Performance study on simultaneous tar removal and bio-syngas methanation by combining catalysis with nonthermal plasma
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摘要: 以含甲苯的模拟气化燃气(SGG)为对象,在介质阻挡放电耦合Ni/γ-Al2O3反应器上开展同时甲苯脱除及SGG甲烷化实验研究。考察了反应温度、H2/CO比、H2O添加的影响。结果表明,等离子体耦合催化可在400 ℃实现高效的同时甲苯脱除与SGG甲烷化。H2/CO比为3.2时,甲苯脱除率与焦油脱除率可达100%和97%,CO转化率与CH4选择性可达88%和97%,甲苯脱除与SGG甲烷化过程能量效率可达9.7 g/(kW·h)和17.3 mol/(kW·h)。高H2/CO比与H2O添加可促进甲苯脱除和SGG甲烷化,降低催化剂积炭量并提升积炭石墨化程度,其中,高H2/CO比还可提升SGG热值,获得高甲苯脱除及SGG甲烷化过程能量效率;而H2O添加会降低热值且难获得高CH4选择性,同时不利于SGG甲烷化过程能量效率的提升。此外,SGG甲烷化会抑制甲苯的脱除,而甲苯因浓度较低对甲烷化过程的影响较小。Abstract: In this work, simultaneous toluene removal and syngas methanation using the combination of packed-bed dielectric barrier discharge and Ni/γ-Al2O3 catalyst were conducted with the research object of simulated gasification gas (SGG) containing toluene. The effects of reaction temperature, H2/CO ratio and H2O addition on the reaction performances of both toluene removal and SGG methanation were investigated. The results show that high-efficiency simultaneous toluene removal and SGG methanation can be achieved at 400°C under plasma catalysis treatment. When the H2/CO ratio is 3.2, the toluene removal rate and the tar removal rate are close to 100% and 97%, the CO conversion rate and CH4 selectivity approach about 88% and 97%, and the energy efficiencies in toluene removal and SGG methanation processes can reach 9.7 g/(kW·h) and 17.3 mol/(kW·h). Both the high H2/CO ratio and the H2O addition can promote toluene removal and SGG methanation, and reduce the amount of carbon deposition but increase its graphitized degree. Moreover, high H2/CO ratio can rise the heating value of SGG and achieve higher energy efficiencies in both toluene removal and SGG methanation processes, while the H2O addition is difficult to obtain high CH4 selectivity to increase the heating value and is not conducive to the promotion of energy efficiency in SGG methanation process. In addition, for these two simultaneous processes, the SGG methanation process exerts a significant inhibiting effect on toluene removal, but process of toluene removal has less influence on the other process due to the lower concentration of toluene.
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Key words:
- biomass gasification /
- tar removal /
- methanation /
- nonthermal plasma /
- catalysis
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表 1 不同工况反应后催化剂的表面氧物种
Table 1 Surface oxygen species derived from O 1s spectra
Proces Oxygen concentration/% O′α/Oβ ratio Oβ O′α Oα Fresh catalyst 41.45 42.72 15.83 1.03 Catalyst alone 45.49 39.39 15.13 0.86 Plasma catalysis 41.53 42.40 16.07 1.02 表 2 不同工况下反应60 min后的催化剂积炭量
Table 2 Amount of carbon deposition on the catalysts reacted under different conditions for 60 min
Process Carbon deposition w/% SGG 1.38 H2/CO = 1.5 0.57 H2/CO = 2.2 0.16 H2/CO = 3.2 0.10 10 % H2O addition 0.17 20 % H2O addition 0.12 30 % H2O addition 0.03 表 3 400 ℃不同工况下的SGG 热值及能量效率
Table 3 LHV of SGG and energy efficiencies under different conditions operated at 400 ℃
H2/CO ratio H2O addition/% 0.8 1.5 2.2 3.2 10 20 30 QLHV Inlet/(MJ·m−3) 4.43 5.01 5.70 6.34 4.43 4.43 4.43 Outlet/(MJ·m−3) 4.06 5.06 6.01 7.49 3.97 3.83 3.72 Growth rate/% −8.4 0.1 5.4 18.1 −0.2 −13.5 −16.0 Energy efficiency Etoluene/(g·(kW·h)−1) 8.8 9.4 9.6 9.7 9.4 9.4 9.3 $ E_{{\rm{CH_4}}} $/(mol·(kW·h)−1) 4.3 9.6 13.7 17.3 6.1 5.0 3.1 -
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