黄恪, 朱超, 师楠, 温福山, 王韶华, 吴雷, 门卓武, 刘东. Pt-MOR/MCM-41催化剂制备与加氢异构化评价[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.YH20.0159
引用本文: 黄恪, 朱超, 师楠, 温福山, 王韶华, 吴雷, 门卓武, 刘东. Pt-MOR/MCM-41催化剂制备与加氢异构化评价[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.YH20.0159
HUANG Ke, ZHU Chao, SHI Nan, WEN Fushan, WANG Shaohua, WU Lei, LIU Dong, . Preparation of Pt-MOR / MCM-41 catalyst and evaluation of hydroisomerization[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.YH20.0159
Citation: HUANG Ke, ZHU Chao, SHI Nan, WEN Fushan, WANG Shaohua, WU Lei, LIU Dong, . Preparation of Pt-MOR / MCM-41 catalyst and evaluation of hydroisomerization[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.YH20.0159

Pt-MOR/MCM-41催化剂制备与加氢异构化评价

Preparation of Pt-MOR / MCM-41 catalyst and evaluation of hydroisomerization

  • 摘要: 费托合成产物中低碳直链烷烃经加氢异构化后,产物可用于优质高辛烷值汽油,是实现煤炭资源清洁化利用的一种重要手段。通过调控MOR沸石晶体碱溶解程度,以沸石溶解液为硅铝源合成介孔MCM-41,采用重结晶法制备了一系列MOR/MCM-41微-介孔复合材料,与金属活性组分离子交换后得到MOR/MCM-41为载体的Pt系催化剂,并选取正己烷为费托低碳烃模型化合物进行加氢异构化性能评价。分别通过SEM、TEM、吡啶红外、XRD、BET、氮气吸脱附等手段表征复合材料形貌、孔道结构及理化性质,表征结果表明,经过原位重结晶改性后,MOR晶粒粒径减小,外表面成功包覆MCM-41材料,吸附性能得到改善,适当的碱处理能够改善MOR沸石的颗粒易聚集现象,调变了Brønsted酸和Lewis酸的比值,弱酸量基本不变而中强酸量显著减少。加氢异构化性能评价结果表明,在反应温度为200~280 ℃,转化率随反应温度的升高而升高,且在相同转化率水平下,具有较高的正己烷加氢异构化选择性。随碱处理浓度增大,异构产物的选择性得到提高,且裂化程度减弱,主要归因于复合材料碱处理对MOR颗粒的分散作用与重结晶合成MCM-41带来的扩孔效果,通过调变催化剂孔道结构,缩短反应物分子与活性中心间传质路径,提高异构化催化性能。通过制备微-介孔复合材料并建立改性体系,可在相近转化率水平下提高正己烷加氢异构化的选择性。本研究为低碳正构烷烃加氢异构化催化剂载体的制备提供参考依据,有望通过对介孔复合的调控实现异构产物的高效转化。

     

    Abstract: Hydroisomerization of the low carbon straight chain alkanes in the products of F-T synthesis,which could be used in high quality gasoline with high octane number,is promising to realize clean utilization of coal resources. Here- in,a series of MOR / MCM-41 micro-mesoporous composites are prepared by in-situ recrystallization method,with the degree of alkali dissolution of MOR zeolite crystals being controlled and the mesoporous MCM-41 being synthesized by using zeolite solution as Si and Al sources. A series of Pt-loaded catalysts are obtained by ion exchange and impregna- tion of metal active components,and n-hexane is selected as the model compound of F-T low carbon n-alkanes for hydroisomerization performance evaluation. TEM, SEM, XRD, BET, Pyridine-IR, and N2 adsorption-desorption iso- therms measurements are introduced to characterize the morphologies,structures and chemical and physical properties of the hybrids. After in-situ recrystallization modification,the grain size of MOR crystals decrease,the outer surface of MOR is coated with MCM-41,and the adsorption performance of MOR is improved,which indicates that appropriate al- kali treatment could reduce the particle aggregation of MOR zeolite and adjust the ratio of Brönsted acid to Lewis acid. In catalytic performance evaluation,the conversion rate of n-hexane increases when the reaction temperature is in- creased from 200 ℃ to 280 ℃ . With the increasing of the alkali treatment concentration,the selectivity of isomer prod- ucts is improved,and the degree of cracking is reduced,mainly due to the composite alkali treatment effect on MOR particle dispersion. Additionally,the synthesis method of MCM-41 could expand the channels through adjusting the cat- alyst pore structure and shorten the mass transfer path between the reactant molecules and the active center,also con- tributes to the selectivity improvement. The selectivity of n-hexane hydroisomerization can be improved by preparing micro-mesoporous composites and setting up a modified system. This study will provide reference for more efficient conversion of low carbon n-alkanes hydroisomerization.

     

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