Catalytic Pyrolysis of Chilean Oak: Influence of Brønsted Acid Sites of Chilean Natural Zeolite

Abstract

This paper proposes the Chilean natural zeolite as catalyst on bio-oil upgrade processes. The aim of this study was to analyze chemical composition of bio-oil samples obtained from catalytic pyrolysis of Chilean native oak in order to increase bio-oil stability during storage. In order to identify chemical compounds before and after storage, biomass pyrolysis was carried out in a fixed bed reactor at 623 K and bio-oil samples were characterized by gas chromatography/mass spectrophotometry (GC/MS). A bio-oil fractionation method was successfully applied here. Results indicate that bio-oil viscosity decreases due to active sites on the zeolite framework. Active acids sites were associated with an increment of alcohols, aldehydes, and hydrocarbon content during storage. Higher composition on aldehydes and alcohols after storage could be attributed to the occurrence of carbonyl reduction reactions that promotes them. These reactions are influenced by zeolite surface characteristics and could be achieved via the direct contribution of Brønsted acid sites to Chilean natural zeolite.

Optimizing the Aromatic Product Distribution from Catalytic Fast Pyrolysis of Biomass Using Hydrothermally Synthesized Ga-MFI Zeolites

“…During CFP of biomass, the framework and acidity of zeolite catalysts play an important role in the distribution of final products [6][7][8][9]. Among many zeolites that have been tested, ZSM-5 zeolite has been shown to produce high aromatic yields from biomass-derived feedstocks [8,10,11].…”

Influence of Chemical Surface Characteristics of Ammonium-Modified Chilean Zeolite on Oak Catalytic Pyrolysis

“…Compositional fluctuations in stored bio-oil samples are due to potential aging reactions (e.g., alcohols reacting with organic acids forming esters and water, aldehydes reacting with each other to form polyacetal oligomers and polymers, aldehydes or ketones reacting with water to form hydrates, alcohols reacting with aldehydes forming hemiacetals, aldehydes and alcohols reacting to form acetals, and phenol/aldehyde reactions), as suggested by other studies [18,39]. Therefore, a lower Figure 2 shows a decrease in the composition of the following families (esters, ethers, and acids) as a result of the catalytic activity of modified (NHZ and 2NHZ) zeolite samples.…”

“…TG/DTG/DTA (thermogravimetric/derivative thermogravimetric/differential thermogravimetric analysis) profiles show an active pyrolysis (hemicellulose and cellulose degradation) zone around 476 to 668 K, and passive pyrolysis (lignin degradation) zone at T > 668 K. Maximum degradation of hemicellulose occurs at 576 K and cellulose maximum degradation rate (0.01 mg•s −1 ) was achieved at 628 K, removing 59% of the initial mass at this temperature. Thermogravimetric profiles of Chilean Oak were reported in a previous article [18]. Considering the above, pyrolysis experiments were conducted at 723 K to assure the complete thermal transformation of the biomass.…”

“…Nevertheless, the activity of natural zeolites can be significantly improved through appropriate modifications [15]. Thus, researchers have conducted some investigations incorporating natural zeolites as the catalyst in biomass catalytic pyrolysis studies [16][17][18]. An increase of bio-oil yield was linked to the usage of natural zeolite (clinoptilolite) as a catalyst in Euphorbia rigida pyrolysis [19].…”

Catalytic Processes for The Valorization of Biomass Derived Molecules

“…Martín et al propose a natural zeolite (Chilean) as an innovative catalyst for bio-oil upgrade processes [29]. The results clearly show that Chilean-zeolites efficiently increase both quality and stability of the bio-oil obtained from the catalytic pyrolysis of the Chilean native oak.…”