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Hydrodeoxygenation Of Lignin-derived Single-ring Phenolic Compounds To Hydrocarbons

Posted on:2017-04-20Degree:MasterType:Thesis
Country:ChinaCandidate:W W TangFull Text:PDF
GTID:2271330485451037Subject:Organic Chemistry
Abstract/Summary:PDF Full Text Request
Biomass is getting more and more intention because fossil energy is reducing day by day and series of environment problems are caused by overusing fossil. Moreover, biomass has many advantages such as it is diversity, renewable, and easy getting. Large amount of fuels and chemicals can obtained from biomass in the world every year. Lignin, the maximum amount of renewable natural aromatic macromolecule in the nature, is 15%-30% in weight and has nearly 40% of the energy in plant biomass. A lot of work has been done on the production of phenolic compounds from lignin.. However, these phenolic compounds are a series of complex mixtures with high oxygen content. The oxygenate lead to some negative properties, such as high viscosity, thermal and chemical instability, corrosiveness, poor heating value and immiscibility with hydrocarbon fuels. Fortunately, these phenolic compounds can be converted into hydrocarbons via hydrodeoxygenation (HDO). The HDO products have high octane numbers and the carbon atom number (C6-C10) is exactly in the range of commercial gasoline. The HDO catalyst usually is bifunctional catalyst comprised of active metal and solid acid.To explore the effect of support on the catalytic properties, HDO reaction of anisole with the Ni-based catalyst supported on α-Al2O3, γ-Al2O3, SiO2, TiO2 and ZrO2 was carried out. Effect of reaction temperature, reaction time and catalyst dosage in HDO reaction of anisole was investigated. On the optimal condition, the highest yield of hydrocarbons (90.47%) was obtained over Ni/α-Al2O3 catalyst. Cyclohexane was the main component, and its yield was as high as 90.02%. Based on this result, it can be speculated that anisole was converted to phenol via demethylation firstly, followed by hydrogenation of aromatic ring to form cyclohexanol and then cyclohexane. The detected cyclohexanol and cyclohexene were the key evidences for this presumption. Interestingly, methoxycyclohexane was detected in the products obtained over Ni/α-Al2O3, suggesting that hydrogenation of the aromatic ring of anisole could occur prior to the demethylation. Anisole was also efficiently converted with high hydrocarbons yield when the catalyst Ni/α-Al2O3 was repeatedly used for five times. This result implied that the catalyst Ni/α-Al2O3 had a stable catalytic activity for the HDO of anisole.HDO reaction of mixed phenolics with the Ni/α-Al2O3 were also carried out. Effect of reaction temperature, reaction time and nickel content in HDO reaction of mixed phenolics was investigated. Under the optimal condition (T=330℃,t=10 H,PH2=4MPa), conversion of mixed phenolics was 88.96% and yield of hydrocarbons was 46.82%. However, the conversion of mixed phenolics was only 40.48% when furfural was added into the phenolic mixtures. This result indicated that furfural had a negative effection on on the HDO of phenolic mixtures. This can be explained as this. Phenolic resin formed with furfural and phenolics deposited on the surface of catalyst, thereby leading to a decrease for the catalytic activity for HDO reaction.Heavy fraction of bio-oil can be hardly hydrodeoxygenated because of its extreme complex composition. However, HDO reaction of the heavy bio-oil fraction with the Ru-based catalyst supported on α-Al2O3, γ-Al2O3,SiO2, TiO2 and ZrO2 was also studied in this paper. Effect of reaction temperature and reaction time on the HDO reaction of heavy fraction was investigated. The result exhibited that Ru/α-Al2O3 had a stable catalytic activity and excellent resistance to coking. When the HDO process was carried out at 260 ℃ for 24h, yield of hydrocarbons was 22.46%.
Keywords/Search Tags:Lignin, Phenolic, Bio-oil, Hydrodeoxgenation(HDO), Ni/α-Al2O3
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