Glycerol Molar Ratio Research Articles

Preparation and application of triglyceride plasticizers for poly(vinyl chloride)

AbstractA series of triglyceride plasticizers were prepared from glycerol, acetic acid, and benzoic acid through a two‐step reaction to develop potential uses of glycerol. The optimum reaction conditions were determined by the esterification of glycerol and acetic acid to produce glyceryl triacetate. When the molar ratio of glycerol to benzoic acid to acetic acid was 1:1:3.5, a novel plasticizer triglyceride mixture (GTM) was successfully synthesized; it had a good plasticizing effect on poly(vinyl chloride) (PVC). The elongation at break of PVC composites containing 80 phr GTM increased around 350%; the corresponding hardness (Shore D) and tensile strength decreased to around 35 D and 20 MPa, respectively. Moreover, the glass‐transition temperature (Tg) of PVC composites containing 40 phr GTM decreased to around 50°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Retracted Article: One-pot synthesis of glycidol from glycerol and dimethyl carbonate over a highly efficient and easily available solid catalyst NaAlO2

The one-pot synthesis of glycidol from glycerol and dimethyl carbonate (DMC) was developed by using a solid base catalyst. A series of solid base catalysts have been investigated in this reaction. It was found that NaAlO2, a cheap and easily available raw material, was a highly efficient heterogeneous catalyst for the one-pot synthesis of glycidol, and it can be easily recovered and reused. Under the reaction conditions of a DMC–glycerol molar ratio of 2, catalyst–glycerol weight ratio of 3%, reaction time of 90 min, and temperature of 80–92 °C, the conversion of glycerol and the selectivity to glycidol reached 94.7% and 80.7%, respectively. Activity tests of the catalyst after exposure to the air showed that, to a certain extent, the NaAlO2 catalyst is tolerant to water and carbon dioxide, which makes the present system a practically interesting process for glycidol synthesis.

Efficient SO2 absorption by renewable choline chloride–glycerol deep eutectic solvents

The utilization of cheap and renewable materials is an important topic in green chemistry. In this work we studied the absorption of SO2 by choline chloride (ChCl)–glycerol deep eutectic solvents (DESs) at various temperatures and SO2 partial pressures, and the molar ratios of ChCl and glycerol ranged from 1 : 4 to 1 : 1. It was demonstrated that the solubility of SO2 in the DESs increased as the ChCl concentration in the DESs increased. The SO2 absorption capacity of the DESs with a ChCl–glycerol molar ratio of 1 : 1 could be as high as 0.678 g SO2 per g DES at 20 °C and 1 atm. Moreover, the absorbed SO2 could be easily released, and their excellent properties of high absorption capacity and rapid absorption/desorption rates remained during the five consecutive absorption/desorption cycles. The Henry's constants of SO2 in the DESs were calculated based on the solubility data.

Steam Reforming of Glycerol for Hydrogen Production over Ni/SiO2 Catalyst

The performance of Ni/SiO2 catalyst for glycerol reforming has been investigated in fixed-bed reactor using careful tailoring of the operational conditions. In this paper, a commercial Engelhard catalyst has been sized and compared to gas product distribution versus catalyst size, water-to-carbon ratio, and stability of the catalyst system. Ni/SiO2 catalysts of three sizes (2×2, 2×4, and 3×5 mm) are evaluated using glycerol: water mixture at 600°C to produce 2 L H2 g−1 cat h−1. The results indicate that 3×5 mm size pellet is showing minimum coking and maintaining same level of conversion even after several hours of reforming activity. Whereas studies on 2×2 and 2×4 mm pellets indicate that carbon formation is affecting the reforming activity. Under accelerated aging studies, with 1 : 9 molar ratio of glycerol to water, 3 mg carbon g−1 cat h−1 was generated in 20 cycles, whereas 1 : 18 feed produced only 1.5 mg carbon g−1 cat h−1 during the same cycles of operation. The catalysts were characterized before and after evaluation by X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDAX), CHNS analysis, transmission electron microscopy (TEM), and X-ray photo electron spectroscopy (XPS).

Reforming of glycerol for producing hydrogen in a Pd/Ag membrane reactor

Due to the greenhouse effect and the soaring of oil prices internationally in recent years, biodiesel, which retains environmental benign characteristics that can mitigate climate change and pollution problems, has been becoming a major surrogate for fossil diesel. Theoretically, ten percent of glycerol is produced as the by-product through transesterification of fatty acid for manufacturing biodiesel; the increasing demand of biodiesel will make the glycerol become excess. Glut of glycerol must be converted into some useful chemicals and hydrogen is one of which can be used directly in the fuel cell and produces zero pollutant emissions. In this study, steam reforming of glycerol was carried out in a traditional reactor and an electrolessly plated Pd/Ag alloy membrane reactor, which were packed with an appropriate amount of Ni/CeO2/Al2O3 catalyst. Since membrane reactors offer the possibility of overcoming the equilibrium conversion through selectively removing one of the products, i.e., hydrogen, from the reaction zone, a higher conversion rate is expected. With its high H/C ratio feature, glycerol is reformed with steam to produce hydrogen and the process is optimized to achieve a highest performance, with varying temperatures, weight hourly specific velocities (WHSV) and water glycerol molar ratios (WGMR). When temperature at 800 °C, WHSV = 5 h−1 and WGMR = 5, it is found that the conversion of glycerol is 96.24% and the best hydrogen yield is 83.21% in a traditional reactor. In comparison, as the glycerol steam reforming was conducted in the Pd–Ag membrane reactor, the results show that the membrane reactor can increase the glycerol conversion, but at high pressure, the conversion will decline. The activity of the CeO2 modified catalysts under 20-h period operation was higher than that of the unmodified ones. TGA measurement confirmed that CeO2 can effectively reduce the carbon deposition rate.

Bioadditive synthesis from H3PW12O40-catalyzed glycerol esterification with HOAc under mild reaction conditions

In this work, the H3PW12O40 heteropolyacid, a versatile Brønsted acid catalyst promoted a selective conversion of glycerol into mono and diacetylglycerol, in reactions with acetic acid under mild conditions. The activity of the H3PW12O40 catalyst was compared to other Brønsted acid catalysts commonly used in esterification reactions (i.e. p-toluene sulfonic acid and sulfuric acid). The highest glycerol conversions were achieved in H3PW12O40-catalyzed esterification reactions. We demonstrated that unlikely than others homogeneous catalysts, H3PW12O40 may be repeatedly used without loss activity; this way it is also an attractive alternative that may avoid the serious drawbacks of the solid catalysts such as leaching and deactivation. Effects of the HOAc:glycerol molar ratio, acid strength and concentration of the catalysts were also assessed. Additionally, activation energy of the H3PW12O40-catalyzed esterification of glycerol was determined.

Hydrogen production in steam reforming of glycerol by conventional and membrane reactors

The aim of this study is to produce hydrogen through the glycerol steam reforming process. The reaction is carried out in a traditional reactor and an electrolessly plated Pd/Ag alloy membrane reactor, with varying reaction temperature, weight hourly specific velocity (WHSV) and water glycerol molar ratio (WGMR). The non-catalytic test was also employed for comparative purposes. The results show that the reaction is highly depending on temperature, and the maximum glycerol conversion achieved to 96.24% at 800 °C with a hydrogen yield of 5.82 mol-H2/mol-C3H8O3. It also found that the Pd/Ag membrane can effectively separate hydrogen from the reaction side and subsequently enhance the reaction rate in the membrane reactor. TGA measurements were employed to quantify the amounts of deposited carbon and the results also confirmed that the CeO2 modified catalyst can improve the carbon resistance as well as activity and stability.

Hydrogen by glycerol steam reforming on a nickel–alumina catalyst: Deactivation processes and regeneration

Hydrogen energy has attracted considerable attention because of its efficiency and environmental benefits, and the increasing demand requires finding renewable sources of raw materials to produce it. Glycerol, by-product of biodiesel production and coming from renewable raw materials, could be a bio-renewable substrate to produce hydrogen. The glycerol steam reforming to obtain hydrogen was evaluated using a 5.1 wt% Ni impregnated on Al2O3 catalyst, characterized by nitrogen adsorption, XRD, and FTIR. Deactivation processes were analyzed in successive cycles of reaction at 700 °C, atmospheric pressure, 5 h−1 WHSV, and 3:1 water:glycerol molar ratio, during 12 h. Between reaction cycles, regenerating took place using a He/Air stream. Hydrogen was the main product on the fresh catalyst, following by CO and CH4; during reaction, carbonaceous deposits deactivated catalyst, decreasing H2 and increasing both CO and CH4. Carbonaceous deposits were characterized by TPO, showing a main peak centered at 690 °C; the carbon content reached 11.9%.

One-pot conversion of CO2 and glycerol to value-added products using propylene oxide as the coupling agent

The effective conversion of carbon dioxide (CO2) and glycerol is an interesting topic in green chemistry. In this work, we studied the simultaneous transformation of CO2 and glycerol to value-added products using propylene oxide (PO) as coupling agent catalyzed by alkali metal halides. The effects of reaction temperature, CO2 pressure, reaction time, amount of catalyst, and PO to glycerol molar ratio on the reaction were investigated. It was discovered that the coupled catalytic reaction could produce glycerol carbonate (GC), propylene glycol (PG) and propylene carbonate (PC) very effectively using KI, an abundant and cheap salt, as the catalyst. The main reasons are that glycerol and PG are not only the reactant and product, respectively, but also act as the effective co-catalysts to promote the key step of the coupled reaction, and the reaction is thermodynamically favorable. This effective and atom economic route to convert glycerol and CO2 simultaneously has great potential application.

Synthesis and characterization of mono‐acylglycerols through the glycerolysis of methyl esters obtained from linseed oil

AbstractHere we investigate the production and characterization of mono‐acylglycerols through the glycerolysis of biodiesel, a methyl ester mixture, obtained from linseed oil. The biodiesel employed was derived from linseed oil through transesterification according to transesterification double step process 1. The efficiency of H2SO4, CaO, and NaOH as catalysts was evaluated for the production of mono‐acylglycerols. The glycerolysis reactions were performed by varying the molar ratio of the reagents (biodiesel:glycerol), the type and amount of catalyst, reaction time and temperature. Systematic evaluation of reaction yield is shown as a function of these parameters. Reaction products were characterized through IR spectroscopy, hydrogen NMR, and the GC techniques. The study of three different catalysts indicated that the most efficient was 5% NaOH in a 1:5 biodiesel–glycerol molar ratio with 10 h reaction time. The reaction reached a maximum of 85% biodiesel conversion with a mono‐acylglycerol yield of 72% at 130°C.

Phase equilibrium data of the system CO 2 + glycerol + methanol at high pressures

In this work, phase equilibrium data of the ternary system CO 2(1) + glycerol(2) + methanol(3) at high pressures are presented. The static synthetic method using a variable-volume view cell was employed to obtain the phase envelope in the temperature range of 303.15–343.15 K and at pressures up to 22 MPa. For the pressure transition measurements a given amount of carbon dioxide was injected into a methanol:glycerol mixture with a known molar ratio. Three different methanol to glycerol molar ratios were investigated (1:30, 1:20 and 1:12). The mole fraction of carbon dioxide was varied according to the system as follows: 0.3373–0.9741 for the glycerol to methanol molar ratio of 1:30, 0.2524–0.9949 for the molar ratio of 1:20, 0.2625–0.9940 for the molar ratio of 1:12. A complex phase behavior including vapor–liquid (VL), liquid–liquid (LL) and vapor–liquid–liquid (VLL) transitions were observed for these systems.

Synthesis and characterization of polyurethane coatings based on soybean oil–polyester polyols

Soybean oil was esterified by glycerol (1:3) molar ratio to produce monoglycerides, and then reacted with phthalic anhydride at ratios 20%, 40% and 60% to produce polyester polyols denoted by PES20, PES40 and PES60. They were investigated by IR spectra and solubility in methanol. Diphenylmethane diisocyanate was reacted with these polyols at NCO/OH ratios 1.2, 1.4, 1.6 using toluene as a solvent to produce polyester–polyurethane coatings, which were characterized by IR spectra. The prepared coatings were characterized by flexibility, pencil hardness, impact resistance and chemical resistance. Good properties of the prepared coatings increase in the direction of increasing hard segments in the sample.

Kinetic modelling of the esterification of rosin and glycerol: Application to industrial operation

The esterification of glycerol and rosin is a reaction of importance in the coating and adhesive industries, main consumers of the triglyceride of rosin acids. While this chemical transformation has led to some of the most useful products of rosin, kinetics of the reactions involved have not been studied in depth. In this study, a new analytical method based on gel permeation chromatography (GPC) is applied and compared to classical acid titration, the industrial standard. Experimental data on rosin esterification with glycerol were obtained at laboratory scale, covering a wide range of operational conditions, changing rosin to glycerol molar ratio (between 2 and 4) and temperature (between 240 and 280 °C). Afterwards, different kinetic models were fitted to experimental data to select between first- and second-order potential and hyperbolic kinetic models. Linear and non-linear regression techniques with numerical integration of the differential equations were used to fit the proposed kinetic models. A hyperbolic model coupled with glycerol mass balance that considered stripping of this polyalcohol proportional to the global reaction rate and to glycerol concentration proved to be the most adequate both at a given temperature and in all the temperature intervals studied. On the other hand, samples were analysed by H NMR and ionic chromatography to determine the glycerol amount in the reaction medium and in the distillate, respectively, observing the stripping of the polyalcohol. Finally, the selected model was used to simulate and fit runs executed at the usual industrial mode, a transient temperature operation followed by an isothermal operation with gradual addition of glycerol (fed-batch operation). These runs were performed at lab and at industrial scale, and the selected kinetic model and glycerol mass balance were adequate to simulate rosin conversion.

Novel Esterification of Glycerol Catalysed by Tin Chloride (II): A Recyclable and Less Corrosive Process for Production of Bio-Additives

In this work, a novel process based on use of a SnCl2·2H2O catalyst which is less corrosive, inexpensive, and a water tolerant Lewis acid was employed for synthesis of fuel bio-additives from glycerol. High yields and selectivities were achieved for glycerol esterification with acetic acid under mild reaction conditions. The SnCl2 catalyst showed to be as active as p-toluene sulfonic and sulfuric acid, catalysts commonly used in acid-catalysed esterification reactions. However, its use has significant advantages in comparison to these Bronsted acid catalysts, including lower reactor corrosion and unnecessary neutralization at the end reaction. The SnCl2 catalyst can also be recovered and reused without loss of catalytic activity. Additionally, effects of reaction temperature, HOAc:glycerol molar ratio and catalyst concentration on both selectivity and yield of glycerol acetates were also investigated. The lower corrosiveness, facilitated handling, as well as potential for reuse without activity loss after simple recycle protocols are positive aspects of SnCl2 catalysts. SnCl2-catalyzed glycerol esterification with HOAc at the molar ratio of 3:1 at 60 °C.

Poly(oleic diacid-co-glycerol): Comparison of Polymer Structure Resulting from Chemical and Lipase Catalysis

This study compares the synthesis and structure of poly(oleic diacid-co-glycerol) that results by using immobilized Candida antarctica Lipase B (Novozym 435, N435) and dibutyl tin oxide (DBTO) as catalysts. By using N435 catalysis and an oleic diacid to glycerol molar ratio of 1.0:1.0, the resulting polyester number-average molecular weights (Mn) were 6000 g/mol at 6 h and 9100 g/mol at 24 h with low branching degree (Den% of glycerol 13%−16%). 13C NMR spectra of these polyesters revealed their chain-ends consist exclusively of monosubstituted glycerol units. Further diversification in polymer structure was achieved by using N435 catalysis and by changing the feed ratio of oleic diacid to glycerol from 1.0:1.0 to 1.5:1.0 in 0.1 increments. Resulting polyesters were not cross-linked (no observed gel fraction), had similar Mn values (generally between 4800 and 6000 g/mol), but differed in dendritic unit content, glycerol unit degree of substitution, and end-group structure (monosubstituted glyercol versus c...

Hydrogen production from glycerol steam reforming for low- and high-temperature PEMFCs

This paper presents a thermodynamic study of a glycerol steam reforming process, with the aim of determining the optimal hydrogen production conditions for low- and high-temperature proton exchange membrane fuel cells (LT-PEMFCs and HT-PEMFCs). The results show that for LT-PEMFCs, the optimal temperature and steam to glycerol molar ratio of the glycerol reforming process (consisting of a steam reformer and a water gas shift reactor) are 1000 K and 6, respectively; under these conditions, the maximum hydrogen yield was obtained. Increasing the steam to glycerol ratio over its optimal value insignificantly enhanced the performance of the fuel processor. For HT-PEMFCs, to keep the CO content of the reformate gas within a desired range, the steam reformer can be operated at lower temperatures; however, a high steam to glycerol ratio is required. This requirement results in an increase in the energy consumption for steam generation. To determine the optimal conditions of glycerol steam reforming for HT-PEMFC, both the hydrogen yield and energy requirements were taken into consideration. The operational boundary of the glycerol steam reformer was also explored as a basic tool to design the reforming process for HT-PEMFC.

Ultrasound-assisted enzymatic transesterification of methyl benzoate and glycerol to 1-glyceryl benzoate in organic solvent

The aim of this work is to report the enzymatic transesterification production of 1-glyceryl benzoate under ultrasound irradiation, using a commercial immobilized lipase, Novozym 435. Firstly, a preliminary evaluation was carried out at 2, 4 and 6 h, at constant temperature of 50 °C, methyl benzoate to glycerol molar ratio of 1:1 and 5.5 wt% of enzyme concentration. After analyzing the results obtained, the experimental design technique was used to evaluate the effects of temperature, substrates molar ratio, enzyme concentration, solvent volume and ultrasonic power on the 1-glyceryl benzoate production. The highest conversion, around 16%, was obtained at 65 °C, 1:1 of methyl benzoate to glycerol molar ratio, 15 wt% of enzyme concentration, 7 mL of solvent and 40% ultrasonic power in 4 h of reaction. A preliminary kinetic experiment carried out varying the enzyme concentration (15 and 20 wt%) keeping fixed the temperature at 35 °C, 1:1 of substrates molar ratio, 3 mL of solvent and 40% of maximum ultrasonic power led to lower (around 15% after 12 h of reaction) conversions compared to that achieved in the experimental design.

Enzyme-catalyzed production of 1-glyceryl benzoate in compressed n-butane

The aim of this work is to report the enzymatic transesterification production of 1-glyceryl benzoate in compressed n-butane, using a commercial immobilized lipase, Novozym 435. For this purpose, reaction experiments were performed on the basis of phase equilibrium data of the system methyl benzoate/n-butane, measured using the static synthetic method with a variable-volume view cell in the temperature range of 313.15–343.15K and pressures up to 12MPa, in the entire compositional range of n-butane. Results indicate the existence of a relatively complex phase behavior for all temperatures investigated with the occurrence of vapor–liquid and liquid–liquid phase transitions. Reaction results showed that the strategy adopted for the experimental design proved to be useful in optimizing the reaction conversion in pressurized n-butane and Novozym 435. The optimum conditions were found to be 5.5wt% of enzyme, methyl benzoate to glycerol molar ratio of 3:1, 50°C and 6h of reaction, affording about 6% of 1-glyceryl benzoate yield.

Hydrogen production from glycerol on Ni/Al 2O 3 catalyst

The growing demand of hydrogen needs renewable sources of raw materials to produce it. Glycerol, by-product of biodiesel synthesis, could be a bio-renewable substrate to obtain hydrogen. A Ni(5.8%)-alumina catalyst was evaluated in the steam reforming of glycerol at 600–700 °C, atmospheric pressure, 16:1 water:glycerol molar ratio, and 3.4–10.0 h −1 WHSV. A glycerol aqueous solution was fed, while a nitrogen stream was co-fed. After 4 h-on-stream, conversion was 96.8% at 600 °C increasing to 99.4% at 700 °C, reaching the largest hydrogen selectivity (99.7%) at 650 °C. After 8 h, conversion decreases more significantly at 600 °C, while the hydrogen selectivity does not significantly change with temperature and increases by decreasing WHSV. After 4 h, the main by-product was methane (76–97%), increasing at higher temperature, followed by ethene, ethane, propene, and propane. At 700 °C and 10.0 h −1 WHSV, the main by-products were ethene (47%) and methane (37%); it could be associated to catalyst deactivation.

Selective hydrogenolysis of glycerol to propanediols on supported Cu-containing bimetallic catalysts

Supported Cu-containing bimetallic catalysts were prepared and used to convert glycerol to propanediols. The effects of supports, metals, metal loadings, and impregnation sequences were examined. A synergistic effect was observed between Cu and Ag when they were impregnated on γ-Al2O3. Characterizations revealed that the addition of Ag not only resulted in an in situ reduction of CuO, but also improved the dispersion of the Cu species on the support. A CuAg/Al2O3 catalyst with optimal amounts of Cu and Ag (Cu/Ag molar ratio 7 : 3, 2.7 mmol Cu+Ag per gram of γ-Al2O3) showed a near 100% selectivity to propanediols with a glycerol conversion of about 27% under mild reaction conditions (200 °C, 1.5 MPa initial H2 pressure, 10 h, (Cu+Ag)/glycerol molar ratio of 3/100). Compared with a commercial copper chromite catalyst commonly used for this reaction, the CuAg/Al2O3 catalyst had much higher activity and did not need a reduction pretreatment.