Catalytic transesterification of crude rapeseed oil by liquid organic amine and co-catalyst in supercritical methanol

Liquid organic amines, Ethylenediamine (EDA), Diethylamine (DEA) or Triethylamine (TEA), could speed up the production of methyl ester from crude rapeseed oil in supercritical methanol. The order of the catalytic activity was EDA > DEA > TEA. Acyl amine appeared in the products when EDA or DEA was used as the catalyst; however, this phenomenon didn’t occur when TEA was used. With Propylene oxide as the co-catalyst, the catalytic activity of TEA was greatly improved. In 10 min, the yield of methyl ester could reach 89.5%, which was seven times faster than that without the co-catalyst. Optimum molar ratio of methanol to crude rapeseed oil should not be lower than 24:1.     

Selective Removal of Carbon Dioxide from Wet CO2/H2 Mixtures via Facilitated Transport Membranes containing Amine Blends as Carriers

The selective separation of carbon dioxide (CO₂) from a wet gaseous mixture of CO₂/H₂ through facilitated transport membranes containing immobilized aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), ethylenediamine (EDA) and monoprotonated ethylenediamine (EDAH⁺) and their blends was experimentally investigated. The effect of CO₂ partial pressure, amine concentration, feed side pressure and amine species on the CO₂ and H₂ permeances were studied. The CO₂ permeability through amine solution membranes decreased with increasing CO₂ feed partial pressure but the H₂ permeance was almost independent of the H₂ partial pressure. A comparison of experimental results showed that single or blended amines with low viscosity and a moderate equilibrium constant, i.e., large forward and reverse reaction rate of CO₂‐amine, are suitable for effective separation of CO₂. The permeability of CO₂ generally increased with an increase in amine concentration, although this increase may be compromised by the salting out effect and decrease in diffusivities of species. The results obtained indicated that CO₂ permeance across a variety of amines are in the order of DEA (2 M) > MD (2 M) > MD (1 M) > MEA (2 M) > MEA (4 M) > MD (4 M) > DEA (1 M) > DEA (4 M) > MEA (1 M) for various concentrations of MEA + DEA blend and are in the order of EDAH⁺ (2 M) > DEA (2 M) > MH (2 M) > DH (2 M) > ED (2 M) > EDA (2 M) > MEA (2 M) for various blends of amine.     

A study on the reaction between CO2 and alkanolamines in aqueous solutions

Literature data on the rates of reaction between CO₂ and alkanolamines (MEA, DEA, DIPA, TEA and MDEA) in aqueous solution are discussed. These data induced us to carry out absorption experiments of CO₂ into aqueous DEA, DIPA, TEA and MDEA solutions from which the respective rate constantsThe results for DEA and DIPA were analysed by means of a zwitterion-mechanism which was derived from the mechanism originally proposed by Danckwerts [1The reaction rate of CO₂ with aqueous TEA and MDEA solutions shows a significant base catalysis effect which is also reported by Donaldson and Nguy     

A study on the reaction between CO2 and alkanolamines in aqueous solutions

Literature data on the rates of reaction between CO₂ and alkanolamines (MEA, DEA, DIPA, TEA and MDEA) in aqueous solution are discussed. These data induced us to carry out absorption experiments of CO₂ into aqueous DEA, DIPA, TEA and MDEA solutions from which the respective rate constants were derived. The experimental technique was similar to that used by Laddha and Danckwerts[30].The results for DEA and DIPA were analysed by means of a zwitterion-mechanism which was derived from the mechanism originally proposed by Danckwerts[16The reaction rate of CO₂ with aqueous TEA and MDEA solutions shows a significant base catalysis effect which is also reported by Donaldson and Nguy     

Ethanolamines used for degumming of rapeseed and sunflower oils as diesel fuels

Pure vegetable oils can be used as alternative fuel for standard unmodified diesel engines, provided the oil viscosity has been lowered by heating before they enter the fuel injection system. In its role as diesel fuel, a vegetable oil has to have, among other parameters, a low acidity and low contents of phosphorus and the alkali earth metals Ca + Mg. Such parameters can be achieved by appropriate partial refining of oil by degumming. In this article, three common ethanolamines, monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA), were used as degumming agents for removing non‐hydratable phospholipids from crude rapeseed and sunflower oils. Among the studied ethanolamines, MEA is the most effective for the removal of phosphorus. After degumming with MEA (0.5 wt‐%), the phosphorus content in rapeseed oil was reduced from 445 to 3.5 ppm, and from 163 to 2.2 ppm in sunflower oil. After oil treatment with MEA (1.0 wt‐%), the residual content of Ca and Mg decreased from 136 to 4.2 ppm and from 55.4 to 1.1 ppm in rapeseed oil. In sunflower oil, the values of Ca and Mg decreased from 23.9 to 1.5 ppm and from 24.6 to 1.0 ppm. The acid value of the oils also decreased after degumming with ethanolamines. The advantage of this oil treatment process is that it takes place at ambient temperature, resulting in lower production costs and simpler technology.     

Application of a Homogeneous Dodecakis(NCN‐PdII) Catalyst in a Nanofiltration Membrane Reactor under Continuous Reaction Conditions

A shape‐persistent nanosize dodecakis(NCN‐Pd^II‐aqua) complex ( 4b ) was applied as a homogeneous catalyst in the double Michael reaction between methyl vinyl ketone and ethyl α‐cyanoacetate under continuous reaction conditions in a nanofiltration membrane reactor. Due to its macromolecular dimensions, the catalyst is retained in the reactor (R=99.5% determined by ICP‐AAS) during catalysis. In addition, the catalyst was found to be stable under the continuous reaction conditions as a constant activity was obtained at prolonged reaction times (26 h, 65 exchanged reactor volumes). The turnover number of the catalyst was thus increased by a factor greater than 40 from 80 (batch) up to >3000 mol/mol Pd. Further development of this technology will allow an increase of the number of (industrial) catalytic processes in which homogeneous catalysts are applied.     

Study on the Adaptability of Alkanolamide (LDEA) Lowering Oil/Water Interfacial Tension to Different Crude Oils

In order to investigate the high interfacial activity and fair oil phase adaptability of alkanolamide, “1:1” type lauric acid diethanolamide impurities (LDEA) were synthesized and purified by the column chromatography method to obtain dodecanoic acid diethanolamide (C₁₂DEA), ester mixture, etc. The exact structures of these compounds were further confirmed by IR, gas chromatogrph with mass spectroscopy (GC–MS), and NMR. The influence of each component on the interfacial tension of oil/water (IFT) was studied by systematic quantitative analysis. The results showed that (i) the strength of each system to reduce oil/water IFT is C₁₂DEA /DEA ≈ LDEA > C₁₂DEA/DEA/ESTER > C₁₂DEA/NaOH > C₁₂DEA > C₁₂DEA/ESTER > DEA. This indicates that LDEA contributes to the reduction of the oil/water IFT and the enhanced adaptability of crude oil in this order: DEA > > ESTER; (ii) when the IFT of the LDEA/DEA system reached an ultralow value, the minimum content of DEA in the system was 1%, and the maximum ester content was less than 5% when the LDEA/DEA/ESTER system reached the ultralow IFT; (iii) the possible mechanism of effect of LDEA components on the IFT and oil phase adaptability was proposed as the synergistic process among the hydrogen bonding, alkali effect, and interface self-assembly of molecules in the interfacial layer. The contribution of these three factors were hydrogen bonding > alkali effect > interface self-assembly.     

环氧乙烷-氨法生产乙醇胺的反应过程模拟研究

应用PRO II软件开发了环氧乙烷-氨法(EO-NH3)生产乙醇胺工艺流程的反应模型,经与工厂实际生产数据比较,该模型可以很好地计算EO-NH3的反应过程。使用该模型计算了进料中不同NH3和EO摩尔比条件下的产品分布,计算了一乙醇胺、二乙醇胺循环量对产品分布的影响,并给出了当目标产品分别是单乙醇胺、二乙醇胺及三乙醇胺时最优操作参数的选择方法。对于期望的产品分布,可通过对不同条件下的反应过程进行模拟计算,找出最适宜的操作条件,使目标产品的产量最大。     

Kinetics of heterogeneously MgO-catalyzed transesterification

The transesterification of ethyl acetate with methanol over magnesium oxide as solid base catalyst was investigated. Intrinsic kinetic data have been obtained in a perfectly mixed slurry batch reactor. The influence of the temperature (283–323 K) and the initial methanol to ethyl acetate molar ratio (M/E: from 0.1 to 10) was investigated over a broad ethyl acetate conversion range (1–95%). A kinetic model was developed based on a three-step ‘Eley–Rideal’ type of mechanism applied in liquid phase, describing the experimental data over the investigated range of experimental conditions. Transesterification reaction occurs between methanol adsorbed on a magnesium oxide free basic site and ethyl acetate from the liquid phase. Methanol adsorption is assumed to be rate-determining. Other models derived from other mechanisms were rejected based on statistical analysis, mechanistic considerations and physicochemical interpretation of the parameters. The calculation of activity coefficients accounting for non-ideality had to be incorporated in the parameter estimation procedure.     

Degradation of alkanolamine blends by carbon dioxide

Aqueous solutions of MDEA, MDEA + DEA and MDEA + MEA containing 4.2 kmol/m³ total amine, were contacted with CO₂ at a partial pressure of 2.58 MPa and temperatures ranging from 120 to 180°C, in a stainless steel batch reactor. The reaction products include the known degradation compounds of the amines as well as products formed from secondary interactions in the amine blends. The rate of degradation was first order in the amines and, in magnitude, followed the sequence MDEA < MEA < DEA. Furthermore, the rate constant for MDEA was independent of amine substitution level and blend constituents. From a practical standpoint, MDEA + DEA blends would require frequent DEA make-up to maintain treating efficiency.     

Reaction kinetics of 2‐((2‐aminoethyl) amino) ethanol in aqueous and non‐aqueous solutions using the stopped‐flow technique

Observed pseudo‐first‐order rate constants (k_o) for the reaction between CO₂ and 2‐((2‐aminoethyl) amino) ethanol (AEEA) were measured using the stopped‐flow technique in an aqueous system at 298, 303, 308 and 313 K, and in non‐aqueous systems of methanol and ethanol at 293, 298, 303 and 308 K. Alkanolamine concentrations ranged from 9.93 to 80.29 mol m^?3 for the aqueous system, 29.99–88.3 mol m^?3 for methanol and 44.17–99.28 mol m^?3 for ethanol. Experimentally obtained rate constants were correlated with two mechanisms. For both the aqueous‐ and non‐aqueous‐AEEA systems, the zwitterion mechanism with a fast deprotonation step correlated the data well as assessed by the reported statistical analysis. As expected, the reaction rate of CO₂ in the aqueous‐AEEA system was found to be much faster than in methanol or ethanol. Compared to other promising amines and diamines studied using the stopped‐flow apparatus, the pseudo‐first‐order reaction rate constants were found to obey the following order: PZ (cyclic‐diamine) > EDA (diamine) > AEEA (diamine) > 3‐AP (primary amine) > MEA (primary amine) > EEA (primary amine) > MO (cyclic‐amine). The reaction rate constant of CO₂ in aqueous‐AEEA was double that in aqueous‐MEA, and the difference increased with an increase in concentration. All reaction orders were practically unity. With a higher capacity for carbon dioxide and a higher reaction rate, AEEA could have been a good substitute to MEA if not for its high thermal degradation. AEEA kinetic behaviour is still of interest as a degradation product of MEA. © 2012 Canadian Society for Chemical Engineering     

Transesterification of sunflower oil in a countercurrent trickle-bed reactor packed with a CaO catalyst

Transesterification of sunflower oil with methanol to form biodiesel was performed in a countercurrent trickle-bed reactor, using calcium oxide particles 1-2 mm in diameter as a packed, solid base catalyst. Although biodiesel production generally requires a reaction temperature below the boiling point of methanol to maintain a heterogeneous, liquid-liquid reaction, in the present study the reaction temperature was varied from 80 to 140 °C to confirm the progress of transesterification in a gas-liquid-solid phase reaction system. Oil droplets released from a thin tube flowed downward, while vaporized methanol flowed upward in the bed. The effects of the reaction temperature, methanol and oil flow rates, and the bed height on the FAME yield were investigated. The oil residence time in the reactor, which was controlled by changing both the oil flow rate and the bed height, had a significant effect on the FAME yield. In addition, the FAME yield increased with reaction temperature and was maximal at 373 K due to the change in residence time associated with reduced oil viscosity at higher temperatures. The FAME yield was 98% at a reaction temperature of 373 K when the methanol and oil flow rates were 3.8 and 4.1 mL/h, respectively.     

Investigation mechanism of DEA as an activator on aqueous MEA solution for postcombustion CO2 capture

In this work, Diethanolamine (DEA) was considered as an activator to enhance the CO₂ capture performance of Monoethanolamine (MEA). The addition of DEA into MEA system was expected to improve disadvantages of MEA on regeneration heat, degradation, and corrosivity. To understand the reaction mechanism of blended MEA‐DEA solvent and CO₂, ¹³C nuclear magnetic resonance (NMR) technique was used to study the ions (MEACOO^‐, DEACOO^–, MEA, DEA, MEAH⁺, DEAH⁺, , ) speciation in the blended MEA‐DEA‐CO₂‐H₂O systems with CO₂ loading range from 0 to 0.7 mol CO₂/mol amine at the temperature of 301 K. The different ratios of MEA and DEA (MEA: DEA = 2.0:0, 1.5:0.5, 1.0:1.0, and 0:2.0) were studied to comprehensively investigate the role of DEA in the system of MEA‐DEA‐CO₂‐H₂O. The results revealed that DEA performs the coordinative role at the low CO₂ loading and the competitive role at high CO₂ loading. Additionally, the mechanism was also proposed to interpret the reaction process of the blended solvent with CO₂. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2515–2525, 2018     

Size controlled synthesis of well-distributed nano-silver on hydroxyapatite using alkanolamine compounds

A well-distributed nano-silver hydroxyapatite composite has been successfully prepared by a one-pot synthesis method. Hydroxyapatite was separately synthesized by a sol-gel method, then impregnated with silver nanoparticles with the mediation of Uncaria gambir Roxb. leaf extract in the presence of three kinds of alkanolamine compound; monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) as capping agents. The effect of different capping agents on the properties of the silver nanoparticles and the nano-silver hydroxyapatite composite were studied. UV–visible spectrophotometer analysis exhibited absorbance peaks at 402–439 nm which specifically corresponds to spherical silver nanoparticles. Higher optical absorbance was observed in TEA-capped silver nanoparticles, than in DEA and MEA-capped ones. X-ray diffraction (XRD) analysis showed a highly crystalline hexagonal structure for hydroxyapatite and no detected metallic silver. However, the presence of 1.65% silver was confirmed by energy dispersive x-ray (EDX) spectroscopy analysis. Transmission electron microscopy (TEM) analysis revealed spherical silver nanoparticles with a size range of 2–62 nm (smallest mean diameter of 2 nm) adhered to the hydroxyapatite surface. The TEA capped impregnated silver nanoparticles were the smallest, corresponding to the best capping performance, followed by those capped by DEA and MEA. Small-sized nanoparticles on hydroxyapatite are beneficial for highly antibacterial bone implants.     

Kinetics for phenolysis of ethyl 2‐bromoisobutyrate via phase‐transfer catalysis in a solid–liquid system

The kinetics of phase‐transfer catalyzed etherification of sodium phenoxide with ethyl 2‐bromoisobutyrate to produce ethyl 2‐phenoxyisobutyrate in a solid–liquid system has been investigated. Being catalyzed by the quaternary ‘onium salts, the reaction was carried out in a stirred batch reactor to explore the effects of various operating variables. At a temperature of 80 °C and a molar ratio of tetra‐n‐butylammonium bromide to sodium phenoxide equal to 0.372, 94% conversion was obtained after 4 h, and no other side products were observed. A kinetic model of pseudo‐first‐order reaction accompanied by catalyst deactivation was proposed to describe the overall reaction. A deactivation function was employed to evaluate the kinetic parameters. The decay of catalytic activity was mainly caused by the deposition of the salts produced on the surface of solid particles. The results show that the initial reaction rate was not influenced by the agitation rate when exceeding 350 rpm, but the deactivation rate increased with increasing stirring speed and the amount of catalyst used. The intrinsic organic reaction was conducted by the phase‐transfer catalytic intermediate. The order of reactivity for different phase‐transfer catalysts was determined as tetra‐n‐butylphosphonium bromide > tetra‐n‐butylammonium bromide > tetra‐n‐butylammonium iodide ≈ tetra‐n‐butylammonium hydrogen sulfate ≈ Aliquat 336. The apparent activation energy for tetra‐n‐butylammonium bromide was estimated as 51.4 kJ mol⁻¹. This work provides an improved method for synthesizing phenolic substances in solid–liquid phases and preventing unfavorable side reactions. © 2000 Society of Chemical Industry     

Optimization of a Mixed Additive and its Effect on Physicochemical Properties of Bio‐Oil

A final optimal mixed additive consisting of methanol, acetone, and ethyl acetate in specific proportions was obtained by one‐factor multi‐objective optimization of the Design‐Expert software and performed well in a verification experiment. The mixed additive of methanol and ethyl acetate was first prepared separately and then added to bio‐oil, followed by acetone. The viscosity of the additive/bio‐oil mixture was significantly lower than of the crude bio‐oil. Among all chemical compound groups in the bio‐oil, the content of phenols was the highest one. Chemical compounds in bio‐oil after aging had higher molecular mass weights than before. The addition of the final optimal mixed additive and the accelerated aging process could slightly change the intensity and positions of some absorption peaks.     

Formation of catalytic active sites in copper and manganese modified SBA-15 mesoporous silica

A series of copper and manganese oxides modified SBA-15 mesoporous silicas with different composition was prepared by incipient wetness impregnation with the corresponding nitrate precursors and compared with the analogous materials supported on conventional SiO₂. Nitrogen physisorption, XDR, FTIR, UV–Vis and temperature programmed reduction with hydrogen were used for samples characterization. Their catalytic activity was tested in ethyl acetate oxidation and methanol decomposition. The ordered porous structure of the support facilitates the interaction between different metal oxide nanoparticles and increases their dispersion due to the formation of mixed oxide phase. The ethyl acetate oxidation on SBA-15 binary materials is suppressed due to the lower accessibility of the metal oxide particles, located deeply into the micro-meso pores of the support. The reaction medium which forms during the methanol decomposition provides the reduction/decomposition transformations with the mixed oxide phase. The final phase composition of finely dispersed Cu/CuO and MnO_x particles stabilizes in a highly dispersed state into the porous matrix of SBA-15 support and increases the catalytic activity in methanol decomposition due to the appearance of synergistic effect between them.     

Solvothermal synthesis of microsphere ZnO nanostructures in DEA media

Microsphere ZnO nanostructures (ZnO-MNs) were synthesized via solvothermal method in diethanolamine (DEA) media. DEA was utilized to terminate the growth of ZnO nanoparticles which forms the ZnO-MNs. The ZnO-MNs were characterized by a number of techniques, including X-ray diffraction analysis (XRD) and field emission scanning electron microscopy (SEM). The ZnO-MNs prepared by solvothermal process at the temperature of 150 °C for 6, 12, 18, and 24 h exhibited a hexagonal (wurtzite) structure with sizes ranging from 2 to 4 μm. The growth mechanism and morphology of the ZnO-MNs were also investigated, and it was found that the ZnO-MNs were formed by ZnO nanoparticles with average particle size of 25 ± 5 nm. To show role of DEA in the formation of Zn-MNs, effect of MEA (monoethanolamine) and TEA (triethanolamine) on morphology of the final product are also investigated. The results showed that DEA is a good polymerization agent that can be used as a stabilizer in the solvothermal technique for preparing fine ZnO powder.     

New epoxy resins based on recycled poly(ethylene terephthalate) as organic coatings

Glycolysis of poly(ethylene terephthalate), PET, waste using trimethylol propane (TMP), triethanolamine (TEA), diethylene glycol (DEG) and diethanolamine (DEA) was used to produce suitable hydroxy-oligomers for epoxy. The glycolyzed products were reacted with epichlorohydrine to prepare a series of di- and tetraglycidyl epoxy resins with different molecular weights. The glycolysis was carried out in presence of manganese acetate as a catalyst at normal and high pressure in presence and absence of xylene at 210 °C. The produced resins were cured with different mole ratios of 1-(2-amino ethyl) piprazine as curing agent at room temperature. The mechanical properties of the cured epoxy resins were evaluated. The chemical resistances of the cured resins were evaluated through salt spray resistance, hot water, solvents, acid and alkali resistance measurements. The data indicate that the cured epoxy resins based on glycolyzed oligomer of PET and DEA have excellent chemical resistances as organic coatings among other cured resins.     

Methyl tert-butyl ether decomposition over heteropoly acid catalyst in a cellulose acetate membrane reactor

In this study the methyl tert-butyl ether (MTBE) decomposition over H₃PW₁₂O₄₀ was carried out in a cellulose acetate membrane reactor. The permeability of methanol through the cellulose acetate membrane was about 30 and 300 times higher than that of either isobutene or MTBE, respectively. The isobutene selectivity in the fixed bed reactor was only slightly higher than the methanol selectivity due to the side reaction. In the cellulose acetate membrane reactor, however, the isobutene selectivity in the rejected stream was 68% and the methanol selectivity in the permeated stream was up to 97%. The MTBE conversion in the membrane reactor was about 7% higher than that in the membrane-free fixed bed reactor under the same reaction conditions. The enhanced performance of the membrane reactor in this reversible reaction was mainly due to the selective permeation of methanol which resulted in a methanol-deficient condition suppressing MTBE synthesis reaction.