ABSTRACT
Metal catalysts, when precipitated, have a tendency to occlude foreign ions such as sodium or other alkali or an anionic component such as sulfate or chloride. Usually, volatile components such as nitrate or carbonate are not considered to be harmful occluded ions. However, if the precipitate is a carbonate, hydroxide, or gel-like type, these ions will be so firmly occluded that washing simply will not remove them adequately. In the laboratory this ion exchange is performed by agitating in a beaker. The ion exchange can be effected at essentially any temperature that does not promote the decomposition of the ammonium carbonate. Many people viewing a catalyst plant for the first time say it is nothing but an overgrown chemical laboratory with tanks instead of beakers, agitators instead of stirrers, and presses or rotary filtration instead of filters.
