Valorization of Vine Prunings by Slow Pyrolysis in a Fixed-Bed Reactor

Suzana Ioana Calcan,Oana Cristina Pârvulescu,Diana Egri,Violeta Alexandra Ion,Andrei Moț,Cristian Eugen Răducanu,Mihaela Emanuela Crăciun,Liliana Bădulescu,Tănase Dobre,Vlad Popa

doi:10.3390/pr10010037

Abstract

The paper aimed at studying the slow pyrolysis of vine pruning waste in a fixed bed reactor and characterizing the pyrolysis products. Pyrolysis experiments were conducted for 60 min, using CO2 as a carrier gas and oxidizing agent. The distribution of biochar and bio-oil was dependent on variations in heat flux (4244–5777 W/m2), CO2 superficial velocity (0.004–0.008 m/s), and mean size of vegetal material (0.007–0.011 m). Relationships among these factors and process performances in terms of yields of biochar (0.286–0.328) and bio-oil (0.260–0.350), expressed as ratio between the final mass of pyrolysis product and initial mass of vegetal material, and final value of fixed bed temperature (401.1–486.5 °C) were established using a 23 factorial design. Proximate and ultimate analyses, FT-IR and SEM analyses, measurements of bulk density (0.112 ± 0.001 g/cm3), electrical conductivity (0.55 ± 0.03 dS/m), pH (10.35 ± 0.06), and water holding capacity (58.99 ± 14.51%) were performed for biochar. Water content (33.2 ± 1.27%), density (1.027 ± 0.014 g/cm3), pH (3.34 ± 0.02), refractive index (1.3553 ± 0.0027), and iodine value (87.98 ± 4.38 g I2/100 g bio-oil) were measured for bio-oil. Moreover, chemical composition of bio-oil was evaluated using GC-MS analysis, with 27 organic compounds being identified.

Highlights

IntroductionDue to its low cost, abundance, and carbon neutrality, residual lignocellulosic biomass represents an attractive renewable resource for producing biofuels and chemicals [1,6]
Slow pyrolysis of vine pruning waste was performed for 60 min in a fixed bed reactor, in the presence of CO2 as a carrier gas and oxidizing agent
Bio-oil, and pyrolysis gases were produced under different operating conditions, according to a 23 factorial design

Summary

Introduction

Due to its low cost, abundance, and carbon neutrality, residual lignocellulosic biomass represents an attractive renewable resource for producing biofuels and chemicals [1,6]. Lignocellulosic biomass, which is mainly composed of polysaccharides [hemicellulose (15–40%) and cellulose (25–50%)] and aromatic polymers [lignin (10–40%)], can be valorized using different thermo-chemical technologies, e.g., combustion, pyrolysis, gasification, hydrothermal liquefaction, or biochemical routes, including fermentation and anaerobic digestion [3,4,5,6,7,8,9,10,11,12]. Pyrolysis is a very promising technology which involves lower energy consumption and costs than other conversion routes as well as high addedvalue products [3,5,7,11]. Volatile compounds are further condensed producing permanent gases and a pyrolytic liquid (bio-oil) containing 15–35%

Methods

Results

Conclusion