Processes for transitioning between different polymerization catalysts in a polymerization reactor

A process for transitioning from a metallocene catalyst to a Ziegler-Natta catalyst in a gas phase polymerization reactor, comprising:

• introducing a first olefin, an anti-static agent, a first carrier gas, and a plurality of metallocene catalyst particles into the reactor under conditions effective to maintain the metallocene catalyst particles in a fluidized state and to polymerize the first olefin in the presence of the metallocene catalyst particles to produce a first polymer product;
• stopping introduction of the metallocene catalyst particles and the anti-static agent into the reactor;
• introducing a kill agent into the reactor to stop polymerization of the first olefin within the reactor;
• stopping introducing of the first olefin into the reactor;
• removing a first portion of the first olefin from the reactor;
• removing the first polymer product, the metallocene catalyst particles, and the anti-static agent from the reactor;
• removing a second portion of the first olefin within the reactor such that the reactor contains ≤1,000 ppmv of the first olefin;
• introducing a first aluminum-containing compound into the reactor after the concentration of the first olefin is reduced to ≤1,000 ppmv, wherein the first aluminum-containing compound reacts with at least a portion of any residual anti-static agent that remains within the reactor to produce a first reaction product comprising an alkane and at least one additional product;
• removing at least a portion of the alkane in the first reaction product from the reactor;
• introducing water into the reactor, wherein the water reacts with at least a portion of any residual first aluminum-containing compound remaining within the reactor to produce a second reaction product comprising an alkane and a first alkylaluminum hydroxide;
• removing at least a portion of the alkane in the second reaction product from the reactor;
• introducing a seedbed produced with a Ziegler-Natta catalyst into the reactor;
• introducing a second carrier gas into the reactor and venting the reactor to dry the seed bed to a water concentration of ≤20 ppmv;
• introducing a second aluminum-containing compound into the reactor, wherein the second aluminum-containing compound reacts with at least a portion of any residual water within the reactor to produce a third reaction product comprising an alkane and a second alkylaluminum hydroxide;
• removing at least a portion of the alkane in the third reaction product from the reactor;
• introducing a second olefin into the reactor;
• and
• introducing a plurality of Ziegler-Natta catalyst particles and a third carrier gas into the reactor under conditions effective to maintain the Ziegler-Natta catalyst particles in a fluidized state and to polymerize the second olefin in the presence of the Ziegler-Natta catalyst particles to produce a second polymer product.