Initial Hydrogen Pressure Research Articles

Catalytic hydrogenation of straight vegetable oil using NiMo/ Al2O3 catalyst for biodiesel production

The attractiveness of biodiesel as an alternative fuel compared to fossil fuels because it has many advantages such as the availability of abundant raw materials, more environmentally friendly, high combustion efficiency, low sulphur content, high cetane number and biodegradability. Making biodiesel from straight vegetable oil (VGO) has been done through the catalytic hydrogenation process. A VGO of callophylum inophyllum oil was treated via degumming and neutralisation to remove all impurities before hydroprocessing. Hydroprocessing was carried out in a 500ml autoclave at 30 – 50 MPa of initial hydrogen pressure, 300 – 400oC of reaction temperature and equipped with stirrer and cooling system. NiMo/Al2O3 catalyst was activated with CS2 mixture at 370oC prior to the reaction. Some physical and chemical properties of the catalytic hydroprocessing product have been investigated in accordance to ASTM standard. The measurement result of product varies according to the operation condition. The result showed that callophyllum inophyllum oil can be used as raw material for biodiesel production over NiMo/Al2O3. Sulfided NiMo/Al2O3 catalysts are preferred due to high diesel yield.

Measurements of electric characteristics in high-current high-pressure discharge with current amplitude of 590–1200 kA by magnetic probe

Soft x-ray radiation (SXR) oscillation were registered for discharge with current amplitude of 1200 kA at initial hydrogen pressure of 5 MPa. Near current maximum the fluctuations of SXR from the channel have been registered. Speed of current channel contraction, channel radius and its oscillation amplitude for current amplitude of 1200 kA were measured by magnetic probe with extrapolation for currents of 590 and 900 kA. The electric field strength in discharge channel and near electrode voltage drops was determined by comparison of channel radius oscillations with synchronous voltage changing. Also this method was used for oscillation amplitude estimation at current of 1200 kA. Satisfactory agreement for the estimations was received. Oscillation amplitudes are needed for calculation of x-ray intensity modulation. Channel plasma parameters were determined for contraction near current maximum.

Hydrodeoxygenation of fast pyrolysis oil with novel activated carbon-supported NiP and CoP catalysts

Catalytic hydrodeoxygenation (HDO) has been considered as a promising technical route to upgrade fast pyrolysis oil to liquid transportation fuels. In this work, a series of active and inexpensive catalysts were synthesized for bio-oil HDO, i.e., activated carbon (AC)-supported nickel phosphide and cobalt phosphide catalysts, with a metal/P molar ratio varying from 5/2, 3/2, 1/1, 1/2, 1/3. For comparison, AC-support pure metal catalysts without P were also prepared. Effects of phosphorus content on HDO performance of the catalysts were investigated on a 100 mL bench-scale reactor system using a wood-derived pyrolysis oil at 300 °C and initial hydrogen pressure of 50 bar for 3 h. The results showed that the properties of the upgraded bio-oils were greatly affected by the phosphorus content in both Ni and Co catalysts. The best performance seemed to be achieved with the catalysts at a metal/P molar ratio of about 3/2. Moreover, 0.5 wt% of Ru was further added to the catalysts at a metal/P molar ratio of 3/2 and to the pure metal catalysts. The addition of a small amount of Ru was found to markedly decrease the relative molecular weight of the upgraded bio-oils, and achieved high quality bio-oil products similar to that obtained with an expensive commercially available 5 wt% Ru/C catalyst.

Interpretation of negative temperature dependence of hydriding reaction in LaNi5-Mg alloys by modified Chou model

A modified Chou model with parameters of temperature (T), initial hydrogen pressure (P0), enthalpy change (ΔH) and entropy change (ΔS) is proposed in consideration of thermodynamic driving force. The meaningful activation energy Ev can be calculated for the negative temperature dependence of hydriding reaction in hydrogen storage materials. This model is verified by the hydriding/dehydriding experimental data of (LaNi5)1−xMgx (x=0, 0.018, 0.041, 0.063). The calculated results indicate that the hydriding kinetics of (LaNi5)1−xMgx alloys are controlled by diffusion of hydrogen atom in hydride. The addition of small amount of magnesium improves the kinetic performance of LaNi5 slightly. Furthermore, the modified Chou model was compared with the previous model that successfully explain the negative temperature depending hydrogenation reaction of Mg-based alloys. The fitting results show that the modified Chou model can describe the hydrogen absorption kinetic mechanism of negative temperature dependent materials more accurately.

Stable region of ZrCo under hydrogen atmosphere at high temperature

In this work, the unusual reproportionation phenomenon, which occurs under hydrogen atmosphere, has been studied for the first time by combing temperature-programmed dehydrogenation and XRD characterization. The phase transition from ZrCo2–ZrH2 to ZrCo for reproportionation was clearly observed without vacuum pumping. It was shown that the reproportionation could take place even under hydrogen pressure of 0.65 bar at 640 °C. In addition, the reproportionation behaviors under different initial hydrogen pressures were investigated and the onset boundary for reproportionation was successfully established. The original insight into the unusual reproportionation phenomenon reveals that there is a stable region for ZrCo under hydrogen atmosphere at high temperature. On the basis of this work, it is hopeful that the application of ZrCo at high temperature will be substantially broadened.

Research on Improving Low Rank Coal Caking Ability by Moderate Hydrogenation

The hydrogenation test of low metamorphic coal was carried out by using a continuous hydrogen reactor at the temperature of (350-400)°C and the initial hydrogen pressure of 3 ~ 6Mpa. The purpose of the experiment was to increase the caking property, and the heating time was controlled from 30 to 50min. The test results show that the mild hydrogenation test, no adhesion of low metamorphic coal can be transformed into a product having adhesion, oxygen elements in coal have good removal, the calorific value of the product has been improved significantly and coal particles during pyrolysis, swelling, catalyst, hydrogenation, structural changes and the combined effects of particles a new component formed between financial and is a major cause of coal caking enhancement and lithofacies change, coal blending test showed that the product can be used effectively in the coking industry.

Upgrading of pinyon-juniper catalytic pyrolysis oil via hydrodeoxygenation

Abstract In this study we discuss hydrodeoxygenation (HDO) of pinyon juniper (PJ) catalytic pyrolysis oil over Ni/SiO2 Al2O3 catalyst in a batch reactor to improve the physicochemical properties of the oil. The influence of temperature (350–500 °C), reaction time (15–90 min), and initial hydrogen pressure (3.5–10 MPa), on hydrodeoxygenation of PJ pyrolysis oil was investigated. After hydrogenation was completed, gas, coke, and a liquid product of two immiscible phases (aqueous and organic), were obtained. Maximum HDO of bio-oil was achieved at 450° C while the initial hydrogen pressure was 7 MPa and the reaction time was 30 min. Under these conditions, the H/C and O/C atomic ratios changed from 1.29 to 0.29 respectively for bio-oil to 2.36 and 0 for HDO oil respectively. The higher heating value increased from 27.64 MJ/kg of bio-oil to 45.58 MJ/kg of upgraded oil. The water content of organic liquid product was less than 0.05 wt% while it was 1.63 wt% in the feed. The viscosity of upgraded oil was 1.26 cP compared to119 cP for the crude bio-oil.

Dehydrogenation of Surface-Oxidized Mixtures of 2LiBH4 + Al/Additives (TiF3 or CeO2)

Research for suitable hydrogen storage materials is an important ongoing subject. LiBH4–Al mixtures could be attractive; however, several issues must be solved. Here, the dehydrogenation reactions of surface-oxidized 2LiBH4 + Al mixtures plus an additive (TiF3 or CeO2) at two different pressures are presented. The mixtures were produced by mechanical milling and handled under welding-grade argon. The dehydrogenation reactions were studied by means of temperature programmed desorption (TPD) at 400 °C and at 3 or 5 bar initial hydrogen pressure. The milled and dehydrogenated materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FT-IR) The additives and the surface oxidation, promoted by the impurities in the welding-grade argon, induced a reduction in the dehydrogenation temperature and an increase in the reaction kinetics, as compared to pure (reported) LiBH4. The dehydrogenation reactions were observed to take place in two main steps, with onsets at 100 °C and 200–300 °C. The maximum released hydrogen was 9.3 wt % in the 2LiBH4 + Al/TiF3 material, and 7.9 wt % in the 2LiBH4 + Al/CeO2 material. Formation of CeB6 after dehydrogenation of 2LiBH4 + Al/CeO2 was confirmed.

Hydrotreatment of the carbohydrate-rich fraction of pyrolysis liquids using bimetallic Ni based catalyst: Catalyst activity and product property relations

The use of novel nickel based catalysts for the catalytic hydrotreatment of pyrolytic sugars, the carbohydrate-rich fraction of pine derived pyrolysis liquids, is reported. The catalysts are characterized by a high nickel loading (38 to 57wt%), promoted by Cu, Pd, and/or Mo and a SiO2 based inorganic matrix. Experiments were carried out at 180°C and 120bar initial hydrogen pressure (room temperature) in a batch reactor set-up to gain insight in catalyst activity and product properties as a function of the catalyst composition. The most promising catalyst in terms of activity, as measured by the hydrogen uptake during reaction, was the Ni-Mo/SiO2-Al2O3 catalyst whereas the performance of the monometallic Ni/SiO2-Al2O3 catalyst was the lowest. As a result, the product oil obtained by the bimetallic Ni-Mo catalyst showed the highest H/C ratio and the lowest molecular weight of all catalysts tested. A detailed catalyst characterization study revealed that addition of Mo to the Ni catalyst suppresses the agglomeration of nickel nanoparticles during the catalytic hydrotreatment reaction.

Microemulsion-mediated hydrothermal synthesis of flower-like MoS2 nanomaterials with enhanced catalytic activities for anthracene hydrogenation

Flower-like intercalated MoS2 nanomaterials have been successfully synthesized via a microemulsionmediated hydrothermal (MMH) method, and characterized by X-ray diffraction, Raman spectroscopy, element analysis, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy in detail. Their catalytic performance for anthracene hydrogenation was evaluated using a slurry-bed batch reactor with an initial hydrogen pressure of 80 bar at 350 °C for 4 h. The intercalated MoS2 nanoflowers synthesized from Na2MoO4 (MoS2-S) and H2MoO4 (MoS2-A) as molybdenum precursors have diameters of about 150 and 50 nm, respectively. MoS2 nanosheets on MoS2-S and MoS2-A possess stacking layer numbers of 5–10 and 2–5, and slab lengths of about 15 and 10 nm, respectively. The interlayer distances of MoS2-S and MoS2-A are both enlarged from 0.62 nm to about 0.95 nm due to the intercalation of NH4 + and surfactant molecules. The MoS2 nanoflowers have high catalytic activities for anthracene hydrogenation. The selectivity for octahydroanthracene, a deeply hydrogenated product, over MoS2-A is 89.8%, which is 31.0 times higher than that over commercial bulk MoS2. Fully hydrogenated product (perhydroanthracene) was also detected over MoS2 nanoflowers with a selectivity of 3.7%. The enhanced hydrogenation activities of MoS2 nanoflowers can be ascribed to the high exposure of catalytic active sites, resulting from the smaller particle size, fewer stacking layer, shorter slab length and enlarged interlayer distance of MoS2 nanoflowers compared with commercial bulk MoS2. In addition, a possible growth mechanism of MoS2 nanoflowers synthesized via the MMH method was proposed.

Reductive Amination of 2-Amino-2-methyl-1-propanol and Ammonia to Produce 2-Methyl-1,2-propanediamine over Raney Nickel Catalyst

The selective synthesis of 2-methyl-1,2-propyldiamine (MPDA) directly from 2-amino-2-methyl-1-propanol (AMP) and ammonia via one-pot reaction is reported for the first time. The effects of catalyst species and reaction variables on the synthetic performance of MPDA were systematically studied. In contrast to other catalysts, a high MPDA selectivity of 88.3% and AMP conversion of 45.6% were obtained over Raney Ni catalyst. The components of the final reaction mixtures were particularly dependent on the initial hydrogen pressure and stirring speed. Furthermore, a possible mechanism of the reaction was proposed on the basis of experimental results, which has great implications in the development of more efficient and higher selectivity catalysts.

Characteristics of slurry-phase hydrocracking for vacuum residue with reaction temperature and concentrations of MoS2 dispersed catalysts

This study investigated the characteristics of slurry-phase hydrocracking of vacuum residue (VR >524°C) at a high conversion (40–95wt.%) with a change of reaction temperatures and concentrations of the dispersed molybdenum (Mo Conc. 100–2000wt.ppm) catalyst. Experiments were carried out with an initial hydrogen pressure of 80bar (at 80°C) at a reaction temperature from 385 to 440°C for four hours in a batch reactor. As results, it was found that the sediment formation is mainly dependent on the VR conversion by the reaction temperature and started over 70wt.% of VR conversion. Up to 70–80wt.% of VR conversion, the higher catalysts showed the higher asphaltene conversion and prevented the sediment formation at the boundary of its formation, but it didn’t show any effect over 80wt.% of VR conversion anymore. Based on the analysis of the structural change and ξ-potential of asphaltene from the liquid and sediment, and SARA compositional change in the liquid, the reason for sediment formation was explained.

Hydrocracking of Cerbera manghas Oil with Co-Ni/HZSM-5 as Double Promoted Catalyst

The effect of various reaction temperature on the hydrocracking of Cerbera manghas oil to produce a paraffin-rich mixture of hydrocarbons with Co-Ni/HZSM-5 as doubled promoted catalyst were studied. The Co-Ni/HZSM-5 catalyst with various metal loading and metal ratio was prepared by incipient wetness impregnation. The catalysts were characterized by XRD, AAS, and N2 adsorption-desorption. Surface area, pore diameter, and pore volume of catalysts decreased with the increasing of metals loading. The hydrocracking process was conducted under hydrogen initial pressure in batch reactor equipped with a mechanical stirrer. The reaction was carried out at a temperature of 300-375 oC for 2 h. Depending on the experimental condition, the reaction pressure changed between 10 bar and 15 bar. Several parameters were used to evaluate biofuel produced, including oxygen removal, hydrocarbon composition and gasoline/kerosene/diesel yields. Biofuel was analyzed by Fourier Transform Infrared Spectroscopic (FTIR) and gas chromatography-mass spectrometry (GC-MS). The composition of hydrocarbon compounds in liquid products was similar to the compounds in the gasoil sold in unit of Pertamina Gas Stations, namely pentadecane, hexadecane, heptadecane, octadecane, and nonadecane with different amounts for each biofuel produced at different reaction temperatures. However, isoparaffin compounds were not formed at all operating conditions. Pentadecane (n-C15) and heptadecane (n-C17) were the most abundant composition in gasoil when Co-Ni/HZSM-5 catalyst was used. Cerbera Manghas oil can be recommended as the source of non-edible vegetable oil to produce gasoil as an environmentally friendly transportation fuel.

Hydrogenolysis and Activation of Soda Lignin Using [BMIM]Cl as a Catalyst and Solvent.

To improve the reactivity of the soda lignin, an acid ionic liquid 1-butyl-3-mthylimidazolium chloride ([BMIM]Cl) was used as the catalyst and solvent to degrade the soda lignin through hydrogenolysis. Structural elucidation of the lignin samples was conducted by using a combination of analytical methods including chemical analysis, ultraviolet spectrophotometry (UV spectrophotometry), Fourier transform infrared spectroscopy (FT-IR spectra), two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) techniques, and gel permeation chromatography (GPC). The antioxidant activities of the lignin samples were evaluated using the diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS+) radical scavenging and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods. The degradation mechanism was proposed based on the characterization results. The optimal reaction condition was as follows: the concentration of [BMIM]Cl in the solution was 10 wt %, the hydrogen initial pressure was 3 MPa, and the solution was heated for 4 h at 90 °C. After the reaction, the total hydroxyl content of the soda lignin increased by 81.3%, while the phenolic hydroxyl content increased by 23.1%. At the same time, the weight-average molar mass of the soda lignin sample decreased from 8220 to 6450 g/mol with an improved antioxidant activity. In addition, approximately 56.7% of the β-O-4 linkages were degraded in the lreaction. The main effect of the acid ionic liquid [BMIM]C1 was related to the cleavage of β-O-4 linkages. This study has shown the potential of using the catalyzed soda lignin as a natural polymer antioxidant.

Mono-, bi-, and tri-metallic Ni-based catalysts for the catalytic hydrotreatment of pyrolysis liquids

Catalytic hydrotreatment is a promising technology to convert pyrolysis liquids into intermediates with improved properties. Here, we report a catalyst screening study on the catalytic hydrotreatment of pyrolysis liquids using bi- and tri-metallic nickel-based catalysts in a batch autoclave (initial hydrogen pressure of 140 bar, 350 °C, 4 h). The catalysts are characterized by a high nickel metal loading (41 to 57 wt%), promoted by Cu, Pd, Mo, and/or combination thereof, in a SiO2, SiO2-ZrO2, or SiO2-Al2O3 matrix. The hydrotreatment results were compared with a benchmark Ru/C catalyst. The results revealed that the monometallic Ni catalyst is the least active and that particularly the use of Mo as the promoter is favored when considering activity and product properties. For Mo promotion, a product oil with improved properties viz. the highest H/C molar ratio and the lowest coking tendency was obtained. A drawback when using Mo as the promoter is the relatively high methane yield, which is close to that for Ru/C. 1H, 13C-NMR, heteronuclear single quantum coherence (HSQC), and two-dimensional gas chromatography (GC × GC) of the product oils reveal that representative component classes of the sugar fraction of pyrolysis liquids like carbonyl compounds (aldehydes and ketones and carbohydrates) are converted to a large extent. The pyrolytic lignin fraction is less reactive, though some degree of hydrocracking is observed.

Formation of hydrocarbon compounds during the hydrocracking of non-edible vegetable oils with cobalt-nickel supported on hierarchical HZSM-5 catalyst

The hierarchical Co-Ni/HZSM-5 catalyst with hierarchical pore structure was prepared by desilication and incipient wetness impregnation. Hydrocracking of non-edible vegetable oils at temperature of 400 °C, 20±5 bar for 2 h was performed in the presence of this type of catalyst under hydrogen initial pressure in pressured batch reactor. Non-edible vegetable oils, such as Reutealis trisperma (Blanco) airy shaw (sunan candlenut) and Hevea brasiliensis (rubber seed) were chosen to study the effect of the degree of saturation and lateral chain length on hydrocarbon compounds obtained through hydrocracking. Cerbera manghas oil was also tested for comparison because the composition of fatty acid was different with the other oils The hydrocracking test indicated that liquid product produced has a similar hydrocarbon compounds with petroleum diesel. The most abundant hydrocarbon is pentadecane (n-C15) and heptadecane (n-C17). The high aromatic compounds were found in liquid product produced in hydrocracking of Sunan candlenut oil.

Catalytic hydroconversion of lignite-related model compounds over difunctional Ni-Mg2Si/γ-Al2O3

Catalysts Ni/γ-Al2O3, Mg2Si/γ-Al2O3, and Ni-Mg2Si/γ-Al2O3 were prepared. Their activities for catalytic hydroconversions (CHCs) of some lignite-related model compounds were examined. For the CHCs of oxydibenzene (ODB), benzyloxybenzene, and oxybis(methylene)dibenzene, the suitable loadings of Ni and Mg2Si are 33 and 20% in Ni-Mg2Si/γ-Al2O3, respectively, and the optimal reaction conditions are 4MPa of initial hydrogen pressure, 240°C, and 2h, under which ODB was almost completely converted to cyclohexane. The formation of possible intermediates during the CHC of ODB was discussed. Ni-Mg2Si/γ-Al2O3 was proposed to have 3 functions, i.e., activating H2 to biatomic active hydrogen (H⋯H), releasing H−, and heterolytically splitting H⋯H to release H− as well, resulting in the hydrogenation of aromatic rings and the hydrocracking of CO bonds, respectively.

Hydrogenation of polycyclic aromatic hydrocarbons over a solid superacid

Hydrogenation reactions of some polycyclic aromatic hydrocarbons (PAHs), including anthracene, 9-phenylanthracene (9-PA) and 9,10-diphenylanthracene (9,10-DPA), were carried out under moderate reaction conditions (with the initial hydrogen pressure of 5MPa at room temperature, reaction temperature was 300°C) over a solid superacid (SSA). The results showed that the reactivity of the PAHs decreased in the order of anthracene >9-PA>9,10-DPA. It was found that not only the hydrogenation and the reversible dehydrogenation through hydrogen atom transfer, but also disproportionation reaction by intermolecular hydrogen transfer took place in the process of PAHs reactions. The catalyst proved to be versatile for the hydrogenation of anthracene and 9-PA through biatomic hydrogen transfer (BAHT) and for the hydrocraking of 9,10-DPA by monatomic hydrogen transfer (MAHT). The SSA is able to catalyze the cleavage of the CarCar bridge bond in 9,10-DPA to produce 9-PA and benzene, in which the key step is the generation of the mobile H+ as well as the H+ transferring to the ipso-position of anthracene ring in 9,10-DPA. The SSA has the selectivity to catalyze the hydrogenation or hydrocracking of different PAHs.

Selective liquid-phase hydrogenation of fructose to d-mannitol over copper-supported metallic nanoparticles

The selective liquid-phase hydrogenation of d-fructose was studied on Cu-based catalyst, using an ethanol-water (70:30) mixture as solvent. The catalysts were prepared by three different methods: incipient wetness impregnation (Cu/SiO2-I and Cu/Al2O3-I), precipitation–deposition (Cu/SiO2-PD) and co-precipitation (CuMgAl and CuZnAl). After the thermal treatment, the samples were characterized by X-ray diffraction (XRD) and temperature-programmed reduction (TPR). Only a tenorite-like polycrystalline phase, formed by large CuO crystallites, was identified in Cu/SiO2-I, while none crystalline phase was observed in the case of Cu/SiO2-PD. Instead, a unique spinel-like phase was detected with Cu/Al2O3-I, CuMgAl and CuZnAl. Combining XRD and TPR results, we concluded that Cu2+ is highly dispersed in the Cu/SiO2-PD, Cu/Al2O3-I, CuMgAl and CuZnAl calcined precursors. As a consequence, after reduction in H2 flow, the metal dispersion and hydrogen chemisorption capacity of these four samples were one order higher than for Cu/SiO2-I. The catalytic tests showed that Cu/SiO2-PD was not only the most active but also the most selective and stable catalyst of these series: a D-fructose conversion of around 100% was reached after 6h reaction, with a selectivity to d-mannitol of around 78–80%. These results show that selective hydrogenation of fructose to d-mannitol is favoured over metal Cu nanoparticles dispersed on the surface of a neutral support as SiO2. Additional catalytic tests, varying fructose initial concentration (0.028–0.220M) and hydrogen pressure (20–40bar), were carried out with Cu/SiO2-PD. A zero reaction order respect to D-fructose and a second reaction order respect to H2 were estimated. In addition, it was found that d-mannitol selectivity is not dependent on reactant initial concentration and hydrogen pressure.

Mechanism of self-ignition of pressurized hydrogen flowing into the channel through rupturing diaphragm

The paper considers numerically the mechanism of hydrogen self-ignition occurring when hydrogen flows into the channel through gradually rupturing diaphragm. The analysis focuses on the near-critical self-ignition regimes arising at initial hydrogen pressure ∼60 atm that is marginal for self-ignition occurrence for selected channel geometry. Numerical simulation reproduces two types of ignition kernels observed experimentally. Both types of kernels arise on the contact surface between the released hydrogen and air heated behind the outrunning shock wave. In the initial stage the self-ignition kernels arise on the side contact surface interacting with channel walls and compression waves reflected from the walls. However, because of oxygen deficit these ignition kernels are extinguished. In the subsequent stage the self-ignition kernel arises in the region where the side contact surface penetrates into the boundary layer heated behind the shock wave. The further evolution of the ignition kernel is provided by the vortical structures evolving at the side contact surface and defining the mixing of hydrogen with air as well as the sustained supply of the mixture into the ignition kernel.