Effect of Ca modified HZSM-5 zeolites on catalytic pyrolysis of oil shale
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摘要: 采用热重质谱红外光谱(TG-MS-FTIR)联用技术和管式热解炉,探究了Ca改性前后HZSM-5分子筛对油页岩热解的催化行为,并采取BET、NH3-TPD、TG手段对分子筛进行表征。结果表明,改性前后的HZSM-5均可以显著提高C1−4脂肪烃类产物的产量,降低其析出温度。Ca改性后的HZSM-5可以降低CO2的产量。对页岩油的分析表明,改性后的HZSM-5可以提高页岩油产量,并且有效降低页岩油中脂肪链长度。但是对芳构化促进作用更强。分子筛中Brönsted酸位点对脂肪烃催化效果明显,Lewis酸位点有利于芳构化反应的发生。Abstract: The catalytic behaviors of Ca-modified HZSM-5 during oil shale pyrolysis process were investigated in a tubular rector and by TG-MS-FTIR. The physicochemical properties of the molecular sieve were characterized by BET, NH3-TPD, and TG. The results show that the molecular sieve can significantly increase yields of C1−4 aliphatic hydrocarbons and reduce their evolution temperatures. After modified, Ca/HZSM-5 can reduce yields of CO2, increase yields of shale oil and decrease lengths of aliphatic chains in shale oil. But Ca/HZSM-5 has a strong catalytic effect on aromatization. Brönsted acid sites have an obvious catalytic effect on aliphatic hydrocarbons, while Lewis acid sites are more targeted at aromatization process of pyrolysis products.
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Key words:
- oil shale /
- catalytic pyrolysis /
- HZSM-5 /
- metal modified.
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表 1 抚顺油页岩的基本性质
Table 1 Basic properties of Fushun oil shale
Proximate analysis wad/% Ultimate analysis wad/% Fischer assay retort w/% M V A FCa C H Ob N S oil moisture char gas 2.40 18.10 77.36 2.14 9.89 1.80 6.16 0.82 0.57 8.10 4.30 84.10 3.20 a: calculated,b: by difference 表 2 Ca改性前后HZSM-5分子筛的物理化学性质
Table 2 Physicochemical properties of HZSM-5 and Ca/HZSM-5
Catalyst Porosity characteristics Acidic properties Cf /%d surface areaa
A/(m2·g−1)Pore sizeb/
nmMicropore volumec
v/(cm3·g−1)Brönsted acidity/
(mmol·g−1)Lewis acidity/
(mmol·g−1)HZSM-5 186.2 5.9 0.04 2.53 0.95 3.3 3%Ca/HZSM-5 138.5 6.69 0.03 0.82 2.19 6.7 9%Ca/HZSM-5 104.0 9.6 0.01 − 2.71 6.0 a: from BET method; b: from BJH analysis; c: from t-plot analysis; d: the mass loss of catalysts 表 3 页岩油中烃类成分
Table 3 Hydrocarbons distribution in shale oil
Hydrocarbons Content [area/%] RS HS Ca3%MHS Ca9%MHS Aliphatic hydrocarbons Alkane < C10 0.42 − − − C10−20 26.85 24.59 36.64 44.57 > C20 26.88 17.58 12.97 13.64 Alkene < C10 − − 6.30 3.35 C10−20 16.29 17.17 5.81 8.78 > C20 17.63 14.14 − 0.54 Aromatic hydrocarbons Benzene derivatives 1.12 − 2.22 4.92 PAHs 1.59 7.31 11.67 7.79 -
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