Kinetics of jatropha oil transesterification catalyzed by modified bentonite and biodiesel purification

doi:10.11949/j.issn.0438-1157.20150813

Abstract

Abstract:

A bentonite catalyst was prepared using acid-treated bentonite modified by calcium hydroxide and sodium hydroxide with wet method, and it was applied in the transesterification of jatropha oil with methanol to form biodiesel. Firstly, the kinetics of this transesterification reaction was studied in the temperature range of 323.15—338.15 K after eliminating both inner and outer diffusion effects. Then, the crude biodiesel from the transesterification was purified using the adsorption of natural bentonite at room temperature, and the effects of bentonite dosage as well as adsorption time on the removal of free glycerin were investigated. The results showed that the conversion of jatropha oil to biodiesel on the prepared catalyst reached 96.7% under the optimized conditions. And the transesterification can be well described using the pseudo-first-order kinetic model with the activation energy of 67.87 kJ·mol^-1. The purified product could meet the requirements of European Standard for biodiesel fuel (EN 14214) with the yield of biodiesel over 96%, when the purification process was performed with a bentonite dosage of 3% (mass) and reaction time of 30 min.

Key words: catalysis, kinetics, biodiesel, solid base, transesterification, bentonite, purification

摘要：

用氢氧化钙和氢氧化钠联合改性活性白土制备了膨润土固体碱催化剂,并用于麻疯树油和甲醇酯交换反应合成生物柴油。主要目的是研究酯交换反应的动力学及纯化反应获得的粗生物柴油使其达到相关国际标准。首先在消除内外扩散的条件下,测定323.15～338.15 K温度范围内的反应动力学数据,并用拟均相模型进行拟合。在室温下使用膨润土为吸附剂对粗生物柴油进行纯化,以移除游离甘油为目标,考察吸附剂用量和吸附时间的影响,以获得适宜纯化条件。结果表明,膨润土固体碱催化剂有较高的活性和稳定性,所得生物柴油粗产品质量较好;反应过程符合拟一级反应动力学机理,活化能67.87 kJ·mol^-1;在3%(质量分数)的膨润土用量,室温吸附30 min的条件下,纯化后的生物柴油符合欧洲标准(EN 14214)且产品收率超过96%。

关键词: 催化, 动力学, 生物柴油, 固体碱, 酯交换, 膨润土, 纯化

CLC Number:

TQ645.8

HU Xueling, WEI Tengyou, WU Lian, ZHANG Hanbing, TONG Zhangfa. Kinetics of jatropha oil transesterification catalyzed by modified bentonite and biodiesel purification[J]. CIESC Journal, 2015, 66(8): 3113-3119.

胡雪玲, 韦藤幼, 吴炼, 张寒冰, 童张法. 改性膨润土催化麻疯树油酯交换反应动力学及生物柴油纯化[J]. 化工学报, 2015, 66(8): 3113-3119.

References 32

[1]	Shahla S, Ngoh G C, Yusoff R. The evaluation of various kinetic models for base-catalyzed ethanolysis of palm oil [J]. Bioresource Technol., 2011, 104: 1-5.
[2]	Gao Yixia (高艺霞), Yan Libin (闫理宾), Xin Zhong (辛忠). Component confirmation and process of biodiesel produced in supercritical conditions with addition of tiny KOH [J].CIESC Journal (化工学报), 2013, 64 (2): 683-688.
[3]	Ding Y, Sun H, Duan J, et al. Mesoporous Li/ZrO2 as a solid base catalyst for biodiesel production from transesterification of soybean oil with methanol [J]. Catal. Commun., 2010, 12 (7): 606-610.
[4]	Fan M, Zhang P, Ma Q. Enhancement of biodiesel synthesis from soybean oil by potassium fluoride modification of a calcium magnesium oxides catalyst [J]. Bioresource Technol., 2012, 104: 447-450.
[5]	Akbar E, Binitha N, Yaakob Z, et al. Preparation of Na doped SiO2 solid catalysts by the sol-gel method for the production of biodiesel from jatropha oil [J]. Green Chem., 2009, 11 (11): 1862-1866.
[6]	Li J, Xu H, Fei Z A, et al. CaO/NaA combined with enzymatic catalyst for biodiesel transesterification [J]. Catal. Commun., 2012, 28: 52-57.
[7]	Boz N, Degirmenbasi N, Kalyon D M. Transesterification of canola oil to biodiesel using calcium bentonite functionalized with K compounds [J]. Appl. Catal. B-Environ., 2013, 138-139: 236-242.
[8]	Cross H E, Parkes G, Brown D R. Microwave calcination of Cu/Mg/Al hydrotalcite catalyst precursor [J]. Appl. Catal. A: General, 2012, 429/430: 24-30.
[9]	Zhang Hanbing (张寒冰), Hu Xueling (胡雪玲), Wei Tengyou (韦藤幼), et al. Progress of preparation and applications of alkaline Ca-bentonite [J]. Chem. Ind. Eng. Prog. (化工进展), 2012, 31: 1395-1401.
[10]	Fan Xinmei (樊欣梅), Zhang Dehu (张德虎), Huang Biao (黄彪), et al. Preparation of solid base catalyst supported on bentonite and its application in synthesis of biodiesel [J]. Chem. Ind. Eng. Prog. (化工进展), 2009, 28: 1951-1954.
[11]	Mao Geqing (毛格清), Wu Lian (吴炼), Wei Tengyou (韦藤幼), et al. The preparation and utilization in biodiesel of strong alkaline clay catalyst [J]. Non-Metallic Mines (非金属矿), 2012, 35: 39-42.
[12]	Chantrasa A, Phlernjai N, Goodwin Jr J G. Kinetics of hydrotalcite catalyzed transesterification of tricaprylin and methanol for biodiesel synthesis [J]. Chem. Eng. Journal, 2011, 168 (1): 333-340.
[13]	Vujicic D, Comic D, Zarubica A, et al. Kinetics of biodiesel synthesis from sunflower oil over CaO heterogeneous catalyst [J]. Fuel, 2010, 89 (8): 2054-2061.
[14]	Singh A K, Fernando S D. Preparation and reaction kinetics studies of Na-based mixed metal oxide for transesterification [J]. Energ. Fuel, 2009, 23 (10): 5160-5164.
[15]	Xiao Y, Gao L, Xiao G, et al. Kinetics of the transesterification reaction catalyzed by solid base in a fixed-bed reactor [J]. Energ. Fuel, 2010, 24 (11): 5829-5833.
[16]	Dang T H, Chen B H, Lee D J. Application of kaolin-based catalysts in biodiesel production via transesterification of vegetable oils in excess methanol [J]. Bioresource Technol., 2013, 145: 175-181.
[17]	Berrios M, Martín M A, Chica A F, et al. Purification of biodiesel from used cooking oils [J]. App. Energ., 2011, 88:3625-3631.
[18]	Mazzieri V A, Vera C R, Yori J C. Adsorptive properties of silica gel for biodiesel refining [J]. Energ. Fuel, 2008, 22 (6): 4281-4284.
[19]	Cunha M E D. Dry washing in biodiesel purification: a comparative study of adsorbents [J]. J. Braz. Chem. Soc., 2011, 22 (3): 558-563.
[20]	Hu Xueling (胡雪玲), Wei Tengyou (韦藤幼), Mao Geqing (毛格清), et al. Refinement of jatropha oil by modified activated clay [J]. Fine Chemicals (精细化工), 2011, 28 (10): 974-977.
[21]	Rashtizadeh E, Farzaneh F, Ghandi M. A comparative study of KOH loaded on double aluminosilicate layers, microporous and mesoporous materials as catalyst for biodiesel production via transesterification of soybean oil [J]. Fuel, 2010, 89 (11): 3393-3398.
[22]	Meher L, Dharmagadda V S S, Naik S. Optimization of alkali-catalyzed transesterification of Pongamia pinnata oil for production of biodiesel [J]. Bioresource Technol., 2006, 97 (12): 1392-1397.
[23]	Lü Yangxiao (吕扬效), Yang Jiguo (杨继国), Yang Bo (杨博). A method for determination of trace free glycerol in oil [J]. China Oils and Fats (中国油脂), 2006, 31: 66-68.
[24]	Guo Pingmei (郭萍梅), Huang Qingde (黄庆德). Study on analytical method of free glycerin and total glycerin in biodiesel [J]. Cereals and Oils (粮食与油脂), 2003, (8): 41-42.
[25]	Noiroj K, Intarapong P, Luengnaruemitchai A, et al. A comparative study of KOH/Al2O3 and KOH/NaY catalysts for biodiesel production via transesterification from palm oil [J]. Renew. Energ., 2009, 34 (4): 1145-1150.
[26]	Mutreja V, Singh S, Ali A. Biodiesel from mutton fat using KOH impregnated MgO as heterogeneous catalysts [J]. Renew. Energy, 2011, 36 (8): 2253-2258.
[27]	Liu H, Su L, Liu F, et al. Cinder supported K2CO3 as catalyst for biodiesel production [J]. Appl. Catal., 2011, 106 (3/4): 550-558.
[28]	Soetaredjo F E, Ayucitra A, Ismadji S, et al. KOH/bentonite catalysts for transesterification of palm oil to biodiesel [J]. Appl. Clay Sci., 2011, 53: 341-346.
[29]	Li E, Xu Z P, Rudolph V. MgCoAl-LDH derived heterogeneous catalysts for the ethanol transesterification of canola oil to biodiesel [J]. Appl. Catal., 2009, 88 (1): 42-49.
[30]	Liu X, He H, Wang Y, et al. Transesterification of soybean oil to biodiesel using SrO as a solid base catalyst [J]. Catal. Commun., 2007, 8 (7): 1107-1111.
[31]	Liu X, He H, Wang Y, et al. Transesterification of soybean oil to biodiesel using CaO as a solid base catalyst [J]. Fuel, 2008, 87 (2): 216-221.
[32]	Jacobson K, Gopinath R, Meher L C, et al. Solid acid catalyzed biodiesel production from waste cooking oil [J]. Appl. Catal., 2008, 85 (1/2): 86-91.