Incorporation of hydrogen by-product from NaOCH3 production for methanol synthesis via CO2 hydrogenation: Process analysis and economic evaluation

Abstract

A major problem regarding the production of methanol via the CO2 hydrogenation is the source of hydrogen that is still expensive and not economically sustainable. Utilization of hydrogen available as a by-product from other processes may resolve such issue. In this work; therefore, we evaluate the potentiality of incorporating the hydrogen by-product from the NaOCH3 production for the synthesis of methanol via hydrogenation of CO2, a greenhouse gas released from industry. Due to the limited availability of hydrogen from NaOCH3 production, a detailed analysis of kinetic in the reactor systems including, 1) the adiabatic fixed bed, 2) the isothermal multi-tube, and 3) the adiabatic fixed-bed reactors with an intercooler, are simulated using Aspen Plus in order to select the most appropriate reactor system that maximizes the conversion of hydrogen and CO2. The adiabatic fixed bed reactor appears the most appropriate since it consumes the highest amount of CO2, and shows the highest Profitability Index when compared to other reactor systems. In addition, methanol produced from this proposed process can provide a 16.4% reduction in the methanol feedstock required for the upstream process of NaOCH3 production.An analysis using Aspen Economic is also performed in this work which reveals that the saving cost generated from the recycle of methanol to the upstream process is almost comparable to the costs of construction and operation of the process of methanol synthesis. According to our useful sensitivity analysis, a methanol price as well as hydrogen and CO2 feed rates directly influenced the feasibility of the proposed process. The obtained result indicates that this proposed process is potentially feasible when 1) the price of methanol increases, and 2) the availability of hydrogen increases due to the increased NaOCH3 production capacity over than 1.5 times of the current scale.