新型Brönsted-Lewis酸性催化剂LaPW12O40/SiO2制备及其在催化酯化反应合成生物柴油中的应用

舒庆; 唐国强; 刘峰生; 邹文强; 贺江凡

新型Brönsted-Lewis酸性催化剂LaPW₁₂O₄₀/SiO₂制备及其在催化酯化反应合成生物柴油中的应用

江西理工大学冶金与化学工程学院, 江西赣州 341000

基金项目:

国家自然科学基金 21206062

国家自然科学基金 21466013

江西省自然科学（青年）基金计划重大项目 20143ACB21018

详细信息

通讯作者:
舒庆, Tel: 07978312204, E-mail: shuqing@jxust.edu.cn

中图分类号: TQ645.8
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出版历程
- 收稿日期: 2017-03-28
- 修回日期: 2017-06-01
- 网络出版日期: 2021-01-23
- 刊出日期: 2017-08-10

Preparation and application of a novel Brönsted-Lewis acid catalyst LaPW₁₂O₄₀/SiO₂ for the synthesis of biodiesel via esterification reaction

College of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China

Funds:

The project was supported by the National Natural Science Foundation of China 21206062

The project was supported by the National Natural Science Foundation of China 21466013

Major project of Natural Science Foundation of Jiangxi Province for Youth 20143ACB21018

摘要

摘要: 以十二磷钨杂多酸（Tungstophosphoric acid，H₃PW₁₂O₄₀）为基体，分别通过普通浸渍法、溶胶凝胶法和超声浸渍法进行了La³⁺改性作用，合成了三种固体酸催化剂A-LaPW₁₂O₄₀、B-LaPW₁₂O₄₀/SiO₂和C-LaPW₁₂O₄₀。采用X射线荧光光谱（XRF）、孔径比表面积测定、X射线粉末衍射（XRD）、透射电镜（TEM）、红外光谱（FT-IR）、热重（TG）、N₂吸附-脱附、NH₃程序升温脱附（NH₃-TPD）、吡啶吸附红外光谱（Py-FTIR）、X射线光电子能谱（XPS）等方法对合成的催化剂进行了表征，并比较了以上催化剂在用于催化以油酸和甲醇为反应物经酯化反应合成生物柴油时的活性和稳定性。结果表明，B-LaPW₁₂O₄₀/SiO₂具有最高催化活性，当甲醇与油酸的物质的量比为8:1，催化剂用量为反应物总质量的2%，反应温度为65 ℃，反应1 h后，油酸的转化率即高达93%。循环使用B-LaPW₁₂O₄₀/SiO₂催化剂六次后，油酸的转化率仍高达86.4%。B-LaPW₁₂O₄₀/SiO₂的高催化活性和稳定性可归因于在溶胶凝胶的转化过程中，作为硅源材料的四乙氧基硅（TEOS）易在酸性条件下发生水解反应形成SiO₂网络，进而SiO₂网络中的硅醇键与H₃PW₁₂O₄₀中的H⁺发生配位作用，生成具有强静电吸附力的（≡Si-OH²⁺）（H₂PW₁₂O₄₀^-）络合物。随着该络合物的形成，促进了La³⁺在SiO₂表面的吸附而堵塞了H₃PW₁₂O₄₀的孔道结构，抑制了H₃PW₁₂O₄₀颗粒在焙烧过程中进一步聚集长大。SiO₂将作为载体并以干凝胶状态存在于B-LaPW₁₂O₄₀/SiO₂催化剂中，由于SiO₂凝胶的高比表面积而使B-LaPW₁₂O₄₀/SiO₂具有了较大的比表面积，从H₃PW₁₂O₄₀的1.4 m²/g增加至31.3 m²/g。并且，通过吡啶吸附红外光谱确定B-LaPW₁₂O₄₀/SiO₂为Brönsted-Lewis酸型固体酸，由于Brönsted酸位易与酯化反应过程中生成的水发生水合反应而失活，因而Lewis酸位的形成有助于减少催化剂的失活现象发生。Lewis酸位的出现可归因于（≡Si-OH²⁺）（H₂PW₁₂O₄₀^-）与吸附在其表面的具有强吸电子作用的La³⁺发生键合作用后生成了LaPW₁₂O₄₀/SiO₂。
- 镧改性 /
- 磷钨杂多酸 /
- 溶胶-凝胶法 /
- Brönsted-Lewis固体酸 /
- 酯化反应
Abstract: In this study, H₃PW₁₂O₄₀ (Tungstophosphoric acid) was applied as matrix, and which was modified by La³⁺ through conventional impregnation method, ultrasonic impregnation method and sol-gel method, obtained three solid acid catalysts: A-LaPW₁₂O₄₀, B-LaPW₁₂O₄₀/SiO₂ and C-LaPW₁₂O₄₀. These above catalysts were characterized by X-ray fluorescence spectrometer, specific surface area and porosity analyzer, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectoscopy, thermogravimetric analysis, N₂/adsorption-desorption, NH₃ temperature programmed desorption, pyridine adsorption IR spectra and X-ray photoelectron spectroscopy. The catalytic activities and stabilities of them were compared when they were used for the catalytic synthesis of biodiesel from the esterification reaction of oleic acid and methanol. Results shown that the B-LaPW₁₂O₄₀/SiO₂ has highest catalytic activity and stability: the conversion of oleic acid can be high to 93% when the molar ratio of methanol to oleic acid was 8:1, mass ratio of catalyst to reactants was 2%, reaction temperature was 65 ℃ and reaction time was 1 h; the conversion of oleic acid maintained 86.4% after B-LaPW₁₂O₄₀/SiO₂ had been cycled six times. The high catalytic activity and stability of B-LaPW₁₂O₄₀/SiO₂ can be explained as follows: a SiO₂ network was formed from the hydrolytic action of Si(OC₂H₅)₄ (TEOS) under acidic conditions via Sol-Gel process. The H⁺ of H₃PW₁₂O₄₀ will bond with Si-OH in SiO₂ network to form a (≡Si-OH²⁺)(H₂PW₁₂O₄₀^-) complex with strong electrostatic adsorption force, thus promoting the adsorption of La³⁺ on the surface of SiO₂, greatly. As a result, the pore structure of H₃PW₁₂O₄₀ will be blockaged, the grow up of H₃PW₁₂O₄₀ particles in the roasting process also will be inhibited. In addition, SiO₂ may be existed in the form of dry gel in the B-LaPW₁₂O₄₀/SiO₂ catalyst and acted as carrier. It will be favorable for the improvent of the surface area of B-LaPW₁₂O₄₀/SiO₂ since SiO₂ has high surface area, so the surface area of B-LaPW₁₂O₄₀/SiO₂ has increased from the 1.4 m²/g of H₃PW₁₂O₄₀ to the 31.3 m²/g. And more, LaPW₁₂O₄₀/SiO₂ has been determined from the Py-FTIR spectra of pyridine adsorption analysis, which is a Brönsted-Lewis solid acid. The formation of Lewis acid sites can help to reduce the deactivation of a solid acid catalyst: some H₂O will be generated from the esterification reaction, and hydration will occur between Brönsted acid site and H₂O, so the deactivation will occur. The formation of Lewis acid sites can be ascribed to the strong electrophilic action of La³⁺ after it has been bonded with (≡Si-OH²⁺)(H₂PW₁₂O₄₀^-) to form LaPW₁₂O₄₀/SiO₂.
- lanthanum modification /
- tungstophosphoric acid /
- sol-gel method /
- Brönsted-Lewis solid acid /
- esterification

HTML全文

图 1 A-LaPW₁₂O₄₀、B-LaPW₁₂O₄₀/SiO₂、C-LaPW₁₂O₄₀和H₃PW₁₂O₄₀催化剂的透射电镜照片

Figure 1 TEM images of A-LaPW₁₂O₄₀, B-LaPW₁₂O₄₀/SiO₂, C-LaPW₁₂O₄₀ and H₃PW₁₂O₄₀

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图 2 催化剂的XRD谱图

Figure 2 XRD patterns of four catalysts

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图 3 催化剂的TG、DTA、DTG曲线

Figure 3 TG, DTA, DTG analysis of four catalysts

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图 4 催化剂的红外光谱谱图

Figure 4 Infrared spectra of four catalysts

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图 5 催化剂的N₂吸附-脱附等温线

Figure 5 N₂ adsorption-desorption isotherms of four catalysts

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图 6 催化剂的氨程序升温脱附曲线

Figure 6 NH₃ temperture-programmed desorption profiles of four catalysts

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图 7 催化剂的活性对比

the molar ratio of methanol to oleic acid was 8:1, mass ratio of catalyst to reactants was 2%, reaction temperature was 65 ℃ and reaction time was 8 h

Figure 7 Comparison of catalytic activity

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图 8 催化剂的稳定性

the molar ratio of methanol to oleic acid was 8:1, reaction temperature was 65 ℃, mass ratio of catalyst to reactants was 2% and reaction time was 1 h

Figure 8 Comparison of catalytic stability

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图 9 B-LaPW₁₂O₄₀/SiO₂催化剂的吡啶红外吸附谱图

Figure 9 Pyridine adsorption Py-FTIR spectrum of B-LaPW₁₂O₄₀/SiO₂ catalyst

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图 10 催化剂B的X射线光电子能谱图

Figure 10 Catalyst B X-ray photoelectron spectroscopy of La 3d(a), W 4f(b), O 1s(c), P 2p(d), Si 2p(e)

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表 1 催化剂中各元素的含量

Table 1 Atomic percentages of different elements of four catalysts

表 2 催化剂的比表面积、孔容和孔径

Table 2 Surface area, pore volume and pore size of catalysts

表 3 不同固体酸在催化油酸和甲醇酯化反应合成生物柴油时的催化活性比较

Table 3 Comparison of activity of different solid acids for the synthesis of biodiesel from esterification of oleci acid and methanol

参考文献(22)

[1]	HAJJARI M, TABATABAEI M, AGHBASHLO M, GHANAVATI H. A review on the prospects of sustainable biodiesel production: A global scenario with an emphasis on waste-oil biodiesel utilization[J]. Renew Sustain Energy Rev, 2017, 72: 445-464. doi: 10.1016/j.rser.2017.01.034
[2]	XU Y J, LI G X, SUN Z Y. Development of biodiesel industry in China: Upon the terms of production and consumption[J]. Renew Sustain Energy Rev, 2016, 54: 318-330. doi: 10.1016/j.rser.2015.10.035
[3]	VHAD M R, MARCHETTI J M. A review on recent advancement in catalytic materials for biodiesel production[J]. Sust Energ Rev, 2015, 50: 696-718. doi: 10.1016/j.rser.2015.05.038
[4]	SINGH S, PATEL A. Selective green esterification and oxidation of glycerol over 12-tungstophosphoric acid anchored to MCM-48[J]. Ind Eng Chem Res, 2014, 53: 14592-14600. doi: 10.1021/ie5026858
[5]	SERT E, ATALAY F S. Esterification of acrylic acid with different alcohols catalyzed by zirconia supported tungstophosphoric acid[J]. Ind Eng Chem Res, 2012, 51: 6666-6671. doi: 10.1021/ie202609f
[6]	LI L X, LIU B Y, WU Z W, YUAN X, LUO H A. Preparation of Keggin-type mono-lacunary phosphotungstic-ammonium salt and its catalytic performance in ammoximation of cyclohexanone[J]. Chem Eng J, 2015, 280: 670-676. doi: 10.1016/j.cej.2015.06.048
[7]	CAICEDO A M E, RENGIFO-HERRERA J A, FLORIAN P, BLANCO M N, ROMANELLI G P, PIZZIO L R. Valorization of biomass derivatives: Keggin heteropolyacids supported on titania as catalysts in the suitable synthesis of 2-phenoxyethyl-2-furoate[J]. J Mol Catal A: Chem, 2016, 425: 266-274. doi: 10.1016/j.molcata.2016.10.024
[8]	ZHANG X Y, ZHANG D, SUN Z, XUE L F, WANG X H, JIANG Z J. Highly efficient preparation of HMF from cellulose using temperature-responsive heteropolyacid catalysts in cascade reaction[J]. Appl Catal B: Environ, 2016, 196: 50-56. doi: 10.1016/j.apcatb.2016.05.019
[9]	WU X Z, LIU Y T, LIU R, WANG L L, LU Y B, XIA X N. Hydroxyalkylation of phenol to bisphenol F over heteropolyacid catalysts: The effect of catalyst acid strength on isomer distribution and kinetics[J]. J Colloid Interf Sci, 2016, 481: 75-81. doi: 10.1016/j.jcis.2016.07.043
[10]	SHI H X, ZHANG T Y, AN T C, LI B, WANG X. Enhancement of photocatalytic activity of nano-scale TiO₂, particles co-doped by rare earth elements and heteropolyacids[J]. J Colloid Interf Sci, 2012, 380: 121-127. doi: 10.1016/j.jcis.2012.04.069
[11]	戈军伟, 杜治平, 袁华, 杨小俊, 吴元欣. Keggin型磷钼矾杂多化合物在氧化羰基化合成碳酸二苯酯中的应用[J].应用化工, 2009, 38(1): 19-22. http://www.cnki.com.cn/Article/CJFDTOTAL-SXHG200901007.htm GE Jun-wei, DU Zhi-ping, YUAN Hua, YANG Xiao-jun, WU Yan-xin. Application of Keggin type molybdovanadophosphoric compounds in synthesis of diphenyl carbonate by oxidative carbonylation with phenol [J]. Appl Chem Ind, 2009, 38(1): 19-22. http://www.cnki.com.cn/Article/CJFDTOTAL-SXHG200901007.htm
[12]	郭晓俊, 黄崇品.反荷离子及制备方法对Keggin型杂多化合物结构和性质的影响[J].石油化工, 2008, 37(3): 216-221. http://www.cnki.com.cn/Article/CJFDTOTAL-SYHG200803005.htm GUO Xiao-jun, HUANG Chong-pin. Effects of counter-ions and preparation methods on structures and properties of Keggin-type heteropoly compounds[J]. Petrochem Technol, 2008, 37(3): 216-221. http://www.cnki.com.cn/Article/CJFDTOTAL-SYHG200803005.htm
[13]	MATTOS F C G D, SOUZA J A D S D, COTRIM A B D A, MACEDO J L, DIAS J A, DIAS S C L, GHESTI G F. Lewis acid/surfactant rare earth trisdodecylsulfate catalysts for biodiesel production from waste cooking oil[J]. Appl Catal A: Gel, 2012, 423/424(8): 1-6. http://www.sciencedirect.com/science/article/pii/S0926860X12001081
[14]	MARCI G, GARCIA-LOPEZ E I, POMILLA F R, LIOTTA L F, PALMISANO L. Enhanced (photo) catalytic activity of Wells-Dawson (H₆P₂W₁₈O₆₂) in comparison to Keggin (H₃PW₁₂O₄₀) heteropolyacids for 2-propanol dehydration in gas-solid regime[J]. Appl Catal A: Gen, 2016, 528: 113-122. doi: 10.1016/j.apcata.2016.10.002
[15]	WANG Z, FAN Y, Li Y W, QU F R, WU D Y, KONG H N. Synthesis of zeolite/hydrous lanthanum oxide composite from coal fly ash for efficient phosphate removal from lake water[J]. Micropor Mesopor Mat, 2016, 222: 226-234. doi: 10.1016/j.micromeso.2015.10.028
[16]	ZHANG Y, WONG W T, YUNG K F. Biodiesel production via, esterification of oleic acid catalyzed by chlorosulfonic acid modified zirconia[J]. Appl Energy, 2014, 116(1): 191-198. http://www.cabdirect.org/abstracts/20143319972.html
[17]	SANTOS J S, DIAS J A, DIAS S C L, DE MACEDO J L, GARCIA F A C, ALMEIDA L S, D E CAVALHO E N C B. Acidic characterization and activity of (NH₄)_xCs_2.5-xH_0.5PW₁₂O₄₀ catalysts in the esterification reaction of oleic acid with ethanol[J]. Appl Catal A: Gen, 2012, 443/444: 33-39. doi: 10.1016/j.apcata.2012.07.013
[18]	MORENO J I, JAIMES R, GOMEZ R, GOMEZ M E N. Evaluation of sulfated tin oxides in the esterification reaction of free fatty acids[J]. Catal Today, 2011, 172(1): 34-40. doi: 10.1016/j.cattod.2011.03.052
[19]	JUNIOR C A R M, ALBURQUERQUE C E R, CARNEIRO J S A, DARIVA C, FORTUNY M, SANTOS A F, EGUES S M S, RAMOS A L. Solid-acid-catalyzed esterification of oleic acid assisted by microwave heating[J]. Ind Eng Chem Res, 2010, 49(23): 12135-12139. doi: 10.1021/ie100501d
[20]	CAMPOSECO R, CASTILLO S, MEJIA-CENTENO I, NAVARRETE J, RODRIGUEZ-GONZALEZ V. Behavior of lewis and brönsted surface acidity featured by Ag, Au, Ce, La, Fe, Mn, Pd, Pt, V and W decorated on protonated titanate nanotubes[J]. Micropor Mesopor Mat, 2016, 236: 235-243. doi: 10.1016/j.micromeso.2016.08.033
[21]	JALIL P A, FAIZ M, TABET N, HAMDAN N M, HUSSAIN Z. A study of the stability of tungstophosphoric acid, H₃PW₁₂O₄₀, using synchrotron XPS, XANES, hexane cracking, XRD, and IR spectroscopy[J]. J Catal, 2002, 217: 292-297. http://www.sciencedirect.com/science/article/pii/S0021951703000666
[22]	ZHANG J Q, WONG H, KAKUSHIMA K, IWAI H. XPS study on the effects of thermal annealing on CeO₂/La₂O₃ stacked gate dielectrics[J]. Thin Solid Films, 2016, 600: 30-35. doi: 10.1016/j.tsf.2016.01.001