Search

In this work, an efficient and green glycerolysis reaction catalyzed by zinc glycerolate was developed to prepare biodiesel from oleic acid. The active phase of zinc glycerolate was investigated by XRD, FTIR, 1H NMR, and 13C NMR. An interesting result was obtained that zinc glycerolate was first dissolved to form zinc oleate and then regenerated to zinc glycerolate during the reaction, which was essential for the conversion of oleic acid. The relationship between dissolved zinc glycerolate and conversion of oleic acid was determined. The regeneration of zinc glycerolate was achieved when the molar ratio of glycerol to oleic acid was higher than 0.6:1. A plausible pathway for the glycerolysis reaction catalyzed by zinc glycerolate was proposed. Zinc glycerolate could be recycled 10 times with no obvious decrease in catalytic activity, and the oleic acid conversion of 98% was achieved. In addition, zinc glycerolate was applied to catalyze glycerolysis reaction of different feedstock and demonstrated excellent performance. The results show that zinc glycerolate is a promising catalyst in glycerolysis reaction for biodiesel production. [Display omitted] [ABSTRACT FROM AUTHOR]

The solubilities of sulfuryl fluoride (SO 2 F 2 ) in propylene carbonate (PC), tributyl phosphate (TBP) and N-methylpyrrolidone (NMP) was measured by isochoric saturation method at the pressure of up to 600 kPa and temperatures ranging from (293.15 to 313.15) K. Results showed that SO 2 F 2 solubility increased with increasing pressure and decreased with increasing temperature in the three solvents, and the dissolution of SO 2 F 2 in the solvents was a physical process. Moreover, Henry’s law constants and thermodynamic properties such as standard Gibbs free energy, enthalpy, and entropy changes of SO 2 F 2 solvation were further calculated according to the experimental solubility data. The solubility of SO 2 F 2 in these three solvents followed the order of TBP > PC > NMP. The results illustrated that TBP possessed the potentiality to capture SO 2 F 2 among the present absorbents due to the relatively large solubility and low absorption enthalpy for SO 2 F 2 . [ABSTRACT FROM AUTHOR]

The solubility of sulfuryl fluoride in water was experimentally measured over the pressure from P = (0 to 600) kPa and T = (283.15 to 308.15) K using isochoric saturation method. Results show that SO 2 F 2 solubility increases with increasing pressure and decreases with increasing temperature. Using the experimental solubility data, Henry’s law constants and the thermodynamic properties such as the standard Gibbs free energy, enthalpy, and entropy changes of SO 2 F 2 solvation were obtained. Henry’s law constant based on mole fraction and molality of SO 2 F 2 in water vary from (432.21 to 1052.96) MPa and (7.78 to 18.96) MPa at T = (283.15 to 308.15) K, respectively. [ABSTRACT FROM AUTHOR]

Chemical absorption was employed for the harmless treatment of sulfuryl fluoride (SO2F2) in the simulated residual fumigant. SO2F2 was absorbed by sodium hydroxide (NaOH) solution in a packed column. Effects of spray density, gas flow rate, concentration of NaOH solution, and inlet SO2F2 volume concentration on SO2F2 removal efficiency were investigated at room temperature. It was found that SO2F2 could be removed completely when inlet SO2F2 volume concentration, spray density, gas flow rate, and NaOH concentration were 0.50%, 12 m3/(m2 · h), 0.12 m3/h, and 0.68 mol/L, respectively. According to the two-film theory, a mathematical model based on Onda correlations was developed to describe the removal efficiency of SO2F2. Comparison between the experimental data and the calculated data proved that the predictability of the proposed model was within the maximum deviation of 8.0%. Aqueous NaOH solution after absorption was analyzed. It was found that the SO2F2 was fixed and converted to NaF, NaSO3F, and Na2SO4. [ABSTRACT FROM AUTHOR]

Biodiesel is a widely recognized and favored liquid biofuel, primarily attributed to its biodegradability and non-toxicity. However, the development of biodiesel is hindered by its high production costs. Here, we developed a method that combines glycerol esterification and transesterification reaction catalyzed using nano-hydrated CaO for the green production of biodiesel from high acid value oil. Waste eggshell was chosen as the calcium source to examine the effect of hydration temperature and duration. The catalysts were optimized using a synthesis process involving under calcination for 3 h at 875 °C, followed by hydration at 60 °C for 6 h and subsequent dehydration at 725 °C. The catalyst loading, alcohol-to-oil mass ratio, reaction temperature, and duration were optimized to 2.5 wt%, 35%, 60 °C, and 2 h, respectively. Under the optimized conditions, the yield of fatty acid methyl ester reached 94.44%. The catalyst was successfully reused eight cycles while maintaining a yield of fatty acid methyl ester at 80.52%. In addition, a comprehensive overview was summarized to compare the catalyst preparation methods, reaction conditions, biodiesel yield, and reusability in the production of biodiesel using eggshell-derived CaO. [ABSTRACT FROM AUTHOR]

Oily sludge, as a critical hazardous waste, requires appropriate treatment for resource recovery and harmfulness reduction. Here, fast microwave-assisted pyrolysis (MAP) of oily sludge was conducted for oil removal and fuel production. The results indicated the priority of the fast MAP compared with the MAP under premixing mode, with the oil content in solid residues after pyrolysis reaching below 0.2%. The effects of pyrolysis temperature and time on product distribution and compositions were examined. In addition, pyrolysis kinetics can be well described using the Kissinger-Akahira-Sunose (KAS) and the Flynn-Wall-Ozawa (FWO) methods, with the activation energy being 169.7–319.1 kJ/mol in the feedstock conversional fraction range of 0.2–0.7. Subsequently, the pyrolysis residues were further treated by thermal plasma vitrification to immobilize the existing heavy metals. The amorphous phase and the glassy matrix were formed in the molten slags, resulting in bonding and, hence, immobilization of heavy metals. Operating parameters, including working current and melting time, were optimized to reduce the leaching concentrations of heavy metals, as well as to decrease their volatilization during vitrification. [ABSTRACT FROM AUTHOR]

Desulfurization is important to the enhancement of biodiesel quality. In this study, the effects of reactant and catalyst addition and operations conducted on sulfur content at each stage during the biodiesel preparation process were examined. Based on the results of sulfide qualification and quantification, a high vacuum distillation method was developed to remove the sulfides in crude biodiesel. Biodiesel was separated into different fractions based on the boiling point and the sulfur content of each fraction was determined. Experimental results showed that most sulfides were distilled out with light and heavy fractions. Intermediate fraction was separated from the other fractions, resulting in high quality biodiesel with low sulfur content. The total yield of distillation fractions with sulfur content lower than 10 ppm reached 84.1%. A set of distillation facility with capacity of 10 m3/h was designed and developed accordingly for large-scale tests. The yield of low-sulfur biodiesel was around 83%, close to that obtained in the laboratory studies. In addition, economic analysis showed that the distillation facility can make revenue of more than $1.8 million per year, indicating that high vacuum distillation is economically feasible and promising for biodiesel desulfurization, especially in industrial application. Image 104946 • A high vacuum distillation method was proposed to remove sulfides in crude biodiesel. • Sulfides in crude biodiesel were qualitatively and quantitatively analyzed. • The total yield of biodiesel with sulfur content lower than 10 ppm was 84.1%. • Distillation facility with capacity of 10 m3/h was developed for large-scale tests. • The process is economically feasible for low-sulfur biodiesel production. [ABSTRACT FROM AUTHOR]

Trimethylolpropane fatty acid triester (TFATE) is a promising biolubricant as an environmentally friendly substitute to conventional mineral-based lubricants. However, the issues of extensive energy consumption from vacuum maintenance and feedstock saponification caused by strong alkaline catalysts exist in current TFATE-based biolubricant synthesis. Here, sustainable production of biolubricant was achieved with methyl oleate (MO) from non-edible oil sources as the feedstock and moderate alkaline K 2 CO 3 as the catalyst. Nitrogen gas stripping method instead of vacuum was adopted for methanol removal. The effects of agitation speed, N 2 flow rate, catalyst amount, MO to trimethylolpropane (TMP) molar ratio and temperature on MO conversion and TFATE selectivity were examined. The TFATE selectivity reached 95.6% under the optimized conditions. Leaching tests indicated neglectable K 2 CO 3 dissolution in reaction products. The kinetic parameters for the three consecutive transesterification reactions were calculated. In addition, the synthesized biolubricants exhibit low acid value and volatility, moderate iodine value, superior thermal stability, and good rheological and frictional properties. [Display omitted] • Biolubricant TFATE was produced by methyl oleate transesterification over K 2 CO 3 catalyst. • Nitrogen gas stripping method instead of vacuum was adopted for methanol removal. • The TFATE selectivity reached 95.6% under the optimized conditions. • Kinetic parameters for three consecutive transesterification reactions were calculated. • Products show superior thermal stability and good rheological and frictional properties. [ABSTRACT FROM AUTHOR]