Strategies of Coping with Deactivation of NH3-SCR Catalysts Due to Biomass Firing

Strategy and Technical Progress of Recycling of Spent Vanadium-Titanium-Based Selective Catalytic Reduction Catalysts

Selective catalytic reduction denitration technology, abbreviated as SCR, is essential for the removal of nitrogen oxide from the flue gas of coal-fired power stations and has been widely used. Due to the strong demand for energy and the requirements for environmental protection, a large amount of SCR catalyst waste is produced. The spent SCR catalyst contains high-grade valuable metals, and proper disposal or treatment of the SCR catalyst can protect the environment and realize resource recycling. This review focuses on the two main routes of regeneration and recycling of spent vanadium-titanium SCR catalysts that are currently most widely commercially used and summarizes in detail the technologies of recycling, high-efficiency recycling, and recycling of valuable components of spent vanadium-titanium SCR catalysts. This review also discusses in depth the future development direction of recycling spent vanadium-titanium SCR catalysts. It provides a reference for promoting recycling, which is crucial for resource recovery and green and low-carbon development.

Modeling the Process and Properties of Ash Formation during Pulverized Biomass Combustion

The present work mainly developed a mathematical model based on the plug flow model and coarse fly ash particles’ fragmentation model to describe the behavior and evolution of ash formation and the influence of the biomass feeding rate and flue gas cooling rate on ash properties, which is validated by literature data. The model considers homogeneous nucleation of alkali vapors, heterogeneous condensation of vapors on newly formed particles and fly ash particles, and collision-coagulation between aerosol particles, which is also applied to numerically study and analyze the ash formation characteristics in the cases of practical boiler pulverized fuel combustion and SO2 sulfation. The results show that the mathematical model can reasonably describe the ash formation and the influence of the biomass feeding rate and the flue gas cooling rate on the mass PSDs of PM10 and its elements. The initial nucleation temperature and initial nucleation particle size increase with the biomass feeding rate, which is of great importance to the cooling rate on the initial nucleation number concentration and the initial nucleation particle size. Elements Na, K, and Cl are mainly concentrated in PM1, but rarely distributed in PM1–10. The condensation of Na, K, and Cl on coarse particles increases with the biomass feeding rate and decreases with the cooling rate. The ash characteristics obtained from the experiment condition with an ultra-high flue gas cooling rate and minimum biomass selected may have a large deviation from that of practical biomass combustion, and the sulfated reaction may reduce Cl corrosion rather than ash deposition.

NH3-SCR of NO with novel active, supported vanadium-containing Keggin-type heteropolyacid catalysts

Supported vanadium-substituted Keggin polyoxometalates (POMs) were applied as catalysts for the selective catalytic reduction of NO using NH₃ as reductant (NH₃-SCR).

Selective Catalytic Reduction of NOx

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