## Materials and Methods
### Characterization of Pyrolysis Products  
The solid products of the pyrolysis process were characterized in accordance with the European Standard as above to determine organic matter, ash content, elemental composition and calorific value, and the slagging/fouling indices were calculated. For the liquid products of the pyrolysis process, physicochemical properties, such as density, viscosity and pH, were measured, and elemental analysis was conducted using the CHNS analyzer previously mentioned. The ASTM Standard 1298 [38] was adopted for measurement of the density of the oils using a 1 mL micropipette and a high-accuracy analytical balance. For pH measurement, a bench Mettler Toledo pH-meter was used. A Grace M3500 Couette-type viscometer with an R1-B1-F1 configuration was used to determine the dynamic viscosity of the bio- oils. This type of viscometer consists of an outer cylinder that rotates at predefined speeds, producing flow and creating torque on a static concentric inner cylinder, which is connected to the sensing unit with a spindle. The major advantage of this viscometer is the absence of turbulent flow on low-viscosity fluids at high shear. The gap between the inner and the outer cylinders was adjusted to 1 mm. Each  
Figure 1: Diagram of experimental setup: (1) N\({}_{2}\) cylinder, (2) flow control valve, (3) mass flow meter, (4) thermoprogrammable furnace, (5) sample, (6) reactor, (7) thermocouple with indicator and (8) ice baths. sample was transferred to a 50 mL beaker (filled to the brim) and the viscometer cylinders were then lowered into the beaker. The outer cylinder was then started at a rotation speed of 100 rpm for 1 min, in order to effectively mix the sample and remove any gas bubbles that may have been trapped between the two cylinders. After the mixing time, the outer cylinder was set to subsequent rotational speeds of 3, 6, 100, 200, 300 and 600 rpm, with 1 min duration for each step, at a constant temperature of 50 \({}^{\circ}\)C, and measurements of the shear stress and shear velocity were taken every 10 s. The shear stress versus shear velocity data for each sample were plotted on rheograms to verify the Newtonian flow behavior, and the viscosity was calculated by fitting the data to the Newtonian flow model (straight line) via a regression technique and subsequently computing the line slope. The higher heating value of the bio-oils was calculated according to the equation [39]:  
\[HHV_{bioosil}=0.3383C+1.422(H-\frac{O}{8}) \tag{5}\]  
In order to characterize the gaseous products of the pyrolysis process, the biomass materials were also pyrolyzed in a PerkinElmer TG/DTG thermal analyzer (accuracy 0.2%wt, sensitivity < 5 ug, temperature precision \(\pm\) 2 \({}^{\circ}\)C) coupled online with a Balzers MS QME-200 quadrupole mass spectrometer. High-purity Ar at a flow rate of 35 mL/min was used for the tests, which were carried out at up to 550 \({}^{\circ}\)C, at a heating rate of 10 \({}^{\circ}\)C/min. Product gases were transferred to the MS through a fused silicon capillary line insulated and heated to 200 \({}^{\circ}\)C to prevent condensation. The ions, separated according to their mass-to-charge ratio, were detected by a secondary electron multiplier (82 eV, 1-400 atomic mass), and data processing was performed using Pyris v3.5 (Perkin Elmer Int., Rotkreuz, Switzerland) and Quadstar 422 (Balzers, Zuerich, Switzerland) software. The mass-to-charge ratios (\(m/z\)) 2, 15, 18, 24-27, 28 and 44, corresponding to H\({}_{2}\), CH\({}_{4}\), H\({}_{2}\)O, C\({}_{2}\)-C\({}_{3}\), CO and CO\({}_{2}\), respectively, were continuously recorded by the MS and, for each m/z ratio, the intensity of fragments from other compounds was considered. For quantitative analysis, calibration tests were conducted, maintaining the same conditions as those employed during the pyrolysis experiments.