Process Design and Analysis of Aromatics Production from Coal via Methanol with a High Yield

Abstract

Producing aromatics from coal via methanol is a novel technology, which could mitigate the energy shortage in a petroleum-poor area. However, the selectivity of methanol to aromatics is merely 40–70 wt % due to the byproducts of light hydrocarbons. In this paper, three novel designs are proposed to improve the aromatics yield by directly or indirectly converting light hydrocarbons into aromatics. In addition, cofeeding of coal and natural gas is applied in two of the three designs. On the basis of detailed process modeling and simulation, the process designs are assessed by mass balance, technoeconomic, and life cycle analyses. The results show that the aromatics yield is significantly improved by integrating light hydrocarbon conversion units. The CO₂ emissions and water consumption are notably decreased in the two cofeeding designs. In addition, the net present value of the design integrated with steam reforming of C₂– hydrocarbons and aromatization of C₃₊ hydrocarbons is the highest, about 1.9 times as much as that of the nonintegrated design. The cofeeding design integrated with steam reforming of C₂– hydrocarbons and aromatization of C₃₊ hydrocarbons leads to the lowest global warming potential and abiotic depletion potential, only 46.1 and 71.1% of the nonintegrated design, respectively. It implies that a more complex design shows better environmental performances.