钾对Cu-SSZ-13催化剂脱硝性能及水热稳定性影响的研究

doi:10.19964/j.issn.1006-4990.2024-0642

摘要/Abstract

摘要：

为探究化学中毒与高温水热老化协同作用对Cu-SSZ-13催化剂NH₃-SCR性能的影响机制，经发动机台架中毒和高温处理，得到不同样件。结合BET、SEM、NH₃-TPD和H₂-TPR等表征分析其物化特性与活性演变规律。结果表明：K通过置换骨架位活性Cu²⁺和B酸位质子，导致活性Cu²⁺数量和酸量降低，孔道部分堵塞；老化时，K会加剧分子筛骨架坍塌和加速Cu²⁺→Cu _x O _y 的转化，进而抑制Al（OH）₃再键合，导致其比表面积和氧化还原性性能显著降低。采用固定床反应器进行活性评价发现，K削弱催化剂活性和水热稳定性。中毒后Cu-SSZ-13催化剂（CZ）在200 ℃和500 ℃下NO _x 转化率分别从92.84%和89.38%下降到85.64%和83.22%（KCZ-1）。老化后转化率进一步劣化至74.24%和76.02%（KCZ-HT1），较未中毒老化样品（CZ-HT）下降15.7%和10.8%。此外，K的沉积量沿气流方向梯度递减。研究阐明K通过质子置换及活性位竞争等多途径协同劣化催化剂活性和高温水热稳定性的机制，指出D6R位Cu²⁺对K中毒的敏感性，而老化过程中8MRs位Cu²⁺稳定性亦受显著影响，为抗中毒催化剂的定向设计提供理论依据。

关键词: Cu-SSZ-13, K中毒, 高温水热稳定性, NH₃-SCR, 脱硝性能

Abstract:

To explore the mechanism of the synergistic effect of chemical poisoning and high-temperature hydrothermal aging on the NH₃-SCR performance of Cu-SSZ-13 catalysts，various samples were generated by subjecting the catalysts to poisoning and high-temperature treatment on an engine test bench.The physicochemical properties of catalyst coatings at different locations within the monolithic catalyst were investigated by using BET，SEM，NH₃-TPD，and H₂-TPR.The results revealed that K deposition on the fresh catalyst displaced isolated Cu²⁺ and protons on framework Brønsted acid sites，leading to a reduction in the number of active Cu²⁺ ions in the catalyst framework，a decrease in acidity without crystal structure damage，and partial pore blockage.During the high-temperature hydrothermal aging process，the presence of K exacerbated the collapse of the zeolite framework and accelerated the transformation of Cu²⁺into Cu _x O _y species，which in turn inhibited the recombination of Al（OH）₃，leading to a significant decrease in specific surface area and redox properties.The deNO _x activity of the catalyst was examined by means of a fixed-bed reactor，and it was found that K weakened the activity and undermined the hydrothermal stability of the catalyst.After poisoning，the deNO _x efficiency of CZ at 200 ℃ and 500 ℃ was decreased from 92.84% and 89.38% to 85.64% and 83.22%（KCZ-1），respectively.After aging，the deNO _x efficiency of KCZ-HT1 at 200 ℃ and 500 ℃ was further deteriorated to 74.24% and 76.02%，a decrease of 15.7% and 10.8% compared to the unpolluted aged sample（CZ-HT）.In addition，the deposition of K in the catalyst was decreased along the gas flow direction，and the higher deposition at the front end resulted in poorer stability of the catalyst than at the back end.These findings provided an important basis for optimizing the design of anti-poisoning catalysts.This study clarified the mechanism by which K synergistically deteriorated catalyst activity and high-temperature hydrothermal stability through proton displacement and active site competition，etc，highlighting the sensitivity of D6R site Cu²⁺ to K poisoning and the significant impact on the stability of 8MRs site Cu²⁺ during aging，providing a theoretical basis for the targeted design of anti-poisoning catalysts.

Key words: Cu-SSZ-13, K poisoning, high-temperature hydrothermal stability, NH₃-SCR, deNO _x performance

中图分类号:

TQ127.2

冯锡, 吕亮, 孙睿, 赖益能, 杨兰, 王瑞芳. 钾对Cu-SSZ-13催化剂脱硝性能及水热稳定性影响的研究[J]. 无机盐工业, 2025, 57(12): 123-130.

FENG Xi, LÜ Liang, SUN Rui, LAI Yineng, YANG Lan, WANG Ruifang. Study on effect of potassium on deNO _x performance and hydrothermal stability of Cu-SSZ-13 catalysts[J]. Inorganic Chemicals Industry, 2025, 57(12): 123-130.

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样品	WHTC-冷		WHTC-热		WHTC 加权排放量/（g·kW^-1·h^-1）	法规限值/ （g·kW^-1·h^-1）
样品	NO _x 排放量/（g·kW^-1·h^-1）	平均温度/ ℃	NO _x 排放量/（g·kW^-1·h^-1）	平均温度/ ℃	WHTC 加权排放量/（g·kW^-1·h^-1）	法规限值/ （g·kW^-1·h^-1）
DCZ	0.62	225.7	0.11	253.0	0.18	0.46
DCZ-HT	0.68	230.7	0.27	258.2	0.33
KCZ	0.72	227.9	0.12	257.4	0.20
KCZ-HT	1.00	224.2	0.40	256.3	0.48

催化剂	比表面积^a/ （m²·g^-1）	孔容^a/ （cm³·g^-1）	w（Cu）^b/ %	w（K）^b/ %
堇青石载体	13.67	0.02
H-SSZ-13	528.16	0.27
CZ	520.61	0.26
CZ-HT	489.31	0.24	2.76
KCZ-1	497.19	0.25
KCZ-HT1	405.98	0.20	2.63	1.21
KCZ-2	504.57	0.26
KCZ-HT2	453.81	0.23	2.79	0.37

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