Deoxygenation of guaiacol and woody tar over reduced catalysts

Abstract

The effect of various reduced catalysts for the upgrading of bio-oil produced by fast pyrolysis in a small batch reactor was evaluated using reduced Ni/SiO 2 , Co/SiO 2 , Pt/SiO 2 , Pd/SiO 2 , and conventional sulfided CoMo/Al 2 O 3 catalysts. All of the reduced catalysts were prepared by incipient wetness impregnation. Hydrodeoxygenation (HDO) reactions carried out in the H 2 pressure range of 1-5 MPa and temperature range of 300-350 °C using guaiacol and woody tar as model compounds for fast pyrolysis oil demonstrated that at 300 °C, higher guaiacol conversion was achieved with the reduced Co/SiO 2 , Ni/SiO 2 , and Pd/SiO 2 catalysts compared with the conventional sulfide CoMo/Al 2 O 3 catalyst. However, only the reduced Co/SiO 2 catalyst exhibited high HDO activity and selectivity towards aromatics in the guaiacol HDO reaction. The reduced Co/SiO 2 catalyst also exhibited high HDO activity and selectivity towards aromatics in the HDO of woody tar, indicating that this catalyst may be active for direct deoxygenation of phenol yielding mostly benzene. Thus, the reduced catalysts, especially the Co/SiO 2 catalyst, can be considered to be potential candidates for use as HDO catalysts with improved activity and selectivity.

Hydropyrolysis of Lignin Using Pd/HZSM-5

“…However, the demand and price for these metals puts them at an economic disadvantage. Other catalysts, such as nickel (Ni), cobalt (Co) [38], iron (Fe) [39], and copper (Cu) [40] conversion/96.4% HDO and 40% and 53% selectivity for both products respectively [38]. The authors also varied guaiacol content from 5% to 20% and noticed a steady decline in conversion, but no significant variation in selectivity.…”

“…Phenol is then directly deoxygenated (DDO) into benzene and hydrogenated to form cyclohexane. This reaction scheme is shown in Figure 2 The DDO reaction mechanism was hypothesized to occur as follows: weakly acidic silica sites bind directly to oxygen atoms on the hydroxyl and methoxyl bonds, while adsorbed hydrogen on the metal (Co) "spill-over" to complete the DDO reaction [38]. This scheme is shown in Figure 2-11.…”

Catalytic study in the HDO HDT reaction of guaiacyl model compound for the direct valorization of biomasses pyrolysis oil

“…One of the most widely studied route for the pyrolysis oil upgrading is represented by the catalytic hydrodeoxygenation (HDO), where oxygen is removed by utilizing high pressure hydrogen and heterogeneous catalysts [9][10][11][12][13]. Many model compounds, as phenols, esters, ethers and organic acids, were used to prove the performance of catalysts in the HDO process of bio-oils from wood pyrolysis [9][10][11][12][13][14], among the different model compounds, Guaiacyl species deserve of special consideration in reason of two factors: first, the huge content into the crude woody TAR and second the complexity of reactions and phenomena occurring during the catalytic HDO [11,15]. Recently, Mochizuki et al [11] have analyzed the effect of catalyst reduction in the Guaiacol HDO reactions for Ni/SiO 2 , Co/SiO 2 , Pt/SiO 2 and Pd/SiO 2 catalysts, while Pinheiro et al [18] have performed HDO/HDT process over sulfided CoMo/Al 2 O 3 catalyst by co-feeding Straight-RunGas-Oil (SRGO) and Guaiacol as pyrolysis model compounds, ascertaining the feasibility of simultaneous treating oxygenates and hydrocarbons.…”

“…Many model compounds, as phenols, esters, ethers and organic acids, were used to prove the performance of catalysts in the HDO process of bio-oils from wood pyrolysis [9][10][11][12][13][14], among the different model compounds, Guaiacyl species deserve of special consideration in reason of two factors: first, the huge content into the crude woody TAR and second the complexity of reactions and phenomena occurring during the catalytic HDO [11,15]. Recently, Mochizuki et al [11] have analyzed the effect of catalyst reduction in the Guaiacol HDO reactions for Ni/SiO 2 , Co/SiO 2 , Pt/SiO 2 and Pd/SiO 2 catalysts, while Pinheiro et al [18] have performed HDO/HDT process over sulfided CoMo/Al 2 O 3 catalyst by co-feeding Straight-RunGas-Oil (SRGO) and Guaiacol as pyrolysis model compounds, ascertaining the feasibility of simultaneous treating oxygenates and hydrocarbons. In spite of the extensive work carried out, the influence of the chemical composition of bio-oils in the reactivity of molybdenum base catalyst in the HDO/HDT processes is still under debate [11].…”

“…The sulfur content is negligible while they are rich in oxygenated molecules which are responsible for several deleterious properties of these crudes as high viscosity, low volatility, corrosiveness, thermal instability and tendency to polymerize under exposure to oxygen [1,2] Then, the large amount of refractory compounds, as the Guaiacyl species, and the unsaturated hydrocarbons chains, must be converted to be useful as alternative fuel or as liquid and easily storable hydrogen source for mobile applications [1,2,8]. One of the most widely studied route for the pyrolysis oil upgrading is represented by the catalytic hydrodeoxygenation (HDO), where oxygen is removed by utilizing high pressure hydrogen and heterogeneous catalysts [9][10][11][12][13]. Many model compounds, as phenols, esters, ethers and organic acids, were used to prove the performance of catalysts in the HDO process of bio-oils from wood pyrolysis [9][10][11][12][13][14], among the different model compounds, Guaiacyl species deserve of special consideration in reason of two factors: first, the huge content into the crude woody TAR and second the complexity of reactions and phenomena occurring during the catalytic HDO [11,15].…”