两步晶化合成ZSM-22分子筛及其临氢异构反应性能

doi:10.11949/0438-1157.20240307

摘要/Abstract

摘要：

采用两步晶化法，通过调节加入铝源的时间合成了一系列ZSM-22分子筛，并对其酸性位点的分布进行调控。采用XRD、SEM、N₂吸附/脱附、NH₃-TPD、FTIR、Py-IR、ICP、TEM-EDS等表征方法对其物相、形貌、织构性质、酸性和元素进行表征分析。结果表明，第二步晶化时，加入铝源，在模板剂诱导作用下，促使第一步晶化后高硅ZSM-22表面未晶化的无定形硅酸盐原位合成了ZSM-22分子筛，使高硅ZSM-22表面生长一层低硅铝比ZSM-22分子筛，从而使分子筛的酸性位点发生改变。制备了Pt负载双功能催化剂，研究其正十二烷的临氢异构化反应性能。结果表明，两步晶化ZSM-22分子筛可以抑制微孔内的裂化反应，获得更高异构产物选择性，其中S6-C在330℃时，转化率为89.3%，选择性89.4%，产率79.8%。通过两步晶化方式合成的ZSM-22分子筛，活性位点更多地位于分子筛的外表面和孔口附近，进而改变其异构体产物的分布，降低支链位于碳链端位异构体的比例，更倾向于生成支链位于碳链中间位置的异构体，S12-C的2-甲基十一烷分布比例比常规ZSM-22降低10%左右。

关键词: 分子筛, 催化剂, 两步晶化, 临氢异构化, 正十二烷

Abstract:

A series of ZSM-22 molecular sieves were synthesized by adjusting the time of adding aluminum source by two-step crystallization method, and the distribution of acid sites was regulated. XRD, SEM, N₂^{adsorption/desorption, NH₃-TPD, FTIR, Py-IR,ICP, TEM-EDS and other characterization methods were used to characterize the phase, morphology, texture properties, acidity and element. The results show that ZSM-22 molecular sieve is synthesized in situ from amorphous silicate which is not crystallized on the surface of high silicon ZSM-22 after the first step of crystallization with the addition of aluminum source under the induction of template agent, and a layer of ZSM-22 molecular sieve with low Si/Al ratio is grown on the surface of high silicon ZSM-22, thus changing the acid site of the molecular sieve. The Pt-supported bifunctional catalyst was prepared and its hydroisomerization performance of n-dodecane was studied. The results show that the two-step crystallization of ZSM-22 can inhibit the cracking reaction in micropores and obtain higher isomerization selectivity. The conversion of S6-C at 330℃ is 89.3%, the selectivity is 89.4%, and the yield is 79.8%. ZSM-22 molecular sieve synthesized by two-step crystallization had more active sites located on the outer surface and near the pore mouth of the molecular sieve, thus changing the distribution of its isomers, reducing the proportion of isomers with branch chains at the end of the carbon chain, and preferring to generate isomers with branch chains at the middle of the carbon chain. The distribution ratio of 2-methylundecane in S12-C is about 10% lower than that of conventional ZSM-22.}

Key words: molecular sieve, catalyst, two-step crystallization, hydroisomerization, n-dodecane

中图分类号:

TE 624

王树振, 王玉婷, 马梦茜, 张巍, 向江南, 鲁海莹, 王琰, 范彬彬, 郑家军, 代卫炯, 李瑞丰. 两步晶化合成ZSM-22分子筛及其临氢异构反应性能[J]. 化工学报, 2024, 75(9): 3176-3187.

Shuzhen WANG, Yuting WANG, Mengxi MA, Wei ZHANG, Jiangnan XIANG, Haiying LU, Yan WANG, Binbin FAN, Jiajun ZHENG, Weijiong DAI, Ruifeng LI. Synthesis of ZSM-22 molecular sieve by two-step crystallization and its hydroisomerization performance[J]. CIESC Journal, 2024, 75(9): 3176-3187.

图/表 15

图1 高硅ZSM-22分子筛不同晶化时间的XRD谱图和FTIR谱图

Fig.1 XRD patterns and FTIR spectra of high-silicon ZSM-22 molecular sieve at different crystallization time

图2 高硅ZSM-22分子筛不同晶化时间的SEM图

Fig.2 SEM images of different crystallization time of high-silicon ZSM-22 molecular sieve

图3 两步晶化样品的XRD谱图

Fig.3 XRD patterns of the two-step crystallization synthesized samples

图4 两步晶化样品的SEM图

Fig.4 SEM images of two-step crystallization synthesized samples

图5 两步晶化样品的N2吸附-脱附曲线和孔径分布

Fig.5 N2 adsorption-desorption curve and pore size distribution of the two-step crystallized samples

表1 两步晶化样品的织构性质

Table 1 Texture properties of the two-step crystallized samples

样品	BET比表面积/(m²/g)	微孔比表面积/(m²/g)	外比表面积/(m²/g)	孔体积/(cm³/g)	微孔体积/(cm³/g)	介孔体积/(cm³/g)
Z-22	209	169	40	0.15	0.07	0.08
S6-C	226	185	41	0.14	0.07	0.07
S7-C	247	212	35	0.17	0.08	0.09
S8-C	267	227	40	0.16	0.08	0.08
S12-C	270	251	19	0.14	0.09	0.05
S&C	228	203	25	0.15	0.08	0.07
S36	297	278	19	0.14	0.1	0.04

图6 两步晶化样品的NH3-TPD图

Fig.6 NH3-TPD image of two-step crystallization samples

表2 由NH3-TPD曲线计算的酸浓度特性和元素分析

Table 2 Acidity properties calculated by NH3-TPD curve and elemental analysis

样品	酸量/(μmol/g)		总酸量/(μmol/g)	表面Si/Al^①	Si/Al^②	R^③
样品	弱酸	强酸	总酸量/(μmol/g)	表面Si/Al^①	Si/Al^②	R^③
Z-22	435	308	743	21	45	2.14
S6-C	273	207	480	26	65	2.51
S7-C	228	168	396	25	76	3.04
S8-C	223	152	377	22	79	3.61
S12-C	189	149	338	32	122	3.81
S&C	190	151	341	—	—
S36	25	23	48	85	—

图7 两步晶化样品S7-C的TEM-EDS元素分布（Si和Al）

Fig.7 TEM-EDS element distribution of two-step crystallization sample S7-C (Si and Al)

图8 Z-22、S6-C和S12-C的吡啶红外谱图

Fig.8 Py-IR spectra of Z-22, S6-C and S12-C

表3 通过吡啶红外曲线计算出分子筛的酸特性

Table 3 Acidity properties of molecular sieve calculated by Py-IR spectra

样品	150℃时酸量/(μmol/g)		350℃时酸量/(μmol/g)		总酸量			B_W^①/%
样品	B	L	B	L	B	L	B/L	B_W^①/%
Z-22	12	15	93	21	105	36	2.92	11.4
S6-C	19	17	56	12	75	29	2.58	25.3
S12-C	2	18	43	9	45	27	1.67	4.4

图9 合成的S7-C-t的SEM图

Fig.9 SEM images of synthesized S7-C-t

图10 不同分子筛催化剂的正十二烷异构化转化率和选择性曲线

Fig.10 Curves of conversion and selectivity of n-dodecane isomerization for different molecular sieve catalysts

图11 不同分子筛催化剂临氢异构反应中单甲基异构体产物分布

Fig.11 Distribution of monomethyl isomer products in hydroisomerization reaction of different molecular sieve catalysts

图12 不同分子筛催化剂最高产率与对应的不同产物的产率

Fig.12 Maximum yield of different molecular sieve catalysts and corresponding yield of different products

参考文献 34

1	Wei C H, Zhang G H, Zhao L, et al. Effect of metal-acid balance and textual modifications on hydroisomerization catalysts for n-alkanes with different chain length: a mini-review[J]. Fuel, 2022, 315: 122809.
2	Shamzhy M, Opanasenko M, Concepción P, et al. New trends in tailoring active sites in zeolite-based catalysts[J]. Chemical Society Reviews, 2019, 48(4): 1095-1149.
3	Niu P Y, Xi H J, Ren J, et al. Micropore blocked core-shell ZSM-22 designed via epitaxial growth with enhanced shape selectivity and high n-dodecane hydroisomerization performance[J]. Catalysis Science & Technology, 2018, 8(24): 6407-6419.
4	Song H, Zhao L L, Wang N. Rare earth metals modified Ni-S₂O₈ ^2-/ZrO₂-Al₂O₃ catalysts for n-pentane isomerization[J]. Chinese Journal of Chemical Engineering, 2017, 25(1): 74-78.
5	Liu P, Yao Y, Zhang X G, et al. Rare earth metals ion-exchanged β-zeolites as supports of platinum catalysts for hydroisomerization of n-heptane[J]. Chinese Journal of Chemical Engineering, 2011, 19(2): 278-284.
6	Smeeth M, Spikes H, Gunsel S. Boundary film formation by viscosity index improvers[J]. Tribology Transactions, 1996, 39(3): 726-734.
7	Xiang J N, Zhang W, Zhang H P, et al. Effect of Fe substitution over ZSM-48 on performance of n-dodecane hydroisomerization and distribution of isomers[J]. Solid State Sciences, 2023, 142: 107250.
8	Needham D E, Wei I C, Seybold P G. Molecular modeling of the physical properties of alkanes[J]. Journal of the American Chemical Society, 1988, 110(13): 4186-4194.
9	Brennan J A. Wide-temperature range synthetic hydrocarbon fluids[J]. Industrial & Engineering Chemistry Product Research and Development, 1980, 19(1): 2-6.
10	Claude M C, Martens J A. Monomethyl-branching of long n-alkanes in the range from decane to tetracosane on Pt/H-ZSM-22 bifunctional catalyst[J]. Journal of Catalysis, 2000, 190(1): 39-48.
11	Jaroszewska K, Masalska A, Grzechowiak J R. Hydroisomerization of long-chain bio-derived n-alkanes into monobranched high cetane isomers via a dual-component catalyst bed[J]. Fuel, 2020, 268: 117239.
12	Roldán R, Beale A M, Sánchez-Sánchez M, et al. Effect of the impregnation order on the nature of metal particles of bi-functional Pt/Pd-supported zeolite beta materials and on their catalytic activity for the hydroisomerization of alkanes[J]. Journal of Catalysis, 2008, 254(1): 12-26.
13	Childers D, Saha A, Schweitzer N, et al. Correlating heat of adsorption of CO to reaction selectivity: geometric effects vs electronic effects in neopentane isomerization over Pt and Pd catalysts[J]. ACS Catalysis, 2013, 3(11): 2487-2496.
14	Meng L Q, Vanbutsele G, Pestman R, et al. Mechanistic aspects of n-paraffins hydrocracking: influence of zeolite morphology and acidity of Pd(Pt)/ZSM-5 catalysts[J]. Journal of Catalysis, 2020, 389: 544-555.
15	Munusamy K, Das R K, Ghosh S, et al. Synthesis, characterization and hydroisomerization activity of ZSM-22/23 intergrowth zeolite[J]. Microporous and Mesoporous Materials, 2018, 266: 141-148.
16	Choudhury I R, Hayasaka K, Thybaut J W, et al. Pt/H-ZSM-22 hydroisomerization catalysts optimization guided by single-event microkinetic modeling[J]. Journal of Catalysis, 2012, 290: 165-176.
17	Laxmi Narasimhan C S, Thybaut J W, Marin G B, et al. Relumped single-event microkinetic model for alkane hydrocracking on shape-selective catalysts: catalysis on ZSM-22 pore mouths, bridge acid sites and micropores[J]. Chemical Engineering Science, 2004, 59(22/23): 4765-4772.
18	Liu S Y, He Y R, Zhang H K, et al. Design and synthesis of Ga-doped ZSM-22 zeolites as highly selective and stable catalysts for n-dodecane isomerization[J]. Catalysis Science & Technology, 2019, 9(11): 2812-2827.
19	Niu P Y, Liu P, Xi H J, et al. Crystallization mechanism of pure-silica ZSM-22 in the seed-assistant system[J]. Crystal Growth & Design, 2018, 18(11): 6591-6601.
20	Wang X Y, Zhang X W, Wang Q F. n-Dodecane hydroisomerization over hierarchical ZSM-22 prepared by a dual-protected alkali treatment[J]. Industrial & Engineering Chemistry Research, 2019, 58(19): 8495-8505.
21	Jacobs P A, Beyer H K, Valyon J. Properties of the end members in the Pentasil-family of zeolites: characterization as adsorbents[J]. Zeolites, 1981, 1(3): 161-168.
22	Zhao J, Yin Y C, Li Y, et al. Synthesis and characterization of mesoporous zeolite Y by using block copolymers as templates[J]. Chemical Engineering Journal, 2016, 284: 405-411.
23	Lu P, Chen L, Zhang Y F, et al. Rapid synthesis of ZSM-22 zeolites using imidazolium-based ionic liquids as OSDAs in fluoride media[J]. Microporous and Mesoporous Materials, 2016, 236: 193-201.
24	程群. X射线衍射法测定高岭石合成的NaY分子筛物相组成、结晶度、晶胞参数及硅铝比研究[J]. 冶金标准化与质量, 2006, 44(2): 8-10.
	Cheng Q. Study on determining composition, crystallinity, cell parameter and ratio of silicate to aluminium of zeolite NaY treated from kaolinite by X-ray diffractometer[J]. Metallurgical Standardization & Quality, 2006, 44(2): 8-10.
25	储刚,陈刚. X射线衍射法测定ZSM-5分子筛硅铝比[J]. 石油化工, 1995, 24(7): 498-506.
	Chu G, Chen G. Determination of SiO₂/Al₂O₃ ratio of ZSM-5 molecular sieve by X-ray diffraction[J]. Petrochemical Technology, 1995, 24(7): 498-499, 506.
26	Niu P Y, Xi H J, Ren J, et al. High selectivity for n-dodecane hydroisomerization over highly siliceous ZSM-22 with low Pt loading[J]. Catalysis Science & Technology, 2017, 7(21): 5055-5068.
27	Emeis C A. Determination of integrated molar extinction coefficients for infrared absorption bands of pyridine adsorbed on solid acid catalysts[J]. Journal of Catalysis, 1993, 141(2): 347-354.
28	Zholobenko V, Freitas C, Jendrlin M, et al. Probing the acid sites of zeolites with pyridine: quantitative AGIR measurements of the molar absorption coefficients[J]. Journal of Catalysis, 2020, 385: 52-60.
29	Pieterse J A Z, Veefkind-Reyes S, Seshan K, et al. On the accessibility of acid sites in ferrierite for pyridine[J]. Journal of Catalysis, 1999, 187(2): 518-520.
30	Wang L, Niu P Y, Xi H J, et al. Controllable synthesis of core-shell structured ZSM-22 via one-pot approach[J]. Journal of Solid State Chemistry, 2023, 317: 123663.
31	Hayasaka K, Liang D D, Huybrechts W, et al. Formation of ZSM-22 zeolite catalytic particles by fusion of elementary nanorods[J]. Chemistry, 2007, 13(36): 10070-10077.
32	Wang L, Niu P Y, Xi H J, et al. Facile synthesis of size-controlled ZSM-22 zeolite along the [001] direction via two-step crystallization[J]. Industrial & Engineering Chemistry Research, 2021, 60(47): 17006-17015.
33	Liu L L, Zhang M W, Wang L, et al. Modulating acid site distribution in MTT channels for controllable hydroisomerization of long-chain n-alkanes[J]. Fuel Processing Technology, 2023, 241: 107605.
34	Zhang M W, Liu L L, Wang L, et al. Four-carbon segmented discrete hydrocracking of long-chain paraffins in MTT channels following a pore-mouth mechanism[J]. ACS Catalysis, 2022, 12(16): 10313-10325.

[1]	王冉, 王焕, 熊晓云, 关慧敏, 郑云锋, 陈彩琳, 秦玉才, 宋丽娟. FCC催化剂传质强化活性位利用效率的可视化分析[J]. 化工学报, 2024, 75(9): 3198-3209.
[2]	王靖宇, 刘佳, 徐继香, 王磊. 薄片状PtZn@Silicalite-1分子筛的合成及催化丙烷脱氢性能研究[J]. 化工学报, 2024, 75(9): 3188-3197.
[3]	刘亚超, 谭晓杰, 李旭东, 王瑞, 王慧, 韩璇, 赵青山. DES合成高活性CoCO₃纳米片及析氧反应性能研究[J]. 化工学报, 2024, 75(9): 3320-3328.
[4]	张梦婷, 王书林, 桑熙, 元兴昊, 徐刚. 人工Cu-TM1459金属酶催化不对称迈克尔加成反应[J]. 化工学报, 2024, 75(9): 3255-3265.
[5]	刘旭升, 李泽洋, 杨宇森, 卫敏. 电催化二氧化碳还原制备气态产物的研究进展[J]. 化工学报, 2024, 75(7): 2385-2408.
[6]	罗莉, 陈文尧, 张晶, 钱刚, 周兴贵, 段学志. 氧化铝结构与表面性质调控及其催化甲醇脱水制二甲醚性能研究[J]. 化工学报, 2024, 75(7): 2522-2532.
[7]	王寅, 初鹏飞, 刘虎, 吕静, 黄守莹, 王胜平, 马新宾. 不同pH铝溶胶对二甲醚羰基化成型丝光沸石催化剂性能的影响[J]. 化工学报, 2024, 75(7): 2533-2543.
[8]	杨露, 刘聪聪, 孟彤彤, 张博远, 杨腾飞, 邓文安, 王晓斌. 分散型催化剂在煤/重油共炼体系中的加氢抑焦作用[J]. 化工学报, 2024, 75(7): 2556-2564.
[9]	黄静茹, 陈佳轩, 张群锋, 阮晋, 朱来, 叶光华, 周兴贵. ZSM-5分子筛结构对苯烷基化反应性能影响的数值模拟研究[J]. 化工学报, 2024, 75(7): 2544-2555.
[10]	王天闻, 闫肃, 赵梦园, 杨天让, 刘建国. 固体氧化物电池空气电极铬中毒机理及抗铬性能研究进展[J]. 化工学报, 2024, 75(6): 2091-2108.
[11]	冀钟, 赵彦玲, 陈雨濛, 高林霞, 王翼鹏, 刘欢. ZSM-5分子筛对典型涂装VOCs的吸附性能及机理研究[J]. 化工学报, 2024, 75(6): 2332-2343.
[12]	丁禹, 杨昌泽, 李军, 孙会东, 商辉. 原子尺度钼系加氢脱硫催化剂的研究进展与展望[J]. 化工学报, 2024, 75(5): 1735-1749.
[13]	赵亭亭, 鄢立祥, 唐福利, 肖敏之, 谭烨, 宋刘斌, 肖忠良, 李灵均. 光辅助锂-二氧化碳电池催化剂的设计策略与反应机理研究进展[J]. 化工学报, 2024, 75(5): 1750-1764.
[14]	莫锦洪, 韩雪, 朱毅翔, 李菁, 王旭裕, 纪红兵. Pt-Ga/CeO₂-ZrO₂-Al₂O₃脱氢裂解双功能催化剂用于正丁烷催化制烯烃研究[J]. 化工学报, 2024, 75(5): 1855-1869.
[15]	秦晗淞, 李国梁, 闫昊, 冯翔, 刘熠斌, 陈小博, 杨朝合. 多级孔ZSM-5分子筛中油酸甲酯催化裂解吸附和扩散行为模拟研究[J]. 化工学报, 2024, 75(5): 1870-1881.