• Energy Research

Abstract In this study, thermal liquefaction of natural rubber was performed using different alcohols to produce valuable intermediate product. The experiment was conducted in autoclave reactor at different temperatures (250–375 °C), different solvent-to-natural rubber mass ratios (0.5:1 to 4:1), and at different reaction times (15–75 min.). The results showed the maximum liquid yield of 89.53 wt.% was obtained by using propanol at optimum conditions. Around 51.23% and 10.65% of liquid comprised of D-limonene and Isoprene respectively, which are being used as potential feedstock in different industrial sectors. Besides these compounds, the liquid product also consisted other hydrocarbon such as aromatics, alkyls, and alkene with high HHV (46 MJ/kg), and low oxygen contents (1.02%). These properties make this liquid suitable to be used for substitution the conventional fossil fuels. In addition, alcohol solvents played an important role to facilitate the liquefaction process by providing milder process conditions and hydrogen donor. Among the solvents, propanol has significant improvement on the liquid yield, solvent recovery and energy density.

Abstract In this study, thermal liquefaction of natural rubber was performed using different alcohols to produce valuable intermediate product. The experiment was conducted in autoclave reactor at different temperatures (250–375 °C), different solvent-to-natural rubber mass ratios (0.5:1 to 4:1), and at different reaction times (15–75 min.). The results showed the maximum liquid yield of 89.53 wt.% was obtained by using propanol at optimum conditions. Around 51.23% and 10.65% of liquid comprised of D-limonene and Isoprene respectively, which are being used as potential feedstock in different industrial sectors. Besides these compounds, the liquid product also consisted other hydrocarbon such as aromatics, alkyls, and alkene with high HHV (46 MJ/kg), and low oxygen contents (1.02%). These properties make this liquid suitable to be used for substitution the conventional fossil fuels. In addition, alcohol solvents played an important role to facilitate the liquefaction process by providing milder process conditions and hydrogen donor. Among the solvents, propanol has significant improvement on the liquid yield, solvent recovery and energy density.

Plastic waste is a problematic issue impacting the environment and human health. A proper recycling of plastics to valuable products is highly needed to meet the increase in energy demand. Plastics have high heating value; therefore, the thermochemical recycling of plastic waste is a valid and feasible approach. Recently, ethanol has attracted wide applications such as the conversion of ethanol to olefins, and hydrocarbons. It burns completely and cleanly, where it reduces the emissions of greenhouses compared to the usual fuels. Hydrogen and other higher hydrocarbons are also crucial in meeting the energy demand. In this study, the plastic waste, mainly polyethylene and polypropylene (due to their availability) were gasified using steam gasification process to produce syngas which then was further processed to hydrogen, ethanol, and other valuable liquid hydrocarbons. An alternative design is constructed integrating steam methane reforming (SMR) with plastic gasification to utilize the heat at the outlet of the gasifier and to enhance the syngas heating value. The two models were compared in terms of syngas heating value, energy analysis and economic analysis. The main parameters that have been evaluated are the production rate of fuel per total feedstock, total required heat, overall process efficiency, and fuel levelized production cost. The results indicated that Case 2 generates syngas with a higher heating value of 55 %, produces four times more H2, and comparable amount of ethanol and other fuels than Case 1. The analysis also revealed that Case 2 has a process efficiency that is 3 % better and a 37.5 % lower fuel production cost than Case 1. Overall, the design of Case 2 was found to be more efficient and cost-effective than the Case 1 design.

Plastic waste is a problematic issue impacting the environment and human health. A proper recycling of plastics to valuable products is highly needed to meet the increase in energy demand. Plastics have high heating value; therefore, the thermochemical recycling of plastic waste is a valid and feasible approach. Recently, ethanol has attracted wide applications such as the conversion of ethanol to olefins, and hydrocarbons. It burns completely and cleanly, where it reduces the emissions of greenhouses compared to the usual fuels. Hydrogen and other higher hydrocarbons are also crucial in meeting the energy demand. In this study, the plastic waste, mainly polyethylene and polypropylene (due to their availability) were gasified using steam gasification process to produce syngas which then was further processed to hydrogen, ethanol, and other valuable liquid hydrocarbons. An alternative design is constructed integrating steam methane reforming (SMR) with plastic gasification to utilize the heat at the outlet of the gasifier and to enhance the syngas heating value. The two models were compared in terms of syngas heating value, energy analysis and economic analysis. The main parameters that have been evaluated are the production rate of fuel per total feedstock, total required heat, overall process efficiency, and fuel levelized production cost. The results indicated that Case 2 generates syngas with a higher heating value of 55 %, produces four times more H2, and comparable amount of ethanol and other fuels than Case 1. The analysis also revealed that Case 2 has a process efficiency that is 3 % better and a 37.5 % lower fuel production cost than Case 1. Overall, the design of Case 2 was found to be more efficient and cost-effective than the Case 1 design.

Natural rubber is a tropical plantation crop that mainly consists of polyisoprene (cis-1,4-polyisoprene). It can be converted into fuels and other useful chemical commodities by depolymerization processes, with the hydrous pyrolysis being the most cost-effective.

Natural rubber is a tropical plantation crop that mainly consists of polyisoprene (cis-1,4-polyisoprene). It can be converted into fuels and other useful chemical commodities by depolymerization processes, with the hydrous pyrolysis being the most cost-effective.

Environmental concerns surrounding the use of high-sulfur fuel oil (HFO), a marine fuel derived from refinery vacuum residue, motivate the exploration of alternative solutions. Burning high-sulfur fuel oil (HFO) is a major source of air pollution, acid rain, ocean acidification, and climate change. When HFO is burned, it releases sulfur dioxide (SO2) into the air, a harmful gas that can cause respiratory problems, heart disease, and cancer. SO2 emissions can also contribute to acid rain, which can damage forests and lakes. Several countries and international organizations have taken steps to reduce HFO emissions from ships. For example, the International Maritime Organization (IMO) has implemented a global sulfur cap for marine fuels, which limits the sulfur content of fuel to 0.5% by mass. In addition, there is a worldwide effort to encourage the use of low-carbon gases to help reduce greenhouse gas (GHG) emissions. There are several alternative fuels that can be used in ships instead of HFO, such as liquefied natural gas (LNG), methanol, and hydrogen. These fuels are cleaner and more environmentally friendly than HFO. The aim of this study is to develop a process integration framework to co-produce methanol and hydrogen from vacuum residue while minimizing the sulfur and carbon emissions. Two process models have been developed in this study to produce methanol and hydrogen from vacuum residue. In case 1, vacuum residue is gasified using oxygen—steam and the syngas leaving the gasifier is processed to produce both methanol and hydrogen. Case 2 shares the same process model as case 1 except it is concentrated on mainly methanol production from vacuum residue. Both models are techno-economically compared in terms of methanol and H2 production rates, specific energy requirements, carbon conversion, CO2 specific emissions, overall process efficiencies, and project feasibility while considering the fluctuation of vacuum residue feed price from 0.022 $/kg to 0.11 $/kg. The comparative analysis showed that case 2 offers an 86.01% lower specific energy requirement (GJ) for each kilogram (kg) of fuel produced. The CO2 specific emission also decreased in case 2 by 69.76% compared to case 1. In addition, the calculated total net fuel production cost is 0.453 $/kg and 0.223 $/kg at 0.066 $/kg for case 1 and 2, respectively. Overall, case 2 exhibits better project feasibility compared to case 1 with higher process performance and lower production costs.

Environmental concerns surrounding the use of high-sulfur fuel oil (HFO), a marine fuel derived from refinery vacuum residue, motivate the exploration of alternative solutions. Burning high-sulfur fuel oil (HFO) is a major source of air pollution, acid rain, ocean acidification, and climate change. When HFO is burned, it releases sulfur dioxide (SO2) into the air, a harmful gas that can cause respiratory problems, heart disease, and cancer. SO2 emissions can also contribute to acid rain, which can damage forests and lakes. Several countries and international organizations have taken steps to reduce HFO emissions from ships. For example, the International Maritime Organization (IMO) has implemented a global sulfur cap for marine fuels, which limits the sulfur content of fuel to 0.5% by mass. In addition, there is a worldwide effort to encourage the use of low-carbon gases to help reduce greenhouse gas (GHG) emissions. There are several alternative fuels that can be used in ships instead of HFO, such as liquefied natural gas (LNG), methanol, and hydrogen. These fuels are cleaner and more environmentally friendly than HFO. The aim of this study is to develop a process integration framework to co-produce methanol and hydrogen from vacuum residue while minimizing the sulfur and carbon emissions. Two process models have been developed in this study to produce methanol and hydrogen from vacuum residue. In case 1, vacuum residue is gasified using oxygen—steam and the syngas leaving the gasifier is processed to produce both methanol and hydrogen. Case 2 shares the same process model as case 1 except it is concentrated on mainly methanol production from vacuum residue. Both models are techno-economically compared in terms of methanol and H2 production rates, specific energy requirements, carbon conversion, CO2 specific emissions, overall process efficiencies, and project feasibility while considering the fluctuation of vacuum residue feed price from 0.022 $/kg to 0.11 $/kg. The comparative analysis showed that case 2 offers an 86.01% lower specific energy requirement (GJ) for each kilogram (kg) of fuel produced. The CO2 specific emission also decreased in case 2 by 69.76% compared to case 1. In addition, the calculated total net fuel production cost is 0.453 $/kg and 0.223 $/kg at 0.066 $/kg for case 1 and 2, respectively. Overall, case 2 exhibits better project feasibility compared to case 1 with higher process performance and lower production costs.