The main objective of this work was to examine the influence of pyrolysis pressure on product yield from wheat straw pyrolysis. The experiments were performed in a tubular reactor at different pressures (10, 20, 30, and 40 psi) with a constant flow rate of nitrogen (50 cc/min) at a temperature of 500 °C. During pyrolysis, the products obtained are oil, gas, and char. The maximum oil yield was 37.6%, obtained at high pressure (40 psi). Liquid product was analyzed using gas chromatography/mass spectrometry (GC-MS). The percentage of bio-oil compounds increased as operating pressure increased. The major components present in the bio-oil were phenols, methoxyphenols, and substituted methoxyphenols such as eugenol and vanillin. The gas products were mainly CO, H 2 , CO 2 , CH 4 , C 2 H 4 , C 2 H 6 , C 4 H 10 , and C 3 's. Char characteristics were measured using scanning electron microscopy (SEM) and ultimate analysis. Van Krevelen diagram shows that the chars obtained from wheat straw pyrolysis have very less H: C and O: C ratios than the raw wheat straw. On the basis of the results of this study, it may be concluded that, within the pressure range studied, 20 psi is the optimum pressure for the pyrolysis of the wheat straw in a tubular reactor with respect to products (char, bio-oil, and gas) yield.

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The distributed activation energy model (DAEM) has been shown to be more descriptive of the pyrolysis reaction than other applicable models. In this study, the temperature dependency of the preexponential factor has been included in the DAEM. The model equation has been solved using Simpson's 1/3 rule, and the kinetic parameters were determined using an optimization method. Simulated annealing method has been used to determine the DAEM kinetic parameters for the nonisothermal pyrolysis of lignin using thermogravimetric analysis (TGA) data. The nonisothermal pyrolysis of lignin was conducted at three different heating rates of 5, 10, and 15 °C/min under nitrogen atmosphere. Predicted results from the optimum kinetic parameters have been compared with the experimental data. The DAEM equation predicts the experimental data very well for different heating rates.

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