ABSTRACT
An integrated strategy is developed to utilize all three primary components (cellulose, hemicellulose, and lignin) of lignocellulosic biomass for the coproduction of hydrocarbon fuel (5-nonanone) and bio-chemicals (furfural and high purity lignin). After biomass fractionation, (1) 5-nonanone is produced with high yield of 89% using cellulose-derived γ-valerolactone (GVL), which can potentially serve as a platform molecule for the production of liquid hydrocarbon fuels for the transportation sector; (2) furfural, a valuable platform chemical, is produced using hemicellulose; and (3) production of high-purity lignin, which can be used to produce carbon foams or battery anodes. Separation subsystems are designed to effectively recover the solvents for reuse in the conversion processes, which ultimately improves the economic feasibility of the integrated process, resulting in achieving lower minimum selling price (MSP) of $5.47 GGE-1 for 5-nonanone compared to market price. Heat pump is introduced to perform heat integration, which reduces utility requirements more than 85%. Finally, a wide range of techno-economic analysis is performed to highlight the major cost and technological drivers of the integrated process.
Subject(s)
Furaldehyde , Lignin , Lignin/chemistry , Biomass , Cellulose/chemistry , HydrocarbonsABSTRACT
Valorization of waste such as waste tires offers a way to manage and reduce urban waste while deriving economic benefits. The rubber portion of waste tires has high potential to produce pyrolysis fuels that can be used for energy production or further upgraded for use as blend fuel with diesel. In the preset work, waste tire oil (WTO) was produced from the pyrolysis of waste tires in an electric heating furnace at 500-550 °C in the absence of oxygen. Pyrolysis (in nitrogen) and oxidation (in air) of the obtained WTO sample were then performed in a thermogravimetric (TG) furnace that was connected to a Fourier transform infrared cell where the evolved gases were analyzed. The WTO sample was heated up to 800 °C in the TG furnace where the temperature of the sample was ramped up at three heating rates, namely, 5, 10, and 20 °C/min. The TG mass loss and differential thermogravimetric mass loss plots were used to analyze the thermal degradation pathways. Kinetic analysis was performed using the distributed activation energy model to estimate the activation energies along the various stages of the reaction. The pollutant gases, namely, CO2, CO, NO, and H2O, formed during WTO oxidation were evaluated by means of the characteristic infrared absorbance. The functional groups evolved during pyrolysis, namely, alkanes, alkenes, aromatics, and carbonyl groups, were also analyzed. The obtained information can be used for the better design of gasifiers and combustors, to ensure the formation of high-value gaseous products while reducing the emissions. The utilization of waste tires by producing pyrolysis oils thus offers a way of tackling the menace of waste tires while acting as a potential energy source.
ABSTRACT
The global energy demand is expected to increase by 30% within the next two decades. Plastic thermochemical recycling is a potential alternative to meet this tremendous demand because of its availability and high heating value. Polypropylene (PP) and polyethylene (PE) are considered in this study because of their substantial worldwide availability in the category of plastic wastes. Two cases were modeled to produce hydrogen from the waste plastics using Aspen Plus®. Case 1 is the base design containing three main processes (plastic gasification, syngas conversion, and acid gas removal), where the results were validated with the literature. On the other hand, case 2 integrates the plastic gasification with steam methane reforming (SMR) to enhance the overall hydrogen production. The two cases were then analyzed in terms of syngas heating values, hydrogen production rates, energy efficiency, greenhouse gas emissions, and process economics. The results reveal that case 2 produces 5.6% more hydrogen than case 1. The overall process efficiency was enhanced by 4.13%. Case 2 reduces the CO2 specific emissions by 4.0% and lowers the hydrogen production cost by 29%. This substantial reduction in the H2 production cost confirms the dominance of the integrated model over the standalone plastic gasification model.
ABSTRACT
The worldwide demand for energy is increasing significantly, and the landfill disposal of waste tires and their stockpiles contributes to huge environmental impacts. Thermochemical recycling of waste tires to produce energy and fuels is an attractive option for reducing waste with the added benefit of meeting energy needs. Hydrogen is a clean fuel that could be produced via the gasification of waste tires followed by syngas processing. In this study, two process models were developed to evaluate the hydrogen production potential from waste tires. Case 1 involves three main processes: the steam gasification of waste tires, water gas shift, and acid gas removal to produce hydrogen. On the other hand, case 2 represents the integration of the waste tire gasification system with the natural gas reforming unit, where the energy from the gasifier-derived syngas can provide sufficient heat to the steam methane reforming (SMR) unit. Both models were also analyzed in terms of syngas compositions, H2 production rate, H2 purity, overall process efficiency, CO2 emissions, and H2 production cost. The results revealed that case 2 produced syngas with a 55% higher heating value, 28% higher H2 production, 7% higher H2 purity, and 26% lower CO2 emissions as compared to case 1. The results showed that case 2 offers 10.4% higher process efficiency and 28.5% lower H2 production costs as compared to case 1. Additionally, the second case has 26% lower CO2-specific emissions than the first, which significantly enhances the process performance in terms of environmental aspects. Overall, the case 2 design has been found to be more efficient and cost-effective compared to the base case design.
ABSTRACT
Gasoline is one of the most important distillate fuels obtained from crude refining; it is mainly used as an automotive fuel to propel spark-ignited (SI) engines. It is a complex hydrocarbon fuel that is known to possess several hundred individual molecules of varying sizes and chemical classes. These large numbers of individual molecules can be assembled into a finite set of molecular moieties or functional groups that can independently represent the chemical composition. Identification and quantification of groups enables the prediction of many fuel properties that otherwise may be difficult and expensive to measure experimentally. In the present work, high resolution 1H nuclear magnetic resonance (NMR) spectroscopy, an advanced structure elucidation technique, was employed for the molecular characterization of a gasoline sample in order to analyze the functional groups. The chemical composition of the gasoline sample was then expressed using six hydrocarbon functional groups, as follows: paraffinic groups (CH, CH2 and CH3), naphthenic CH-CH2 groups and aromatic C-CH groups. The obtained functional groups were then used to predict a number of fuel properties, including research octane number (RON), motor octane number (MON), derived cetane number (DCN), threshold sooting index (TSI) and yield sooting index (YSI).
