The principle of passivation of the catalyst is to reduce the catalytic ability of the catalyst, for example, in the process of reducing the alkyne to an alkene, if the palladium is used as a catalyst, the alkyne will be directly reduced to an alkane, at this time, it is necessary to poison the catalyst (that is, passivation), usually with pyridine or lead acetate as a poison agent, catalyzed on the calcium carbonate carrier!