Srinivas Palanki

Microwave-assisted acid activation creates an early kinetic window for preferential REE release relative to Fe, while thermomorphic [Hbet][Tf ₂ N] facilitates subsequent phase partitioning.

There is a growing interest in utilizing plastic waste to produce olefins and aromatics, which serve as essential building blocks for polyolefin production. In this paper, a novel microwave-assisted catalytic process is developed for converting polypropylene plastic waste into propylene, with simultaneous co-production of ethylene, aromatics, and alkanes, thereby closing the material loop by returning end-of-life plastic waste back into the petrochemical value chain as a high-value chemical feedstock, a key principle of the circular economy. A technoeconomic analysis conducted for several scenarios shows that the net present value of the proposed novel process ranges from a low value of USD 1332.56 million to a maximum of USD 2000.65 million at the investigated capacity, depending on co-product valorization and off-gas recovery for process heat generation. The sensitivity analysis performed reveals that the cost of the plastic waste feedstock and selling price of propylene are among the most influential parameters on the economics of the proposed plant. A life cycle assessment is then conducted for the novel plant, which is benchmarked against the simulated conventional propane dehydrogenation plant, whose calculated global warming potential amounts to 2.22 kg CO2-eq/kg propylene. Results show that the global warming potential of the novel plant ranges between 2.41 and 0.71 kg CO2-eq/kg propylene, depending on the carbon intensity of the electricity grid used and successive valorization of co-product streams. Overall, the economic viability and environmental sustainability of the proposed process are strongly contingent on the extent of co-product recovery. The proposed circular economy pathway of valorizing plastic waste into high-value chemicals via electrified microwave-assisted heating provides a compelling case for electrified, waste-based production routes as a sustainable alternative to conventional processes.

This study proposes a novel microwave-assisted process for converting waste low-density polyethylene into polymer-grade ethylene at an industrial scale, producing approximately 77 tons per hour. Experimental data from a laboratory-scale microwave reactor were utilized to design and evaluate the process through a detailed technoeconomic analysis. The results indicate that the microwave-assisted system exhibits a lower capital expenditure and a comparable operating expenditure relative to conventional ethane steam cracking, while generating additional valuable co-products such as propylene and aromatic hydrocarbons, leading to a higher net present value potential. Sensitivity analyses reveal that electricity price has the most significant impact on both net present value and levelized cost of production, followed by low-density polyethylene feedstock cost, whereas microwave reactor investment shows only a minor effect. Furthermore, when renewable electricity is used, the novel microwave process has the potential to substantially reduce the global warming potential. Overall, the proposed process demonstrates economic robustness and strong potential for sustainable, circular production of ethylene from waste plastics.

Ethylene is a critical feedstock in industrial processes, serving as a raw material in the petrochemical industry to produce plastics and commodity chemicals. Conventional ethylene production routes are energy-intensive and contribute substantially to the carbon footprint of chemical manufacturing. In this study, an industrial-scale novel microwave process was simulated using ASPEN Plus to assess its economic viability. Technoeconomic analysis confirmed the economic competitiveness of the novel microwave process, with a levelized cost of ethylene of USD 0.51/kg compared to USD 0.56/kg for the conventional base case. Key economic drivers of the process were identified, and sensitivity analyses were conducted to evaluate their impact on project economics. Furthermore, 87.7% of the total utility consumption in the novel microwave process is electricity, highlighting its potential to contribute to the electrification of the chemical industry. The findings of this study confirm the economic feasibility of both industrial-scale microwave reactors and modular plant configurations for the production of ethylene from methane, offering a promising alternative to conventional processes.

Polyethylene is the most used plastic in the world, and over 90% of this plastic is ultimately disposed of in landfills or released into the environment, leading to severe ecological implications. In this research, the technoeconomic feasibility of upcycling low-density polyethylene (LDPE) to produce ethylene is studied. The catalytic conversion of LDPE to ethylene is considered in microwave heating mode and Joule heating mode. Experimental data is obtained under conditions where most of the upcycled products are in the gas phase. A flowsheet is developed that produces industrial quantities of ethylene for both heating modes. A technoeconomic analysis and a life cycle analysis are conducted and compared with the traditional ethane cracking process for producing ethylene. Simulation results indicate that the upcycling system exhibits a lower capital expenditure and a comparable operating expenditure relative to conventional ethane steam cracking while generating additional valuable co-products, such as propylene and aromatic hydrocarbons, leading to a higher net present value potential. Sensitivity analyses reveal that the electricity price has the most significant impact on both the net present value and levelized cost of production, followed by the low-density polyethylene feedstock cost. Life-cycle assessment reveals a substantial reduction in greenhouse-gas emissions in the upcycled process compared to the fossil-based ethane steam-cracking route, primarily due to the use of renewable electricity, the lower reaction temperature that reduces utility demand, and the use of plastic waste as the feedstock. Overall, the proposed process demonstrates strong potential for the sustainable production of ethylene from waste LDPE.

Acid mine drainage (AMD) is both an environmental pollutant and a secondary source of rare earth elements (REEs).

In recent years, there has been growing interest in the electrification of the chemical process industry as a pathway toward decarbonization and sustainable manufacturing. However, for electrification to be economically feasible in a chemical plant, it is necessary to study the economics of power generation. In this study, a techno-economic analysis (TEA) of a 420 MW natural gas combined-cycle (NGCC) power plant is conducted to evaluate the impact of natural gas price volatility on key economic indicators. A steady-state process model is developed in ASPEN Plus to simulate the integrated gas and steam turbine configuration, including detailed modeling of combustion, heat recovery, and steam expansion stages. Capital and operating expenditures are estimated using ASPEN Process Economic Analyzer and literature-based costing frameworks. Base case results indicate a total capital cost of $133.65 million, an annual operating cost of $48.56 million, and a revenue stream of $201.72 million/year, yielding a Net Present Value (NPV) of $302.99 million and a Levelized Cost of Electricity (LCOE) of $22.38/MWh. Sensitivity analyses demonstrate that fuel price is the dominant driver of economic performance. As natural gas prices increase from $2/MMBtu to $14/MMBtu, LCOE rises from $22.38/MWh to over $110/MWh, while NPV can decline below breakeven levels depending on electricity price assumptions. Time-series analysis using historical fuel price data (daily, weekly, and monthly) further reveals that market variability introduces significant uncertainty in long-term profitability, particularly under low electricity tariffs.