Characterization of products from fast and isothermal hydrothermal liquefaction of microalgae

We investigated nonisothermal (fast) and nominally isothermal hydrothermal liquefaction (HTL) of Nannochloropsis sp. microalgae for the production of biocrude. Biocrude yields ranged from 36 to 45 wt % (dry weight), with fast HTL with low mass loading giving the highest yield. This condition also gave the biocrude with the lowest heating value, which indicates there are compromises to be made between biocrude quantity and quality. The aqueous phase and biocrude product fractions were characterized using elemental analysis and Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR MS). This detailed level of analysis identified more than 30,000 unique molecular products. The aqueous phase products included compounds with the same molecular formulae as known herbicides, which may inform efforts in genetic engineering of algae and/or bacteria for cultivation on the aqueous phase. This detailed molecular‐level characterization provides some clues regarding the types of reactions that may take place during HTL. © 2016 American Institute of Chemical Engineers AIChE J, 62: 815–828, 2016     

反应条件对玉米秸秆水热液化产物分布及特性的影响

利用间歇式生物质水热液化反应釜,通过正交试验设计考察不同反应条件对玉米秸秆水热液化（HTL）的影响,过程参数包括反应温度（250~350℃）,反应时间（0~60 min）和含固量（5%~15%）。从元素组成、官能团分布、主要化学成分以及结构形貌等对玉米秸秆水热液化产物的特性进行了分析。研究结果表明：玉米秸秆水热液化的较优条件为反应温度300℃、反应时间30 min、含固量5%,此时生物原油（BO）、固体残渣（SR）、其他产物（气相和水相产物）的产率以及液化率分别为22.85%、15.02%、62.13%和84.98%。过程参数对玉米秸秆水热液化的产物分布有显著影响。不同反应条件下玉米秸秆组分降解程度不同,生物原油的产率8.31%~22.85%,热值30.56~32.69 MJ/kg,水相产物的总有机碳（TOC）7 711.5~12 336.0 mg/L,固体产物的组成和表面形貌也不同。FT-IR结果显示：生物原油的官能团分布相似,仅某些峰强度有所差异,表明不同水热条件制备的生物原油中化合物种类相似但含量存在差异。GC-MS分析结果显示：生物原油组成包括酚类、酮类、有机酸类、醛类、醇类、含氮化合物和呋喃类等化合物。     

Conversion of yeast by hydrothermal treatment under reducing conditions

In the work reported here, baker’s yeast (Saccharomyces cerevisiae) was used as feed for the production of liquid biofuels in a continuous one-step process under hydrothermal conditions in the presence of excess hydrogen and K₂CO₃. The yeast conversion experiments were performed in an up-flow reactor under near-critical water conditions (T 330–450 °C, p 20–32 MPa). The products consisted of three phases, an oil-like organic phase, a gaseous phase, and an aqueous phase. Higher concentrations of organic carbon in the process resulted in a higher product yield. The heating value of the organic phase was up to 38.6 MJ/kg. Liquefaction of yeast without any addition of K₂CO₃ also resulted in liquid oil, but the quality and the yield of the oil product were lower. A reaction temperature of 400 °C was found to be optimal for the oil yield and quality.     

Preparation of sorbitol from D‐glucose hydrogenation in gas–liquid–solid three‐phase flow airlift loop reactor

A new process for D ‐glucose hydrogenation in 50 wt% aqueous solution, into sorbitol in a 1.5 m³ gas–liquid–solid three‐phase flow airlift loop reactor (ALR) over Raney Nickel catalysts has been developed. Five main factors affecting the reaction time and molar yield to sorbitol, including reaction temperature (T_R), reaction pressure (P_R), pH, hydrogen gas flowrate (Q_g) and content of active hydrogen, were investigated and optimized. The average reaction time and molar yield were 70 min and 98.6% under the optimum operating conditions, respectively. The efficiencies of preparation of sorbitol between the gas–liquid–solid three‐phase flow ALR and stirred tank reactor (STR) under the same operating conditions were compared. Copyright © 2004 Society of Chemical Industry     

Hydrogen Production from Glycerol Over Nickel Catalysts Supported on Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Modified by Mg,Zr, Ce or La

Hydrogen production from glycerol reforming in liquid (aqueous phase reforming, APR) and vapor (steam reforming SR) phase over alumina-supported nickel catalysts modified with Ce, Mg, Zr and La was studied. Characterization of catalysts by temperature programmed reduction and XPS analyses revealed important structural effects: (i) the intercalation of Mg between nickel and alumina that inhibited the alumina incorporation to nickel phases, (ii) the close contact between Ni and Zr phases and, (iii) the close surface interaction of La and Ce ions with NiO phases. The catalytic activity of the samples studied in this work clearly indicated the different catalyst functionalities necessary to carry out aqueous-phase and vapor-phase steam reforming of glycerol. For aqueous phase reforming of glycerol, the addition of Ce, La and Zr to Ni/Al₂O₃ improves the initial glycerol conversions obtained over the Ni/Al₂O₃ supported catalyst. It is suggested that the differences in catalytic activities are related with geometric effects caused by the decoration of Ni phases by Ce and La or by the close interaction between Ni and Zr. In spite that nickel catalysts showed high APR activities at initial times on stream, all samples showed, independently of support, important deactivation rates that deactivate the catalysts after few hours under operation. Catalysts characterization after APR showed the oxidation of the active metallic Ni during reaction as the main cause of the observed deactivation. In the case of the glycerol steam reforming in vapor phase, the use of Ce, La, Mg and Zr as promoters of Ni based catalysts increases the hydrogen selectivity. Differences in activity were explained in terms of enhancement in: surface nickel concentration (Mg), capacity to activate steam (Zr) and stability of nickel phases under reaction conditions (Ce and La).     

Homogeneous liquid–liquid extraction using perfluorooctanesulfonic acid and calcium and its application to the separation and recovery of vitamin B12

A new phase separation phenomenon was observed in which the perfluorooctanesulfonate ion (PFOS⁻) and calcium ion form an ion‐pair associator and the sedimented liquid phase occurs from the homogeneous aqueous solution. This phenomenon was observed in the neutral pH region at room temperature (25 °C). The optimum concentration conditions for the reagents were [PFOS⁻]_T = 7 × 10⁻³ mol dm^‐3 and [Ca²⁺]_T = 1.1 mol dm^‐3. When these findings were applied to the homogeneous liquid–liquid extraction of vitamin B₁₂, the extraction percentage (E) was 83% and the concentration ratio (ie V_a/V_s, where V_a is the volume of the aqueous phase and V_s is the volume of the sedimented liquid phase) was a maximum of 149. The recovery of vitamin B₁₂ was achieved by adding the propanol–acetone (20 : 80 v/v%) mixed solvent to the sedimented liquid phase; the vitamin B₁₂ precipitated and was filtered. Both the PFOS⁻ and Ca²⁺ were removed by dissolution in the mixed solvent. The recovery percentage of vitamin B₁₂ was 78%. © 1999 Society of Chemical Industry     

COSMO-RS modeling on the extraction of stimulant drugs from urine sample by the double actions of supercritical carbon dioxide and ionic liquid

This work presents the first research linking chemical engineering and sport science as far as we know. The COSMO-RS (conductor-like screening model for real solvents) model was used to make a priori prediction for the extraction of stimulants from aqueous solution by the double action of supercritical carbon dioxide (SC CO₂) and ionic liquid. It was found that the suitable ionic liquids should have small molecular volume, unbranched group and no sterical shielding effect around anion charge center, and thus [C₂MIM]⁺[OAc]^- is the best among all the ionic liquids investigated. The calculated results from the COSMO-RS model were qualitatively consistent with those from experiments. On this basis, partition coefficients of amphetamine (C9N) and nikethamide (C10N) between aqueous phase and supercritical fluid (or MTBE) phase at different temperatures were calculated. It was shown that the separation efficiency of supercritical extraction with ionic liquid is generally higher than that of traditional liquid-liquid extraction. The modeling present can also be extended to the separation of trace amount of organic substances from aqueous solutions for other purposes.     

Highly Efficient and Selective Transport of Cu(II) with a Cooperative Carrier Composed of Tetraaza-14-Crown-4 and Oleic Acid through a Bulk Liquid Membrane

Tetraaza-14-crown-4 and oleic acid was successfully applied for transport of Cu(II) in chloroform bulk liquid membrane. The uphill moving of Cu(II) during the liquid membrane transport process has occurred. The main effective variable such as the type of the metal ion acceptor in the receiving phase and its concentration, tetraaza-14-crown-4 and oleic acid concentration in the organic phase on the efficiency of the ion-transport system were examined. By using L-cysteine as a metal ion acceptor in the receiving phase, the maximum amount of copper (II) transported across the liquid membrane was achieved to 96 ± 1.5% after 140 minutes. The selectivity of copper ion transport from the aqueous solutions containing Pb²⁺, Tl⁺, Ag⁺, Co²⁺, Ni²⁺, Mg²⁺, Zn²⁺, Hg²⁺, Cd²⁺ and Ca²⁺ ions were investigated. In the presence of CH₃COONH₄ and Na₄P₂O₇ as suitable masking agents in the source phase, the interfering effects of Pb⁺² and Cd²⁺ were diminished drastically.     

Liquid‐liquid phase split in ionic liquid + toluene mixtures induced by CO2

High pressure carbon dioxide was dissolved in ionic liquid + toluene mixtures to obtain the conditions of pressure and composition where a liquid‐liquid phase split occurs at constant temperature. Ionic liquids (ILs) with four different cations paired with the bis(trifluoromethylsulfonyl)imide ([Tf₂N]^?) anion were selected: 1‐hexyl‐3‐methylimidazolium ([hmim]⁺), 1‐hexyl‐3‐methylpyridinium ([hmpy]⁺), triethyloctylphosphonium ([P₂₂₂₈]⁺), and tetradecyltrihexylphosphonium ([P₆₆₆₁₄]⁺). The solubility of CO₂ was measured in the liquid mixtures at temperatures between 298 and 333 K and at pressures up to 8 MPa, or until the second liquid phase appeared, for initial liquid phase compositions of 0.30, 0.50, and 0.70 mole fraction of IL. Ternary isotherms were compared with the binary solubility of CO₂ in each IL and pure toluene. The lowest pressure for separating toluene in a second liquid phase was achieved by decreasing the temperature of the system, increasing the amount of toluene in the initial liquid mixture and using [hmim][Tf₂N]. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2968–2976, 2015     

Low-temperature catalytic decomposition of hydrogen sulfide on metal catalysts under layer of solvent

When hydrogen sulfide decomposition {2 H₂S ? 2 H₂?+?S₂^(gas)} is carried out in the flow regime at room temperature on metal catalysts placed in a liquid capable of dissolving H₂S and sulfur, the reaction equilibrium can be significantly (up to 100%) shifted to the right yielding the desired product – hydrogen. The process efficiency was demonstrated using aqueous solutions of monoethanolamine (MEA), sodium carbonate, which is widely used in industry for H₂S absorption from tail gases, and aqueous hydrazine as examples. IR and Raman spectroscopy data demonstrated that sulfur obtained in the solutions is in the form of diatomic molecules. DFT calculations showed that diatomic sulfur forms weakly bound coordinative complexes with solvent molecules. Some problems related to sulfur accumulation and recovery from the solvents are discussed.     

The influence of different zeolitic supports on hydrogen production and waste degradation

The photocatalyst composition affects the chemical–physical properties and directly impacts photocatalytic activity, both in the hydrogen production and degradation of organic contaminants. In this work, the influence of zeolitic structures NaA, NaY, and ZSM-5 combined with a 10% active phase, TiO₂ catalyst doped with 1% copper, and cobalt cocatalysts was tested to mineralize the reactive blue dye (CI250) and to produce hydrogen by photocatalysis under ultraviolet radiation. The band gap energy was affected mainly by the cocatalyst, while the Brunauer-Emmett-Teller method (BET) area was affected by the zeolite structure as well as the X-ray diffraction (XRD). The most active catalyst was the Cu@TiO₂/NaY, which promoted a hydrogen production rate of 240 μmolH₂gcat⁻¹ using 10% ethanol (v/v) aqueous solution as a sacrificial agent and mineralization of 53% of the organic dye, followed by the catalysts impregnated on ZSM-5 zeolites, which had discolouration up to 50% and hydrogen evolution of 92.6 and 109.7 μmolH₂gcat⁻¹ for the catalyst doped with Cu and Co, respectively.     

Hydrolysis of chlorpyrifos in aqueous and colloidal systems

Hydrolysis of chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] to TCP (3,5,6-trichloro-2-pyridinol) is an important degradation process influencing the fate of chlorpyrifos in aquatic environments. The effects of water chemistry and suspended colloids (smectites, humic acid, and river sediment) on the hydrolysis of chlorpyrifos were investigated in this study. Chlorpyrifos was incubated in various aqueous and colloidal systems at 23 ± 2 °C for up to 100 days, and aqueous phase concentrations of chlorpyrifos and TCP were determined using solid phase extraction-high performance liquid chromatography (SPE-HPLC). Chlorpyrifos degraded in the aqueous solutions with half-lives ranging from 27 to 158 days, depending on the initial concentration of chlorpyrifos and the chemistry of the aqueous solutions. The rate of degradation was slower in systems containing low concentrations of suspended colloids (1 g L⁻¹ in 0.01 M CaCl₂) than in the control (0.01 M CaCl₂, with no colloids), and negligible hydrolysis of chlorpyrifos was found for concentrated colloidal systems (20 g L⁻¹ in 0.01 M CaCl₂). Total recoveries of chlorpyrifos for the concentrated colloidal systems ranged from 78% to 97%, with a tendency to decrease with incubation time. The study indicates that the formation of chlorpyrifos-colloid complexes inhibits the hydrolysis of chlorpyrifos in aqueous systems and that chlorpyrifos-colloid complexes may act as a buffer by slowly releasing chlorpyrifos to the aqueous phase.     

Highly Efficient Cooperative Membrane Transport of Lead(II) Ions by Aza-18-crown-6 and Palmitic Acid

Abstract

A chloroform membrane system containing a given mixture of aza-18-crown-6 and palmitic acid was applied for the uphill transport of Pb²⁺ ions. In the presence of P₂O₇ ^4? ion as a suitable metal ion acceptor in the receiving phase, the amount of lead ion transported across the liquid membrane after 100 minutes is 89.1 ± 1.3%. The selectivity and efficiency of lead transport from aqueous solutions containing other cations such as Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, Fe²⁺, Pd²⁺, and Ag⁺ ions were investigated. In the presence of S₂O₃ ^2? ion as a proper masking agent in the source phase, the interfering effects of Cu²⁺ ion were diminished drastically.     

Aqueous-phase reforming of ethylene glycol over supported Pt and Pd bimetallic catalysts

More than 130 Pt and Pd bimetallic catalysts were screened for hydrogen production by aqueous-phase reforming (APR) of ethylene glycol solutions using a high-throughput reactor. Promising catalysts were characterized by CO chemisorption and tested further in a fixed bed reactor. Bimetallic PtNi, PtCo, PtFe and PdFe catalysts were significantly more active per gram of catalyst and had higher turnover frequencies for hydrogen production (TOF_H2) than monometallic Pt and Pd catalysts. The PtNi/Al₂O₃ and PtCo/Al₂O₃ catalysts, with Pt to Co or Ni atomic ratios ranging from 1:1 to 1:9, had TOF_H2 values (based on CO chemisorption uptake) equal to 2.8–5.2 min⁻¹ at 483 K for APR of ethylene glycol solutions, compared to 1.9 min⁻¹ for Pt/Al₂O₃ under similar reaction conditions. A Pt₁Fe₉/Al₂O₃ catalyst showed TOF_H2 values of 0.3–4.3 min⁻¹ at 453–483 K, about three times higher than Pt/Al₂O₃ under identical reaction conditions. A Pd₁Fe₉/Al₂O₃ catalyst had values of TOF_H2 equal to 1.4 and 4.3 min⁻¹ at temperatures of 453 and 483 K, respectively, and these values are 39–46 times higher than Pd/Al₂O₃ at the same reaction conditions. Catalysts consisting of Pd supported on high surface area Fe₂O₃ (Nanocat) showed the highest turnover frequencies for H₂ production among those catalysts tested, with values of TOF_H2 equal to 14.6, 39.1 and 60.1 min⁻¹ at temperatures of 453, 483 and 498 K, respectively. These results suggest that the activity of Pt-based catalysts for APR can be increased by alloying Pt with a metal (Ni or Co) that decreases the strengths with which CO and hydrogen interact with the surface (because these species inhibit the reaction), thereby increasing the fraction of catalytic sites available for reaction with ethylene glycol. The activity of Pd-based catalysts for APR can be increased by adding a water-gas shift promoter (e.g. Fe₂O₃).     

Separation of As(III) and As(V) by hollow fiber supported liquid membrane based on the mass transfer theory

Separation of As(III) and As(V) ions from sulphate media by hollow fiber supported liquid membrane has been examined. Cyanex 923 was diluted in toluene and used as an extractant. Water was used as a stripping solution. The extractability of As(V) was higher than As(III). When the concentration of sulphuric acid in feed solution and Cyanex 923 in liquid membrane increased, more arsenic ions were extracted into liquid membrane and recovered into the stripping solution. The mathematical model was focused on the extraction side of the liquid membrane system. The mass transfer coefficients of the aqueous phase (k _i ) and organic phase (k _m ) are 7.15×10⁻³ and 3.45×10⁻² cm/s for As(III), and 1.07×10⁻² and 1.79×10⁻² cm/s for As(V). Therefore, the rate-controlling step for As(III) and As(V) in liquid membrane process is the mass transfer in the aqueous film between the feed solution and liquid membrane. The calculated mass transfer coefficients agree with the experimental results.     

Nickel Nanoparticles Supported on Silica of Low Surface Area. Hydrogen Chemisorption and TPD and Catalytic Properties

Nickel metal nanoparticles supported on silica of low surface area (15 m² g^-1) were prepared by reduction of nickel acetate by hydrazine in aqueous medium. Their gas-phase stability and surface properties depended on thermal pre-treatment under H₂ or air atmosphere. Small nickel particles (<10 nm), in oxidized or reduced state, are strongly resistant to reductive or oxidative treatment respectively. For H₂-treated catalysts, H₂ chemisorption and TPD results suggested the occurrence of spillover hydrogen between the metal nickel phase and silica. For air then H₂ treated catalysts, hydrogen spillover seemed to involve the NiO phase. The activity of the catalysts in gas-phase benzene hydrogenation also depended on the thermal pre-treatment. Pre-calcined then reduced catalysts exhibited higher TOFs than non pre-calcined catalysts, suggesting that the presence of NiO phase may have influenced the hydrogenation process.     

Selective hydrogenation of furfural to cyclopentanone over Cu-Ni-Al hydrotalcite-based catalysts

A series of Cu-Ni-Al hydrotalcites derived oxides with a (Cu+Ni)/Al mole ratio of 3 with varied Cu/Ni mole ratio (from 0.017 to 0.5, with a Cu ratio of 0.0125 to 0.25) were prepared by co-precipitation method, then applied to the hydrogenation of furfural in aqueous. Their catalytic performance for liquid phase hydrogenation of furfural to prepare cyclopentanone was described in detail, considering reaction temperature, catalyst composition, reaction time and so on. The yield of cyclopentanone was influenced by the mole ratio of Cu-Ni-Al based heterogeneous catalyst and depended on the reaction conditions. The yield of cyclopentanone was up to 95.8% when the reaction was carried out under 413 K with H₂ pressure of 40 bar for 8 h. The catalysts were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and H₂ temperature-programmed reduction (H₂-TPR).     

A selective uphill transport of copper through bulk liquid membrane using Janus Green as an anion carrier

A bulk liquid membrane consisted of 1.8×10⁻⁴ M Janus Green in chloroform that placed between an aqueous source phase containing 0.5 M sodium thiocyanate at pH 7 and an aqueous receiving phase with 0.1 5 M histidine at pH 7 results in an uphill transport of copper from the source phase to the receiving phase. The amount of copper transport through the liquid membrane after 180 min was 97.0±1.7%. The presence of other metals such as Cd²⁺, Zn²⁺, Hg²⁺, Mg²⁺, Ag¹⁺, Ni²⁺, Pb²⁺, Fe³⁺, K¹⁺, Co²⁺ doesn't change the efficiency of copper transport.     

以Ce3+/Ce4+为媒质间接电合成1,4-萘醌

探讨了以Ce³⁺/Ce⁴⁺为媒质的1,4-萘醌间接电化学合成反应。考察了液相氧化、Ce³⁺电解氧化过程的影响因素,并进行了萘醌的间接电合成实验。结果发现,硫酸浓度、溶液温度对铈离子的氧化能力和电化学反应活性具有重要的影响;当温度为70℃、硫酸浓度为1.0 mol·L^-1时,液相氧化反应的收率最高(85.8%)。Ce³⁺电解氧化的最优条件为:电流密度50 mA·cm^-2、硫酸浓度1.0 mol·L^-1、温度为50℃,其电流效率可达90.6%;间接电合成实验过程中萘醌的平均收率达85.7%,Ce³⁺电解氧化的平均电流效率达87.8%,并且电解过程具有良好的稳定性,表明该技术具有良好的产业化应用前景。     

Electrochemical bromination and oxidation of alkyl aromatic compounds by two-phase electrolysis

A simple, regioselective, environmentally clean and economical method for the preparation of side chain/ ring brominated aromatic compounds is reported in 70–98% yield by an electrochemical method using two phase electrolysis technique. Electrochemical reactions were carried out using aqueous 25–50 wt% sodium bromide containing catalytic amount (5 wt%) of hydrobromic acid as an aqueous phase and chloroform containing alkyl aromatic compounds as an organic phase, at a temperature of 0–30 °C in an undivided cell. The same two-phase electrolytic system can be used for the oxidation of benzylic alcohols to the corresponding benzaldehydes in 80–94% yield without over oxidation to carboxylic acids. The advantage of this very mild procedure is a room temperature reaction used with an undivided cell. Excellent conversions are observed. After completion of alcohol oxidation the electrolyte can be reused for a number of times, demonstrating “spent reagent” free electro organic reaction as an attractive one. In the case of side chain/ring bromination of alkyl aromatic compounds, the electrolyte can be reused after making up the concentration of the electrolyte with 47 wt% HBr solution. In some cases homogeneous electrolysis is applied, where the two-phase electrolysis did not work. Styrene epoxidation and α-bromination of ketones underwent homogeneous electrolysis at room temperature without any catalyst. The reaction was performed in CH₃CN-water (3: 2) using equimolar amount of NaBr as an electrolyte to get 68% of styrene epoxide. Use of an ionic liquid 1-butyl 3-methyl imidazolium bromide (Bmim) Br, instead of NaBr improved the yield and current efficiency of styrene epoxide to 86%.