The effect of ZSM-5 catalyst support in catalytic pyrolysis of biomass and compounds abundant in pyrolysis bio-oils

Abstract

Supported ZSM-5 is commonly used for in-situ biomass pyrolysis vapor upgrading in fluidized bed reactors. In this work, we investigate the effects of catalyst support on the pyrolysis product distribution by studying pyrolysis of woody biomass and bio-oil derived model compounds. Specifically, miscanthus, toluene and furan are catalytically pyrolyzed over bulk ZSM-5, supported ZSM-5 and a commercial Al2O3 support. The pyrolysis product distributions of biomass and each model compound are presented and discussed. The coke formed on the catalysts and support, which is also responsible for catalyst deactivation, is analyzed using temperature programmed oxidation (TPO). It is shown that pyrolysis of miscanthus, toluene and furan over supported ZSM-5 produces less liquid products, particularly mono-aromatic hydrocarbons, than over bulk ZSM-5, mainly due to the dilution of Brønsted acid sites by the catalyst support. The Lewis acidity of the Al2O3 support promotes alkylation and cyclization of propylene leading to enhanced benzene production. The Lewis acidity of the support also enhances coke production with a less condensed structure, while selectivity to poly-aromatics is deteriorated.

Biomass pyrolysis: A review of the process development and challenges from initial researches up to the commercialisation stage

“…Catalytic pyrolysis is another method developed to deoxygenate the bio-oil in situ during the pyrolysis. In this process, the catalyst was directly added inside the reactor to convert the heavy species inside the bio-oil to lighter ones [8][9][10][11][12] . Some catalysts such as zeolite base ones were also tested or developed for catalytic pyrolysis of biomass.…”

A study of guaiacol, cellulose, and Hinoki wood pyrolysis with silica, ZrO2&TiO2 and ZSM-5 catalysts

“…In order to better understand the interactions between the catalyst and biomass vapors, Stefanidis et al and Zheng et al pyrolyzed the individual components of biomass with ZSM-5 and compared them to uncatalyzed products [4,5]. Other researchers such as Shoucheng Du et al have studied model compounds (toluene, furane and miscanthus) from biomass and pyrolyzed them over ZSM-5 to get a better understanding of the catalytic mechanism [6]. Haian Xia et al studied the effects of ZSM-5 and other catalysts on cellulose pyrolysis [7].…”

Counteracting Rapid Catalyst Deactivation by Concomitant Temperature Increase during Catalytic Upgrading of Biomass Pyrolysis Vapors Using Solid Acid Catalysts

“…The coke combusted under an oxidizing atmosphere in the temperature range 350-650 °C, as shown by the differential thermogravimetric (DTG) curves in Figure 7. Coke on γ-Al2O3 combusted more readily (main weight loss around 475 °C), while the coke on P/HZSM-5/γ-Al2O3 that combusted at higher temperatures, is attributed to coke in the zeolite component [28,57]. Table 2 provides an overview of the carbon recovery of different product groups.…”