In-situ acid regulation and hydroisomerization performance of Pt/ZSM-22 catalyst

doi:10.11949/0438-1157.20230362

Abstract

Abstract:

A hydrothermal method was used to synthesize ZSM-22 molecular sieve and prepare a catalyst carrier. By loading precious metal Pt, a highly dispersed Pt/H-ZSM-22 hydroisomerization catalyst was prepared. Using n-C₁₂ as feedstock, the hydroisomerization performance of the catalyst was investigated. By introducing a certain amount of nitrogen-containing species in the reaction process, the acid of catalyst was adjusted in the hydroisomerization reactor, and the change of the catalyst performance was investigated. The results showed that, as the reaction temperature increased, the liquid yield of Pt/N-ZSM-22 decreased slowly, and the isomerization selectivity of Pt/N-ZSM-22 were about 3 percentage points higher than Pt/H-ZSM-22 under the same conversion rate above 85%. The acid sites of Pt/N-ZSM-22 catalyst which was absorbed by the nitrogen-containing species can also be restored during raising the reaction temperature. The catalyst after acid regulation was used for hydroisomerization of the hydrocracking UCO, and the base oil yield was significantly higher than the catalyst before regulation.

Key words: molecular sieve, hydroisomerization, catalyst, acid regulation, selectivity, lube base oil

摘要：

采用水热法合成ZSM-22分子筛并制备催化剂载体，通过负载贵金属Pt，制备出高分散Pt/H-ZSM-22加氢异构催化剂。以n-C₁₂为原料，考察催化剂的加氢异构性能，在正构烷烃加氢异构反应过程中，通过在原料油中引入一定量含氮物种二正丁胺，使其在催化剂酸性位上发生化学吸附，对催化剂酸性进行原位调控，考察催化剂性能变化。结果表明，随着反应温度提高，酸性调控后的Pt/N-ZSM-22液体收率下降缓慢，且转化率达到85%以上时，Pt/N-ZSM-22的异构选择性比Pt/H-ZSM-22高出约3个百分点。酸性调控后的Pt/N-ZSM-22可通过提高反应温度进行含氮物种脱附，恢复催化剂酸位点的可接近性。采用酸性调控后的催化剂用于以加氢裂化尾油为原料的加氢异构反应，基础油收率均较调控前催化剂有明显提高。

关键词: 分子筛, 加氢异构, 催化剂, 酸性调控, 选择性, 润滑油基础油

CLC Number:

TQ 424.81

Shanbin GAO, Mengchen LI, Hongyue YU, Yuge SHEN, Liang QIAO, Kebin CHI, Dejun SHI. In-situ acid regulation and hydroisomerization performance of Pt/ZSM-22 catalyst[J]. CIESC Journal, 2023, 74(10): 4164-4172.

高善彬, 李梦晨, 于宏悦, 沈雨歌, 乔亮, 迟克彬, 史得军. Pt/ZSM-22催化剂酸性原位调控及加氢异构性能[J]. 化工学报, 2023, 74(10): 4164-4172.

Figures/Tables 16

Fig.1 Flowchart of micro reactor-chromatogram unit

Fig.2 Flowchart of high pressure hydrogenation unit

Fig.3 XRD pattern of ZSM-22 zeolite

Fig.4 SEM images of ZSM-22 zeolite

Fig.5 NH3-TPD profiles of Pt/H-ZSM-22 and Pt/K-ZSM-22 catalysts

Fig.6 HAADF-STEM images of Pt/H-ZSM-22 catalyst

Fig.7 NH3-TPD profiles of Pt/H-ZSM-22 and Pt/N-ZSM-22 catalysts

Fig.8 Liquid yield of Pt/H-ZSM-22 and Pt/N-ZSM-22 catalysts with different reaction temperature

Fig.9 Conversion and isomerization selectivity of Pt/H-ZSM-22 and Pt/N-ZSM-22 catalysts with different reaction temperatures

Fig.10 Isomerization selectivity of Pt/H-ZSM-22 and Pt/N-ZSM-22 catalysts with different conversion

Fig.11 Liquid yield of Pt/N-ZSM-22 and Pt/R-ZSM-22 catalysts with different reaction temperatures

Table 1 Py-IR results of Pt/H-ZSM-22， Pt/N-ZSM-22 and Pt/R-ZSM-22 catalysts

温度/℃	Pt/H-ZSM-22/(mmol/g)	Pt/N-ZSM-22/(mmol/g)	Pt/R380-ZSM-22/(mmol/g)	Pt/R390-ZSM-22/(mmol/g)
200	0.534	0.415	0.446	0.493
350	0.370	0.257	0.289	0.328

Fig.12 Conversion and isomerization selectivity of Pt/N-ZSM-22 and Pt/R-ZSM-22 catalysts with different reaction temperatures

Fig.13 n-C12 reaction path of catalyst before and after acid regulation

Table 2 Properties of hydrocracking UCO

参数	数值
S/(μg/g)	1.71
N/(μg/g)	<1.1
凝点/℃	32.9
100℃运动黏度/(mm²/s)	4.865
黏度指数	130
闪点/℃	212
密度（20℃）/(g/cm³)	0.841
馏程/℃
HK/5%/10%/30% 50%/70%/90%/95%/ KK	315/374/386/407 426/453/495/511/534
组成/%（质量）
饱和烃	96.61
芳烃	3.02
极性化合物	0.37

Table 3 Hydroisomerization results of Pt/H-ZSM-22 and Pt/N-ZSM-22 catalysts

参数	Pt/H-ZSM-22	Pt/N-ZSM-22
异构反应温度/℃	340	360
全馏分凝点/℃	-34	-33
总基础油收率（＞280℃），ω/%	85.18	88.31
重质基础油收率（＞400℃），ω/%	61.09	69.48
100℃运动黏度/(mm²/s)	5.832	5.754
黏度指数	123	125
倾点/℃	-18	-18
浊点/℃	-9	-8
饱和烃/%（质量）	99	99

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