No abstract

Deep eutectic solvents (DESs) have received significant attention as potential extracting agents in recent years due to their favorable characteristics including low cost, easy preparation and environmentally safe starting materials. Experimentally screening for highly efficient DESs meeting various requirements for natural gas sweetening remains a challenging task. Thus, an extensive database of estimated Henry's law constants (H i) and solubilities (x i) of CO 2 in 170 different DESs at 25˚C has been constructed using the COSMO-RS method to select potential DESs. Based on the COSMO-RS study, three DESs, namely tetrabutylammonium bromide (TBAB)+polyethylene glycol (PEG-8) (on a molar basis 1:4), TBAB+octanoic acid (OCT) (1:4), and methyltriphenylphosphonium bromide (MTPB)+PEG-8 (1:10), were chosen for further experimentation up to 2 bar at 25˚C using a vapor-liquid equilibria (VLE) apparatus. Reliable thermophysical properties were determined experimentally, and a detailed equilibrium-based model was developed for one of the glycol-based DESs (i.e., TBAB+PEG-8 (1:4)). This information is an essential prerequisite for carrying out process simulations of natural gas sweetening plants using ASPEN PLUS. The simulation results for the proposed DES were compared to those of monoethylene glycol (MEG). Here, we find that the aqueous TBAB+PEG-8 (1:4) solvent shows~60% lower total energy consumption and higher CO 2 removal when compared to those using the MEG solvent.

In this study, an algae biomass gasification process using a dual fluidized bed with combined power and methanol cogeneration was developed. The gasification process was modeled using Aspen Plus and validated using experimental data of two microalgae species (Nannochloropsis oculata and Dunaliella salina) commonly found on the western coast of Saudi Arabia. The impacts of different operating conditions, including the gasifier temperature, steam-to-biomass ratio, and algae-char split ratio, on the compositions of four main gases (CO, CO2, CH4, and H2) were investigated. The results of the parametric studies indicated that the gasification temperature has a significant effect on the composition of the synthesis gas, where 700–850 °C was the ideal operating range for gasification. Altering the ratio of biomass to steam showed a slightly smaller effect on the synthesis gas composition. The char split ratio should be kept below 75% to ensure an adequate heat supply to the process. The proposed process successfully converted 45.7% of the biomass feed to methanol at a production capacity of 290 metric tons per day. On the other hand, 38 MW of electricity capacity was generated in the combined power cycle.