金属前躯体溶剂对Pt/ZSM-22催化剂临氢异构性能的影响

宁强; 刘粟侥; 张怀科; 陈志强; 任杰

金属前躯体溶剂对Pt/ZSM-22催化剂临氢异构性能的影响

宁强^{1, 2},
刘粟侥³,
张怀科^{1, 3},
陈志强^{1, 2},
任杰^{1, 3, ,}

1.
中国科学院山西煤炭化学研究所, 煤转化国家重点实验室, 山西太原 030001
2.
中国科学院大学, 北京 100049
3.
中科合成油技术有限公司, 国家能源煤基液体燃料研发中心, 北京 101407

详细信息

本文的英文电子版由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/science/journal/18725813).
中图分类号: O643
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出版历程
- 收稿日期: 2018-09-19
- 修回日期: 2018-10-16
- 网络出版日期: 2021-01-23
- 刊出日期: 2018-12-10

Effect of metal precursor solvent on n-dodecane isomerization of Pt/ZSM-22

NING Qiang^{1, 2},
LIU Su-yao³,
ZHANG Huai-ke^{1, 3},
CHEN Zhi-qiang^{1, 2},
REN Jie^{1, 3
, ,}

1.
State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China
2.
University of Chinese Academy of Sciences, Beijing 100049, China
3.
National Energy Center for Coal to Liquids, Synfuels China Co., Ltd, Beijing 101407, China

More Information

Corresponding author: REN Jie, Tel: +86-010-6966-7855, E-mail: renjie@sxicc.ac.cn

摘要

摘要: 将Pt前驱体分别溶解于水、乙醇、丙酮、乙酸中，采用浸渍法制备了一系列成型Pt/ZSM-22催化剂。通过XRD、BET、TEM、CO-chemisorption、CO-FTIR和Py-FTIR等表征手段对催化剂的物相结构、织构性质、金属性质和酸性进行了系统地考察并以正十二烷为模型化合物，研究了前躯体溶剂对临氢异构反应性能的影响。结果表明，溶剂极性是造成Pt分散差异的主要原因；以乙醇、丙酮和乙酸为浸渍溶剂制备的催化剂，Pt多分布于ZSM-22分子筛上，并与酸性位相互作用造成Pt缺电子；而以水为溶剂则造成Pt多分布于氧化铝黏结剂上，对Pt的电子性质影响较小。在临氢异构反应中，与Pt落位于氧化铝相比，Pt分布于ZSM-22分子筛上表现出更高的活性和异构选择性，表明缩短酸性位与金属位间距可使反应物和异构中间体迅速扩散至金属位上发生脱氢和加氢反应。
- Pt/ZSM-22 /
- 前躯体溶剂 /
- 金属落位 /
- 电子状态 /
- 临氢异构化
Abstract: A series of Pt/ZSM-22 bifunctional catalysts were prepared by using different metal precursor solvents including water, methanol, acetone and acetic acid. The phase structure, texture properties, metal properties and acidity were systematically investigated by XRD, BET, TEM, CO-chemisorption, CO-FTIR and Py-FTIR. The effect of metal precursor solvents on n-dodecane isomerization was also studied. The results indicate that the solvents with different polarities lead to different locations of Pt particles. Part of Pt particles locate on ZSM-22 when methanol, acetone and acetic acid are used as solvents, and the interaction between Pt and acid sites lead to the electron-deficient of Pt. However, the Pt particles almost locate on the Al₂O₃ binders when water is used as solvent, and their electronic properties are little affected. Higher activity and selectivity are achieved when Pt particles locate on ZSM-22 in the n-dodecane isomerization reactions. These results indicate that shorten the distance between acid sites and metal sites can expedite the diffusion of reactants and isomerized intermediates to proceed dehydrogenation and hydrogenation reactions.
- Pt/ZSM-22 /
- precursor solvent /
- metal location /
- electronic property /
- hydroisomerization
注释:

1) 本文的英文电子版由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/science/journal/18725813).

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图 1 不同还原样品的XRD谱图

Figure 1 XRD patterns of different reduced samples(all catalysts are reduced in H₂ flow at 400 ℃ for 2 h)

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图 2 不同还原样品的TEM照片

Figure 2 TEM images of different reduced samples(all catalysts are reduced in H₂ flow at 400 ℃ for 2 h)

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图 3 不同催化剂的CO吸附漫反射红外光谱谱图

Figure 3 CO-FTIR spectra of different catalysts

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图 4 不同催化剂样品异构化反应的转化率(a)和选择性(b)

Figure 4 Conversion (a) and selectivity (b) of n-dodecane isomerization over different bifunctional catalysts (reaction condition: H₂/n-dodecane = 600, LHSV = 2.0 h^-1, p=2.0 MPa)

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图 5 不同前躯体溶剂制备催化剂异构化反应的转化率(a)和选择性(b)

Figure 5 Conversion (a) and selectivity (b) of n-dodecane isomerization over bifunctional catalysts prepared using different precursor solvents (reaction condition: H₂/n-dodecane = 600, LHSV = 2.0 h^-1, p=2.0 MPa)

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表 1 不同样品的物理化学性质

Table 1 Physicochemical properties of different samples

Sample	Pt contents w/%^a	Micropore surface area A/(m²·g^-1) ^b	Micropore volume v/(cm³·g^-1) ^b	Pt diameter d/nm^c	Pt dispersion /%^c
ZSM-22	-	148.8	0.075	-	-
Pt-WAT	0.5	147.9	0.074	1.3	85.9
Pt-ETH	0.5	142.6	0.070	1.6	72.2
Pt-ACE	0.5	143.9	0.071	1.7	67.9
Pt-ACI	0.5	142.4	0.070	2.0	58.8
Pt-WAT-120	0.5	149.2	0.075	1.3	86.3
^a: determined by ICP-AES; ^b: obtained by the N₂-adsorption at -196 ℃; ^c: determined by CO chemisorption

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表 2 不同样品的酸性表征

Table 2 Acidity of different samples determined by Py-FTIR spectra

Sample	Acid types /(μmol·g^-1) ^a
	B acid sites		L acid sites
	200 ℃	350 ℃	200 ℃	350 ℃
ZSM-22	84	80	77	42
Pt-WAT	83	78	74	40
Pt-WAT-0.8	81	76	73	38
Pt-WAT-120	75	70	68	35
Pt-ETH	61	50	50	30
Pt-ACE	59	49	41	28
Pt-ACI	52	49	37	26
^a: Brønsted and Lewis acid sites calculated from the peak area of FT-IR spectra by pyridine desorption at different temperatures

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