An efficient and robust bimetallic catalyst has been developed for the transfer hydrogenation of biomass derived ethyl levulinate to γ-valerolactone with 2-butanol as the hydrogen donor. Several bimetallic catalysts were prepared and characterized by Brunauer−Emmett−Teller, transmission electron microscopy, X-ray power diffraction and X-ray photoelectron spectrometry. They exhibited different catalytic activities in the catalytic transfer hydrogenation (CTH) reaction. Results showed that 10Cu-5Ni/Al 2 O 3 had the highest activity, providing a 97% yield of GVL product in 12 h at 150 °C. The reaction temperature, reaction time and catalyst loading were also investigated and found to affect the product yield. The catalyst was also successfully applied to the CTH of various levulinate esters with different secondary alcohols. Comparing experiments between Cu−Ni and Cu catalysts and the poisoning experiments revealed that the introduction of Ni to Cu remarkably enhanced the catalyst's activity and stability, showing an outstanding recycling ability in the 10 runs recycling experiments without notable loss in the activity.

The optimum conditions, such as pH, immobilization time, temperature, and enzyme dose, for carbonic anhydrase (CA) immobilized on the polyester polyurethane prepolymer 80 were investigated. Simultaneously, the performances (e.g., pH, thermal, operational, and storage stabilities) of immobilized CA and free CA were compared. The results revealed that the optimum conditions, such as pH value of Tris−HCl buffer, immobilization time, temperature, and enzyme dose, of immobilized CA were 7.5, 24 h, 35 °C, and 1 mL of enzyme solution (0.1 mg/mL)/0.1 g of polyester 80, respectively. Moreover, pH and operational, thermal, and storage stabilities of immobilized CA were higher than those of free CA. On this basis, the experiment was conducted to immobilize CA to absorb CO 2 . The results indicated that the CO 2 concentration, liquid/gas ratio, and gas flow rate may affect the properties of CO 2 absorption. The CO 2 absorption efficiency dropped from 63 to 42.7% with an increase in the CO 2 concentration from 9 to 15.4%. With the increase of the gas flow rate, the CO 2 absorption efficiency first increased and subsequently decreased. The absorption efficiency increased from 30.9 to 57.7% with an increase in the liquid/gas ratio from 26 to 34 L/m 3 . The optimal operating conditions can accelerate the absorption rate of CO 2 and reduce the usage of immobilized CA, which can reduce the cost of CO 2 sequestration.

The limestone–gypsum wet flue gas desulfurization (WFGD) process has a significant influence on the emission characteristics of soluble ions in particulates. In this study, a simulated limestone–gypsum WFGD platform was used to study the emission characteristics of water-soluble ions in flue gas after desulfurization. The experimental results indicated that the entrainment of desulfurization slurry droplets was the main source of water-soluble ions emission while water-soluble ions cannot be carried by vaporous water in flue gas. The limestone–gypsum desulfurization process can form soluble ionic particles with particle size less than 1 μm. In addition to Ca2+, Mg2+, SO4 2–, and Cl–, which were the main ion components in the slurry, NH4 + was also the main ion composition of the soluble ionic particles, indicating that the entrainment and evaporation of slurry droplets and condensation of volatile components were the formation mechanism of the soluble ionic particles. Reducing the gas velocity and liquid–gas ratio was beneficial to weakening the entrainment of the desulfurization slurry droplets, thereby reducing the discharge of soluble ionic particles and water-soluble ions. Besides this, with the decline of the slurry concentration and flue gas temperature, the soluble ionic particles level emitted from desulfurization process also decreased.

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