Dr Salman Khoshk Rish

This study compares the performance, including reactivity and stability, of Pd¿Cu/Al2O3 and Cu/Al2O3 catalysts during catalytic hydrogen combustion in a temperature range of 20¿600 °C. The physicochemical and catalytic properties of catalysts were characterized using various analytical techniques. The reaction rates were measured using a fixed-bed reactor connected to a micro-gas chromatograph, and the rate law equations containing a term for steam partial pressure were determined. The effects of reaction temperature and catalyst composition on the reaction mechanism were investigated using in-situ Fourier-transform infrared spectroscopy analysis, and the generation of OH groups was analyzed to compare the reaction pathways of catalytic hydrogen combustion over Pd¿Cu/Al2O3 and Cu/Al2O3 catalysts. The results showed that at temperatures above 500 °C, Cu/Al2O3 achieved a comparable hydrogen conversion (96.5 and 98%) to that of Pd¿Cu/Al2O3. The rate-limiting steps of catalytic combustion over Pd¿Cu/Al2O3 and Cu/Al2O3 were the formation and breaking of metal-oxygen bonding, respectively. It was also found that the difference between the reactivity of Pd¿Cu/Al2O3 and Cu/Al2O3 was less pronounced under wet conditions.

New ternary deep eutectic solvents (DESs), including imidazole (Im), ethylene glycol (EG), and methyltriphenyl phosphonium bromide (MTPB), were synthesized at different molar ratios to absorb SO2in flue gas. Excitingly, the EG-Im-MTPB (1:2:1) DES has achieved the unexpected achievement of its absorption capacity being greatly improved to 0.65 g of SO2/g of DES (4.43 mol/mol) at 3000 ppm and 30 °C, which is the best performing DES for capturing SO2under the same conditions ever reported. The aftereffects of thermodynamic investigation demonstrate that there is a solid compound communication between EG-Im-MTPB (1:2:1) DES and SO2. In particular, the enthalpy change (¿rHm), entropy change (¿rSm), and Gibbs free energy change (¿rGm) were plainly determined as -50.45 kJ/mol, -114.57 J mol-1K-1, and -16.20 kJ/mol, separately. The Fourier transform infrared, 1H nuclear magnetic resonance, and quantum chemistry calculation results confirm that multiple active sites, including the N atom of Im and the Br atom of MTPB, are the main factors by which DES effectively absorbs SO2. Further, a UNIQUAC method by Aspen Plus V12 is set up for the SO2absorption process with 6000 m3/h flue gas, indicating that the EG-Im-MTPB (1:2:1) DES can completely absorb SO2in the flue gas when the consumption of DES is 26.8 m3/h.

Deep eutectic solvents (DESs) cannot absorb SO2 at high temperatures, due to the lower solubility of the toxic gas in DESs at high temperatures, limiting their wider uptake in industrial applications. To address this knowledge gap, we added Na2S to a series of DESs to improve SO2 adsorption capacity at elevated operating temperatures in this work. The experimental results show that the newly designed Na2S-EG-MTPB DESs can adsorb SO2 effectively up to 90 °C. Solid products resulted from the interaction of SO2 and Na2S-EG-MTPB DES is mainly elemental sulfur (S8) and sodium sulfite (Na2SO3). DESs can be reused for SO2 absorption for at least five times by adding additional Na2S. Therefore, Na2S-EG-MTPB DESs have great potential as substitutes for existing SO2 absorbents due to their excellent high temperature resistance, high SO2 absorption capacity and low cost.