Bio-gasoline and Bio-kerosene Production by Fractional Distillation of Pyrolysis Bio-Oil Açaí Seeds

Distillation of Pyrolysis Bio-Oil Açaí Seeds D. A. R. de Castro; H. J. da Silva Ribeiro; L. H. H. Guerreiro; L. P. Bernar; S. J. Bremer; H. da Silva Almeida; M. C. Santos ; S. Duvoisin Jr.; L. E. P. Borges; *N. T. Machado aProgram of Chemical Engineering-UFPA bGraduate Program of Natural Resources Engineering-UFPA cFaculty of Sanitary and Environmental Engineering-UFPA Rua Augusto Corrêia No 1, CEP: 66075-900, Belém-Pará-Brazil


Introduction
Açaí (Euterpe oleracea Mart.) is a native palm of natural occurrence in tropical Central and South America [1]. The palm gives a dark-purple, berry-like fruit, clustered into bunches [2]. The fresh fruits are traditionally processed by crushing and/or extracting the pulp and skin with warm water to produce a thick, purple-colored beverage/juice or a paste [3][4]. The fruit is a staple food in rural and urban areas of the Amazon River estuary, particularly in the State Pará (Pará-Brazil), with a great economic importance at both rural livelihoods and regional levels [5]. It has become one of the most important export products of the Amazon River estuary to other parts of Brazil [5], as well as oversees [6].
Of the total 1.228.811 tons/year of fruits produced by the State Pará, between 85% [7] and 83% (wt.) [8], is a residue (Açaí seeds), thus producing between 1.019.913 and 1.044.489 tons/year of a residue. The mechanical processing of Açaí fruits in nature produces around 175.7 tons residue/day in off-season crop and 448.0 tons residue/day in the season crop in the metropolitan region of Belém (Pará-Brazil), posing a complex environmental problem of solid waste management [9,10]. The Açaí fruit is a small dark-purple, berry-like fruit, almost spherical, weighing between 2.6 to 3.0 g [11], with a diameter around 10.0 and 20.0 mm [11], containing a large core seed that occupies almost 85% (vol./vol.) of its volume [3]. Açaí (Euterpe oleracea Mart.) fruit has an oily-fiber seed, rich in lignin-cellulose material [12][13][14][15].
In this work, fractional distillation of bio-oil obtained by pyrolysis of Açaí seeds at 450 ºC, 1.0 atmosphere, in technical scale, has been investigated systematically using a laboratoryscale column (Vigreux) to produce fuels-like fractions (gasoline, light kerosene, and kerosene), as well as to determine the physical-chemistry properties (density, kinematic viscosity, acid value and refractive index) and chemical composition of distillation fractions.

Materials and methods
2.1. Materials, pre-treatment, and characterization of Açai (Euterpe oleracea, Mart.) seeds in nature The seeds of Açaí (Euterpe oleracea Mart.) in nature obtained in a small store of Açaí commercialization, located in the City of Belém-Pará-Brazil [73]. The seeds were submitted to pre-treatments of drying and grinding as reported elsewhere [73]. The dried and grinded seeds were physical-chemistry characterized for moisture, volatile matter, ash, fixed carbon, lipids, proteins, fibers, and insoluble lignin according to official methods [73,75,76].

Distillation: Experimental apparatus and procedures
The fractional distillation of bio-oil was performed by using an experimental apparatus and procedures described elsewhere [73,[77][78]. The aqueous phase presented in the distillation fractions was separated from the organic phase by decantation using a 250 ml glass separator funnel. Afterwards, filtration was applied to remove small solid particles present in the organic phase. The distillation fractions were (gasoline, light kerosene, and kerosene) physicalchemistry characterized for acid value (AOCS Cd 3d-63), density (ASTM D4052) at 25°C, kinematic viscosity (ASTM D445/D446) at 40°C, and refractive index (AOCS Cc 7-25) [81].

Chemical composition of distillation fractions
The chemical composition of distillation fractions determined by CG-MS and the equipment and operational procedures described in details elsewhere [73].

Physical-chemical properties of distillation fractions
The physical-chemical properties of distillation fractions (gasoline, 80-175°C; light kerosene, 175-200°C; and kerosene-like fraction, 200-215°C) of bio-oil are illustrated in Table   2. It can be observed that acidity of distillation fractions increases with boiling temperature. However, the acidity of gasoline-like fraction is much lower than that of raw biooil (70.26 mg KOH/g), as described in Table 3. The high acid value of bio-oil is due to the presence of 78.48% (area.) oxygenates, as shown in Table 4. The same behavior was observed for the densities, kinematic viscosities, and refractive indexes of gasoline, light kerosene, and kerosene-like like fractions with increasing boiling temperature. This is probably due to the high concentration of higher-boiling-point compounds in the distillate fractions, such as phenols, cresols (p-cresol, o-cresol), and furans, as the concentration of those compounds in the distillation fractions increases with increasing boiling temperature as reported elsewhere [66,70,72], corroborate in Tables 5, 6, and 7.

Chemical compositional of bio-oil by GC-MS
The chromatogram of bio-oil is shown in Figure 3. The peaks are concentrated between retention times of 8.0 and 22.0 minutes, with the highest one around 12.5 minutes. The GC-MS identified hydrocarbons (alkanes, alkenes, aromatic hydrocarbons, and cycloalkenes) and oxygenates (esters, phenols, cresols, carboxylic acids, ketones, furans, and aldehydes) in biooil, being composed of 21.52% (area.) hydrocarbons and 78.48% (area.) oxygenates [73]. The high acidity of bio-oil, described in Table 3, is probably due to the presence of carboxylic acids, ketones, aldehydes, phenols and cresols confer the high acidity of bio-oil. The composition of bio-oil shows similarity to those reported in the literature [27, 34, 41, 47-48, 53, 61], showing the presence of hydrocarbons, phenols, cresols, furans, carboxylic acids, and esters, among other classes of compounds [73]. The identification of hydrocarbons with carbon chain length between C11 and C15, shows the presence of heavy gasoline compounds with C11 (C5-C11), light kerosene-like fractions (C11-C12), and light diesel-like fractions (C13-C15), according to Table 4.

Chemical compositional of distillation fractions by GC-MS
The chromatogram of bio-oil distillation fractions (gasoline: 40-175°C, light kerosene: 175-200°C, and kerosene-like fraction: 200-215°C) are shown in Figures 4,5,and 6, respectively. One observes that the spectrum of peaks is moving to the right, showing that distillation was effective to fractionate the bio-oil.

Conclusions
The yield of distillation fractions (gasoline, light kerosene, and kerosene-like like fractions), 77.61% (wt.), is higher but according than those reported in the literature for both atmospheric and vacuum conditions [17-19, 21, 41, 46-48, 53, 66, 70, 72]. The acid values of distillation fractions increase with increasing boiling temperature. However, the acidity of gasoline-like fraction is much lower than that of raw bio-oil (70.26 mg KOH/g). The same behavior was observed for the densities, kinematic viscosities, and refractive indexes of gasoline, light kerosene, and kerosene-like like fractions with increasing boiling temperature.
The FT-IR analysis of bio-oil and distillation fraction identify the presence of hydrocarbons (alkanes, alkenes, and aromatic hydrocarbons) and oxygenates (phenols, cresols, carboxylic acids, alcohols, ethers, ketones, and furans). The bio-oil is composed of 21.52% (area) hydrocarbons and 78.48% (area) oxygenates. The presence of carboxylic acids, as well as phenols and cresols is associated to the high acidity of bio-oil.