Evaluating the optimum operating parameters of biodiesel production process from soybean oil using the Li2TiO3 catalyst

One-pot synthesis of acid-base bifunctional catalysts for biodiesel production

Acid-base bifunctional heterogeneous solid catalysts, known as the active site with base-acid properties, exhibited relatively good performance on the transesterification for soybean oil for green fuel production. We investigated the use of niobium and three alkali metal oxides (Li, Na, and K) as M_yNbO_X (M = Li, Na, K) composite as acid-base catalysts for biodiesel production. M_yNbO_X catalysts were prepared using a simple solid-state reaction, mixing, and grinding niobium dioxide with alkali metal carbonates calcined at 800 °C in air for 4 h. XRD, BET, FE-SEM, TEM and TPD techniques were employed for catalysts characterization. The highest biodiesel yield (98.08%) was achieved under the transesterification condition of 65 °C, 6 h, 24 methanol/oil molar ratio and 2 wt% of LiNbO₃ as the catalyst. The results showed that LiNbO₃ could be efficiently reused at least 10 cycles with an insignificant reduction in the biodiesel yield. The physicochemical properties of the biodiesel were further studied and compared with the ASTM and the EN biodiesel specifications. The results showed that the properties of the biodiesel produced complied with the international standard specifications.

Low-cost biodiesel production using waste oil and catalyst

With the production of renewable biofuels, concerns about the end of fossil fuels have been partially eliminated. On the other hand, the utilization of low-cost and waste materials to provide the raw essential substances to manufacture these fuels is of paramount importance. Biodiesel is one of these fuels and the required raw materials for the reaction are oil (triglycerides), alcohol and catalyst. In this work, travertine stone powder (as waste in the manufacture of building materials) was used as a catalyst and waste frying oil as a source of triglyceride for biodiesel production. Using thermogravimetric and X-ray diffraction analysis, optimum temperature for catalyst calcination was selected at 900°C. Furthermore, X-ray fluorescence, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, transmission electron microscopy and scanning electron microscopy analyses were performed. Using the design of experiments Response Surface Methodology, the optimum reaction conditions for biodiesel production yield of 97.74% were: reaction temperature 59.52°C (~60°C), time 3.8 h (228 min), catalyst concentration 1.36 wt.% and the methanol to oil molar ratio of 11:6. After reusing four times, the catalyst efficiency was reduced a little, and the biodiesel yield was 89.84%, indicating high strength and stability of the catalyst.

The optimization of biodiesel production from transesterification of sesame oil via applying ultrasound-assisted techniques: comparison of RSM and ANN–PSO hybrid model

Due to the finite source of fossil fuels and their high emissions, it is remarkable to recognize appropriate ways to produce alternative fuels with less pollution. In this paper, the production of biodiesel (fatty acid methyl ester) from transesterification of methanol with sesame oil under ultrasound-assisted waves (using a homogeneous sodium hydroxide catalyst) was investigated. In addition, the optimization and prediction of biodiesel production was studied and compared with the two methods of response surface methodology (RSM) and the combined model of artificial neural network (ANN) – particle swarm algorithm (PSO). The central composite design (CCD) was used to investigate the effect of independent variables (methanol/oil molar ratio, catalyst percentage, reaction time and temperature) on the yield of biodiesel in Expert Design software. Analysis of experimental results was performed using RSM and ANN–PSO hybrid methods and also the optimal conditions for maximizing the yield were calculated. The highest yield of biodiesel predicted by RSM and ANN–PSO were 87.4 and 90.58%, respectively. RSM and ANN–PSO hybrid models were compared based on least squared errors statistically. The correlation coefficients in the RSM and ANN–PSO hybrid models were 0.959 and 0.999 respectively. While both models demonstrated a good agreement with actual results, but the ANN–PSO hybrid model had a powerful prediction for the optimal points over the RSM.

Smart waste management of waste cooking oil for large scale high quality biodiesel production using Sr-Ti mixed metal oxide as solid catalyst: Optimization and E-metrics studies

Biodiesel was prepared at laboratory scale via transesterification reaction from waste cooking oil using Sr-Ti mixed metal oxide as a heterogeneous base catalyst. The solid base catalyst was synthesized by polymer precursor method. The most efficient active phase of catalyst was explored by varying the Sr/Ti atomic ratio in mixed metals oxides. The synthesized catalyst underwent for TGA, Powder XRD, SEM, EDX, FT-IR, XPS, and BET surface area analysis to assess its physicochemical characteristics. Additionally, basicity which has been observed as the most process governing factor was also evaluated through Hammett indicator-benzoic acid titration method. The Sr-Ti mixed metals oxide with 4:1 was observed with highest catalytic activity for methanolysis reaction. Its potency was facilitated by fairly acquired BET surface area (43.6 m²/g) and basic strength (2.89 mmol/g). The appreciable values of both the parameters imparted the high catalytic activity in Sr-Ti mixed metals oxide with atomic ratio 4:1. Onward, transesterification reaction was optimized for the maximum FAME conversion through RSM using CCD. The confirmatory tests showed the consistency with the conclusions drawn from RSM study regarding optimized values of concerned process variables. Transesterification reaction turned out 98% FAME conversion exerting catalyst dose (1.0 wt%), methanol to oil molar ratio (11:1), and reaction time (80 min) at reaction temperature (65 °C) and agitation speed (600 rpm) featured by RSM study. The closeness in optimized value of anticipated and confirmatory results perceived the efficiency of CCD and approving its potency as successful tool to estimate the highest FAME conversion. Next, a pseudo-first-order kinetic model of transesterification reaction was established. In addition to this, the thermodynamic functions were also computed through Eyring plot dictating the non-spontaneity and endergonic nature of transesterification reaction. The Environment-factor (E-factor) and Turn Over Frequency (TOF) were enumerated and they approved the prepared Sr-Ti mixed metals oxide as an efficient and sustainable catalyst for biodiesel production through transesterification. Finally, all the important fuel properties of prepared biodiesel from waste cooking oil was discerned within the range laid by ASTM D-6751 standards for biodiesel which coined the compatibility of prepared methyl ester with CI engines as a substitute of diesel fuel.

Biodiesel Production Using Solid Acid Catalysts Based on Metal Oxides

The development of solid acid catalysts, especially based on metal oxides and different magnetic nanoparticles, gained much awareness recently as a result of the development of different nano-based materials. Solid acid catalysts based on metal oxides are promising for the (trans)esterification reactions of different oils and waste materials for biodiesel production. This review gives a brief overview of recent developments in various solid acid catalysts based on different metal oxides, such as zirconia, zinc, titanium, iron, tungsten, and magnetic materials, where the catalysts are optimized for various reaction parameters, such as the amount of catalyst, molar ratio of oil to alcohol, reaction time, and temperature. Furthermore, yields and conversions for biodiesel production are compared. Such metal-oxide-based solid acid catalysts provide more sustainable, green, and easy-separation synthesis routes with high catalytic activity and reusability than traditionally used catalysts.

Preparation of Ni-Doped Li2TiO3 Using an Inorganic Precipitation–Peptization Method

The precursor for a lithium-ion sieve is prepared using an inorganic precipitation-peptization method with titanium sulfate as the titanium source and lithium acetate as the lithium source. The effects of Ni2+ (Nickel ions) doping on the stability of the sol, crystal morphology and interplanar spacing of Li2TiO3 are investigated. The results indicate that, after Ni2+ doping with varying fractions, the stability of the precursor sol first increases then decreases, and the maximum stabilization time of the precursor sol doped with 1% Ni2+ is 87 h. When doped with 1% Ni2+, the sol performance is most stable, the porous Li2TiO3 is obtained, and the specific surface area of Li2TiO3 increases by up to 1.349 m2/g from 0.911 m2/g. Accompanying the increase in calcination temperature, the inhibition of Ni2+ doping on the growth and crystallization of grains decreases. When the temperature is lower than 750 °C, Ni atoms replace the Ti atoms that are substituted for Li atoms in the original pure Li layer, forming lattice defects, resulting in the disappearance of (002) and (−131) diffraction peaks for Li2TiO3, the reduced ordering of crystal structure, a decrease in the interplanar spacing of the (002) plane, lattice expansion and an increase in the particle size to 100–200 nm. When the temperature exceeds 750 °C, with the increase of calcination temperature, the influence of Ni doping on the growth and crystallinity of grains decreases, and the (002) crystal surface starts to grow again.

Process dynamic investigations and emission analyses of biodiesel produced using Sr-Ce mixed metal oxide heterogeneous catalyst

The present study explores the feasibility of Sr-Ce based mixed metal oxides for its performance in transesterification reaction of waste cooking oil. The catalyst synthesis was carried out through gel combustion route and was characterized through several techniques including thermal analysis (TGA-DTA), X-ray diffraction (XRD), attenuated total reflectance based Fourier transform infrared spectroscopy (ATR-FTIR), high resolution scanning electron microscopy (HR-SEM) assisted with EDX, BET specific surface area and Hammett indicator basicity. The enhanced activity of the catalyst was investigated at pH 7.0 with Sr-Ce atomic ratio of 3:1 at 900 °C of calcination temperature. Influences of various process parameters on transesterification efficiency were carefully investigated. The experimental results demonstrated that maximum transesterification efficacy of 99.5% was achieved under optimized reaction conditions with catalyst dose of 2.0 wt %, oil-to-methanol ratio 1:14, reaction time 120 min, reaction temperature 65 °C and stirring speed of 700 rpm. For better interpretation of the process, the reaction rate was computed by employing pseudo-first and pseudo-second order kinetics model at varying reaction temperature (50 °C-75 °C). The transesterification data agreed well with pseudo-first order model with highest rate constant value of 2.5 × 10^-3 min^-1 was evaluated at 65 °C. Activation energy and frequency of the reaction was quantified from the Arrhenius expression as 17.04 kJ/mol and 9.92 min^-1, respectively. Thermodynamic analysis of the reaction system suggests that the transesterification of the waste cooking oil followed endergonic reaction pathway. Synthesis of biodiesel was ascertained from the H¹-NMR and FTIR analysis of the transesterified product, further, the physicochemical properties of the biodiesel were also compared with that of diesel fuel and the resultant values were found to be within ASTM limits. Reusability study was also conducted and it indicated that the catalyst can be easily regenerated and could be effectively reused up to four runs.