MPa N2 Research Articles

Glucose Isomerizes to Fructose Catalyzed by the Eco‐Friendly and Biodegradable Ionic Liquids

AbstractIn this study, a new and cost‐effective strategy is proposed for the selective isomerization of glucose to fructose in the aqueous solutions involving eco‐friendly and biodegradable ionic liquids, which consist of a choline cation and natural amino acid anions. The results show that these ionic liquid aqueous solutions demonstrate impressive performances on the glucose isomerization. At the reaction conditions of 70 °C for 30 min and 1.0 MPa N2, a 37.6% fructose yield is obtained with a 77.2% selectivity in the presence of choline proline. It is noteworthy that both of these fructose yield and selectivity are higher than those of many current base‐catalyzed techniques. This high performance should be ascribed to the intensive enhancement of choline cation on the catalytic active centre of proline anion which consequentially facilitates the isomerization of glucose. Furthermore, this robust catalyst of [Ch]Pro is recyclable, where a satisfied catalytic activity is shown even after five consecutive runs, indicating its great potential in both biomass valorization and food industry.

Experimental study on catalytic pyrolysis of biomass over a Ni/Ca-promoted Fe catalyst

Herein, we evaluated the potential of a Ni/Ca-promoted Fe catalyst for sustainable hydrogen production by tar abatement at 600–750 °C and 0.1 MPa N2. The catalyst was prepared through impregnation into the biomass (wheat straw) structure, and nickel incorporation led to the formation of a nickel iron alloy. We found that the yields of light aromatic hydrocarbons and hydrogen gas could be significantly improved at a given Fe/Ca/Ni ratio, and maximum hydrogen yields of 72.57 mL/g and 91.19 mL/g can be achieved by using a catalyst composed of 5% Fe + 1.5% Ca + 0.8% Ni at 600 °C and 750 °C, respectively. Analysis of the biomass char revealed details regarding the catalytic pyrolysis process. In particular, the dispersion of iron was promoted by calcium and nickel that caused the action between iron and nickel to be strengthened, which were confirmed through the formation of Fe-Ni alloy. Our results suggested that the interactions of the Fe/Ca/Ni catalyst depend on not only the presence of Ca2Fe2O5 but also the stability of the reaction between nickel and iron under the specified reaction conditions. Ultimately, the Fe/Ca/Ni catalyst was found to contain an active phase (Fe-Ni alloy) that played an important role in tar removal during the wheat straw catalytic pyrolysis process.

Performance of a Ni-Cu-Co/Al2O3 Catalyst on in-situ Hydrodeoxygenation of Bio-derived Phenol

The in-situ hydrodeoxygenation of bio-derived phenol is an attractive routine for upgrading bio-oils. Herein, an active trimetallic Ni-Cu-Co/Al2O3 catalyst was prepared and applied in the in-situ hydrodeoxygenation of bio-derived phenol. Comparison with the monometallic Ni/Al2O3 catalyst and the bimetallic Ni-Co/Al2O3 and Ni-Cu/Al2O3 catalysts, the Ni-Cu-Co/Al2O3 catalyst exhibited the highest catalytic activity because of the formation of Ni-Cu-Co alloy on the catalyst characterized by using X-ray powder diffraction (XRD), temperature programmed reduction (TPR), N2 physisorption, scanning electron microscope (SEM), and transmission electron microscope (TEM). The phenol conversion of 100% and the cyclohexane yield of 98.3% could be achieved in the in-situ hydrodeoxygenation of phenol at 240 °C and 4 MPa N2 for 6 h. The synergistic effects of Ni with Cu and Co of the trimetallic Ni-Cu-Co/Al2O3 catalyst played a significant role in the in-situ hydrodeoxygenation process of phenol, which not only had a positive effect on the production of hydrogen but also owned an excellent hydrogenolysis activity to accelerate the conversion of cyclohexanol to cyclohexane. Furthermore, the catalyst also exhibited excellent recyclability and good potential for the upgrading of bio-oils.

Clean and effective catalytic hydrolysis of bagasse waste to small-molecular compounds over a hydrothermally stable Ru/La(OH)3

Ruthenium/lanthanum hydroxide (Ru/La(OH)3), a hydrothermally stable catalyst, was prepared and used for catalyzing hydrolysis of bagasse, a sugar industry waste, to small-molecular compounds under low initial H2 pressure (IHP 0.2 MPa, 5% H2 in 4 MPa H2 and N2 mixture) at 240 °C. Neither oligomers nor char was formed and bagasse was almost completely converted into soluble portion (SPCH, 59.1 wt%) and gaseous products by the catalytic hydrolysis (CH). Obviously different from the methanol-soluble portion and ethanol-soluble portion from the bagasse methanolysis and ethanolysis, in total 104 organic compounds were detected in SPCH, among which alkyl-substituted phenols & benzenepolyols (38.8%), alkoxy-substituted phenols (22.2%), ketones (15.1%), and carboxylic acids (12.2%) are dominant according to the analysis with a gas chromatograph/mass spectrometer (GC/MS). Based on the analysis with a quadrupole exactive orbitrap mass spectrometer, heteroatom-containing compounds, especially oxygenates, are predominant in the SPs, while more species including smaller molecular fragments, can be identified in SPCH, which is consistent with the analysis with GC/MS. In addition, the catalytic hydroconversion of phenethoxybenzene over Ru/La(OH)3 further confirms that appropriately raising the temperature and reducing the IHP facilitate the formation and transfer of active H∙. In one-pot, clean and effective conversion of bagasse with low H2 consumption and in a green solvent can be achieved through this strategy.

Effect of Cl− Concentration on the SCC Behavior of 13Cr Stainless Steel in High-Pressure CO2 Environment

An effect of Cl− concentration on the stress corrosion cracking (SCC) behavior of 13Cr stainless steel was investigated by employing electrochemical measurements and the slow strain rate tensile tests. These tests were conducted in various solutions with different concentrations of NaCl at 90 °C under 3 MPa CO2 with 3 MPa N2. The results indicate that the passive film of the specimen formed in the 10% NaCl solution has the best protective effect on the matrix. The SCC susceptibility does not increase with increasing the chloride ion concentration, the lowest SCC susceptibility occurs when the NaCl concentration is 10%, and the specimens show higher SCC susceptibility in the 5% NaCl and 20% NaCl solutions.

Effects of Process Parameters on Hydrothermal Liquefaction of Microalgae Biomass Grown in Municipal Wastewater

The emerging fuel crisis necessitates a shift in focus towards alternative renewable forms, so that sustainable development can be achieved. Bio-oil is a promising alternative renewable source of energy which is a third generation bio-fuel. Algae are a popular candidate for bio-fuel production due to their high lipid contents, ease of cultivation and rapid growth rate. In this study, Hydrothermal liquefaction of Scenedesmus obliques biomass cultivated in photo-bio-reactor (PBR) from wastewater was studied. The influence of process parameters on the bio-oil yield and bio-oil upgrading was analysed. Different S. obliques biomass to water ratios (0.025, 0.05, 0.075 and 0.1 g/ml) were liquefied at diverse temperatures ranging from 200 to 340°C under 5 MPa N2 gas atmosphere. The influence of catalyst on bio-oil upgradation was studied at varying catalyst loading of the range 1–5 wt %. Bio-oil was analysed using Gas Chromatography Mass Spectroscopy (GC-MS) and Fourier Transform Infrared Spectroscopy (FTIR). Results showed a maximum bio-oil yield of 24.57 wt % at 300°C, 15 g/200 ml biomass load and 2.5 wt % NaOH at 60 min holding time. Also, it was found that the gas generated from liquefaction process contained 22 vol % Hydrogen gas, 18 vol % Carbon dioxide gas, 27 vol % Carbon monoxide gas, 22 vol % of methane gas and a small amount of other gaseous components (H2S). HTL bio-oil was upgraded and it resulted in 30.15 wt % yield with higher degree of C7−C21 range hydrocarbons in it.

CO2 enhanced flow characteristics of naturally-fractured bituminous coals with N2 injection at different reservoir depths

Coal matrix swelling caused by the adsorption of CO2 during the CO2-ECBM process is the major reason for the decline of coal permeability and CO2 injectivity. Measures to recover this permeability reduction are of significant importance for the field projects. Many studies to date have established the responses of the coal matrix upon the adsorption of CO2 under various laboratory conditions, and some have revealed that the injection of N2 into swelled coal can recover coal permeability to some extent. This study therefore examines the effect of various N2 saturation durations on the permeability alteration of the swelled coals subjected to the adsorption of sub- and super-critical CO2 at different reservoir depths. A series of permeability tests was performed on a tri-axial test rig, and the results show that high adsorption of super-critical CO2 in coal produces greater permeability reduction; the average CO2 permeability recovery rates are 25.08% and 37.31% for 6 MPa and 14 MPa N2 saturation, respectively, as the higher N2 permeating pressure favours greater permeability recovery; longer N2 saturation duration also produces higher permeability recovery, but the permeability recovery process eases with the saturation duration; coal permeability is very susceptible to the poro-elastic effect in high confining environments and the effect of matrix responses on the interaction with gas sorption is therefore negligible.

Preparation, mechanical and thermal properties of Si3N4 ceramics by gelcasting using low–toxic DMAA gelling system and gas pressure sintering

In this work, Si3N4 ceramics were fabricated through an aqueous gelcasting method using a low–toxic monomer called N, N–dimethylacrylamide (DMAA) followed by gas pressure sintering at 1850 °C for 2 h under 6 MPa N2 atmosphere. The effect of solid loading on performance of slurries, green and sintered bodies was investigated systematically. The results show that the slurries with a solid loading as high as 50 vol% (viscosity 0.17 Pa.s at 100 s–1) were achieved. With the increase of solid loading (30–50 vol%), the green bodies exhibited a monotonically decreased, however high enough in general, flexural strength of 16.50–11.52 MPa, which was comparable to that of widely–used neurovirulent acrylamide (AM) gelling system. In regard to the sintered bodies, increasing solid loading significantly promoted sintering and improved mechanical properties and thermal conductivity as a result of the increased density, bimodal distribution structure, as well as suitable interfacial bonding strength. The best performance parameters of Si3N4 ceramics, bulk density of 3.25 g/cm3, apparent porosity of 0.67%, flexural strength of 898.92 MPa, fracture toughness of 6.42 MPa m1/2, Vickers hardness of 2.81 GPa, and thermal conductivity of 34.69 W m–1 K–1, were obtained at 50 vol% solid loading. This work renders low–toxic DMAA gelling system promising prospect in preparation of high–performance Si3N4 ceramics by gelcasting.

Production of furfural with high yields from corncob under extremely low water/solid ratios

Furfural is considered to be one of the top 30 potential chemicals derived from lignocellulosic biomass. Compared to conventional diluted acid catalysis, furfural production from lignocellulose was significantly improved by the addition of an immiscible organic solvent into the diluted acid solution. However, high conversion is usually achieved under a high water/solid ratio (>1, v/m), and the furfural product is distributed in both the organic solvent phase and the aqueous phase, leading to difficulty of furfural recovery and increasing the cost of furfural production. The present work investigated corncob conversion in a diluted sulfuric acid-toluene biphasic system with extremely low water/solid ratios (≤1). It was found that a high furfural yield (65.67 mol%) was achieved in a very short time (10 min) under a high solid loading of 200% (in the aqueous phase) under the conditions of 1.5 MPa N2, 0.5:1 water/solid ratio (v/w), 10:1 toluene/solid ratio (v/m), and 3.85 wt% H2SO4 (in the aqueous phase). After the reaction, no aqueous phase existed, and furfural was completely accumulated in the toluene phase. Further research showed that the majority of the furfural content (84.73%, GC-MS detection) was in the toluene phase, which is beneficial for its recovery. This work provides an effective and inexpensive method for the production of furfural from lignocellulose.

Promoting asphaltene conversion by tetralin for hydrocracking of petroleum pitch

The effects of tetralin as an H-donor on the reactivity of asphaltenes in a petroleum pitch were investigated under thermal cracking or catalytic hydrocracking conditions at 693 K and 10.0 MPa N2 or H2. Reaction temperatures, pressures, and tetralin contents were varied to examine the reactivity of asphaltenes. Thermal cracking of the petroleum pitch led to a considerable amount of coke formation, close to 53.7 wt%, but the addition of tetralin reduced the coke formation down to 23.6 wt%. The coke formation was considerably reduced to 10.3 wt% in the catalytic hydrocracking condition, and was not formed in the presence of tetralin. Kinetic studies on the catalytic hydrocracking of petroleum pitch in the absence or presence of tetralin demonstrated that the addition of tetralin, showing an increase in the hydrogen transfer capacity, contribute to the marked performance of hydrocracking of the petroleum pitch in the presence of dispersed MoS2 catalyst.

Highly efficient conversion of glucose into methyl levulinate catalyzed by tin-exchanged montmorillonite

Abstract Tin-exchanged montmorillonite catalysts were prepared by an ion exchange method and examined as solid acid catalysts. The synthesized catalysts were characterized by X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy, N2 adsorption–desorption analysis, powder X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption analysis, and pyridine adsorption Fourier transform infrared spectroscopy. Subsequently, the catalysts were examined for use in the conversion of glucose into methyl levulinate in methanol. A high yield of methyl levulinate of 59.7% was obtained upon conversion of 0.3 g glucose in 24 g methanol over 0.15 g catalyst at 220 °C under 2 MPa N2 for 6 h. The recyclability of the catalyst was also examined, and the conversions of glucose and methanol remained mostly unchanged under repeated usage of the catalyst in five catalytic runs; in contrast, the yield of methyl levulinate decreased slightly. The excellent catalytic performance of the tin-exchanged montmorillonite catalyst was attributed to a combination of the presence of a large amount of acidic sites and balanced amounts of Lewis and Bronsted acid sites on the catalyst.

Thermal stability and reliability studies of (Sr, Ca) AlSiN3:Eu2+ phosphors for LED application

In this paper, the thermal stability and reliability properties of (Sr, Ca) AlSiN3:0.05Eu2+ phosphors prepared by solid-state reaction in 1.1 MPa N2 atmosphere were studied. The internal quantum efficiency of (Sr, Ca) AlSiN3:0.05Eu2+ could reach as high as about 92% after Sr ions replacing Ca upon excitation in blue light range (450–470 nm). As the temperature increased from 300 to 500 K, PL intensity of SrxCa1−xAlSiN3:0.05Eu2+ phosphor decreases by 66.24, 27.87 and 16.66% of the initial PL intensity for x = 0.2, 0.5 and 0.8, respectively. The relative PL intensity of SrxCa1−xAlSiN3:0.05Eu2+ phosphor decrease to 98.67% from 96.87% as x increased to 0.8 from 0.2 after storing into an ambient condition of 120 °C for 1 h and −40 °C for 1 h by turns for five times. Reliability test results show that, with x value is from 0.2 to 0.8, the relative PL intensity of SrxCa1−xAlSiN3:0.05Eu2+ phosphor is from 95.87 to 86.51% after the ambient condition of 85 °C/RH 85% for the exposure time of 168 h, from 99.86 to 92.45% after soaking the phosphors into boiled water for 3 h. It can be summarized that the addition of Sr increased the thermal stability largely and deteriorates the reliability of the phosphors slightly. And the reactivity of phosphor with water is the main reason for reducing the reliability of the phosphors.

One-Pot Production of Lactic Acid from Acetol over Dealuminated Sn-Beta Supported Gold Catalyst

Staged biomass pyrolysis or condensation of the pyrolysis vapor generates less complex and concentrated liquid product streams, which provide a very promising route to produce value-added chemicals. Acetol is one of the major light oxygenates in fractionated bio-oil. Here we report an efficient one-pot conversion of acetol to lactic acid, a key platform chemical and an important monomer of biodegradable polymer, in aqueous phase over a bifunctional dealuminated Sn-Beta supported gold catalyst. Under relatively mild conditions (393 K, 1.9 MPa N2 + 0.1 MPa O2), 93.4% acetol conversion and 73.2% selectivity toward lactic acid were achieved. On the basis of measured rate constants, the reaction pathway likely proceeds via kinetically relevant oxidation of acetol to form pyruvaldehyde, followed by hydration and 1,2-hydride shift (internal Meerwein–Ponndorf–Verley reduction and Oppenauer oxidation) on Sn-Lewis sites to produce lactic acid.

Highly stable and selective Ru/NiFe2O4 catalysts for transfer hydrogenation of biomass-derived furfural to 2-methylfuran

Spinel ferrites NiFe2O4 supported Ru catalysts have been prepared via a simple sol–gel route and applied for converting biomass-derived furfural to 2-methylfuran. The as-prepared catalysts were characterized by thermogravimetric analysis (TG), N2 adsorption–desorption, X-ray diffraction (XRD), scanning electronic microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that the catalysts had well-dispersed Ru active sites and large surface area for calcination temperature ranging from 300 to 500°C. The conversion of biomass-derived furfural into 2-methylfuran was conducted over Ru/NiFe2O4 through catalytic transfer hydrogenation in liquid-phase with 2-propanol as the hydrogen source. A significantly enhanced activity and increased 2-methylfuran yield have been achieved in this study. Under mild conditions (180°C and 2.1MPa N2), the conversion of furfural exceeds 97% and 2-methylfuran yield was up to 83% over the catalyst containing 8wt% Ru. After five repeated uses, the catalytic activity and the corresponding product yield remained almost unchanged. The excellent catalytic activity and recycling performance provide a broad prospects for various practical applications.

Hydrodeoxygenation of glycerol with in situH2 formation over Pt catalysts supported on Fe modified Al2O3: effect of Fe loading

AbstractBACKGROUNDGlycerol hydrodeoxygenation to 1,2‐propanediol is a reaction of commercial and environmental significance. However, the need for hydrogen supply is a main drawback of the process. This study aims at the development of effective catalysts for glycerol hydrodeoxygenation with in situ H2 formed. Pt/Al2O3 and Pt/Fe2O3‐Al2O3 catalysts with different Fe/Pt ratios were synthesized and evaluated. N2 physisorption, XRD, TPR‐H2, TGA and DRIFTS‐CO characterization techniques were used. Main focus was given on catalyst reusability, while a parametric study was also performed.RESULTSFe addition promotes catalysts activity. Characterization showed that there is an electron interaction between Pt and Fe which is responsible for this enhancement. However, Fe/Pt ratio and reduction temperature affect catalyst performance. The increase of Fe loading leads to lower H2 formation rates but also to more stable catalyst performance. The most promising results were achieved over the Fe richer catalyst which exhibited 51.5% 1,2‐propanediol selectivity, 93.8% glycerol conversion, under 3.5 MPa N2, at 250 °C, 1 h and pre‐reduction at 200 °C.CONCLUSIONThe presence of Fe in Pt/Al2O3 catalysts was proved decisive for the combined cycle of glycerol hydrodeoxygenation–aqueous phase reforming. The high activity and the stable performance in aqueous medium may render these materials as suitable catalysts for various liquid phase hydrodeoxygenation reactions. © 2017 Society of Chemical Industry

Effects of pore diameters on phase, oxidation resistance, and thermal shock resistance of the porous Si2N2O ceramics

AbstractPorous silicon oxynitride (Si2N2O) ceramics were prepared by gas pressure sintering at 1650°C for 2 hour under 1.5 MPa N2 in two different powder beds, that is, h‐BN/Si3N4 or h‐BN/(Si3N4 + SiO2). Effects of the gaseous atmosphere in the powder bed and the pore diameter in the ceramics on formation of the Si2N2O phase and the oxidation resistance of the sintered porous ceramics were investigated. Results showed that presence of the gaseous SiO in the powder bed played a crucial role in suppressing decomposition of the Si2N2O phase at the outer surface of the material. Permeability of the gaseous substances was decreased when the pore diameter was small, to affect the phase composition and the oxidation behavior of the porous Si2N2O ceramics. The oxidation weight gain curves of the porous Si2N2O ceramics fitted the asymptotic law. No significant changes in the dielectric constant of the Si2N2O ceramics were observed after oxidation at 1000°C‐1200°C for up to 30 minutes, whereas the dielectric loss tangent was reduced by oxidation due to formation of SiO2. The as‐obtained porous Si2N2O ceramics could withstand a highest thermal shock of 1200°C when the outer surface could be sealed by the oxidation‐derived SiO2 layer.

Beneficial roles of H-donors as diluent and H-shuttle for asphaltenes in catalytic upgrading of vacuum residue

The effects of various organic solvents having different H-donor index, asphaltene solubility, and alkyl-substitution on the upgrading of vacuum residue (VR) were investigated under thermal cracking or catalytic hydrocracking conditions at 673K and 10.0MPa N2 or H2. Molecular dynamics simulations were also adopted to verify physical interaction between asphaltene species with H-donor solvents. Thermal cracking led to a considerable amount of coke formation, close to 29.8wt.%, but the addition of H-donors reduced the coke formation down to 23.4, 19.0, 12.4, and 4.1wt.% in the presence of naphthalene, 1-methyl naphthalene(1-MN), decalin, and tetralin, respectively. The coke formation was considerably reduced to 7.2wt.% in the hydrocracking condition, and further down to 2.9 and 1.2wt.% in the presence of naphthalene and tetralin, respectively. It was demonstrated that H-donors retaining the H transfer capability coupled with the solubility of asphaltene contributed to the marked performance of VR hydrocracking in the presence of dispersed MoS2 catalyst.

ChemInform Abstract: Green Light‐Excitable Ce‐Doped Nitridomagnesoaluminate Sr[Mg2Al2N4] Phosphor for White Light‐Emitting Diodes.

AbstractPolycrystalline samples of Sr1‐x[Mg2Al2N4]:xCe3+ (x = 0.005—0.08) are prepared by gas pressure sintering of Sr3N2, AlN, Mg3N2, and CeN (Mo crucible, 0.9 MPa N2, 1450 °C, 4 h).

ChemInform Abstract: Synthesis of Ultra‐Incompressible sp3‐Hybridized Carbon Nitride with 1:1 Stoichiometry.

AbstractSuperhard CN is produced from pre‐compressed single crystal natural graphite powder positioned on top of a thin Ir or Pt spacer loaded in a diamond anvil cell with an initial 200 MPa N2 pressure.

A new microcellular foam injection‐molding technology using non‐supercritical fluid physical blowing agents

A new foam injection‐molding technology was developed to produce microcellular foams without using supercritical fluid (SCF) pump units. In this technology, physical blowing agents (PBA), such as nitrogen (N2) and carbon dioxide (CO2), do not need to be brought to their SCF state. PBAs are delivered directly from their gas cylinders into the molten polymer through an injector valve, which can be controlled by a specially designed screw configuration and operation sequence. The excess PBA is discharged from the molten polymer through a venting vessel. Alternatively, additional PBA is introduced through the venting vessel when the polymer is not saturated with PBA. The amount of gas delivered into the molten polymer is controlled by the gas dosing time of the injector valve, the secondary reducing pressure of the gas cylinder and the outlet (back) pressure of the venting vessel. Microcellular polypropylene foams were prepared using the developed foam injection‐molding technology with 2–6 MPa CO2 or 2–8 MPa N2. High expansion foams with an average cell size of less than 25 μm were prepared. The developed technology dispels arguments for the necessity to pressurize N2 or CO2 to the SCF to prepare microcellular foams. POLYM. ENG. SCI., 57:105–113, 2017. © 2016 Society of Plastics Engineers