Proceso para eliminar y recuperar dioxido de azufre selectivamente de un gas que contiene dioxido de azufre que comprende poner en contacto el gas con una solucion tamponada de malato de sodio; y proceso para la eliminacion simultanea de dioxido de azufre y nox y recuperar el dioxido de azufre.

摘要

This invention relates to processes for selective removal of contaminants from effluent gases. A sulfur dioxide absorption/desorption process for selective removal and recovery of sulfur dioxide from effluent gases utilizes a buffered aqueous absorption solution comprising weak inorganic or organic acids or salts thereof, to selectively absorb sulfur dioxide from the effluent gas. Absorbed sulfur dioxide is subsequently stripped to regenerate the absorption solution and produce a sulfur dioxide-enriched gas. A process for simultaneous removal of sulfur dioxide and nitrogen oxides (NOx) from effluent gases and recovery of sulfur dioxide utilizes a buffered aqueous absorption solution including a metal chelate to absorb sulfur dioxide and NOx from the gas and subsequently reducing absorbed NOx to form nitrogen. A process to control sulfate salt contaminant concentration in the absorption solution involves partial crystallization and removal of sulfate salt crystals.