbide

Transformation of cubic molybdenum carbide into hexagonal β-Mo2C was found to follow the Avrami–Erofeev kinetic model with an n parameter of four indicating a slow nucleation step with a polyhedral growth of the transformed phase. The transformation not only occurred at 773 K under atmospheric H2 pressure, but also imperceptibly occurred under the employed hydrogenation reaction conditions (413 K and 70 psig of H2 pressure) when using toluene or 1-octene as reactants, not affecting the activity under the steady state. Our computational studies also revealed that both crystal structures share common atomic cluster arrangements with small differences in angles and interatomic distances. The transformation was triggered by local distortions which favored shorter and more homogeneous interatomic distances as present in the hexagonal phase. The prepared molybdenum carbide materials were selective to the hydrogenation of 1-octene under the mild hydrogenation conditions tested. Hydrogenation of 1-octene was preferential in a 50 wt% mixture of toluene and 1-octene with minimal toluene hydrogenation under the tested conditions.

Transition metal oxide supported on alumina catalysts: a comparative study for the hydrogenation of octanal

Monometallic (10 wt.%) Co, Ni and Cu nanoparticles supported on alumina catalysts were prepared using an ultrasonic impregnation- cavitation method and characterized using ICP, XRD, physisorption, chemisorption and temperature programmed techniques. The copper catalyst showed higher metal dispersion and greater hydrogen and CO chemisorption capacity when compared to the nickel and cobalt catalysts. Hydrogenation of octanal carried out in a continuous flow high pressure fixed bed reactor showed that the rate of reaction and turnover number of octanol depended on the amount of hydrogen chemisorbed. The copper catalyst showed the lowest activation energy, as well as best catalytic activity. The Cu-Al catalyst which showed higher metal dispersion and low acidity, showed the highest selectivity towards octanol with no C24 acetal formation, when compared to the Ni-Al and Co-Al catalysts. Keywords: Octanal hydrogenation, octanol, copper, nickel, cobalt

HETEROGENIZATION OF HOMOGENEOUS PERFLUOROTHIOPHENE Rh(I) COMPLEX AND EXAMINATION OF HYDROGENATION ACTIVITY IN scCO2 MEDIA

Rhodium(I) complex of perfluorinated thiophene ligand was synthesized and heterogenized over the modified silica support. SEM, XRF, TGA and BET methods were used for the characterization of the heterogenized catalyst (SiAPTES-RhL). Heterogenization of catalyst and the catalytic activity tests were carried out in scCO 2 as a greener alternative to traditional reaction media. The catalytic activities of complex were investigated in hydrogenation reactions of some alkenes such as styrene, 1-octene and cyclohexene. 100% ethyl benzene conversion was observed at 370 K, 10 bar H 2 and 1900 psi total pressure in styrene hydrogenation. Also, it was found that the catalyst remains active at least throughout ten cycles. Similarly, the activity of the catalyst in the hydrogenation of 1-octene and cyclohexene was investigated. For 1-octene, 100% n-octan selectivity was obtained at 370 K and 10 Bar H 2 . The catalyst was found to be effective at 370 K while the activity was low at 350 and 360 K in cyclohexen hydrogenation. When compared with the homogenous system, the heterogenized catalyst had more activity and selectivity and also reusability without losing its activity

Controlled Pyrolysis of Ni-MOF-74 as a Promising Precursor for the Creation of Highly Active Ni Nanocatalysts in Size-Selective Hydrogenation.

Metal organic frameworks (MOFs) are a class of porous organic-inorganic crystalline materials that have attracted much attention as H2 storage devices and catalytic supports. In this paper, the synthesis of highly-dispersed Ni nanoparticles (NPs) for the hydrogenation of olefins was achieved by employing Ni-MOF-74 as a precursor. Investigations of the structural transformation of Ni species derived from Ni-MOF-74 during heat treatment were conducted. The transformation was monitored in detail by a combination of XRD, in situ XAFS, and XPS measurements. Ni NPs prepared from Ni-MOF-74 were easily reduced by the generation of reducing gases accompanied by the decomposition of Ni-MOF-74 structures during heat treatment at over 300 °C under N2 flow. Ni-MOF-74-300 exhibited the highest activity for the hydrogenation of 1-octene due to efficient suppression of excess agglomerated Ni species during heat treatment. Moreover, Ni-MOF-74-300 showed not only high activity for the hydrogenation of olefins but also high size-selectivity because of the selective formation of Ni NPs covered by MOFs and the MOF-derived carbonaceous layer.

Operando determination of the liquid-solid mass transfer coefficient during 1-octene hydrogenation

Spatially-resolved and unresolved magnetic resonance measurements are used in combination with a partial least squares regression (PLSR) method to measure chemical composition within catalyst pellets during the 1-octene hydrogenation reaction occurring in a fixed bed of 0.3wt% Pd/Al2O3 catalyst pellets. The PLSR method is used to discriminate between chemical species within and external to the void space of the catalyst pellets. The spatially-resolved data show that the hydrogenation and isomerisation reactions are dominant in the upper and lower region of the reactor, respectively. The local intra-pellet compositions also show product accumulation inside catalyst pellets consistent with reaction occurring under conditions of mass transfer limitation. An average measure of the intra-pellet composition within the whole bed was then used to estimate the liquid-solid mass transfer coefficient during the course of the reaction. The values of kLS obtained from the NMR measurements were in the range 0.15×10−5ms−1<kLS<0.25×10−5ms−1, for reactor operating conditions characterised by gas and liquid Reynolds numbers 0.2<ReL<0.6 and 0.1<ReG<0.3; these values are shown to be consistent with those predicted by existing literature correlations. Closest agreement was found with values predicted from dissolution experiments performed under similar hydrodynamic conditions in trickle flow. In addition to introducing a method for the direct measurement of kLS, the data presented also confirm that estimates of kLS are more accurate when performed in an environment in which the hydrodynamics and fluid-solid contacting conditions are representative of the system of interest.

Ternary (Cu, Ni and Co) Nanocatalysts for Hydrogenation of Octanal to Octanol: An Insight into the Cooperative Effect

Ternary metal oxides (Cu–Ni–Co) with different wt% loadings were supported on alumina by using an ultrasonic cavitation-impregnation method. A comparative silica catalyst was also prepared. Powder X-ray diffraction (XRD) showed the presence of the metal oxides on the surface of the supports and from in situ XRD results, the formation of metallic phases under a reducing atmosphere were observed. Temperature-programmed desorption (TPD) revealed the presence of Lewis and Bronsted acidic sites in the catalysts. The metals supported on alumina showed a better dispersion compared to that on the silica support. All the catalysts were tested for the hydrogenation of octanal in a mixture of 10% octanal in octanol in a continuous flow fixed bed reactor by varying the pressure, temperature and hydrogen molar ratios. Under the hydrogenation conditions, the trimetallic catalysts (with Cu, Ni and Co) showed best catalytic performance for octanal hydrogenation when compared to bimetallic catalysts. The conversion of octanal and the selectivity towards octanol increased in proportion to an increase in the total metallic content and metal dispersion. The alumina based catalysts showed better activity compared to the silica catalyst due to higher metal dispersion. The silica supported catalyst showed a high selectivity towards C24 acetal due to its higher acidity and the product distribution over all the catalysts is in agreement with the distribution of acidic sites.

A Comparative Study of NiO/Al2O3 Catalysts Prepared by Different Combustion Techniques for Octanal Hydrogenation

Four catalysts with the molar ratio of Ni:Al (1:2) were prepared by solution combustion synthesis (SCS) and sol–gel auto combustion synthesis (SGCS) techniques. Two fuels [urea and oxalyldihydrazide (ODH)] with distinct oxygen/carbon (O/C) ratios and chelating capability were chosen for investigating the effect of the fuel on the syntheses of these catalysts. All catalysts were fully characterized by PXRD, ICP-OES, TEM, H2-TPR, pyridine IR, H2-chemisorption and nitrogen physisorption. Pure NiO/Al2O3 (free of spinel) was achieved by application of SGCS and urea as a fuel. Thus, catalysts prepared by urea as a fuel showed high activity for hydrogenation of octanal even under moderate conditions (110 °C). Optimisation showed that the catalyst prepared via SCS using ODH as a fuel gave the best comparative aldehyde conversion and alcohol selectivity (98 and 97 %, respectively) albeit at a higher temperature of 150 °C. The catalysts with NiAl2O4 as the dominant phase presented the lowest acidity, likely due to the non-availability of acidic sites of alumina via formation of the spinel, thus making these catalysts highly selective and also offering a slow release of fresh Ni sites.

Synthesis, Characterization, and Catalytic Hydrogenation Activity of New N-Acyl-Benzotriazole Rh(I) and Ru(III) Complexes in [bmim][BF4

The hydrogenation activity of new N-acyl-benzotriazole Rh(I) and Ru(III) complexes in ionic liquid media is reported in this study. Both complexes were completely soluble in 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4], and they were able to catalyze the hydrogenation of styrene and 1-octene. While ethylbenzene conversion in styrene hydrogenation reached 84% when the Ru complex was used, 100% conversion was obtained with the Rh complex at 393 K in 6 h. Additionally, total conversion in 1-octene hydrogenation reached 100% with the Rh complex in [bmim][BF4] media. The hydrogenation of styrene and 1-octene in dimethyl sulfoxide (DMSO) and toluene was also studied to compare the solvent effect on catalytic system. The effect of some catalytic parameters such as temperature, H2 (g) pressure, and catalyst amount on the conversion was examined, and it was found that the conversion increased parallel to the increasing temperature and H2 pressure. The recyclability of catalysts was also investigated, and it was revealed that the Rh complex in particular maintained the activity for at least 10 cycles.