C<sub>5</sub>烃催化裂解过程中氢转移反应的研究

刘美佳; 王刚; 张忠东; 田爱珍

doi:10.19906/j.cnki.JFCT.2021006

C₅烃催化裂解过程中氢转移反应的研究

doi: 10.19906/j.cnki.JFCT.2021006

刘美佳¹,
王刚^1, ,,
张忠东^2, ,,
田爱珍³

1.
中国石油大学（北京）重质油国家重点实验室，北京 102249
2.
中国石油石油化工研究院，北京 102206
3.
中国石油石油化工研究院兰州化工研究中心，甘肃兰州 730060

基金项目: 中国石油天然气股份有限公司科技开发项目-炼油向化工转型升级技术研究开发（2019A-1809）与深度降低汽油烯烃的灵活催化裂化工艺技术（CCOC）开发及应用（KYWX-19-019）项目资助

详细信息

通讯作者:
E-mail: wanggang@cup.edu.cn

zhangzhongdong@petrochina.com.cn

中图分类号: TE621
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出版历程
- 收稿日期: 2020-08-31
- 修回日期: 2020-09-30
- 刊出日期: 2021-01-29

Study on hydrogen transfer reaction in C₅ hydrocarbons catalytic pyrolysis

1.
State Key Laboratory of Heavy Oil, China University of Petroleum (Beijing), Beijing 102249, China
2.
Petrochemical Research Institute, PetroChina, Beijing 102206, China
3.
Petrochina Petrochemical Research Institute Lanzhou Petrochemical Research Center, Lanzhou 730060, China

Funds: The project was supported by Technology Development Project of China National Petroleum Corporation-Research and Development of Upgrading Technology for the Transformation of Oil Refining to Chemical Industry (2019A-1809) and Development and Application of Flexible Catal Cracking Gasoline Olefins Conversion (CCOC) (KYWX-19-019)

摘要

摘要: 对C₅烃（正戊烷、1-戊烯）的裂解反应产物进行分析，按照理想正碳离子和自由基反应机理，正戊烷和1-戊烯裂解生成低碳烯烃（C₂H₄+C₃H₆+C₄H₈）的摩尔选择性分别达到50%和100%。但是使用MFI-30分子筛，在650 ℃反应条件下，正戊烷和1-戊烯催化裂解生成低碳烯烃的摩尔选择性分别为23.41%和56.79%，说明分别有26.59%和43.21%的低碳烯烃发生了氢转移反应。进一步考察了不同类型分子筛和关键反应温度对C₅烃催化裂解过程中氢转移反应的影响，研究发现，小孔结构、低酸密度的分子筛和较高反应温度，可以不同程度地抑制氢转移反应，提高低碳烯烃的选择性。在650 ℃条件下，当分子筛由大孔结构、高酸量的FAU更换为小孔结构、低酸量的MFI-120时，正戊烷和1-戊烯催化裂解的氢转移系数HTC分别减小96.86%和50.58%，焦炭选择性分别由11.91%和20.77%减小到0.75%和0.89%，低碳烯烃（C₂H₄+C₃H₆+C₄H₈）的选择性分别由14.25%和25.14%增加到46.28%和62.58%。
- C₅ /
- 催化裂解 /
- 氢转移 /
- 低碳烯烃
Abstract: The cracking reaction mechanism of C₅ hydrocarbons(n-pentane, 1-pentene) was analyzed. It is found that according to the ideal carbanion reaction mechanism and free radicals reaction mechanism, the molar selectivity of the cracking of n-pentane and 1-pentene to lower olefins (C₂H₄+C₃H₆+C₄H₈) is 50% and 100%, respectively. However, using MFI-30 zeolite, the molar selectivity of catalytic cracking of n-pentane and 1-pentene to light olefins at 650 ℃ is 23.41% and 56.79%, respectively, suggesting that 26.59% and 43.21% of light olefins have undergone hydrogen transfer reactions. The effects of different zeolites and key reaction temperature on the hydrogen transfer reaction during the catalytic pyrolysis of C₅ hydrocarbons were further investigated. The results show that the zeolite with small pore structure and low acid density and higher reaction temperature can inhibit the hydrogen transfer reaction to varying degrees, thereby increasing the selectivity of light olefins. At 650 ℃, as the zeolite changes from the FAU with a large pore structure and high acid content to the MFI-120 with a small pore structure and low acid content, the hydrogen transfer coefficient HTC of the catalytic pyrolysis of n-pentane and 1-pentene is reduced by 96.86% and 50.58%, respectively, and the coke selectivity is reduced from 11.91% and 20.77% to 0.75% and 0.89%, respectively. However, the selectivity of the lower olefins increases from 14.25% and 25.14% to 46.28% and 62.58%, respectively.
- C₅ /
- catalytic pyrolysis /
- hydrogen transfer /
- light olefins

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图 1 微型固定床实验装置

Figure 1 Micro fixed bed experiment apparatus

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图 2 正戊烷裂解反应机理

Figure 2 Cracking reaction mechanism of n-pentane

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图 3 1-戊烯裂解反应机理

Figure 3 Cracking reaction mechanism of 1-pentene

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图 4 C₅烃在不同拓扑结构分子筛上催化裂解反应

Figure 4 The catalytic pyrolysis reaction of C₅ hydrocarbons on zeolites with different topologies

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图 5 C₅烃在不同硅铝比及酸量分子筛上催化裂解反应

Figure 5 Catalytic pyrolysis reaction of C₅ hydrocarbons on zeolites with different ratios of silicon to aluminum and the acid content

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图 6 C₅烃在不同反应温度下的催化裂解反应

Figure 6 Catalytic pyrolysis reaction of C₅ hydrocarbons at different reaction temperatures

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图 7 各类因素对C₅烃催化裂解过程中氢转移系数HTC和低碳烯烃选择性的影响

Figure 7 Influence of various factors on the hydrogen transfer coefficient HTC and the selectivity of light olefins during the catalytic cracking of C₅ hydrocarbons

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表 1 不同类型分子筛的物化性质

Table 1 Properties of different zeolites

Topology	Si/Al₂	Channel dimension	Maximum spherical diameter contained in zeolite^[12]/nm	S_BET/ (m²·g⁻¹)	v_micro/ (cm³·g⁻¹)	Pore size/nm	Weak acid/ (mmol·g⁻¹)	Strong acid/ (mmol·g⁻¹)	Total acid/ (mmol·g⁻¹)
MFI	30	3	0.636	397.650	0.142	0.520	0.214	0.208	0.422
MFI	40	3	0.636	397.411	0.141	0.520	0.173	0.189	0.362
MFI	120	3	0.636	397.520	0.141	0.520	0.116	0.102	0.218
FER	25	2	0.631	401.698	0.142	0.513	0.149	0.207	0.356
FAU	6	3	1.124	793.403	0.272	0.735	0.127	0.227	0.354

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表 2 C₅烃催化裂解条件下的产品分布

Table 2 Product distribution of C₅ hydrocarbons pyrolysis under catalytic conditions

	n-pentane thermal cracking	1-pentene thermal cracking	n-pentane catalytic pyrolysis	1-pentene catalytic pyrolysis
Conversion w/%	8.83	25.49	97.41	99.78
Product yield w/%
H₂	0.03	0.03	1.26	1.37
CH₄	0.60	2.36	11.35	11.65
C₂H₆	0.96	2.18	16.00	8.42
C₂H₄	1.30	3.27	9.40	13.60
C₃H₈	0.10	0.51	24.70	11.52
C₃H₆	2.01	3.95	8.23	9.58
C₄H₁₀	0.33	0.32	4.70	1.82
C₄H₈	0.64	2.51	2.48	2.27
1-C₅H₁₀	0.79	74.51	0.44	0.22
n-C₅H₁₂	91.17	3.24	2.59	0.01
Aromatics	0.02	0.68	13.63	31.32
Other components	1.89	6.27	4.44	7.16
Coke	0.16	0.16	0.78	1.06

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表 3 C₅烃主要裂解产物的摩尔选择性（650 ℃，MFI-30分子筛，重时空速220 h⁻¹）

Table 3 Molar selectivity of the main products of C₅ hydrocarbons cracking (650 ℃, MFI-30 zeolite, weight hourly space velocity 220 h⁻¹)

Molar selectivity/%	n-pentane	1-pentene
CH₄	28.81	−
C₂H₄+C₃H₆+C₄H₈	23.41	56.79
C₂H₆+C₃H₈+C₄H₁₀	47.78	43.21

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表 4 C₅烃在不同分子筛上的催化裂解（650 ℃）

Table 4 The catalytic pyrolysis reaction of C₅ hydrocarbons on different zeolites (650 ℃)

Reactant	n-pentane		1-pentene
Zeolite	FAU	MFI-120	FAU	MFI-120
HTC	6.68	0.21	0.71	0.35
Coke selectivity s/%	11.91	0.75	20.77	0.89
Light olefins selectivity s/%	14.25	46.28	25.14	62.58

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