Overview of catalytic upgrading of biomass pyrolysis vapors toward the production of fuels and high‐value chemicals

Abstract

with HZSM-5, while the collected bio-oil was of high quality (Table 1) and might be used as transport oil (Zhang et al., 2009).Uzun and Sario glu (2009) also studied different zeolite structures (ZSM-5, H-Y, and USY) for the CP of corn stalks. The highest oil yield was observed with ZSM-5 zeolite and the lowest with USY. They also observed the highest amount of aromatics with USY zeolite, while the H-Y zeolite caused an increase of the aliphatic hydrocarbons. Atutxa, Aguado, Gayubo, Olazar, and Bilbao (2005) studied the effect of H-ZSM-5 zeolite on the in situ pyrolysis/upgrading of sawdust at 400 C in a conical spouted bed reactor. Increasing catalyst mass led to increased gas yields, notably decreased liquid yield and increased proportion of CO over CO 2 . A slight reduction in char was also observed. Atutxa et al. mainly related the reduction in the total liquid product with the transformation of the liquid heavy organic fraction into light liquid (mainly water) fraction and gases. The water fraction was more severely deoxygenated than the heavy organic fraction, which indicates the higher reactivity of the compounds of the lighter water fraction, especially of alcohols and acetic acid. The produced CP oil was less oxygenated, less viscous, less corrosive and more stable (Atutxa et al., 2005). Qi et al. (2006) performed CP of bamboo in a fixed bed reactor in the presence of NaY zeolite and observed that the bio-oil yield increased compared to the non-CP and consisted mainly of carboxylic and carbonylic compounds. Acetic acid was the main component of the catalytic bio-oil and its content was higher than in the thermal pyrolysis oil, while the content of carbonylic compounds was markedly lower (Qi et al., 2006). In an effort to understand the effect of catalyst support (matrix) on the product distribution from biomass CP and bio-oil upgrading, toluene and furan were catalytically pyrolyzed over bulk ZSM-5, supported ZSM-5 and a commercial Al 2 O 3 support (Du, Gamliel, Valla, & Bollas, 2016). It was shown that pyrolysis over supported ZSM-5 produces less liquid products, particularly monoaromatic hydrocarbons, than over bulk ZSM-5, mainly due to the dilution of Brønsted acid sites by the catalyst support. The Lewis acidity of the support does not promote the production of the aromatic products, but contributes to enhanced coke production with a less condensed structure. In summary, the use of supports and matrices in a catalytic formulation for biomass pyrolysis needs to be carefully designed, as they don't seem to be very effective compared to their performance in oil refining. | Ex situ (two-stage) upgrading of biomass pyrolysis vaporsIn a series of works, Horne and Williams (1994) investigated the effect of ZSM-5 zeolite on the catalytic upgrading of biomass pyrolysis oil. They found that oils before catalysis were highly oxygenated, while after catalysis the oxygenated species were markedly reduced and aromatic species were increased, producing a premium grade, gasoline type fuel. Detailed analysis of the u...

Catalytic Fast Pyrolysis of Lignin Isolated by Hybrid Organosolv—Steam Explosion Pretreatment of Hardwood and Softwood Biomass for the Production of Phenolics and Aromatics

“…), naphthalenes, and alkyl-phenols. The penalty is the increased production of water (aqueous fraction of bio-oil) and gases, as well as catalytic coke, at the expense of the organic fraction of bio-oil [57,[60][61][62][63][64]. Similar effects have been observed in the case of lignin CFP, where the use of zeolitic catalysts, including ZSM-5, beta, mordenite, ferrierite, and USY (Ultra Stable Y), has mainly been investigated [43,63,[65][66][67][68][69][70].…”

“…An alternative method for the deoxygenation of lignin bio-oil, avoiding the use of hydrogen, is the catalytic fast pyrolysis (CFP) of lignin, in analogy to the CFP of lignocellulosic biomass, where the initially produced biomass thermal pyrolysis vapors are further converted (in situ or ex situ) on the catalyst active sites [56][57][58][59][60]. Although different types of catalysts, i.e., acidic, basic, metal oxides, bifunctional metal-acidic, etc., have been studied in biomass CFP, leading to varying degrees of deoxygenation and bio-oil composition, the use of zeolites, mainly ZSM-5, induces deep deoxygenation via enhanced dehydration, decarbonylation, and decarboxylation reactions.…”

Hybridization of ZSM‐5 with Spinel Oxides for Biomass Vapour Upgrading

“…However, oxides depolymerization capacity is known to be lower when compared to other catalysts, such as zeolites. [27] By opposition, zeolite suffers fast deactivation due to the condensation of the highly reactive FP oxygenated intermediates inside the zeolite crystalline structure [9c,10] leading to coke formation. Therefore, the deposition of spinel oxide particles, such as MgFe 2 O 4 , in the external surface of the zeolite crystal would enable preliminary deoxygenation of the pyrolysis vapours, thus improving the overall zeolite potential.…”

“…Despite the good deoxygenation properties, metal oxides showed lower biomass depolymerization activity compared to acidic zeolites. [27] Ideally, one would take advantage of zeolite properties to promote dehydration and condensation reactions of cellulose-derived lights intermediates (C 2 , C 3 aldehydes, and alcohols) into condensable aromatic, aliphatic compounds and alter zeolite surface to inhibit further cracking of lignin monomers. By nature, lignin already possesses high aromaticity related to its phenylpropane monomers, which are an ideal renewable feedstock for C 9 chemicals or fuels.…”

Cellulose fast pyrolysis for platform chemicals: assessment of potential targets and suitable reactor technology

“…Its instability and high heating value also entail the improvement of its physicochemical properties through catalysis . Catalytic pyrolysis and hydropyrolysis for upgradation of bio‐oil is pursued fervently but has not been investigated in detail for the production of platform chemicals. The maturity and immediate feasibility of commercial operations of fast pyrolysis make it an attractive option.…”