丙烯酸甲酯改性氧化钙催化制备生物柴油的研究

以丙烯酸甲酯为改性剂,对氧化钙表面进行改性,研究丙烯酸甲酯改性氧化钙催化油脂-甲醇酯交换体系制备生物柴油性能的影响。考察了改性剂用量、醇油摩尔比以及催化剂用量对体系酯化率的影响,并对催化剂进行表征。结果表明,表面改性后,氧化钙的催化性能得到极大改善。在反应温度为65℃、丙烯酸甲酯改性剂用量为0.5%、醇油摩尔比为20∶1、催化剂用量为15%、反应时间2 h条件下,生物柴油产率高达96.55%,与未改性氧化钙相比,相同条件下生物柴油产率提高16.18%。同时,丙烯酸甲酯改性氧化钙还具有良好的耐水性能,在体系含水量1%条件下催化制备生物柴油产率仍能达到81%。催化剂BET表征结果显示,改性后氧化钙较改性前的比表面积、平均孔径和孔体积均增大;热重表征结果表明,氧化钙改性后热稳定性提高,颗粒分散性增强;XRD、FTIR表征显示,丙烯酸甲酯改性剂已经成功键合到氧化钙表面。     

丙烯酸甲酯改性氧化钙催化制备生物柴油的研究

以丙烯酸甲酯为改性剂,对氧化钙表面进行改性,研究丙烯酸甲酯改性氧化钙催化油脂-甲醇酯交换体系制备生物柴油性能的影响。考察了改性剂用量、醇油摩尔比以及催化剂用量对体系酯化率的影响,并对催化剂进行表征。结果表明,表面改性后,氧化钙的催化性能得到极大改善。在反应温度为65℃、丙烯酸甲酯改性剂用量为0.5%、醇油摩尔比为20∶1、催化剂用量为15%、反应时间2 h条件下,生物柴油产率高达96.55%,与未改性氧化钙相比,相同条件下生物柴油产率提高16.18%。同时,丙烯酸甲酯改性氧化钙还具有良好的耐水性能,在体系含水量1%条件下催化制备生物柴油产率仍能达到81%。催化剂BET表征结果显示,改性后氧化钙较改性前的比表面积、平均孔径和孔体积均增大;热重表征结果表明,氧化钙改性后热稳定性提高,颗粒分散性增强;XRD、FTIR表征显示,丙烯酸甲酯改性剂已经成功键合到氧化钙表面。     

改性4A分子筛催化高酸值油脂制备生物柴油

以浓硫酸为改性剂,采用化学键合方法对固体分子筛4A表面进行磺化改性。以此为催化剂催化油酸-菜籽油模拟的高酸值油脂-甲醇酯交换反应制备生物柴油。结果表明,反应体系在65℃,醇/油摩尔比为16∶1条件下反应6h,生物柴油产率可达到88.39%,比相同条件下未改性的分子筛4A和浓硫酸催化高酸油脂制备的生物柴油产率明显提高。     

硝酸镧改性钙镁锌催化剂制备生物柴油

通过掺杂不同比例的硝酸镧实现对钙镁锌三金属氧化物固体碱催化剂的改性,对改性催化剂用于制备生物柴油的工艺条件的了优化,并通过SEM的方法对改性催化剂的表面结构进行表征。结果表明硝酸镧的加入可以降低钙镁锌三金属氧化物固体碱催化剂最适催化温度并减少催化剂用量。添加3%(质量分数)的硝酸镧的改性钙镁锌体系催化剂,在反应温度为50℃时,醇油摩尔比为15∶1,反应时间为1h时,生物柴油产率可达到86.8%。这种改性催化剂更适于工业化应用。     

改性氧化钙在催化羟醛缩合反应中的应用评价

对氧化钙进行改性并进行催化性能和吸湿率评价。实验结果表明,经溴化苄、溴代苯改性后的氧化钙催化羟醛缩合反应的能力大幅度提高,产率高达90%以上。以溴代苯效果更为显著,10-4用量下改性的氧化钙催化性最好,产率高达98%,并且吸湿率大幅度降低,低于20%。红外分析发现溴代苯改性的氧化钙抗二氧化碳腐蚀能力要强于其他修饰剂,这与该改性氧化钙表现出最佳反应活性结果吻合。     

改性氧化钙在催化羟醛缩合反应中的应用评价

对氧化钙进行改性并进行催化性能和吸湿率评价。实验结果表明:经溴化苄、溴代苯改性后的氧化钙催化羟醛缩合反应的能力大幅度提高,产率高达90%以上。以溴代苯效果更为显著,10-4用量下改性的氧化钙催化性最好,产率高达98%,并且吸湿率大幅度降低,低于20%。红外分析发现溴代苯改性的氧化钙抗二氧化碳腐蚀能力要强于其他修饰剂,这与该改性氧化钙表现出最佳反应活性结果吻合。     

改性硅藻土固定化脂肪酶催化蓖麻油制备生物柴油

采用改性硅藻土做为载体,用吸附法对脂肪酶进行固定化,对固定条件进行优化,利用固定化脂肪酶催化蓖麻油制备生物柴油,考察反应时间、温度、醇油比及酶用量对转化率的影响和固定化脂肪酶催化合成生物柴油的稳定性。研究表明,硅烷化试剂添加量0.4%、温度30℃和时间4~6 h时固定化脂肪酶的活性最高,在醇油比为9:1,固定化酶用量为蓖麻油质量的4%,温度为60℃,反应时间为10 h的条件下,生物柴油的产率最高,经过3个批次的反应后,其产率都在40%以上,该固定化酶催化合成生物柴油有良好的工业化前景。     

可膨胀石墨对动物油脂的催化酯交换反应研究

本研究以动物油为原料，可膨胀石墨作催化剂，通过与乙醇的酯交换反应制备了生物柴油。正交试验考察了反应时间、油一醇质量比和催化剂加入量等因素对生物柴油产率的影响。实验确定酯交换反应最佳反应条件为：油醇质量比1：1．5、催化剂用量为油重的20％、反应时间12h、反应温度控制为80℃。极差分析结果表明：反应时间对生物柴油产率的影响最大，其次为催化剂用量及油醇比例。可膨胀石墨的膨胀容积越大，酯交换反应产率越高。加入表面活性剂可以加快反应速度，提高生物柴油产率。加入壬基酚聚氧乙烯醚（OP-4）后，最佳条件下生物柴油产率为0．935g／g。可膨胀石墨可以作为动物油脂与乙醇酯交换反应的催化荆。     

活性炭负载碳酸钠催化猪油制备生物柴油

以猪油为原料,优化了活性炭负载碳酸钠催化猪油制备生物柴油的工艺。分别采用单因素实验和正交实验对反应条件进行了优化,考察了醇油摩尔比、催化剂用量、反应时间、反应温度的影响,结果表明最佳反应条件为:醇油摩尔比9∶1、催化剂用量为9%、反应时间3.5 h、反应温度70℃。在此条件下,生物柴油产率为95.3%。     

棕榈油碱催化制备生物柴油实验研究

用氢氧化钾作催化剂,考察了反应温度、催化剂用量、醇油摩尔比、反应时间对棕榈油和甲醇制备生物柴油产率的影响。结果表明,最佳反应条件为:反应温度40℃,催化剂用量0.6%,醇油摩尔比6∶1,反应时间2.0 h。此时,生物柴油产率可达97.82%。     

Biodiesel production from soybean oil using modified calcium loaded on rice husk activated carbon as a low-cost basic catalyst

Activated carbon was obtained by hydrothermal process using rice husk as raw materials. The study in our lab had been developed to produce high-quality biodiesel from soybean oil with the activated carbon-base catalyst. The polyethylene glycol (PEG 400) modified calcium loaded on the rice husk activated carbon (CaO/AC) catalyst was prepared via the dipping method and then was used as a heterogeneous solid-base catalyst to produce biodiesel. The effects of CaO/AC ratio and calcination time on catalytic performance were researched according to the yield of biodiesel, and the optimum reaction conditions for biodiesel from soybean oil via PEG 400–modified CaO/AC catalyst were evaluated. The results showed that the yield of fatty acid methyl ester (FAME) achieved 93.01% at the reaction temperature of 342 K, methanol/oil molar ratio of 10:1, and reaction time of 6 h. All in all, modified CaO/AC catalyst showed very high activity for transesterification of soybean oil and had catalytic repeated availability.     

Advances on the development of novel heterogeneous catalysts for transesterification of triglycerides in biodiesel

This paper describes experimental work done towards the search for more profitable and sustainable alternatives regarding biodiesel production, using heterogeneous catalysts instead of the conventional homogenous alkaline catalysts, such as NaOH, KOH or sodium methoxide, for the methanolysis reaction. This experimental work is a first stage on the development and optimization of new solid catalysts, able to produce biodiesel from vegetable oils. The heterogeneous catalytic process has many differences from the currently used in industry homogeneous process. The main advantage is that, it requires lower investment costs, since no need for separation steps of methanol/catalyst, biodiesel/catalyst and glycerine/catalyst. This work resulted in the selection of CaO and CaO modified with Li catalysts, which showed very good catalytic performances with high activity and stability. In fact FAME yields higher than 92% were observed in two consecutive reaction batches without expensive intermediate reactivation procedures. Therefore, those catalysts appear to be suitable for biodiesel production.     

Biodiesel production from vegetable oil using heterogenous acid and alkali catalyst

Zanthoxylum bungeanum seed oil (ZSO) with high free fatty acids (FFA) can be used for biodiesel production by ferric sulfate-catalyzed esterification followed by transesterification using calcium oxide (CaO) as an alkaline catalyst. Acid value of ZSO with high FFA can be reduced to less than 2 mg KOH/g by one-step esterification with methanol-to-FFA molar ratio 40.91:1, ferric sulfate 9.75% (based on the weight of FFA), reaction temperature 95 °C and reaction time 2 h, which satisfies transesterification using an alkaline catalyst. The response surface methodology (RSM) was used to optimize the conditions for ZSO biodiesel production using CaO as a catalyst. A quadratic polynomial equation was obtained for biodiesel conversion by multiple regression analysis and verification experiments confirmed the validity of the predicted model. The optimum combination for transesterification was methanol-to-oil molar ratio 11.69:1, catalyst amount 2.52%, and reaction time 2.45 h. At this optimum condition, the conversion to biodiesel reached above 96%. This study provided a practical method to biodiesel production from raw feedstocks with high FFA with high reaction rate, less corrosion, less toxicity, and less environmental problems.     

Microwave irradiation-assisted transesterification of soybean oil to biodiesel catalyzed by nanopowder calcium oxide

This study examined the effect of a heterogeneous base catalyst on the transesterification of soybean oil assisted by microwave irradiation. The results showed that nanopowder calcium oxide (nano CaO) was very efficient in converting soybean oil to biodiesel, and microwave irradiation is more efficient than the conventional bath for biodiesel production. However, the water content of methanol can not improve the conversion rate catalyzed by nano CaO.The suitable reaction conditions that can reach a 96.6% of conversion rate were methanol/oil molar ratio, 7:1; amount of catalyst used, 3.0 wt.%; reaction temperature, 338 K; and reaction time, 60 min. The biodiesel produced is within the limits prescribed by the standard of EN-14214.     

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

Here 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.     

Preparation of a CaO Nanocatalyst and Its Application for Biodiesel Production Using Butea monosperma Oil: An Optimization Study

CaO nanoparticles (NP) were synthesized through solution combustion using crude glycerin (biodiesel by‐product) as the combustion fuel. The synthesized CaO NP were characterized using Fourier transform infrared spectrometer (FTIR), X‐ray diffractometer (XRD), temperature programmed desorption of carbon dioxide (CO₂‐TPD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The CaO NP were successfully used as a catalyst for biodiesel synthesis. Response surface methodology was used to determine the optimal conditions for biodiesel production from Butea monosperma oil (BMO) using central composite design. A total of 20 experiments were designed and conducted to study the effects of the methanol to BMO molar ratio, reaction time, and catalyst loading conditions on the biodiesel yield. A yield of 96.2% of Butea monosperma methyl ester (BMME or biodiesel) was obtained under optimum conditions, namely a molar ratio (methanol to BMO) of 9:1, a reaction time of 70 min, a catalyst loading of 1.60 wt%, a constant temperature of 65 °C, and an agitation speed of 600 rpm. The fatty‐acid composition of BMO was characterized through gas chromatography. Finally, BMME was characterized using FTIR, ¹H NMR, and ¹³C NMR, and the fuel properties of BMME were determined using the test methods of the American Society for Testing and Materials.     

Optimization of biodiesel production process in a continuous microchannel using response surface methodology

We assessed the biodiesel production process in a continuous microchannel through preparation of a heterogeneous catalyst (CaO/MgO) from demineralized water plant sediment. This mixed oxide catalyst was used for transesterification of rapeseed oil as feedstock by methanol to produce biodiesel fuel at various conditions. A microchannel, utilized as a novel reactor, was applied to convert rapeseed oil into biodiesel in multiple steps. The effects of the process variables, such as catalyst concentration, methanol to oil volume ratio, n-hexane to oil volume ratio, and reaction temperature on the purity of biodiesel, were carefully investigated. Box-Behnken experimental design was employed to obtain the maximum purity of biodiesel response surface methodology. The optimum condition for the production of biodiesel was the following: catalyst concentration of 7.875 wt%, methanol to oil volume ratio of 1.75: 3, n-hexane to oil volume ratio of 0.575: 1, and reaction temperature of 70 °C.     

Palm oil transesterification in sub- and supercritical methanol with heterogeneous base catalyst

An environmentally benign process for the production of methyl ester using γ-alumina supported heterogeneous base catalyst in sub- and supercritical methanol has been developed. The production of methyl ester in refluxed methanol conventionally utilized double promoted γ-alumina heterogeneous base catalyst (CaO/KI/γ-alumina); however, this process requires a large amount of catalyst and a long reaction time to produce a high yield of methyl ester. This study carries out methyl ester production in sub- and supercritical methanol with the introduction of an optimized catalyst used in the previous work for the purpose of improving the process and enhancing efficiency. CaO/KI/γ-Al₂O₃ catalyst was prepared by precipitation and impregnation methods. The effects of catalyst amount, reaction temperature, reaction time, and the ratio of oil to methanol on the yield of biodiesel ester were studied. The reaction was carried out in a batch reactor (8.8 ml capacity, stainless steel, AKICO, Japan). Results show that the use of CaO/KI/γ-Al₂O₃ catalyst effectively reduces both reaction time and required catalyst amount. The optimum process conditions were at a temperature of 290 °C, ratio of oil to methanol of 1:24, and a catalyst amount of 3% over 60 min of reaction time. The highest yield of biodiesel obtained under these optimum conditions was almost 95%.     

Transesterification of Canola Oil to Biodiesel Using CaO/Talc Nanopowder as a Mixed Oxide Catalyst

A series of heterogeneous catalysts including different molar ratios of CaO/talc was synthesized to study the transesterification reaction of canola oil and methanol under different reaction conditions. Characterization and kinetic results revealed that the activity of this catalyst was enhanced due to the increase of CaO/talc molar ratio value leading to an improvement in the biodiesel production. Moreover, the effect of various parameters on the activity of the undertaken catalysts was studied in order to determine the optimum process conditions. Leaching measurements and the durability of the CaO/talc catalyst under several reaction cycles were evaluated and proved it to be a stable catalyst.     

Transesterification of Refined Sunflower Oil to Biodiesel Using a CaO/ZSM-5 Powder Catalyst

The production of biodiesel from refined sunflower vegetable oil over basic CaO/ZSM-5 catalysts was investigated. Several catalysts with various loadings of CaO on ZSM-5 were prepared, calcined at 800 °C, and characterized by N₂ adsorption-desorption, X-ray diffraction, Fourier transform infrared spectroscopy, and CO₂-temperature-programmed desorption techniques. Calcined catalysts were tested in the transesterification reaction and reaction conditions were optimized by varying the catalyst-to-oil ratio and reaction time. The most active catalyst was the CaO/ZSM-5 catalyst with a 35 wt % loading which gave the highest fatty acid methyl ester yield. The high catalytic activity was attributed to the active basic sites generated following CaO addition. Furthermore, the catalyst demonstrated stability against the leaching process.