Study on the effect of different metal oxides on the performance of cobalt-based Fischer-Tropsch catalysts
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摘要: 本实验在六方纳米片状的Co3O4(NMS-Co)上分别负载了1%含量的ZrO2、Al2O3和MnO2三种金属氧化物,制备反相催化剂模型,研究金属氧化物对钴基催化剂费托合成性能的影响。通过H2-TPD、CO-TPD以及催化剂性能评价结果发现,ZrO2和Al2O3能够显著增加NMS-Co催化剂的活性位点,在相同转化率条件下,反应温度从230℃分别降低至170、180 ℃,重质烃生成速率分别提升2.5、2倍,CH4选择性从37.8%分别降低至3.6%、12.0%。然而,MnO2使得NMS-Co催化剂CO转化率仅从30.9%增加到45.5%,CH4选择性降低至16.5%。Abstract: In this paper, three metal oxides, ZrO2, Al2O3 and MnO2, loaded with 1% content on hexagonal nanosheets of Co3O4 (NMS-Co), respectively, were prepared as reversed-phase catalyst models to investigate the effects of metal oxides on the performance of cobalt-based catalysts for Fischer-Tropsch synthesis. The results of H2-TPD, CO-TPD and catalyst performance evaluation revealed that ZrO2 and Al2O3 could significantly increase the active sites of NMS-Co catalysts, lower the reaction temperature from 230 ℃ to 170 and 180 ℃, respectively, and increase the heavy hydrocarbon generation rate by 2.5 and 2 times, respectively, under the same conversion conditions. The CH4 selectivity was reduced from 37.8% to 3.6% and 12.0%, respectively. However, MnO2 increased the CO conversion only from 30.9% to 45.5% and decreased the CH4 selectivity to 16.5%. A new idea is proposed to investigate the effect of metal oxides on the performance of cobalt-based Fischer-Tropsch catalysts.
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Key words:
- reversed-phase catalysts /
- Co3O4 /
- metal oxide
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图 7 (a)负载不同金属氧化物催化剂CO化学吸附曲线; (b)负载不同金属氧化物催化剂H2化学吸附曲线; (c)负载不同金属氧化物催化剂TG曲线; (d)负载不同金属氧化物催化剂d(TG)曲线
Figure 7 (a) CO chemisorption curves of catalysts loaded with different metal oxides; (b) H2 chemisorption curves of catalysts loaded with different metal oxides; (c) TG curves of catalysts loaded with different metal oxides; (d) d(TG) curves of catalysts loaded with different metal oxides
表 1 催化剂的物理化学性质
Table 1 Physical and chemical properties of catalyst
Catalyst XRD SEM Reducibility
/% cH2 uptake / (μmol·gcat−1) d d(Co3O4) a
/nmd(Co3O4) b
/nmNMS-Co 24.1 205.54 100 − NMS-Co-1Zr 23.9 199.07 93 23.27 NMS-Co-1Al 19.9 157.50 78 50.44 NMS-Co-1Mn 20.0 157.48 99 7.5 a: crystallite size was calculated by the Scherrer formula based on the strongest diffraction (2θ=36.8°), b: cobalt particle size calculated from the SEM measurement of catalyst samples, c: Reducibility calculated TPR from 200 to 400 ℃, d: By H2-chemisorption method 表 2 催化剂的XPS表征
Table 2 XPS results of catalyst
Sample Binding energy /eV Co 2p3/2 Co 2p1/2 OV OL Zr 3d Al 2p Mn 2p NMS-Co 780.1 795.0 530.2 531.9 NMS-Co-1Zr 780.0 795.1 530.1 531.6 182.3 NMS-Co-1Al 779.5 794.5 529.7 531.4 73.9 NMS-Co-1Mn 779.9 794.9 530.1 531.6 641.9 表 3 不同催化剂中各组分的含量
Table 3 Analysis of the content of each component in different catalysts
Catalyst Co Na Zr Al Mn NMS-Co 0.89 0.1 NMS-Co-1Zr 0.90 0.08 0.01 NMS-Co-1Al 0.91 0.07 0.01 NMS-Co-1Mn 0.91 0.07 0.01 表 4 催化剂的FTS反应性能
Table 4 FTS reaction performance of catalyst
Catalyst Temp. /
℃CO conv. /% Product selectivity /% CH4 C2–C4 C5 + NMS-Co 230 30.9 37.8 22.7 39.5 NMS-Co-1Zr 170 32.9 3.6 5.4 91.0 NMS-Co-1Al 180 31.5 12.0 12.5 75.5 NMS-Co-1Mn 230 45.5 16.5 30.7 52.8 Reaction conditions:H2/CO=2, p=2 MPa,GHSV=1000 h−1,TOS=48 h -
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