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摘要: 在反应温度550 ℃、空速5 500 h-1、H2S体积分数1.2%下对所研制的钼基催化剂进行了耐硫甲烷化活性评价，考察了反应气中添加H2O对Mo基催化剂耐硫甲烷化活性的影响。结果表明，反应气中添加水对Al2O3负载的Mo基催化剂可造成不可逆失活，而添加Co助剂及采用铈铝复合载体的催化剂其稳定性、活性得到了改善和提高。Co的添加能保护Mo基催化剂上的活性组分MoS2，抑制添加水导致的不可逆失活。当反应气中加入水时，催化剂上主要发生水汽变换反应，且随着水含量升高，水汽变换反应速率增大，会严重影响甲烷化反应的进行。此外，随着水含量的增加，其对催化剂的耐硫甲烷化活性和稳定性的影响程度变大。Abstract: The effects of H2O on the performance of the sulfur-resistant Mo-based methanation catalysts were investigated by adding vapor into the reactant gas at the reaction conditions of 550℃, 5 500 h-1, 1.2% of H2S concentration. The results indicate that water caused irreversible deactivation of Mo-based catalyst supported on Al2O3, while additive Co and cerium-aluminum composite carrier can enhance the activity and improve the stability of the Mo-based catalyst for methanation of syngas. The promoter Co protects the active phase MoS2 of Mo-based catalyst, inhibits the irreversible deactivation caused by the addition of water. When the water content in reactant gas is increased, the water gas shift reaction increases and becomes the main reaction on catalysts, and the increase of water leads to further decrease of the catalyst activity and stability.
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Key words:
- sulfur-resistant methanation /
- Mo-based catalyst /
- water /
- water-gas shift /
- deactivation
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图 1 反应气中含10% H2O对Al2O3负载Mo基催化剂活性的影响
: x(CO); : x(H2); : s(CH4); : s(CO2); : s(C2H6); : CB
Figure 1 Effect of 10% H2O on methanation activity of Mo/Al and Co-Mo/Al catalysts
图 2 Al2O3载体负载催化剂的XRD谱图
Figure 2 XRD patterns of Mo/Al and Co-Mo/Al catalysts
a: catalysts after methanation reaction without water; b: catalysts after methanation reaction with water
图 3 催化剂的TEM照片
Figure 3 TEM images of Mo/Al and Co-Mo/Al catalysts
(a): Mo/Al catalyst after methanation reaction without water; (b): Mo/Al catalyst after methanation reaction with water; (c): Co-Mo/Al catalyst after methanation reaction without water; (d): Co-Mo/Al catalyst after methanation reaction with water
图 4 反应气中含10% H2O对铈铝复合载体负载Mo基催化剂活性的影响
: x(CO); : x(H2); : s(CH4); : s(CO2); : s(C2H6); : CB
Figure 4 Effect of 10% H2O on methanation activity of Mo/CeAl and Co-Mo/CeAl catalysts
图 5 铈铝复合载体负载催化剂的XRD谱图
Figure 5 XRD patterns of Mo/CeAl and Co-Mo/CeAl catalysts
a: catalysts after methanation reaction without water; b: catalysts after methanation reaction with water
图 6 反应气中添加20%、30%的H2O对Co-Mo/CeAl催化剂的影响
: x(CO); : x(H2); : s(CH4); : s(CO2); : s(C2H6); : CB
Figure 6 Effect of H2O concentration on Co-Mo/CeAl catalyst activity
图 7 添加不同含量H2O反应后Co-Mo/CeAl催化剂的XRD谱图
■: MoS2; ◆: Co9S8; ◇: CoMoO4; △: CeO2; ▲: Al2O3
Figure 7 XRD patterns of Co-Mo/CeAl catalysts after reactions with different H2O concentrations
图 8 添加不同含量H2O反应后Co-Mo/CeAl催化剂的TEM照片
(a): 10% H2O; (b): 20% H2O; (c): 30% H2O
Figure 8 TEM images of Co-Mo/CeAl catalysts after reactions with different H2O concentrations
表 1 Al2O3负载Mo基催化剂反应后的织构性质
Table 1 Textural properties of Mo/Al and Co-Mo/Al catalysts after reactions with/without H2O
表 2 催化剂加水评价后的织构性质
Table 2 Textural properties of Mo/CeAl and Co-Mo/CeAl catalysts after reactions with/without H2O
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