Lumped Approach in Kinetic Modeling of Microwave Pyrolysis of Kraft Lignin

Abstract

This work presents three kinetic models based on a lumping approach to describe the microwave pyrolysis of kraft lignin. The first model considered the formation of the main pyrolysis products, condensable gas, non-condensable gas, and remaining solid, taking into consideration each as an individual lump. The second model investigated the liquid product while dividing the condensable gas into oil and water products. The oil product contains only chemicals, whereas the water product does not contain any chemicals. In the third model, the oil product was separated into four main groups: (1) phenolics, which contain all of the identified phenolic components using a gas chromatography–mass spectrometry (GC–MS) analyzer, (2) heavy-molecular-weight components, which contain all of the identified heavy-molecular-weight and undefined components, using GC–MS, (3) non-phenolic aromatics with a single ring, and (4) aliphatics. The comparison of the predicted results using the estimated kinetic parameters to the experimental data showed the high capability of the presented models to estimate the product yield under the selected conditions.

A modified microwave thermo-gravimetric-analyzer for kinetic purposes

“…This setup is called microwave thermo-gravimetric-analyzer (MW-TGA) and is equipped with an innovative thermometer, called an air-thermometer, which does not suffer from the problems of traditional thermometers under MWH. Below, the essential details of the MW-TGA and the airthermometer are presented, as it will be referred to in the future works as in Sherif Farag 2014 [34,35]. This MW-TGA can be employed in a wide range of applications; in this study, it is used to examine the kinetics of microwave pyrolysis (MWP) of sawdust.…”

Economics evaluation for on-site pyrolysis of kraft lignin to value-added chemicals

“…Table 1 Ultimate and proximate analysis of kraft lignin (Farag et al, 2014a;Farag et al, 2014b) To achieve the main goal of this work, the following studies were accomplished: (1) An on-site plant for pyrolysis of kraft lignin was designed, (2) the designed plant was processed in Aspen PLUS TM applications for calculating the mass and energy of the plant, (3) the update price for the purchased equipment and the cost of their needs were estimated based on data from the literature, (4) the total capital investment of the plant was calculated according to step #3, (5) the minimal selling price of the obtained dry oil was estimated by considering zero net present worth, (5) the impact of the crucial variables on the estimated selling price were examined and, subsequently, the condition requirements to obtain the optimum price was established, and (6) different scenarios for achieving the best selling price were debated.…”

“…Only 2% is converted into bio-products, while 98% is combusted to recover energy and recycle the pulping chemicals (Farag et al, 2014b). Since lignin is considered the most abundant renewable source of aromatic compounds in nature, it should be noted that there are many bacteria in nature that produce aromatic compounds (Koma et al, 2012); it can also be considered as a renewable resource of valueadded chemicals and products with a great potential.…”

“…In that work, a product distribution of 21 %wt, 19%, 37 wt%, and 23 wt% for the oil phase, aqueous phase, solid, and gas products, respectively, was documented. Subsequently, a novel kinetic model for predicting the quantity and the composition of the products from the pyrolysis of lignin was accomplished (Farag et al, 2014b). In that article, the obtained liquid product was divided into oil (dry oil), which contains only chemicals, and water, which does not contain any chemicals.…”

Supercritical Water-induced Lignin Decomposition Reactions: A Structural and Quantitative Study

“…In pulp mills, black liquor is concentrated by evaporation and has been used to supply over 50% of a mill's energy demands. Annually, over 50 million tons of lignin worldwide is burned in the recovery boilers of pulp mills (Farag et al 2014). In general, although high-quality alkali lignin can be produced by acidification of black liquor, it should be noted that there are many higher-value applications.…”