碱处理对ZnZrO<sub><i>x</i></sub>/SAPO-34催化合成气一步法制低碳烯烃的影响

王弋; 汪旭东; 薛招腾; 毛东森

doi:10.19906/j.cnki.JFCT.2023053

碱处理对ZnZrO_x/SAPO-34催化合成气一步法制低碳烯烃的影响

doi: 10.19906/j.cnki.JFCT.2023053

上海应用技术大学化学与环境工程学院, 上海 201418

基金项目: 上海市自然科学基金(20ZR1455500)和上海应用技术大学协同创新基金(XTCX2023-03)资助

详细信息

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Tel: 021-60877232, E-mail: ztxue@sit.edu.cn

dsmao@sit.edu.cn

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出版历程
- 收稿日期: 2023-06-13
- 修回日期: 2023-06-30
- 录用日期: 2023-06-30
- 网络出版日期: 2023-09-01
- 刊出日期: 2024-02-02

Effect of alkali treatment on ZnZrO_x/SAPO-34 bifunctional catalyst for catalytic synthesis of light olefins from syngas

School of Chemical and Environment Engineering, Shanghai Institute of Technology, Shanghai 201418, China

Funds: The project was supported by the Shanghai Natural Science Foundation (20ZR1455500) and the Shanghai Institute of Technology Collaborative Innovation Fund (XTCX2023-03)

摘要

摘要: 采用ZnZrO_x金属氧化物和SAPO-34分子筛物理混合制备了双功能催化剂，用于合成气一步法制低碳烯烃（STO）反应。考察了三乙胺、四甲基氢氧化铵和四乙基氢氧化铵三种有机碱溶液及不同浓度的三乙胺溶液处理对SAPO-34分子筛织构、结构和酸性的影响，采用XRD、SEM、N₂吸附-脱附、NH₃-TPD对分子筛进行了表征，并考察了碱处理后催化剂的STO反应性能。结果表明，采用0.06 mol/L的三种有机碱后处理均可在SAPO-34分子筛表面刻蚀出部分多级孔道，从而在STO反应中加速金属氧化物表面形成的中间过渡物种从金属氧化物表面扩散进入SAPO-34分子筛孔道，提高了催化剂在STO反应中CO的转化率，同时，三种碱处理均可降低SAPO-34分子筛的酸量及酸强度，从而提高催化剂在STO反应中低碳烯烃选择性；采用0.02−0.10 mol/L的三乙胺处理SAPO-34分子筛，均在SAPO-34分子筛表面刻蚀出的多级孔，提高了STO反应中CO的转化率，且0.02和0.06 mol/L的三乙胺溶液处理后的SAPO-34分子筛，酸强度和酸量的降低，抑制了甲烷的形成和烯烃的加氢，因此，随着碱处理浓度从0、0.02到0.06 mol/L逐步提高，催化剂对低碳烯烃的选择性逐步提高。其中，在400 ℃，3.0 MPa和GHSV=3600 mL/(g∙h)条件下，采用0.06 mol/L的三乙胺处理的SAPO-34物理混合ZnZrO_x，与未经处理的SAPO-34分子筛相比，CO转化率从24.0%提升至26.4%，低碳烯烃选择性从78.2%提升至84.7%，且该催化剂具有较好的催化稳定性。
- 合成气制低碳烯烃 /
- 双功能催化剂 /
- SAPO-34分子筛 /
- 碱处理
Abstract: A bifunctional catalyst was prepared by physical mixing of ZnZrO_x metal oxide and SAPO-34 zeolite for the one-step conversion of synthesis gas to light olefins (STO) reaction. The effects of triethylamine, tetramethylammonium hydroxide and tetraethylammonium hydroxide solutions and different concentrations of triethylamine solution on the texture, structure and acidity of SAPO-34 zeolite were investigated. XRD, SEM, N₂ adsorption and desorption, NH₃-TPD were used to characterize the SAPO-34 zeolite and the STO reaction performance of the catalyst after alkali treatment was investigated. The results show that all three kinds of organic base with 0.06 mol/L post-treatment can etch some hierarchical channels on the surface of SAPO-34 zeolite, thus accelerating the diffusion of intermediate transition species formed on the surface of metal oxides into the channels of SAPO-34 zeolite in STO reaction, improving the CO conversion rate in STO reaction. At the same time, all three kinds of alkali treatments can reduce the acid amount and acid strength of SAPO-34 zeolite, thereby improving the selectivity for light olefins in the STO reaction. The treatment of SAPO-34 zeolite with 0.02−0.10 mol/L triethylamine resulted in the formation of hierarchical pores etched on the surface of SAPO-34 zeolite, which improved the conversion rate of CO in the STO reaction. Moreover, the acid strength and acidity of SAPO-34 zeolite treated with 0.02 and 0.06 mol/L triethylamine solutions decreased, inhibiting the formation of methane and the hydrogenation of light olefins. Therefore, as the concentration of alkali treatment gradually increased from 0, 0.02 to 0.06 mol/L, the selectivity for light olefins gradually increases. Under the reaction conditions of 400 ℃, 3.0 MPa and GHSV=3600 mL/(g·h), the CO conversion rate increased from 24.0% to 26.4%, and the selectivity of light olefins increased from 78.2% to 84.7% on the bifunctional catalyst composed of 0.06 mol/L triethylamine-treated SAPO-34 compared to untreated SAPO-34 zeolite, and the modified bifunctional catalyst had good catalytic stability.
- syngas to light olefins /
- bifunctional catalyst /
- SAPO-34 zeolite /
- alkali treatment

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FIG. 2923. FIG. 2923.

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图 1 ZnZrO_x氧化物的XRD谱图

Figure 1 XRD spectrum of ZnZrO_x

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图 2 ZnZrO_x氧化物的SEM照片

Figure 2 SEM image of ZnZrO_x

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图 3 不同碱处理SAPO-34分子筛的XRD谱图

Figure 3 XRD spectra of SAPO-34 after treatment with different alkalis

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图 4 不同碱处理SAPO-34分子筛的SEM照片

Figure 4 SEM images of SAPO-34 after treatment with different alkalis

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图 5 不同碱处理的SAPO-34分子筛NH₃-TPD谱图

Figure 5 NH₃-TPD profiles of SAPO-34 zeolite treated with different alkalis

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图 6 不同浓度三乙胺溶液处理SAPO-34分子筛的XRD谱图

Figure 6 XRD spectra of SAPO-34 treated with different concentrations of triethylamine solutions

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图 7 不同浓度三乙胺溶液处理SAPO-34分子筛的SEM照片

Figure 7 SEM images of SAPO-34 treated with different concentrations of triethylamine solutions

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图 8 不同浓度三乙胺溶液处理的SAPO-34分子筛NH₃-TPD谱图

Figure 8 NH₃-TPD profiles of SAPO-34 zeolite treated with different concentrations of triethylamine solutions

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图 9 ZnZrO_x-16/S-1-006催化剂的稳定性测试

Figure 9 Stability test for ZnZrO_x-16/S-1-006 catalyst

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表 1 不同碱处理的SAPO-34分子筛的结构性质

Table 1 Structural properties of SAPO-34 after treatment with different alkalis

Sample	A_BET/ (m²·g⁻¹)	A_micro/ (m²·g⁻¹)	v_total/ (cm³·g⁻¹)	v_micro/ (cm³·g⁻¹)	Relative crystallinity^a
S-0	515	505	0.29	0.26	100
S-1-006	490	487	0.30	0.26	80.7
S-2-006	471	465	0.26	0.24	75.8
S-3-006	490	485	0.28	0.25	81.6
^a : The crystallinity of S-0 is defined as 100%.

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表 2 不同碱处理的SAPO-34分子筛的酸性

Table 2 Acid data of SAPO-34 zeolite treated with different alkalis

Sample	Weak acid peak area	Strong acid peak area	Total acid peak area
S-0	348	349	697
S-1-006	282	253	535
S-2-006	162	242	404
S-3-006	324	339	663

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表 3 由不同碱处理SAPO-34分子筛和ZnZrO_x 组成的双功能催化剂的催化性能

Table 3 Catalytic property of bifunctional catalysts composed of SAPO-34 treated with different alkalis and ZnZrO_x

Catalyst	CO conversion/%	CO₂ selectivity/%	Hydrocarbon distribution/%
Catalyst	CO conversion/%	CO₂ selectivity/%	CH₄	${\rm{C} }_{2} ^{0}-{\rm{C} }_{4}^{0} $	${\rm{C} }_{2} ^{=}-{\rm{C} }_{4}^{=} $
ZnZrO_x/S-0	24.0	38.1	8.6	13.1	78.2
ZnZrO_x/S-1-006	26.4	39.5	2.9	12.4	84.7
ZnZrO_x/S-2-006	25.9	40.8	8.9	30.4	60.7
ZnZrO_x/S-3-006	30.6	40.5	3.6	19.3	77.1
Reaction conditions: t=400 ℃, p=3.0 MPa, GHSV=3600 mL/(g∙h), CO:H₂=1:2(vol/vol).

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表 4 不同浓度三乙胺溶液处理的SAPO-34分子筛的结构性质

Table 4 Structural properties of SAPO-34 treated with different concentrations of triethylamine solutions

Sample	A_BET/(m²·g⁻¹)	A_micro/(m²·g⁻¹)	v_total/(cm³·g⁻¹)	v_micro/(cm³·g⁻¹)	Relative crystallinity^a
S-0	515	505	0.29	0.26	100
S-1-002	511	505	0.29	0.26	90.4
S-1-006	490	587	0.30	0.26	80.7
S-1-010	473	465	0.27	0.24	78.3
^a : The crystallinity of S-0 is defined as 100%.

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表 5 不同浓度三乙胺溶液处理的SAPO-34分子筛的酸性

Table 5 Acid data of SAPO-34 zeolite treated with different concentrations of triethylamine solutions

Sample	Weak acid peak area	Strong acid peak area	Total acid peak area
S-0	348	349	697
S-1-002	328	340	668
S-1-006	282	253	535
S-1-010	277	245	522

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表 6 由不同浓度三乙胺溶液处理SAPO-34分子筛和和ZnZrO _x 组成的双功能催化剂的催化性能

Table 6 Catalytic property of bifunctional catalysts composed of SAPO-34 treated with different concentrations of triethylamine solutions and ZnZrO_x

Catalyst	CO conversion/ %	CO₂ selectivity/ %	Hydrocarbon distribution/%
Catalyst	CO conversion/ %	CO₂ selectivity/ %	CH₄	${\rm{C} }_{2} ^{0}-{\rm{C} }_{4}^{0}$	${\rm{C} }_{2} ^{=}-{\rm{C} }_{4}^{=}$
ZnZrO_x/S-0	24.0	38.1	8.6	13.1	78.2
ZnZrO_x/S-1-002	25.2	38.8	2.4	15.5	82.1
ZnZrO_x/S-1-006	26.4	39.5	2.9	12.4	84.7
ZnZrO_x/S-1-010	25.4	40.5	6.9	17.4	75.7
Reaction conditions: t=400 ℃, p=3.0 MPa, GHSV=3600 mL/(g∙h), CO:H₂=1:2(vol/vol).

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表 7 不同双功能催化剂催化性能的比较

Table 7 Comparison of catalytic performance of different bifunctional catalysts

Catalyst	Temperature /℃	Space velocity/(mL∙g⁻¹∙h⁻¹)	Pressure/MPa	CO conv./%	${\rm{C} }_{2} ^{=}-{\rm{C} }_{4}^{=}$ sel./%	Ref.
ZnZrO_x/S-1-006	400	3600	3.0	26.4	84.7	this work
MG-AH/SAPO-34	400	4875	2.5	19.5	81.2	[19]
ZrCeZnO_x/SAPO-34	400	3900	1.0	25.6	78.6	[28]
ZnCr₂O₄/SAPO-34	400	4800	3.0	11	64	[29]
ZnO-ZrO₂/SAPO-34	400	4800	1.0	7.0	69	[30]
ZnZrO_x/SSZ-13	400	1800	3.0	23	75	[26]
ZnZrO/MSAPO	400	7714	2.5	17	80	[13]
ZnZrO_x/AIPO-18	390	1200	4.0	25.2	45	[7]
ZnAl₂O_x/SAPO-18	400	4500	3.0	34.8	70.7	[6]

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