New Magnetic Fe Oxide-Carbon Based Acid Catalyst Prepared from Bio-Oil for Esterification Reactions

Abstract

In this work, bio-oil (an organic matrix rich in oxygen functionalities) was used to efficiently dissolve and disperse Fe 3+ which upon thermal treatment produced a carbon containing dispersed and encapsulated Fe oxide magnetic nanoparticles. These materials were prepared by dissolution of 8, 16 and 24 wt.% Fe 3+ salt in bio-oil followed by treatment at 400, 450, 500 or 600 °C in N 2 atmosphere. X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopies (TEM), elemental analysis, thermogravimetric-mass spectrometry (TG-MS), potentiometric titration, Raman and Mössbauer spectroscopies showed that Fe 3+ species in bio-oil is reduced to produce magnetic nanoparticles phases: magnetite Fe 3 O 4 and maghemite γ-Fe 2 O 3. At low temperatures, the iron phases were less protected, and the carbon matrix was more reactive, while in temperatures above 500 °C, the iron phases were more stable, however, the carbon matrix was less reactive. Reaction of these magnetic carbon materials with concentrated H 2 SO 4 produced surface sulfonic acidic sites (ca. 1 mmol g −1), especially for the materials obtained at 400 and 450 °C. The materials were used as catalysts on esterification reaction of oleic acid with methanol at 100 °C and conversions of 90% were reached, however, after 2 consecutive uses, the conversion decreased to 30%, being required more studies to improve the material stability.

On-Line Thermally Induced Evolved Gas Analysis: An Update—Part 1: EGA-MS

“…New magnetic Fe oxide-carbon-based acid catalysts were prepared by dissolution of iron salt in bio-oil followed by thermal treatment in a nitrogen atmosphere. Results from several characterization techniques showed that these materials can be used as catalysts for the esterification reaction of oleic acid with methanol with a good conversion factor [ 87 ].…”

Acetalization of β-citronellal over a renewable carbon catalyst obtained from bio-oil sulfonation: a green route to obtain valuable feedstocks

“…Upon a simple treatment with H2SO4, bio-oil is dehydrated to produce a stable amphiphilic carbon material containing a high concentration of surface sulfonic acidic groups which can be used as a catalyst [25][26][27].…”