Structure and composition of n-pentane and n-heptane asphaltene from different properties crude
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摘要: 采用SARA四组分分离方法得到石蜡基玉门常压渣油和环烷基马瑞常压渣油的C5和C7沥青质,结合 1H-NMR、FT-IR、VPO及元素分析等方法,对沥青质的结构组成和官能团形态进行表征,考察不同基属渣油沥青质以及不同沉淀剂所得沥青质的结构组成差异。结果表明,四种沥青质的官能团类型基本一致,但分子结构单元存在一定差异,相比于环烷基马瑞沥青质,石蜡基玉门沥青质的分子结构单元更大,芳碳分率较小,但HAU/CA值也较小,分子缩合程度更高;随沉淀剂碳链增长,沥青质收率减少(相同原料的正庚烷沥青质收率约为正戊烷沥青质的80%左右),H/C降低,平均相对分子量升高,C7沥青质具有更高的芳碳率
$ f $ A和更多的结构单元数。各类沥青质中均存在较多的饱和结构,饱和碳分率约为0.5。Abstract: C5 and C7 asphaltene were separated from paraffin base Yumen atmospheric residue and naphthene base Merey atmospheric residue by n-pentane and n-heptane respectively using the method of SARA. The structure parameters and functional groups analyzed and characterized systematically by VPO, 1H-NMR, FT-IR and elemental analysis, in order to comparative studied the differences in asphaltene structure of different residues and asphaltene obtained by different precipitants. The results showed that there was consistent in the functional groups of different asphaltenes basically, but there was some differences in the unit structure of different asphaltene. Yumen paraffinic asphaltenes had significantly higher molecular weight, smaller HAU/CA value and higher condensation degree than Merey naphthenic asphaltenes. With the increase of carbon chain of precipitants, the yield (the yield of n-heptane asphaltene was about 80% of n-pentane for the some feedstook) and the H/C of asphaltene decreased, the molecular weight of asphaltene increased. C7 asphaltenes had higher aromatic carbon ratio ($ f $ A) and more structure units than C5 asphaltene. More saturated structure existed in various asphaltenes and the saturate carbon fraction was about 0.5.-
Key words:
- asphaltene /
- precipitants /
- crude properties /
- structure & composition /
- functional group
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表 1 原料性质
Table 1 Properties of residue
Item YMAR MRAR Density (20℃)/(kg·m−3) 898.5 986.2 Viscosity (100℃)/(mm2·s−1) 10.13 130.70 Carbon residue w/% 5.21 13.40 SARA w/% Saturate 49.62 38.04 Aromatic 24.07 29.80 Resin 15.56 19.34 Asphaltene 10.75 12.81 Elemental w/% C 86.30 84.76 H 12.60 10.84 S 0.77 3.74 N 0.28 0.51 H/C(mol ratio) 1.75 1.53 表 2 沥青质收率
Table 2 Yield of asphaltenes
Asphaltene C5YM C7YM C5MR C7MR Yield w/% 13.58 10.75 16.11 13.23 Note: C5: n-pentane asphaltene; C7: n-heptane asphaltene; YM: Yumen atmospheric residue; MR: Merey atmospheric residue 表 3 沥青质的元素组成及平均相对分子质量
Table 3 Element composition and molecular weight of asphaltene
Asphaltene Vitimate analysis w/% H/C
(mol ratio)M C H S N C5YM 85.58 8.54 2.10 1.13 1.20 4468 C7YM 86.41 7.99 2.42 1.93 1.11 4735 C5MR 83.40 8.08 4.70 1.53 1.16 3561 C7MR 82.94 7.71 4.81 1.73 1.12 4612 表 4 沥青质中不同化学位移的氢含量
Table 4 Different H content of asphaltene
Item C5YM C7YM C5MR C7MR Hγ w/% 30.22 17.08 29.43 32.31 Hβ w/% 52.85 59.77 49.49 42.75 Hα w/% 4.86 14.97 6.01 9.82 HA w/% 12.08 8.17 15.07 15.11 表 5 沥青质结构参数
Table 5 Structural parameters of asphaltene
Structural parameter C5YM C7YM C5MR C7MR CT 318.38 340.68 177.84 318.5 HT 378.58 375.36 205.31 352.8 CA 151.94 168.35 90.66 168.77 RA 49.31 54.78 28.89 54.92 RT 54.12 69.82 30.86 58.72 RN 4.81 15.04 1.97 3.79 RA/RN 10.25 3.64 14.64 14.49 CN 14.43 45.12 5.92 11.37 CP 152.01 127.21 81.26 138.36 HAU/CA 0.36 0.35 0.41 0.42 $ f $A 0.48 0.49 0.51 0.53 $ f $N 0.05 0.13 0.03 0.04 $ f $p 0.48 0.37 0.46 0.43 σ 0.17 0.48 0.17 0.25 n 3.17 3.27 2.42 4.72 Usw 1409.47 1446.25 1056.29 977.54 CA* 47.93 51.42 37.39 35.77 CT* 100.43 104.06 73.35 67.51 HT* 119.42 114.65 84.68 74.78 RT* 17.07 21.33 12.73 12.44 RA* 15.56 16.73 11.91 11.64 RN* 1.52 4.59 0.81 0.80 -
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