LaMnO3/生物炭催化剂低温NH3-SCR催化脱硝性能研究

doi:10.11949/0438-1157.20230455

摘要/Abstract

摘要：

以La-Mn钙钛矿氧化物为活性组分，生物炭为载体，利用浸渍法制备负载型脱硝催化剂LMO/BCNA。利用固定床反应装置考察了催化剂的催化活性以及耐硫耐水性能，100~250℃范围内，NO转化率>80%，N₂选择性>90%，225℃时NO转化率最高，为95.8%，对应的N₂选择性为95.4%。与氧化物相比，负载型催化剂的催化活性大幅提升，同时也扩宽了工作温度区间；生物炭载体的引入，减弱了催化剂对H₂O、SO₂的吸附，增强了耐硫耐水性能。应用稳态动力学方法构建催化反应动力学模型，在实验条件范围且O₂含量为5%时，催化NH₃-SCR反应过程中NO、O₂、NH₃的反应级数分别为0.66、0、0，并得到LMO/BCNA催化的反应活化能为25.52 kJ/mol，低于商用钒钨钛催化剂的化学反应活化能（40~94 kJ/mol）。

关键词: 脱硝, 生物炭, 钙钛矿氧化物, 选择性催化还原, 稳态动力学

Abstract:

Selective catalytic reduction with ammonia (NH₃-SCR) is one of the most widely adopted technology to reduce the emission of nitrogen oxides. The activity and stability of catalyst plays a major role in the denitration process, and the increasing requirements for low working temperature, strong SO₂/H₂O resistance capability have stimulated the development of new type NH₃-SCR catalyst. In this work, La-Mn perovskite oxide as active component and porous biochar as support were introduced to a biochar-supported catalyst, LMO/BCNA. The catalytic performance and SO₂/H₂O resistance of catalysts was tested in a fixed bed reactor. NO conversion achieved over 80% and N₂ selectivity was over 90% within the temperature range of 100—250℃, and the highest NO conversion reached 95.8% with N₂ selectivity of 95.4% at 225℃. Compared to LMO, LMO/biochar catalyst significantly improved denitration efficiency and widened working temperature window due to the synergistic catalytic effect of biochar. The introduction of biochar carrier weakens the catalyst’s adsorption of H₂O and SO_2, and enhances sulfur and water resistance. The kinetic model was built based on steady-state dynamics. On the test conditions and the presence of 5% O₂, the NH₃-SCR reaction order with respect to NO, O₂ and NH₃ was 0.66, 0 and 0, respectively. Accordingly, the activation energy for LMO/BCNA was 25.52 kJ/mol, which was much lower than that for commercial vanadium-wolframium-titanium catalysts of 40—94 kJ/mol.

Key words: denitration, biochar, perovskite oxide, selective catalytic reduction, steady-state dynamics

中图分类号:

X 511

范孝雄, 郝丽芳, 范垂钢, 李松庚. LaMnO₃/生物炭催化剂低温NH₃-SCR催化脱硝性能研究[J]. 化工学报, 2023, 74(9): 3821-3830.

Xiaoxiong FAN, Lifang HAO, Chuigang FAN, Songgeng LI. Study on the catalytic denitrification performance of low-temperature NH₃-SCR over LaMnO₃/biochar catalyst[J]. CIESC Journal, 2023, 74(9): 3821-3830.

图/表 10

图1 催化脱硝性能评价装置示意图

Fig.1 Schematic diagram of the fixed bed reactor for catalyst performance test

图2 条件参数对XNO的影响

Fig.2 Effect of conditional parameters on XNO for LMO/BCNA

图3 催化剂表面的SEM图

Fig.3 SEM images of different LMO loading ratio for LMO/BCNA

图4 100~250℃催化剂的催化脱硝活性[GHSV=16000 h-1; [NO]=[NH3]=670 mg/m3; [O2]=5%(vol); N2 as balance; a total flow rate of 800 ml/min]

Fig.4 NO conversion and N2 selectivity for LMO and LMO/BCNA at 100—250℃

图5 催化剂的耐硫耐水性能[225℃; GHSV=16000 h-1; [NO]=[NH3]=670 mg/m3; [O2]=5%(vol); 10% H2O (when used); 134 mg/m3 SO2 (when used); N2 as balance; a total flow rate of 800 ml/min]

Fig.5 H2O and SO2 resistance performance of catalysts

图6 内、外扩散对NO转化率的影响[200℃; [NH3]=[NO]=670 mg/m3; [O2]=5%(vol); N2 as balance]

Fig.6 Effect of external diffusion and internal diffusion on NO conversion

图7 气体反应物浓度对NO反应速率（RNO）的影响(Particle size of 0.18—0.25 mm; GHSV 232000 h-1; N2 as balance; a total flow rate of 2.9 L/min)

Fig. 7 Dependence of NO conversion rate on NO (a), NH3 (b) and O2 (c) concentration at 120, 160, 200℃

表1 不同质量催化剂在120、160、200℃条件下的NO转化率（XNO）

Table 1 NO conversion （XNO） over catalyst at 120， 160， 200℃

催化剂质量W/g	NO转化率/%
催化剂质量W/g	120℃	160℃	200℃
0.5	4.4	7.6	12.1
0.6	5.0	9.2	15.4
0.8	6.1	12.6	19.7
0.9	7.2	15.3	24.9

图8 不同温度下B-W/V关系

Fig.8 Relationship of B with W/V

图9 lnK-1/T关系

Fig.9 Relationship of lnK with 1/T

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LaMnO₃/生物炭催化剂低温NH₃-SCR催化脱硝性能研究

Study on the catalytic denitrification performance of low-temperature NH₃-SCR over LaMnO₃/biochar catalyst

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