Abstract: This invention is directed to a method for removing calcium material from a substrate or catalytic converter. In particular, this invention is directed to a method for removing calcium material, particularly in the form of calcium-containing fly ash, from a substrate using a partially protonated or non-protonated polycarboxylic acid treatment material.

Abstract: This invention is directed to a process for removing a catalyst inhibitor from a substrate or catalytic converter containing at least one nitrogen oxide (NOx) catalyst using a phosphoric acid composition. The process is particularly suited for removing the catalyst inhibitor, arsenic, from a fly ash-coated substrate or converter. A substantial amount of catalyst inhibitor can be removed from a fly ash-coated catalytic converter without removing a significant portion of one or more of the NOx reduction catalysts in or on the substrate.

Abstract: This invention is directed to a process and chemical composition effective in removing heavy metal from combustion gas. The process and chemical composition are particularly effective in removing undesirable heavy metal from combustion gases that are formed from the combustion of coal. The chemical composition that is used is an aqueous composition of at least one alkali metal sulfide, and at least one alkali metal or alkaline earth metal buffer in amounts that are effective in removing at least a majority of the heavy metal from the combustion gas.