Experimental and Mechanistic Modeling of Fast Pyrolysis of Neat Glucose-Based Carbohydrates. 2. Validation and Evaluation of the Mechanistic Model

Abstract

A computational framework based on continuous distribution kinetics was constructed to solve the mechanistic model that was developed for fast pyrolysis of glucose-based carbohydrates in the first part of this study [Zhou et al. Ind. Eng. Chem. Res. 2014, 53.

Fast pyrolysis of glucose‐based carbohydrates with added NaCl part 1: Experiments and development of a mechanistic model

“…Details on the operating method and quantification procedure can be found in our previous work. 23,24 Briefly, 200 2 500 lg of carbohydrate-salt mixture was loaded into a deactivated stainless steel sample cup. A preheated furnace temperature of 500 8C was used for every experiment.…”

“…The formation of small aldehydes and other low molecular weight products (LMWPs) often involves retro-aldol, retro Diels2Alder, or tautomerization reactions. 23,24 With increasing amounts of NaCl doped into glucose, the yield of formaldehyde was first slightly reduced then sharply increased to its maximum, and then slightly decreased again, while the yields of acetaldehyde and acetol consistently decreased. The yield of glycolaldehyde (GA) decreased from 5.21 6 0.46 to 3.18 6 1.00 wt % in the presence of 0.16 mmol NaCl/g of glucose; however, greater amounts of NaCl led to an increase in this yield to 4.64 6 0.29 wt %.…”

“…While these results alone do not quantitatively rationalize experimentally observed product yields, they provide the necessary data to build a microkinetic model of the reaction chemistry, which can provide quantitative information on the rate of thermoconversion of carbohydrates and their resulting product distribution in the presence of NaCl under various operating conditions of fast pyrolysis. 23,24,32,33 In the absence of mechanistic understanding, a previous kinetic model of the pyrolysis of cellulose and other carbohydrates in the presence of inorganic salts relied on global lumped schemes in which a correlation factor was employed to deal with the impact of inorganic salts on the overall yields of a small number of global lumped pyrolysis products. Specifically, Raveendran et al 8 proposed a correlation in which the change in the total yield of volatile products was expressed as a function of lignin content of biomass and the amounts of potassium and zinc.…”

“…Recently, the Broadbelt group developed detailed mechanistic models for fast pyrolysis of neat glucose-based carbohydrates, the results of which closely matched the experimental yields of various pyrolysis products over a wide range of temperatures and provided information about quantities based on mechanistic insight that was not accessible experimentally, such as the pyrolysis timescale, dynamic evolution of pyrolysis products, and the dominant reaction pathways for individual products. 23,24,33 However, the effects of NaCl on fast pyrolysis were not included.…”

Depolymerization Pathways for Branching Lignin Spirodienone Units Revealed with ab Initio Steered Molecular Dynamics

“…Lignin, in particular, is a biopolymer 8 (20-30% of biomass by weight 9 ) with high structural heterogeneity that has historically limited its utilization to the fast pyrolysis [10][11] generation of low-grade and volatile bio oil 2 of moderate value 12 .…”