合成气一步法制二甲醚催化剂成胶pH对其结构和性能的影响
|
摘要
利用完全液相法,通过添加氨水控制前驱体成胶过程中pH为3、4、6、7、8制备合成气一步法制二甲醚催化剂,考察了pH对催化剂性能和结构的影响。通过120h的催化剂性能评价可知,较未添加氨水的催化剂,当成胶pH为中性时,所得催化剂活性最好,其CO转化率提高了5%二甲醚选择性提高了12%,分别达到60.56%和73.31%。通过XRD、NH_3-TPD、H_2-TPR、BET等表征手段可知,当成胶pH为中性时,其催化剂表面Cu~+含量最少,但其表面Cu~0分散性较其他催化剂有显著提高,且反应前后Cu~0晶粒度变化最小,表明影响催化性能的关键是Cu~0而非Cu~+。
The catalysts for one-step synthesis of dimetheyl ether(DME) from syngas were prepared using the complete liquidphase technology by adding ammonia to keep the sol pH at 3, 4, 6, 7 and 8, respectively, during forming precursor sol-gel. The effect of pH on the structure and performance of catalyst was investigated. The 120 hours performance evaluation results of the catalysts showed that the catalyst prepared at the sol pH of 7 exhibit the best performance, giving a CO conversion of 60.56% and a DME selectivity of 73.31%, which, compared with the catalyst without adding ammonia, increased by 5% and 12%, respectively. The catalysts were characterized by XRD, TEM, N_2-adsorption, H_2-TPR, NH_3-TPD and XPS, and the results indicated that keeping the sol pH at 7, the surface of catalyst have least Cu~+but best dispersion of Cu~0, and there is almost no change of Cu~0 grain size after reaction. The results implies that the key to the catalytic performance is not Cu~+but Cu~0.
The catalysts for one-step synthesis of dimetheyl ether(DME) from syngas were prepared using the complete liquidphase technology by adding ammonia to keep the sol pH at 3, 4, 6, 7 and 8, respectively, during forming precursor sol-gel. The effect of pH on the structure and performance of catalyst was investigated. The 120 hours performance evaluation results of the catalysts showed that the catalyst prepared at the sol pH of 7 exhibit the best performance, giving a CO conversion of 60.56% and a DME selectivity of 73.31%, which, compared with the catalyst without adding ammonia, increased by 5% and 12%, respectively. The catalysts were characterized by XRD, TEM, N_2-adsorption, H_2-TPR, NH_3-TPD and XPS, and the results indicated that keeping the sol pH at 7, the surface of catalyst have least Cu~+but best dispersion of Cu~0, and there is almost no change of Cu~0 grain size after reaction. The results implies that the key to the catalytic performance is not Cu~+but Cu~0.
引文
[1]胡益之,李洪晋,韩冬青. 21世纪洁净燃料———二甲醚[J].煤化工, 2006, 34(5):10-14.
[2]Fleisch T H,Basu A,Sills R A.Introduction and advancement of a new clean global fuel:The status of DME developments in China and beyond[J].J Nat Gas Sci Eng, 2012, 9(2):94-107.
[3]Zhang L, Huang Z. Life cycle study of coal-based dimethyl ether as vehicle fuel for urban bus in China[J].Energy, 2007, 32(10):1896-1904.
[4]Zhou L, Hu S Y, Li Y R, Zhou Q H.Study on co-feed and co-production system based on coal and natural gas for producing DME and electricity[J].Chem Eng J, 2008, 136(1):31-40.
[5]黄伟,高志华,郝利峰,等.一种浆状催化剂及其制备方法[P]. CN:1613560, 2006-12-14.
[6]别良伟,王华.合成气一步法制二甲醚催化剂研究进展[J].工业催化, 2009, 17(2):34—39.
[7]Gonzalez R D, Lopez T, Gomez R. Sol-Gel preparation of supported metal catalysts[J]. Catal Today, 1997, 35:293-317.
[8]Masoudpanah S M, Ebrahimi S A S. Effect of pH value on the structural and magnetic properties of nanocrystalline strontium hexaferrite thin films[J]. J Magn Magn Mater, 2011, 323:2643-2647.
[9]李双明,张丽,许灿,等.溶胶-凝胶自蔓延法制备球形纳米铜粉[J].中国粉体技术, 2012, 18(4):21-23.
[10]Azadmanjiri J, Ebrahimi S A S. Effect of pH changes on phase constituents, microstructure and magnetic properties of nano-sized NiFe2O4powder synthesized by sol-gel auto-combustion method[J]. Phys Met Metallogr,2006, 102:21-23.
[11]Ilican S, Yakuphanoglu F, Caglar M, et al. The role of pH and boron doping on the characteristics of sol gel derived Zn O films[J]. J Alloy Compd, 2011, 509(17):5290-5294.
[12]Qiu W, Ren C J, Gong M C, et al. Structure, surface properties and photocatalytic activity of TiO2and TiO2/SiO2catalysts prepared at different pH values[J]. Acta Phys Chim Sin, 2011, 27(6):1487-1492.
[13]黄伟,高志华,郝利峰,等.浆态床催化剂及制备方法[P]. CN:1314491C, 2007.
[14]Gao Z H, Hao L F, Wei H, et al. A novel liquid-phase technology for the preparation of slurry catalysts[J]. Catal Lett, 2005, 102(3):139-141.
[15]李超,李琢,李建青,等.一步法合成二甲醚整体式催化剂的制备及反应性能研究[J].燃料化学学报, 2011, 39(4):287-292.
[16]孙凯,张小雨,张琳,等.酸碱性硅溶胶对浆状Cu/Zn/Al催化剂性能的影响[J].燃料化学学报, 2015, 43(10):1221-1229.
[17]马强,黄伟,樊金串,等.完全液相法制备的Cu-Zn-Si-Al浆状催化剂一步法合成二甲醚的失活研究[J].分子催化, 2009, 23(6):499-505.
[18]樊金串,吴慧,黄伟,等.表面活性剂对完全液相法制Cu-Zn-Al浆状催化剂结构和性能的影响[J].高等学校化学学报, 2008, 29(5):993-999.
[19]黄伟,刘勇军,左志军. Al含量对完全液相法制备CuZn-Al催化剂合成甲醇的影响[J].太原理工大学学报,2012, 43(4):401-405.
[20]张小雨.完全液相法中前驱体性质对一步法制二甲醚催化剂结构和性能的影响[D].太原:太原理工大学,2016.
[21]孙凯.完全液相一步法二甲醚催化剂制备中Si源和Al源影响的研究[D].太原:太原理工大学, 2015.
[22]Li Z, Zuo Z, Huang W, et al. Research on Si-Al based catalysts prepared by complete liquid-phase method for DME synthesis in a slurry reactor[J]. Appl Surf Sci, 2011,257(6):2180-2183.
[23]Suh Y W, Moon S H, Rhee H K. Active sites in Cu/ZnO/ZrO2, catalysts for methanol synthesis from CO/H2[J]. Catal Today, 2000, 63(2-4):447-452.
[24]Velu S, Suzuki K, Vijayaraj M, et al. In situ XPS investigations of Cu1-xNix ZnAl-mixed metal oxide catalysts used in the oxidative steam reforming of bioethanol[J]. Appl Catal B, 2005, 55(4):287-299.
[25]李志红,黄伟,左志军,等.用XPS研究不同方法制备的CuZnAl一步法二甲醚合成催化剂[J].催化学报,2009, 30(2):171-177.
[2]Fleisch T H,Basu A,Sills R A.Introduction and advancement of a new clean global fuel:The status of DME developments in China and beyond[J].J Nat Gas Sci Eng, 2012, 9(2):94-107.
[3]Zhang L, Huang Z. Life cycle study of coal-based dimethyl ether as vehicle fuel for urban bus in China[J].Energy, 2007, 32(10):1896-1904.
[4]Zhou L, Hu S Y, Li Y R, Zhou Q H.Study on co-feed and co-production system based on coal and natural gas for producing DME and electricity[J].Chem Eng J, 2008, 136(1):31-40.
[5]黄伟,高志华,郝利峰,等.一种浆状催化剂及其制备方法[P]. CN:1613560, 2006-12-14.
[6]别良伟,王华.合成气一步法制二甲醚催化剂研究进展[J].工业催化, 2009, 17(2):34—39.
[7]Gonzalez R D, Lopez T, Gomez R. Sol-Gel preparation of supported metal catalysts[J]. Catal Today, 1997, 35:293-317.
[8]Masoudpanah S M, Ebrahimi S A S. Effect of pH value on the structural and magnetic properties of nanocrystalline strontium hexaferrite thin films[J]. J Magn Magn Mater, 2011, 323:2643-2647.
[9]李双明,张丽,许灿,等.溶胶-凝胶自蔓延法制备球形纳米铜粉[J].中国粉体技术, 2012, 18(4):21-23.
[10]Azadmanjiri J, Ebrahimi S A S. Effect of pH changes on phase constituents, microstructure and magnetic properties of nano-sized NiFe2O4powder synthesized by sol-gel auto-combustion method[J]. Phys Met Metallogr,2006, 102:21-23.
[11]Ilican S, Yakuphanoglu F, Caglar M, et al. The role of pH and boron doping on the characteristics of sol gel derived Zn O films[J]. J Alloy Compd, 2011, 509(17):5290-5294.
[12]Qiu W, Ren C J, Gong M C, et al. Structure, surface properties and photocatalytic activity of TiO2and TiO2/SiO2catalysts prepared at different pH values[J]. Acta Phys Chim Sin, 2011, 27(6):1487-1492.
[13]黄伟,高志华,郝利峰,等.浆态床催化剂及制备方法[P]. CN:1314491C, 2007.
[14]Gao Z H, Hao L F, Wei H, et al. A novel liquid-phase technology for the preparation of slurry catalysts[J]. Catal Lett, 2005, 102(3):139-141.
[15]李超,李琢,李建青,等.一步法合成二甲醚整体式催化剂的制备及反应性能研究[J].燃料化学学报, 2011, 39(4):287-292.
[16]孙凯,张小雨,张琳,等.酸碱性硅溶胶对浆状Cu/Zn/Al催化剂性能的影响[J].燃料化学学报, 2015, 43(10):1221-1229.
[17]马强,黄伟,樊金串,等.完全液相法制备的Cu-Zn-Si-Al浆状催化剂一步法合成二甲醚的失活研究[J].分子催化, 2009, 23(6):499-505.
[18]樊金串,吴慧,黄伟,等.表面活性剂对完全液相法制Cu-Zn-Al浆状催化剂结构和性能的影响[J].高等学校化学学报, 2008, 29(5):993-999.
[19]黄伟,刘勇军,左志军. Al含量对完全液相法制备CuZn-Al催化剂合成甲醇的影响[J].太原理工大学学报,2012, 43(4):401-405.
[20]张小雨.完全液相法中前驱体性质对一步法制二甲醚催化剂结构和性能的影响[D].太原:太原理工大学,2016.
[21]孙凯.完全液相一步法二甲醚催化剂制备中Si源和Al源影响的研究[D].太原:太原理工大学, 2015.
[22]Li Z, Zuo Z, Huang W, et al. Research on Si-Al based catalysts prepared by complete liquid-phase method for DME synthesis in a slurry reactor[J]. Appl Surf Sci, 2011,257(6):2180-2183.
[23]Suh Y W, Moon S H, Rhee H K. Active sites in Cu/ZnO/ZrO2, catalysts for methanol synthesis from CO/H2[J]. Catal Today, 2000, 63(2-4):447-452.
[24]Velu S, Suzuki K, Vijayaraj M, et al. In situ XPS investigations of Cu1-xNix ZnAl-mixed metal oxide catalysts used in the oxidative steam reforming of bioethanol[J]. Appl Catal B, 2005, 55(4):287-299.
[25]李志红,黄伟,左志军,等.用XPS研究不同方法制备的CuZnAl一步法二甲醚合成催化剂[J].催化学报,2009, 30(2):171-177.