The pilot demonstration of a honeycomb catalyst for the DeNO_x of low- temperature flue gas from an industrial coking plant

摘要

The practical low-temperature DeNO(x) catalyst has a huge market demand for the flue gas purification of the widespread small-scale boilers. In this work, the modified V-based low-temperature honeycomb catalyst was produced through the hydrothermal process of metatitanic acid, which exhibited high strength and low SO2 oxidation rate. The pilot test of flue gas from a coking plant demonstrated that the honeycomb catalyst could endure the high content of SOx (400-600 ppm) and H2O ( 15 vol%) in flue gas at 300 degrees C and work stably with adjustable NO removal efficiency and little ammonia slip. After dry desulphurization and dedusting processes, the catalytic activity could still keep stable during the three-week test at as low as 220 degrees C, and the catalyst showed none deactivation. But the obvious deactivation of catalyst was observed at 270 degrees C before dry desulphurization and dedusting processes. The characterization of spent catalyst revealed that the deactivation of catalyst mainly resulted from the covering of catalytic surface by ammonium sulfate and ferric sulfate species, which formed through the gas reaction of inherent SO3 with NH3 for ammonium sulfate species and the corrosion/stripping of Fe based pipe for ferric sulfate species, respectively. After the re-calcination process, the deactivated catalyst could be regenerated with the decomposition of sulfate species.