Biodiesel Production Over Arenesulfonic Acid-Modified Mesostructured Catalysts: Optimization of Reaction Parameters Using Response Surface Methodology

The catalytic activity of different heterogeneous sulfonic acid-modified catalysts has been assayed in the simultaneous esterification of FFA and transesterification of triglycerides of crude palm oil (FFA content of 5.6 wt%) with methanol, demonstrating the applicability of this kind of acid solids to the one-step production of biodiesel from FFA-containing vegetable oils. The yield towards fatty acid methyl esters (FAMEs) obtained over these acid materials is enhanced when increasing the acid strength of the catalytic site. Likewise, the use of mesostructured supports has been shown as a factor improving the catalytic performance as compared with macroporous sulfonic acid-based resins, likely due to an enhancement of the mass transfer rates of large molecules, such as triglycerides, within the catalyst structure. Thus, the combination of the open mesoporous structure of a SBA-15 silica support with relatively strong arenesulfonic acid sites leads to a material able to yield high conversion of triglycerides and free fatty acids. Furthermore, a study on the transesterification reaction of crude palm oil with methanol through a surface response analysis has provided as optimal conditions the following: temperature 160 °C, catalyst loading 5.1 wt% referred to the amount of palm oil, and methanol to oil molar ratio 30. Under these conditions, almost 90% of the starting oil is converted to FAME after reacting for just 2 h of reaction. Likewise, surface response analysis has evidenced a strong interaction between temperature and methanol to oil ratio.     

Na_2CO_3/MCM-41型固体碱催化制备生物柴油

以MCM-41为载体负载Na2CO3制备Na2CO3/MCM-41型酯交换催化剂,用于催化大豆油制备生物柴油。并研究了催化剂用量、反应物的摩尔比、反应温度和反应时间等因素对该反应的影响。结果表明,最佳反应条件是n(甲醇)∶n(大豆油)=16∶1,催化剂用量为大豆油质量的3%,反应温度为60℃,反应时间为3 h条件下,酯交换转化率可达35%以上。     

BIODIESEL PRODUCTION FROM PALM OIL VIA HETEROGENEOUS TRANSESTERIFICATION: OPTIMIZATION STUDY

Fatty acid methyl ester (FAME) prepared by transesterification process using a heterogeneous catalyst has received a lot of interest lately as it could overcome the limitations of the current commercial homogeneous catalytic process. Apart from that, palm oil, being the cheapest edible oil in the world, will always remain the most economical source of FAME. Therefore, in this study, the use of sulfated zirconia alumina as a heterogeneous catalyst to catalyze the transesterification of palm oil with methanol to FAME was carried out using design of experiment (DOE), specifically response surface methodology (RSM) based on four-variable central composite design (CCD) with α = 2. The transesterification process variables are reaction temperature (60–180°C), reaction period (1–5 h), methanol-to-oil ratio (4–12 mol mol^?1), and amount of catalyst (2–10 wt.%). In this study involving many multiple process variables, the design of experiment approach was found to be superior to the conventional one-variable-at-one-time approach. Interactions between variables were found to have significant effect on the yield of FAME. At the conditions of 3 h of reaction period, 127°C reaction temperature, methanol-to-palm oil ratio of 8, and 6 wt.% of catalyst, an optimum FAME yield of 83.3% can be obtained, indicating that sulfated zirconia alumina has potential as a heterogeneous catalyst for the production of FAME from palm oil.     

In situ synthesis and characterization of Ca-Mg-Al hydrotalcite on ceramic membrane for biodiesel production☆

In situ surface synthesis of Ca–Mg–Al hydrotalcite (HT) on inorganic ceramic membrane (CM) was investigated with urea as precipitator. The effects of molar ratio of raw materials, crystallization time, and temperature on surface synthesis of HT were examined. The as-prepared HT/CM samples were characterized by XRD and SEM and an in sit growth mechanismof HT on CMwas proposed. KF/HT/CMobtained by loading potassium fluoride (KF) on the HT layer by impregnation and calcination method was used as catalyst for transesterification between palm oil and methanol. The comparison of KF/HT/CMand pure KF/HT powder under identical reaction conditions shows that the production of fatty acid methyl ester is equivalent, which means that the use of inorganic catalytic membrane in the transesterification is a viable alternative.     

Biodiesel Production from Soybean Oil Catalyzed by Li<Subscript>2</Subscript>CO<Subscript>3</Subscript>

In the present study, we synthesized biodiesel from soybean oil through a transesterification reaction catalyzed by lithium carbonate. Under the optimal reaction conditions of methanol/oil molar ratio 32:1, 12 % (wt/wt oil) catalyst amount, and a reaction temperature of 65 °C for 2 h, there was a 97.2 % conversion to biodiesel from soybean oil. The present study also evaluated the effects of methanol/oil ratio, catalyst amount, and reaction time on conversion. The catalytic activity of solid base catalysts was insensitive to exposure to air prior to use in the transesterification reaction. Results from ICP-OES exhibited non-significant leaching of the Li₂CO₃ active species into the reaction medium, and reusability of the catalyst was tested successfully in ten subsequent cycles. Free fatty acid in the feedstock for biodiesel production should not be higher than 0.12 % to afford a product that passes the EN biodiesel standard. Product quality, ester content, free glycerol, total glycerol, density, flash point, sulfur content, kinematic viscosity, copper corrosion, cetane number, iodine value, and acid value fulfilled ASTM and EN standards. Commercially available Li₂CO₃ is suitable for direct use in biodiesel production without further drying or thermal pretreatment, avoiding the usual solid catalyst need for activation at high temperature.     

Potassium hydroxide catalyst supported on palm shell activated carbon for transesterification of palm oil

In this study, potassium hydroxide catalyst supported on palm shell activated carbon was developed for transesterification of palm oil. The Central Composite Design (CCD) of the Response Surface Methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst loading and methanol to oil molar ratio on the production of biodiesel using activated carbon supported catalyst. The highest yield was obtained at 64.1 °C reaction temperature, 30.3 wt.% catalyst loading and 24:1 methanol to oil molar ratio. The physical and chemical properties of the produced biodiesel met the standard specifications. This study proves that activated carbon supported potassium hydroxide is an effective catalyst for transesterification of palm oil.     

叔丁醇共溶剂用于制备生物柴油的研究

利用叔丁醇作为共溶剂可使棕榈油、甲醇和催化剂形成均相体系,用于酯交换反应制备生物柴油,可以缩短反应时间。实验以棕榈油为原料,氢氧化钠为催化剂,在带夹套的玻璃反应器内进行反应。考察了共溶剂质量分数、催化剂质量分数、反应温度、醇油摩尔比等因素对生物柴油产率的影响,获得了最佳反应条件。实验结果表明,当叔丁醇质量为棕榈油质量的11.6%,催化剂质量为油质量的1.0%,反应温度为60℃,醇油摩尔比为6∶1时,反应2 m in后生物柴油产率达到了90%。     

Biodiesel production from waste cooking palm oil using calcium oxide supported on activated carbon as catalyst in a fixed bed reactor

A reactor has been developed to produce high quality fatty acid methyl esters (FAME) from waste cooking palm oil (WCO). Continuous transesterification of free fatty acids (FFA) from acidified oil with methanol was carried out using a calcium oxide supported on activated carbon (CaO/AC) as a heterogeneous solid-base catalyst. CaO/AC was prepared according to the conventional incipient-wetness impregnation of aqueous solutions of calcium nitrate (Ca(NO₃)₂·4H₂O) precursors on an activated carbon support from palm shell in a fixed bed reactor with an external diameter of 60 mm and a height of 345 mm. Methanol/oil molar ratio, feed flow rate, catalyst bed height and reaction temperature were evaluated to obtain optimum reaction conditions. The results showed that the FFA conversion increased with increases in alcohol/oil molar ratio, catalyst bed height and temperature, whereas decreased with flow rate and initial water content in feedstock increase. The yield of FAME achieved 94% at the reaction temperature 60 °C, methanol/oil molar ratio of 25: 1 and residence time of 8 h. The physical and chemical properties of the produced methyl ester were determined and compared with the standard specifications. The characteristics of the product under the optimum condition were within the ASTM standard. High quality waste cooking palm oil methyl ester was produced by combination of heterogeneous alkali transesterification and separation processes in a fixed bed reactor. In sum, activated carbon shows potential for transesterification of FFA.     

Ultrasonic Pretreatment Transesterification for Solid Basic-Catalyzed Synthesis of Fatty Acid Methyl Esters

Generally, ultrasound irradiation is required throughout the reaction for fatty acid methyl esters (FAME, namely, biodiesel) production, which is energy-consuming and difficult to scale-up. In order to improve the industrial application of ultrasonic technology, a systematic study of ultrasonic pretreatment solid basic (Na₂SiO₃)-catalyzed transesterification for FAME production from cottonseed oil was carried out, and the effect of ultrasonic waves on the properties of Na₂SiO₃ catalyst was assessed by X-ray diffraction (XRD), Fourier transform Infrared (FTIR) and scanning electron microscopy (SEM) characterization of fresh and collected catalysts. An ultrasonic frequency of 30 kHz, ultrasonic power of 200 W and ultrasonic pretreatment irradiation time of 30 min was determined to guarantee a satisfactory degree of transesterification. The optimum production was achieved in the reaction system at 45 °C with methanol/cottonseed oil molar ratio 5:1, catalyst dosage 3% and stirring speed 350 rpm resulting in a FAME yield of above 97% after 60 min of reaction under mechanical stirring with the ultrasonic pretreatment process. The new process has a shorter reaction time, a more moderate reaction temperature, a less amount of methanol and catalyst than only the mechanical stirring process without essential damage to activity and the structure of catalyst. These results are of great significance for applying the ultrasonic pretreatment method to produce FAME.     

Alum as a heterogeneous catalyst for the transesterification of palm oil

Alum has been taken beyond its traditional roles as a water treatment chemical and a confectionary additive to a new role as a catalytic precursor in biodiesel production. Its catalytic potentials were empirically proved via palm oil transesterification with methanol and application of solid state instrumental characterization techniques. The catalyst was very clean, efficient, simple and cheap to produce, and could be clearly separated from the reaction products. When the reaction was carried out under the conditions of catalyst to oil ratio of 7.09 wt%, reaction time of 12 h and temperature of 170 °C, methanol to oil molar ratio of 18:1 and catalyst preconditioned at 550 °C, the yield of fatty acid methyl ester (FAME) obtained was 92.5 wt%.     

Activation of Mg–Al hydrotalcite catalysts for transesterification of rape oil

Mg–Al hydrotalcites with different Mg/Al molar ratios were prepared and characterized by powder X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), thermogravimetric apparatus and differential thermal analysis (TGA-DTA) and scanning electron micrograph (SEM). It was confirmed by XRD that the materials had hydrotalcite structure. The hydrotalcite catalyst calcined at 773 K with Mg/Al molar ratio of 3.0 exhibited the highest catalytic activity in the transesterification. In addition, a study for optimizing the transesterification reaction conditions such as molar ratio of the methanol to oil, the reaction temperature, the reaction time, the stirring speed and the amount of catalyst, was performed. The optimized parameters, 6:1 methanol/oil molar ratio with 1.5% catalyst (w/w of oil) reacted under stirring speed 300 rpm at 65 °C for 4 h reaction, gave a maximum ester conversion of 90.5%. Moreover, the solid catalyst could be easily separated and possibly reused.     

Na/SiO2新型固体碱催化制备生物柴油的研究

以NaOH、正硅酸乙酯和乙醇为原料,经溶胶-凝胶法制备新型固体碱催化剂（Na/SiO₂）,用于催化大豆油与甲醇的酯交换反应制备生物柴油,研究催化剂焙烧温度、n(NaOH)∶n(SiO₂)、n(甲醇)∶n(大豆油)、催化剂用量和反应时间对产率的影响以及催化剂的稳定性。结果表明,固体碱催化剂Na/SiO₂在大豆油与甲醇的酯交换反应中具有较高的催化活性,在催化剂焙烧温度600 ℃、n(NaOH)∶n(SiO₂)=2∶1、n(甲醇)∶n(大豆油)=15∶1、催化剂用量为大豆油质量的7%和反应时间3 h的条件下,脂肪酸甲酯产率可达97.42%,催化剂在稳定性试验中呈现出优良的稳定性。     

酸性离子液体［(CH2)4SO3HMIM］［HSO4］催化潲水油制备生物柴油的研究

制备了酸性离子液体[(CH₂)₄SO₃HMIM］［HSO₄］并用于催化潲水油制备生物柴油,研究了反应时间、反应温度、醇油物质的量比和剂油物质的量比等对酯交换反应转化率的影响,确定了较适宜的反应条件。结果表明,在反应时间4 h、反应温度140 ℃、醇油物质的量比12和剂油物质的量比0.08条件下,酯交换反应转化率为92.13%。制备的生物柴油达到了中国柴油机燃料调合用生物柴油(BD100)标准GB/T20828-2007。     

Biodiesel Production from Sunflower Oil Using K2CO3 Impregnated Kaolin Novel Solid Base Catalyst

Kaolin clay material was loaded with potassium carbonate by impregnation method as a novel, effective, and economically heterogeneous catalyst for biodiesel production of sunflower oil via the transesterification reaction. The structural and chemical properties of the produced catalysts were characterized through several analyses including the X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and Brunauer–Emmett–Teller specific surface area. These revealed the best catalyst for the investigated reaction among different ones prepared based upon various impregnation extent of the potassium carbonate. The influence of this parameter was examined through a comparison of the catalytic activity of differently produced catalysts. The impregnation amount of 20 wt% K₂CO₃ upon the kaolin achieved the highest catalytic activity attributed to its highest basicity. To expand upon the efficiency of transesterification, such reaction parameters including the molar ratio between methanol and oil, reactor loading of the catalyst, and time duration of the reaction were optimized. The highest yield of biodiesel over the K₂O/kaolin catalyst was around 95.3 ± 1.2%, which was achieved using the kaolin support impregnated with 20 wt% of K₂CO₃ under optimum reaction conditions of the catalyst, reactor loading of 5 wt%, reaction temperature of 65 °C, methanol:oil molar ratio of 6:1, and reaction duration time of 4 hours. Ultimately, this optimized catalyst was demonstrated to successfully withstand the aforementioned optimum criteria up to five consecutive reaction cycles while experiencing a rather negligible loss of about 10% of its activity.     

Synthesis of biodiesel from cottonseed oil and methanol using a carbon-based solid acid catalyst

A carbon-based solid acid catalyst was prepared by the sulfonation of carbonized vegetable oil asphalt and used to catalyze the transesterification of methanol with cottonseed oil. This catalyst was characterized by scanning electron microscopy/energy dispersive spectroscopy, BET surface area and pore size measurement, thermogravimetry analysis and Fourier transform infrared spectroscopy. The sulfonated multi-walled carbon nanotubes (s-MWCNTs) was also prepared and used to catalyze the same transesterification as the asphalt catalyst. The asphalt-based catalyst shows higher activity than the s-MWCNTs for the production of biodiesel, which may be correlated to its high acid site density, its loose irregular network and large pores can provide more acid sites for the reactants. The conversion of cottonseed oil 89.93% was obtained (using the asphalt-based catalyst) when the methanol/cottonseed oil molar ratio was 18.2, reaction temperature at 260 °C, reaction time 3.0 h and catalyst/cottonseed oil mass ratio of 0.2%. Also, it can be re-used. The sulfonated polycyclic aromatic hydrocarbons provide an electron-withdrawing function to keep the acid site stable. The catalyst can substantially reduce energy consumption and waste generation in the production of biodiesel.     

Transesterification of karanja (Pongamia pinnata) oil by solid basic catalysts

The transesterification of karanja oil with methanol was carried out using solid basic catalysts. Alkali metal‐impregnated calcium oxide catalysts, due to their strong basicity, catalyze the transesterification of triacylglycerols. The alkali metal (Li, Na, K)‐doped calcium oxide catalysts were prepared and used for the transesterification of karanja oil containing 0.48–5.75% of free fatty acids (FFA). The reaction conditions, such as catalyst concentration, reaction temperature and molar ratio of methanol/oil, were optimized with the solid basic Li/CaO catalyst. This catalyst, at a concentration of 2 wt‐%, resulted in 94.9 wt‐% of methyl esters in 8 h at a reaction temperature of 65 °C and a 12 : 1 molar ratio of methanol to oil, during methanolysis of karanja oil having 1.45% FFA. The yield of methyl esters decreased from 94.9 to 90.3 wt‐% when the FFA content of karanja oil was increased from 0.48 to 5.75%. The performance of this catalyst was not significantly affected in the presence of a high FFA content up to 5.75%. The catalytic activities of Na/CaO and K/CaO were also studied at the optimized reaction conditions. In these two cases, the reaction initially proceeds slowly, however, leading to similar yields as in the case of Li/CaO after 8 h of reaction time. The purified karanja methyl esters have an acid value of 0.36 mg KOH/g and an ester content of 98.6 wt‐%, which satisfy the American as well as the European specifications for biodiesel in terms of acid value and ester content.     

Ca and Zn mixed oxide as a heterogeneous base catalyst for transesterification of palm kernel oil

Transesterification of palm kernel oil with methanol over mixed oxides of Ca and Zn has been investigated batchwise at 60 °C and 1 atm. CaO·ZnO catalysts were prepared via a conventional co-precipitation of the corresponding mixed metal nitrate solution in the presence of a soluble carbonate salt at near neutral conditions. The catalysts were characterized by using techniques of X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA). The results indicated that the mixed oxides possess relatively small particle sizes and high surface areas, compared to pure CaO and ZnO. Moreover, the combination of Ca and Zn reduced the calcination temperature required for decomposition of metal carbonate precipitates to active oxides. Influences of Ca/Zn atomic ratio in the mixed oxide catalyst, catalyst amount, methanol/oil molar ratio, reaction time, and water amount on the methyl ester (ME) content were studied. Under the suitable transesterification conditions at 60 °C (catalyst amount = 10 wt.%, methanol/oil molar ratio = 30, reaction time = 1 h), the ME content of >94% can be achieved over CaO·ZnO catalyst with the Ca/Zn ratio of 0.25. The mixed oxide can be also applied to transesterification of palm olein, soybean, and sunflower oils. Furthermore, the effects of different regeneration methods on the reusability of CaO·ZnO catalyst were investigated.     

Transesterification of edible and non-edible oils over basic solid Mg/Zr catalysts

A series of Mg–Zr catalysts with varying Mg to Zr ratios was prepared by co-precipitation method. These catalysts were characterized by BET surface area, X-ray diffraction, X-ray photo electron spectroscopy and temperature programmed desorption of CO₂. The catalytic activity of these catalysts was evaluated for the room temperature transesterification of both edible and non-edible oils to their corresponding fatty acid methyl esters. The catalyst with Mg/Zr (2:1 wt./wt.%) exhibited exceptional activity towards transesterification reaction within short reaction time. The effects of different reaction parameters such as catalyst to oil mass ratio, reaction temperature, reaction time and methanol to oil molar ratio were studied to optimize the reaction conditions. The reasons for the observed activity of these catalysts are discussed in terms of their basicity and other physico-chemical properties.     

TRANSESTERIFICATION OF PALM OIL AT NEAR-CRITICAL CONDITIONS USING SULFONATED CARBON-BASED ACID CATALYST

This study aims to investigate the production of biodiesel by transesterification of purified palm oil (PPO) at near-critical conditions using a carbon-based catalyst, synthesized by incomplete carbonization of naphthalene in sulfuric acid. The catalyst shows good activity for the reaction; with the most suitable condition found to be at a methanol-to-PPO molar ratio of 12:1, a carbon-based catalyst-to-PPO mass ratio of 0.5 wt.%, a reaction time of 30 min, and a reaction temperature of 270°C. This resulted in a FAME yield of about 95%. However, FAME yields were found to decrease after each reaction cycle from around 95% in the first to 61% in the second cycle, and to only 45% in the third cycle, as a result of catalyst deactivation due to acid leaching.     

Metakaolinite as a catalyst for biodiesel production from waste cooking oil

The use of metakaolinite as a catalyst in the transesterification reaction of waste cooking oil with methanol to obtain fatty acid methyl esters (biodiesel) was studied. Kaolinite was thermally activated by dehydroxylation to obtain the metakaolinite phase. Metakaolinite samples were characterized using X-ray diffraction, N₂ adsorption-desorption, simultaneous thermo-gravimetric analyse/differential scanning calorimetry (TGA/DSC) experiments on the thermal decomposition of kaolinite and Fourier-transform infrared spectrometer (FTIR) analysis. Parameters related to the transesterification reaction, including temperature, time, the amount of catalyst and the molar ratio of waste cooking oil to methanol, were also investigated. The transesterification reaction produced biodiesel in a maximum yield of 95% under the following conditions: metakaolinite, 5 wt-% (relative to oil); molar ratio of oil to methanol, 1∶23; reaction temperature, 160°C; reaction time, 4 h. After eight consecutive reaction cycles, the metakaolinite can be recovered and reused after being washed and dried. The biodiesel thus obtained exhibited a viscosity of 5.4?mm²?s^–1 and a density of 900.1 kg?m^–3. The results showed that metakaolinite is a prominent, inexpensive, reusable and thermally stable catalyst for the transesterification of waste cooking oil.