Catalytic synthesis of anisole over LDHs with different Mg/Al ratios
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摘要: 采用共沉淀法合成了一系列不同镁铝比的类水滑型层状金属氢氧化物(LDHs)，通过XRD、SEM、FT-IR、NH3-TPD、CO2-TPD、TG和ICP-OES方法对MgAl-LDHs和焙烧产物进行表征，并用于催化苯酚与碳酸二甲酯(DMC)气相合成苯甲醚。结果表明，共沉淀法合成的MgAl-LDHs在Mg/Al比为2~4时具有良好的类水滑石结构，主要以球形层片聚集体的形态存在，其层间距、平均孔径和碱酸比在Mg/Al比为2~4之间逐渐增加；所制备的MgAl-LDHs样品均显示出良好的反应活性，并发现苯甲醚的选择性随催化剂酸碱比先增加后减小，当镁铝比为4时，其酸碱比为0.32，此时苯甲醚选择性最高为88.93 %。此外，还考察了反应温度和质量空速对苯甲醚催化效果的影响。Abstract: A series of layered hydroxides(LDHs)with different Mg/Al ratios were synthesized by coprecipitation method.MgAl LDHs and their calcined products were characterized by XRD, SEM, FT-IR, NH3-TPD, CO2- TPD, TG and ICP-OES, and were used to catalyze the vapor phase synthesis of anisole from phenol and dimethyl carbonate(DMC).The results show that MgAl LDHs synthesized by coprecipitation method have good hydrotalcite like structure when Mg/Al ratio is 2 to 4, mainly in the form of spherical lamellar aggregates.The interlayer spacing, average pore size and alkali acid ratio increase gradually when Mg/Al ratio is from 2 to 4.It is found that the selectivity of anisole first increases and then decreases with the acid-base ratio of the catalyst.The highest anisole selectivity of 88.93 % is achieved when the Mg/Al ratio is 4 and the acid/base ratio is 0.32.In addition, the effect of reaction temperature and mass space velocity on the catalytic performance are also investigated.
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Key words:
- hydrotalcite /
- phenol /
- anisole /
- coprecipitation method /
- Mg/Al ratio
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图 2 不同镁铝比焙烧水滑石N2吸附脱附曲线
Figure 2. Adsorption-desorption profiles of calcined hydrotalcite with different Mg/Al ratios
图 3 不同镁铝比焙烧水滑石的孔径分布
Figure 3. Pore size distribution of calcined hydrotalcite with different Mg/Al ratios
图 4 不同镁铝比焙烧水滑石的CO2-TPD
Figure 4. CO2-TPD of calcined hydrotalcite with different Mg/Al ratios
图 5 不同镁铝比焙烧水滑石的NH3-TPD
Figure 5. NH3-TPD of calcined hydrotalcite with different Mg/Al ratios
图 7 不同镁铝比的MgAl-LDHs样品的FT-IR谱图
Figure 7. FT-IR spectra of hydrotalcite with different Mg/Al ratios
图 10 反应温度对苯甲醚合成反应催化性能的影响
反应条件：催化剂0.1 g，苯酚、DMC摩尔比为1∶3，时间150 min，质量空速2 h-1，常压
Figure 10. Effect of temperature on the catalytic performance of anisole synthesis
图 11 WHSV对苯甲醚合成反应催化性能的影响
反应条件：催化剂0.1 g，苯酚、DMC摩尔比为1∶3，温度380 ℃，时间150 min，常压
Figure 11. Effect of WHSV on the catalytic performance of anisole synthesis
表 1 不同镁铝比焙烧水滑石的元素组成
Table 1. Elementary composition of calcined hydrotalcite with different Mg/Al ratios
样品 mMg/(mol·kg-1) mAl/(mol·kg-1) nMg/nAl Mg2Al-LDO 0.364 0.195 1.87 Mg3Al-LDO 0.289 0.130 2.22 Mg4Al-LDO 0.307 0.084 3.65 Mg5Al-LDO 0.306 0.067 4.57 Mg10Al-LDO 0.344 0.038 9.05 
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表 2 MgAl-LDHs的XRD分析结果
Table 2. XRD analysis of MgAl-LDHs
晶面 参数 Mg2Al-LDH Mg3Al-LDH Mg4Al-LDH 003 2θ/(°) 11.82 11.42 11.30 d/nm 0.748 1 0.774 2 0.782 4 FWHM 0.826 0.814 0.775 006 2θ/(°) 23.52 22.92 22.66 d/nm 0.377 9 0.387 7 0.392 1 FWHM 0.942 0.936 0.852 009 2θ/(°) 34.96 34.62 34.54 d/nm 0.256 4 0.258 9 0.259 5 FWHM 0.897 0.922 0.766 110 2θ/(°) 61.12 60.50 60.32 d/nm 0.151 5 0.152 9 0.153 3 FWHM 0.617 0.691 0.723
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表 3 不同镁铝比焙烧水滑石的孔结构参数
Table 3. Pore structure of calcined hydrotalcite with different Mg/Al ratios
样品 比表面积/(m2·g-1) 孔容/(cm3·g-1) 平均孔径/nm Mg2Al-LDO 268.00 0.77 13.94 Mg3Al-LDO 202.73 0.68 16.86 Mg4Al-LDO 230.66 0.95 19.70 Mg5Al-LDO 252.05 0.85 17.51 Mg10Al-LDO 169.47 0.96 27.31
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表 4 不同镁铝比焙烧水滑石的酸碱量
Table 4. Acid and base amount of calcined hydrotalcite with different Mg/Al ratios
样品 总碱/(mol·kg-1) 总酸(mol·kg-1) 总酸/总碱 Mg2Al-LDO 0.491 0.218 0.44 Mg3Al-LDO 0.500 0.184 0.37 Mg4Al-LDO 0.549 0.176 0.32 Mg5Al-LDO 0.549 0.145 0.26 Mg10Al-LDO 0.397 0.201 0.51
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表 5 不同镁铝比水滑石对苯甲醚合成反应的性能
Table 5. Performance of MgAl-LDOs with different Mg/Al ratios for anisole synthesis
转化率/% 选择性/% 收率/% Mg2Al-LDO 99.25 88.04 87.38 Mg3Al-LDO 97.63 87.71 85.63 Mg4Al-LDO 98.87 88.93 87.92 Mg5Al-LDO 99.67 80.51 80.24 Mg10Al-LDO 99.75 85.78 85.57 反应条件：催化剂0.1 g，苯酚、DMC摩尔比为1∶3，进料量0.2 mL/h，时间150 min，温度380 ℃，常压。
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[1] Yadav G D, Goel P K, Joshi A V. Alkylation of dihydroxybenzenes and anisole with methyl-tert-butyl ether(MTBE)over solid acid catalysts[J]. Green Chemistry, 2001, 3(2): 92-99. doi: 10.1039/b100298h [2] 王瀚琳, 王德强, 王凯, 等. 微反应器内苯甲醚连续合成[J]. 化工学报, 2019, 70(3): 922-928. https://www.cnki.com.cn/Article/CJFDTOTAL-HGSZ201903014.htmWang Hanlin, Wang Deqiang, Wang Kai, et al. Continuous synthesis of anisole in microreactor system[J]. CIESC Journal, 2019, 70(3): 922-928. https://www.cnki.com.cn/Article/CJFDTOTAL-HGSZ201903014.htm [3] Achet D, Rocrelle D, Murengezi I, et al. Reactions in slightly hydrated solid/ liquid heterogeneous media: the methylation reaction with dimethyl sulfoxide[J]. Synthesis, 1986, 1986(8): 642-643. doi: 10.1055/s-1986-31729 [4] Hales J, Heaney H, Hollinshead J H, et al. The synthesis and assay of radio labelled benzene derivatives[J]. Tetrahedron, 1995, 51(28): 7741-7754. doi: 10.1016/0040-4020(95)00394-N [5] 邓甜音, 郜丽娟, 马琳鸽, 等. 负载铯催化剂上苯酚与甲醇醚化制苯甲醚[J]. 燃料化学学报, 2016, 44(9): 1138-1144. doi: 10.3969/j.issn.0253-2409.2016.09.016Deng Tianyin, Gao Lijuan, Ma Linge, et al. Phenol etherification with methanol to anisole over supported Cs catalysts[J]. Journal of Fuel Chemistry and Technology, 2016, 44(9): 1138-1144. doi: 10.3969/j.issn.0253-2409.2016.09.016 [6] 梅付名, 裴志, 李光兴. 由碳酸二甲酯合成芳香醚的绿色工艺[J]. 现代化工, 2004, 24(1): 20-23. doi: 10.3321/j.issn:0253-4320.2004.01.006Mei Fuming, Pei Zhi, Li Guangxing. Green process for synthesis of aryl methyl ethers by dimethyl carbonate[J]. Modern Chemical Industry, 2004, 24(1): 20-23 doi: 10.3321/j.issn:0253-4320.2004.01.006 [7] 薛其才, 寇永利, 张生军, 等. 一种用于以苯酚与碳酸二甲酯为原料合成苯甲醚的催化剂及制备方法和应用: CN110841663A[P]. 2020-02-28. [8] 胡海生, 薛冰, 许杰, 等. 苯酚与碳酸二甲酯烷基化反应体系的热力学分析[J]. 精细石油化工, 2012, 29(1): 45-49. https://www.cnki.com.cn/Article/CJFDTOTAL-JXSY201201014.htmHu Haisheng, Xue Bing, Xu Jie, et al. Thermodynamics analysis for the reaction system of the alkylation of phenol with dimethyl carbonate[J]. Speciality Petrochemicals, 2012, 29(1): 45-49. https://www.cnki.com.cn/Article/CJFDTOTAL-JXSY201201014.htm [9] 陈冰, 赵宁, 魏伟, 等. 硝酸盐催化碳酸二甲酯与苯酚合成苯甲醚[J]. 石油化工, 2009, 38(8): 897-902. doi: 10.3321/j.issn:1000-8144.2009.08.018Chen Bing, Zhao Ning, Wei Wei, et al. Synthesis of anisole from phenol with dimethyl carbonate over inorganic nitrate[J]. Petrochemical Technology, 2009, 38(8): 897-902. doi: 10.3321/j.issn:1000-8144.2009.08.018 [10] Wu Gongde, Wang Xiaoli, Chen Bing, et al. Fluorine-modified mesoporous Mg-Al mixed oxides: Mild and stable base catalysts for O-methylation of phenol with dimethyl carbonate[J]. Applied Catalysis A: General, 2007, 329: 106-111. doi: 10.1016/j.apcata.2007.06.031 [11] 李少颖. 复合固体碱催化苯酚与碳酸二甲酯反应制备苯甲醚的研究[D]. 西安: 西安石油大学, 2020. [12] Jyothi T M, Raja T, Talawar M B, et al. Selective methylation of phenol, aniline and catechol with dimethyl carbonate over calcined Mg-Al hydrotalcites[J]. Synthetic Communications, 2000, 30(21): 3929-3934. doi: 10.1080/00397910008086951 [13] 陈冰, 赵宁, 魏伟, 等. KBr催化剂上DMC与苯酚甲基化合成苯甲醚的反应机理研究[J]. 燃料化学学报, 2011, 39(2): 144-148. doi: 10.3969/j.issn.0253-2409.2011.02.013Chen Bing, Zhao Ning, Wei Wei, et al. Mechanism study of anisole synthesis from o-methylation of phenol with DMC over KBr catalyst[J]. Journal of Fuel Chemistry and Technology, 2011, 39(2): 144-148. doi: 10.3969/j.issn.0253-2409.2011.02.013 [14] 陈冰, 肖福魁, 赵宁, 等. 负载型钾盐催化剂用于合成苯甲醚的研究[J]. 燃料化学学报, 2010, 38(5): 600-603. doi: 10.3969/j.issn.0253-2409.2010.05.016Chen Bing, Xiao Fukui, Zhao Ning, et al. A nove-technology for anisole synthesis using supported potassium salt catalyst[J]. Journal of Fuel Chemistry and Technology, 2010, 38(5): 600-603. doi: 10.3969/j.issn.0253-2409.2010.05.016 [15] David G Cantrell, Lisa J Gillie, Adam F Lee, et al. Structure-reactivity correlations in MgAl hydrotalcite catalysts for biodiesel synthesis[J]. Applied Catalysis A: General, 2005, 287(2): 183-190. doi: 10.1016/j.apcata.2005.03.027 [16] 梁颖. 镁铝水滑石的改性研究及其在水处理中的应用[D]. 太原: 太原理工大学, 2019. [17] Tong Dongsheng, Liu Ming, Li Li, et al. Transformation of alunite residuals into layered double hydroxides and oxides for adsorption of acid red G dye[J]. Applied Clay Science, 2012, 70(6): 1-7. [18] 徐倩倩. 混合溶剂中Mg/Al类水滑石的制备与表征[D]. 太原: 太原理工大学, 2012. [19] 周燕婷, 李峰, 杜以波, 等. 镁铝复合金属氧化物结构、催化性能及其在一步法制备醇醚醋酸酯中的应用[J]. 北京化工大学学报: 自然科学版, 2000, 27(1): 70-73 doi: 10.3969/j.issn.1671-4628.2000.01.019Zhou Yanting, Li Feng, Du Yibo, et al. The structure and catalytical property of layered double oxides and the application for preparing 1-methyl-2-ethoxyethyl acetate[J]. Journal of Beijing University of Chemical Technology, 2000, 27(1): 70-73 doi: 10.3969/j.issn.1671-4628.2000.01.019 [20] 唐庆余. 红外光谱测定固体酸催化剂表面酸性[J]. 炼油与化工, 2004, 15(4): 28-29. doi: 10.3969/j.issn.1671-4962.2004.04.013Tang Qingyu. Determination of surface acidity of solid-acid catalysts by FTIR[J]. Refining and Chemicals, 2004, 15(4): 28-29. doi: 10.3969/j.issn.1671-4962.2004.04.013 [21] Olszówka J E, Karcz R, Bielańska E, et al. New insight into the preferred valency of interlayer anions in hydrotalcite-like compounds: The effect of Mg/Al ratio[J]. Applied Clay Science, 2018, 155: 84-94. doi: 10.1016/j.clay.2018.01.013 [22] Prescott H A, Li Z J, Kemnitz E, et al. Application of calcined Mg-Al hydrotalcites for Michael additions: an investigation of catalytic activity and acid-base properties[J]. Journal of Catalysis, 2005, 234(1): 119-130. doi: 10.1016/j.jcat.2005.06.004 [23] Wang X Y, Wang R Y, Gu X M, et al. Light-assisted O-methylation of phenol with dimethyl carbonate over a layered double oxide catalyst[J]. Catalysis Science & Technology, 2019, 9(8): 1774-1778. http://pubs.rsc.org/en/content/articlelanding/2019/cy/c8cy02579g/unauth -
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