Effects of Fe-, Zr-, and Co-Modified Zeolites and Pretreatments on Catalytic Upgrading of Biomass Fast Pyrolysis Vapors

Abstract

To evaluate the influence of metals on the catalytic activity of HZSM-5 zeolite, the catalytic fast pyrolysis of sawdust was investigated using a vertical two-stage reactor with Fe- (different loading amounts), Zr-, and Co-modified zeolite catalysts. Simultaneously, the effects of biomass pretreatments (HCl, NaOH, and NaBH4 impregnation) were also explored. Increasing the temperature of the catalytic reaction from 450 to 650 °C led to simplification of the composition of the bio-oil, and there was a marked increase in the content and yield of aromatic hydrocarbons. With respect to modification of the catalyst, 4Co/HZSM-5 produced the highest gas and coke yields, whereas 4Fe/HZSM-5 and 4Zr/HZSM-5 exhibited similar effects on the product yields and demonstrated better features in the catalytic process than HZSM-5, resulting in a content of over 45% aromatic hydrocarbons in the generated bio-oil. The 4Zr/HZSM-5 catalyst promoted the formation of more benzene and its derivatives, whereas 4Fe/HZSM-5 produced a higher yield of naphthalene and its derivatives. With increased Fe loading, catalytic deoxygenation and hydrocarbon formation became more effective. A reaction pathway leading to aromatics is proposed to describe the catalytic pyrolysis process. HCl and NaBH4 pretreatments largely promoted the formation of hydrocarbons, whereas NaOH pretreatment was favorable for the formation of phenolics. The combined utilization of biomass pretreatments and 4Fe/HZSM-5 catalyst was found to be an effective method for upgrading bio-oil.

Study on furfural conversion into aromatics over Zn/HZSM‐5 and Fe/HZSM‐5 catalysts

“…Especially, the selectivity of naphthalene increases significantly compared to Zncontaining catalysts. This result is completely consistent with the studies of Li et al (2016) [17] or the studies of Mullen et al (2015). [24] The Fe/HZSM-5 catalyst is highly activity for formation of benzene and naphthalene.…”

“…The metal-assisted HZSM-5 catalyst (Zn, Fe) was synthesized by wet impregnation method according to the literatures. [17,18] Zn/HZSM-5 catalysts with 1 wt.%, 3 wt.% and 5 wt.% of Zn were synthesized by stirring a solution of HZSM-5 and Zn(NO 3 ) 2 .6H 2 O (Fisher Acros, 98 wt.%) for 24 hours at 80 °C, was dried for 12 hours at 105 °C and was heated for 6 hours at 550 °C. The catalysts has 1 wt.%, 3 wt.% and 5 wt.% of Zn, they are symboled as 1ZnHZ, 3ZnHZ and 5ZnHZ, respectively.…”

Influence of metal (Fe/Zn) modified ZSM‐5 catalysts on product characteristics based on the bench‐scale pyrolysis and Py‐GC/MS of biomass

“…The acidity of the ZSM‐5 and the metal‐modified ZSM‐5 catalysts was determined using NH 3 ‐TPD analysis. As displayed in Figure , every curve can be divided into three peaks according to the method previously used . The peaks located at 100°C to180°C, 190°C to260°C, and 380°C to530°C correspond to the desorption of NH 3 at weak acid, medium acid, and strong acid sites, respectively.…”

Development of Heterogeneous Catalysts for Thermo-Chemical Conversion of Lignocellulosic Biomass

“…The first group of studies has focused on the investigation of the influence of the addition of selected transition metals (iron, zirconium, and cobalt) to the HZSM-5 structure on the composition of the liquid mixture formed in the catalytic upgrading of biomass (pine sawdust) fast pyrolysis vapors [30]. The obtained results revealed that an introduction of metals into the zeolite structure (via a wet impregnation method using aqueous solutions of the corresponding nitrate salts) resulted in a decrease in the bio-oil yield and an increase in the amount of gaseous fraction and deposited carbon due to the promotion of cracking and reforming reactions.…”