Preparation of High-performance Cu-SAPO-34 Catalysts without Removal of Templating Agents

doi:10.15541/jim20170612

Abstract

Abstract:

The pollution of nitrogen oxides has become a serious environmental problem. Selective catalytic reduction (SCR) with zeolites is one of the most effective ways to remove nitrogen oxides. To reduce the cost of the catalysts’ preparation, a facile fabrication method of high-performance Cu-SAPO-34 catalysts without removal of templating agents was proposed. Zeolite slurry containing templating agents was directly applied as a raw material to prepare the Cu-SAPO-34 catalyst followed by pretreatment, ion exchange and one-time calcination. As prepared catalysts were systematically investigated by XRD, BET, TG, ICP, XPS, SEM, TPR, TPD, and NH₃-SCR. In the ion exchange process, different pH conditions were studied and optimized. The optimized catalyst with Cu content of 2.43% performed a cubic crystal, high acidity and catalytic activity. The NO conversion rate was more than 80% in the range of 200~450℃, and the highest value was 97.8% obtained at 300℃. Compared with the catalyst prepared from commercial SAPO-34, the as-prepared Cu-SAPO-34 catalysts without removal of templating agents exhibited similar microstructure and catalytic performance. These results indicate that the presence of a small amount of templating agent in the SAPO-34 zeolites makes no difference to fabricate high-performance Cu-SAPO-34 catalysts. It is a feasible method to prepare high-performance Cu-SAPO-34 catalysts without removal of templating agents.

Key words: ion exchange, catalyst, zeolite, template agent

CLC Number:

TQ174

KONG Xiang-Li, QIU Ming-Hui, YANG Lu, WANG An-Ran, FAN Yi-Qun, KONG De-Shuang, GU Chang-Jun, HUAN Xiu-Hua, KONG Ling-Ren. Preparation of High-performance Cu-SAPO-34 Catalysts without Removal of Templating Agents[J]. Journal of Inorganic Materials, 2018, 33(9): 956-962.

Figures/Tables 11

Fig. 1 Traditional and present preparation flow chart for Cu-SAPO-34

Table 1 BET results of raw, pretreated and commercial SAPO-34

	Specific surface area/(m²•g^-1)	Pore volume/ (m³•g^-1)	Pore size/nm
Raw SAPO-34	~119.0	~0.123	~5.9
Pretreated SAPO-34	375.8	0.248	10.5
Pretreated SAPO-34 after calcination	489.1	0.265	12.7
Commercial SAPO-34	512.4	0.271	13.3

Fig. 2 XRD patterns of raw, pretreated and commercial SAPO-34

Fig. 3 Thermogravimetric curves of pretreated SAPO-34 and commercial SAPO-34

Fig. 4 XRD patterns (a) and XPS spectra (b) of catalysts prepared with different pH

Table 2 ICP and BET of catalysts prepared with different pH

pH	Cu content/wt%	Specific surface area/(m²•g^-1)	Pore volume/ (m³•g^-1)
4.8	0.82	204.9	0.170
5.0	2.03	184.3	0.165
5.2	2.43	176.4	0.157
5.4	5.15	143.2	0.123
5.6	6.57	139.6	0.118
5.2 (Commercial)	2.50	208.4	0.165

Fig. 5 N2 adsorption-desorption isotherms of catalysts prepared with different pH

Fig. 6 SEM images of catalysts prepared with different pH

Fig. 7 TPR curves of catalysts prepared with different pH

Fig. 8 TPD curves of pretreated and commercial Cu-SAPO-34

Fig. 9 SCR tests of pretreated and commercial Cu-SAPO-34

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