丙炔对Pt-Sn-K/Al_2O_3催化丙烷脱氢过程的影响
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摘要
丙炔是丙烷脱氢过程深度脱氢产物,是裂解反应可能的起始物种,对丙烷脱氢过程有很大影响。采用等体积浸渍法制备了Pt-Sn-K/Al_2O_3催化剂,并用N_2物理吸附、CO化学吸附、HAADF-STEM与ICP-AES等表征了催化剂结构,考察了丙炔引入对催化剂的丙烷脱氢气相产物分布的影响。对反应后的催化剂采用TG、Raman、FI-IR以及pyrolysis GC-MS进行了表征,确定了结焦组成。实验结果表明,φ=0.5%的丙炔添加量对丙烷脱氢生成丙烯的反应基本无影响,但是促进了结焦反应,使结焦量增加。无论是否加入丙炔,催化剂上的结焦均包括直链烃、芳香烃和类石墨化物质三类;丙炔的加入促进了芳香类焦炭的形成,提高了结焦的石墨化程度。
Propyne is a product of deep dehydrogenation of propane. It is a possible starting species for the cracking reaction and has a great influence on the dehydrogenation process of propane. The Pt-Sn-K/Al_2O_3 catalyst was prepared by incipient wetness impregnation method, and its structure was characterized by N_2 physical adsorption, CO chemical adsorption, HAADF-STEM and ICP-AES. The influence of propyne introduction on the distribution of propane dehydrogenation phase product was investigated. The spent catalysts was characterized by TG, Raman, FI-IR and pyrolysis GC-MS to determine the coking composition. The results show that introducing a propyne of 0.5% by volume in the feed gas has little effect on propane dehydrogenation to propylene, but greatly promotes the coking reaction and increases the amount of coke. Regardless of whether or not propyne is added, the cokes on the catalyst includes aliphatics, aromatics and pre-graphite cokes. The introduction of propyne promotes the formation of aromatic coke,and increases the degree of graphitization of the coke.
Propyne is a product of deep dehydrogenation of propane. It is a possible starting species for the cracking reaction and has a great influence on the dehydrogenation process of propane. The Pt-Sn-K/Al_2O_3 catalyst was prepared by incipient wetness impregnation method, and its structure was characterized by N_2 physical adsorption, CO chemical adsorption, HAADF-STEM and ICP-AES. The influence of propyne introduction on the distribution of propane dehydrogenation phase product was investigated. The spent catalysts was characterized by TG, Raman, FI-IR and pyrolysis GC-MS to determine the coking composition. The results show that introducing a propyne of 0.5% by volume in the feed gas has little effect on propane dehydrogenation to propylene, but greatly promotes the coking reaction and increases the amount of coke. Regardless of whether or not propyne is added, the cokes on the catalyst includes aliphatics, aromatics and pre-graphite cokes. The introduction of propyne promotes the formation of aromatic coke,and increases the degree of graphitization of the coke.
引文
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[19]Praserthdam P, Grisdanurak N, Yuangsawatdikul W. Coke formation over Pt-S-K/Al2O3in C3, C5-C8 alkane dehydrogenation[J]. Chem Eng J, 2000, 77(3):215-219.
[2]余长林,葛庆杰,李文钊,等.丙烷脱氢制丙烯研究新进展[J].化工进展,2006, 30(3):977-982.
[3]Sattler J J H B, Ruiz-Martinez J, Santillan-Jimenez E, et al. Catalytic dehydrogenation of light alkanes on metals and metal oxides[J]. Chem Rev, 2014, 114(20):10613-10653.
[4]Larsson M, Hulten M, Blekkan E A, et al. The effect of reaction conditions and time on stream on the coke formed during propane dehydrogenation[J]. J Catal, 1996,164(1):44-53.
[5]Li Q, Sui Z J, Zhou X G, et al. Coke formation on Pt-Sn/Al2O3catalyst in propane dehydrogenation:coke characterization and kinetic study[J]. Top Catal, 2011,54(13-15):888-896.
[6]Iglesias-Juez A, Beale A M, Maaijen K, et al. A combined in situ time-resolved UV-Vis, Raman and high-energy resolution X-ray absorption spectroscopy study on the deactivation behavior of Pt and Pt Sn propane dehydrogenation catalysts under industrial reaction conditions[J]. J Catal, 2010, 276(2):268-279.
[7]Afonso J C, Aranda D A G, Schmal M, et al. Importance of pretreatment on regeneration of a Pt-Sn/Al2O3catalyst[J]. Fuel Process Technol, 1995, 42(1):3-17.
[8]Yang M L, Zhu Y A, Fan C, et al. DFT study of propane dehydrogenation on Pt catalyst:effects of step sites[J].Phys Chem Chem Phys, 2011, 13(8):3257-3267.
[9]Yang M L, Zhu Y A, Fan C, et al. DFT study of propane dehydrogenation on Pt catalyst:Effects of step sites[J].Phys Chem Chem Phys, 2011, 13(8):3257-3267.
[10]Zangeneh F T, Mehrazma S, Sahebdelfar S. The influence of solvent on the performance of Pt-Sn/θ-Al2O3propane dehydrogenation catalyst prepared by co-impregnation method[J]. Fuel Process Technol, 2013, 109:118-123.
[11]李庆,隋志军,周兴贵,等. Pt催化丙烷脱氢过程中结焦反应的粒径效应与Sn的作用[J].化工学报, 2013, 64(2):524-530.
[12]Yu J, Wang R, Ren S, et al. The unique role of CaO in stabilizing the Pt/Al2O3catalyst for the dehydrogenation of cyclohexane[J]. ChemCatChem, 2012, 4(9):1376-1381.
[13]Han Z, Li S, Jiang F, et al. Propane dehydrogenation over Pt-Cu bimetallic catalysts:the nature of coke deposition and the role of copper[J]. Nanoscale, 2014, 6(17):10000-10008.
[14]Shamsi A, Baltrus J P, Spivey J J. Characterization of coke deposited on Pt/alumina catalyst during reforming of liquid hydrocarbons[J].Appl Catal A, 2005, 293:145-152.
[15]吴睿,隋志军,周兴贵,等. Pt系催化剂丙烷脱氢结焦性质比较[J].天然气化工-C1化学与化工, 2017, 39(2):46-51.
[16]Yang J, Stansberry P G, Zondlo J W, et al. Characteristics and carbonization behaviors of coal extracts[J]. Fuel Process Technol, 2002, 79(3):207-215.
[17]Cerqueira H S, Sievers C, Joly G, et al. Multitechnique characterization of coke produced during commercial resid FCC operation[J]. Ind Eng Chem Res, 2005, 44(7):2069-2077.
[18]Ibarra J V, Royo C, Monzón A, et al. Fourier transform infrared spectroscopic study of coke deposits on a Cr2O3-Al2O3catalyst[J]. Vib Spectrosc, 1995, 9(2):191-196.
[19]Praserthdam P, Grisdanurak N, Yuangsawatdikul W. Coke formation over Pt-S-K/Al2O3in C3, C5-C8 alkane dehydrogenation[J]. Chem Eng J, 2000, 77(3):215-219.