The Effect of Acid Gases on Elemental Hg Removal and Experimental Studies Accompanied by Quantum Chemical Calculations (DFT)

Abstract

In the oxy-fuel combustion flue gas, a complex atmosphere of acid gases such as SO2, HCl, and NO generally exist at the same time. In this work, the effects of SO2, HCl, and NO on Hg removal of carbon-based material by NH4Br and HNO3 co-modification are investigated at the experimental level, and the effects of SO2 and NO on Hg removal are studied at the theoretical level. FTIR analysis shows that the co-modification can effectively introduce Br and N–H into the adsorbent. The introduction of HCl and NO can alleviate the inhibitory effect of SO2, which is due to the facilitated conversion of Hg0 to HgCl2 and HgO. XPS results show that the reason adsorbent co-modification with NH4Br and HNO3 possess sulfur resistance effect is that the modification promotes the generation of C–O* and C–Br functional groups and converts Hg0 into HgO and HgBr2, HgBr2 is further converted into HgSO4.The surface adsorption energy, electrostatic potential distribution, bond length variation, and Mulliken charge population transfers of modified char under different working conditions are calculated by DFT simulations. The results indicate that the order of the magnitude of the interaction between different substrates with Hg0 is C–SO2 < C–SO2–NO < C.

Elemental Mercury Removal from Coal-Fired Flue Gas on Sulfur-Modified Activated Biomass Coke: Experiment and Simulation

“…The mercury breakthrough rate represents the proportion of mercury escaped after passing through the adsorbent and is an important indicator for evaluating the adsorption performance of the adsorbent, as shown in eq η = C 0 out C 0 in × 100 % where C 0 out is the mercury concentration at the pipe outlet, μg/m 3 , and C 0 in is the mercury concentration at the pipe inlet, μg/m 3 .…”

Multiscale Understanding of the Mechanism of Mercury Removal by Acid–Chlorine-Modified Biomass Coke: Experiments and Simulations

“…But the conventional chlorine modification is susceptible to temperature-limited activity, considering that acid modification not only facilitates the introduction of additional oxygen-containing functional groups on the surface, 29 but also enhances the reactivity of chlorine, 30 resulting in a more stable immobilization of mercury on the adsorbent surface. 31,32 Therefore, the modification technique of acid-chlorine impregnation will be used to study the influence of the acid−chlorine ratio and mass ratio of modifier to rice straw coke on the performance of modified rice straw coke for mercury removal. Temperature and inlet mercury concentration are important influences that interfere with the removal of mercury from adsorbents.…”

“…According to previous studies, , chloride-modified biomass coke can incorporate active chlorine-containing functional groups on the coke surface, which exhibit high reactivity against Hg 0 , facilitating its capture from flue gas. But the conventional chlorine modification is susceptible to temperature-limited activity, considering that acid modification not only facilitates the introduction of additional oxygen-containing functional groups on the surface, but also enhances the reactivity of chlorine, resulting in a more stable immobilization of mercury on the adsorbent surface. , Therefore, the modification technique of acid-chlorine impregnation will be used to study the influence of the acid–chlorine ratio and mass ratio of modifier to rice straw coke on the performance of modified rice straw coke for mercury removal.…”

New Insight into Hg0 Oxidation over a Mn-Doped VWTi Catalyst at a Wide Temperature Window

“…7 However, the Hg 0 oxidation performance over commercial SCR catalysts is relatively poor at low HCl content. 8 Meanwhile, NH 3 , which is used as the reducing agent for NO reduction, can also inhibit Hg 0 oxidation by competing adsorption sites on the catalyst surface. 9,10 In recent years, along with the implementation of carbon peaking and carbon neutrality goals in China, the proportion of new energy power generation in the power grid has been gradually increasing.…”

“…Researchers have revealed that the selective catalytic reduction (SCR) catalysts for NO x removal, such as V 2 O 5 –WO 3 /TiO 2 and V 2 O 5 –MoO 3 /TiO 2 , exhibit efficient Hg 0 oxidation activity in the presence of HCl, thus achieving efficient and cost-effective mercury removal . However, the Hg 0 oxidation performance over commercial SCR catalysts is relatively poor at low HCl content . Meanwhile, NH 3 , which is used as the reducing agent for NO reduction, can also inhibit Hg 0 oxidation by competing adsorption sites on the catalyst surface. , In recent years, along with the implementation of carbon peaking and carbon neutrality goals in China, the proportion of new energy power generation in the power grid has been gradually increasing.…”