Effects of Ce0.8Cu0.2O2 oxygen carrier-coupled S-1 molecular sieve on chemical-looping performance
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摘要: 在Ce0.8Cu0.2O2氧载体中添加不同质量S-1分子筛,并利用XRD、BET、XPS、SEM、TEM和CH4-TPR & CO2-TPO等表征对氧载体的物化特性和反应性能进行了研究。考察了S-1分子筛添加量对Ce0.8Cu0.2O2氧载体在化学链甲烷重整耦合CO2还原反应中的性能的影响。与单纯的Ce0.8Cu0.2O2氧载体相比,添加了0.3 g S-1分子筛后复合氧载体的比表面积明显增大,从15.44 m2/g提高至73.27 m2/g。同时热稳定性和结构稳定性也得到了很大的改善。添加了0.3 g S-1分子筛的复合氧载体CH4转化率由38.93%提升至56.03%,CO2还原过程中CO产率由1.18 mmol/g增加至2.16 mmol/g。Abstract: Ce0.8Cu0.2O2 oxygen carrier has excellent performance in chemical-looping reforming of methane coupled with CO2 reduction technology. Different mass of S-1 molecular sieve was added to Ce0.8Cu0.2O2 oxygen carrier. The physicochemical properties and reactivity of the carrier were characterized by XRD, BET, XPS, SEM, TEM and CH4-TPR & CO2-TPO. The effect of S-1 molecular sieve on the performance of Ce0.8Cu0.2O2 oxygen carrier in chemical-looping reforming of methane coupled with CO2 reduction was systematically investigated. Compared with Ce0.8Cu0.2O2 oxygen carrier alone, the specific surface area of the composite oxygen carrier increased from 15.44 to 73.27 m2/g after adding 0.3 g S-1 molecular sieve. At the same time, its thermal stability and structural stability were greatly improved. The CH4 conversion rate of composite oxygen carrier with 0.3 g S-1 molecular sieve increased from 38.93% to 56.03%, and the CO yield increased from 1.18 to 2.16 mmol/g during CO2 reduction.
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Key words:
- chemical-looping /
- S-1 molecular sieves /
- reforming of methane /
- CO2 reduction /
- syngas
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图 6 Ce0.8Cu0.2O2 (a)、Ce0.8Cu0.2O2/0.1 g S-1 (b)、Ce0.8Cu0.2O2/0.2 g S-1 (c)、Ce0.8Cu0.2O2/0.3 g S-1 (d)和Ce0.8Cu0.2O2/0.4 g S-1 (e)氧载体和S-1(f)的CH4-TPR谱图
Figure 6 CH4-TPR profiles of Ce0.8Cu0.2O2 (a), Ce0.8Cu0.2O2/0.1 g S-1 (b), Ce0.8Cu0.2O2/0.2 g S-1 (c), Ce0.8Cu0.2O2/0.3 g S-1 (d) and Ce0.8Cu0.2O2/0.4 g S-1 (e) oxygen carriers and S-1(f)
图 7 Ce0.8Cu0.2O2 (a)、Ce0.8Cu0.2O2/0.1 g S-1 (b)、Ce0.8Cu0.2O2/0.2 g S-1 (c)、Ce0.8Cu0.2O2/0.3 g S-1 (d)和Ce0.8Cu0.2O2/0.4 g S-1 (e)氧载体的CO2-TPO谱图
Figure 7 CO2-TPO curves of Ce0.8Cu0.2O2 (a), Ce0.8Cu0.2O2/0.1 g S-1 (b), Ce0.8Cu0.2O2/0.2 g S-1 (c), Ce0.8Cu0.2O2/0.3 g S-1 (d) and Ce0.8Cu0.2O2/0.4 g S-1 (e) oxygen carriers
图 8 Ce0.8Cu0.2O2 (a)、Ce0.8Cu0.2O2/0.1 g S-1 (b)、Ce0.8Cu0.2O2/0.2 g S-1 (c)、Ce0.8Cu0.2O2/0.3 g S-1 (d)和Ce0.8Cu0.2O2/0.4 g S-1(e)氧载体和S-1(f)在850 ℃下甲烷部分氧化反应中气体含量的变化
Figure 8 Gas content change curve of Ce0.8Cu0.2O2 (a), Ce0.8Cu0.2O2/0.1 g S-1 (b), Ce0.8Cu0.2O2/0.2 g S-1 (c), Ce0.8Cu0.2O2/0.3 g S-1 (d), Ce0.8Cu0.2O2/0.4 g S-1 (e) oxygen carriers and S-1 (f) in the CH4 partial oxidation reactions at 850 ℃
图 10 Ce0.8Cu0.2O2((a)/(d))、 Ce0.8Cu0.2O2/0.2 g S-1 ((b)/(e))和Ce0.8Cu0.2O2/0.3 g S-1 ((c)/(f))氧载体在850 ℃时20次redox循环的CH4部分氧化反应和CO2还原反应的气体含量变化
Figure 10 Gas content of Ce0.8Cu0.2O2 ((a)/(d)), Ce0.8Cu0.2O2/0.2 g S-1 ((b)/(e)) and Ce0.8Cu0.2O2/0.3 g S-1 ((c)/(f)) oxygen carriers in CH4 partial oxidation reactions and CO2 reduction reactions during 20 redox cycles at 850 ℃
表 1 Ce0.8Cu0.2O2 样品和耦合不同比例S-1分子筛的Ce0.8Cu0.2O2 样品的平均孔径、比表面积和孔容
Table 1 Average pore diameter, BET surface area and total pore volume of Ce0.8Cu0.2O2 samples and Ce0.8Cu0.2O2 samples coupled with different proportions of S-1 zeolites
Sample Average pore diameter/nm Surface area/(m2·g−1) Total pore volume/(cm3·g−1) S-1 2.61 382.07 0.25 Ce0.8Cu0.2O2 28.38 15.44 0.11 Ce0.8Cu0.2O2/0.1 g S-1 13.79 33.21 0.11 Ce0.8Cu0.2O2/0.2 g S-1 8.15 69.40 0.14 Ce0.8Cu0.2O2/0.3 g S-1 5.11 73.27 0.09 Ce0.8Cu0.2O2/0.4 g S-1 6.62 79.00 0.13 表 2 样品的XPS特性参数
Table 2 XPS characteristic parameters of sample
Sample Surface element composition Oads / Olatt Cu + / Cu2 + Ce3 + / Ce4 + Ce0.8Cu0.2O2 1.01 0.47 0.11 Ce0.8Cu0.2O2/0.2 g S-1 2.58 0.44 0.13 Ce0.8Cu0.2O2/0.3 g S-1 2.45 0.34 0.15 表 3 样品在850 ℃下甲烷部分氧化反应中的气体含量
Table 3 Gas content of sample in the CH4 partial oxidation reactions at 850 ℃
Sample Percent conversion
of CH4/%Yield of CO /
(mmol·g−1)Yield of CO2 /
(mmol·g−1)Yield of carbon deposition /
(mmol·g−1)Ce0.8Cu0.2O2 38.93 1.25 0.19 0.014 Ce0.8Cu0.2O2/0.1 g S-1 44.87 1.68 0.20 0.015 Ce0.8Cu0.2O2/0.2 g S-1 51.07 1.83 0.21 0.033 Ce0.8Cu0.2O2/0.3 g S-1 56.03 2.24 0.19 0.031 Ce0.8Cu0.2O2/0.4 g S-1 57.30 2.20 0.18 0.034 表 4 样品在850 ℃下CO2还原反应中的气体含量
Table 4 Gas content of samples in CO2 reduction reaction at 850 ℃
Sample Yield of CO /
(mmol·g−1)Ce0.8Cu0.2O2 1.18 Ce0.8Cu0.2O2/0.1 g S-1 1.53 Ce0.8Cu0.2O2/0.2 g S-1 1.91 Ce0.8Cu0.2O2/0.3 g S-1 2.16 Ce0.8Cu0.2O2/0.4 g S-1 2.03 表 5 样品在850 ℃时20次循环过程得失氧量与积炭量变化
Table 5 Amount of oxygen gained and lost during the 20 cycles at 850 ℃ and the amount of carbon deposition variated
Sample Ce0.8Cu0.2O2/(mmol·g−1) Ce0.8Cu0.2O2/0.2 g S-1/(mmol·g−1) Ce0.8Cu0.2O2/0.3 g S-1/(mmol·g−1) oxygen
lossoxygen
gaincarbon
depositionoxygen
lossoxygen
gaincarbon
depositionoxygen
lossoxygen
gaincarbon
deposition2 2.07 1.20 0.020 2.42 2.20 0.041 2.30 2.08 0.042 4 1.23 0.71 0.051 1.33 1.27 0.049 1.56 1.57 0.043 6 0.93 0.74 0.048 1.15 1.20 0.048 1.00 1.14 0.046 8 0.90 0.81 0.052 1.00 0.97 0.054 1.17 1.18 0.044 10 0.97 0.66 0.049 0.91 0.89 0.051 1.09 1.12 0.044 12 1.93 1.52 0.016 1.26 0.82 0.028 1.75 1.36 0.017 14 0.87 1.08 0.050 0.65 0.62 0.043 1.10 1.04 0.035 16 1.02 0.95 0.048 0.57 0.54 0.043 0.98 1.04 0.035 18 0.99 0.95 0.049 0.59 0.48 0.044 0.93 0.95 0.038 20 0.87 0.88 0.049 0.48 0.39 0.044 0.88 0.86 0.037 表 6 20次redox循环后样品的平均孔径、比表面积和孔容
Table 6 Average pore diameter, BET surface area and total pore volume of samples after 20 redox cycles
Sample Average pore diameter /
nmSurface area /
(m2·g−1)Total pore volume /
(cm3·g−1)Ce0.8Cu0.2O2 10.48 3.01 0.008 Ce0.8Cu0.2O2/0.2 g S-1 4.02 33.94 0.03 Ce0.8Cu0.2O2/0.3 g S-1 3.52 51.50 0.04 -
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