Abstract: Multimodal polyolefin polymers may be prepared in series-connected polymerization reactors where a prior reactor is a slurry reactor employing light solvent as the slurry medium and hydrogen to limit polymer molecular weight, the polymer product from the prior reactor being substantially freed of hydrogen prior to entry into a subsequent polymerization reactor operating at low hydrogen pressure to produce a high molecular weight olefin. The economics and operating performance of such a series slurry reactor polyethylene process can be significantly improved through the use of an intermediate slurry transfer system and hydrogen removal apparatus that employs flash drums in series in conjunction with a warm recycle solvent slurry diluent.

Abstract: Multimodal polyolefin polymers may be prepared in series-connected polymerization reactors where a prior reactor is a slurry reactor employing light solvent as the slurry medium and hydrogen to limit polymer molecular weight, the polymer product from the prior reactor being substantially freed of hydrogen prior to entry into a subsequent polymerization reactor operating at low hydrogen pressure to produce a high molecular weight olefin. The economics and operating performance of such a series slurry reactor polyethylene process can be significantly improved through the use of an intermediate slurry transfer system and hydrogen removal apparatus that employs flash drums in series in conjunction with a warm recycle solvent slurry diluent.

Abstract: The use of two or more light solvent boiling pool reactors in series allows polymerization of ethylene and comonomer(s) to cost effectively produce bimodal polyethylene copolymers having lower densities than are practically achievable with conventional stirred tank, slurry loop or gas phase reactor technologies. Introducing catalyst to only the first reactor, operating the first reactor at high hydrogen compositions, and using a plurality of series-connected flash drums to remove hydrogen from the first reactor polymer slurry product stream allows for the production of highly homogeneous high molecular weight bimodal polyethylene resins.

Abstract: Multimodal polyolefin polymers may be prepared in series-connected polymerization reactors where a prior reactor is a slurry reactor employing light solvent as the slurry medium and hydrogen to limit polymer molecular weight, the polymer product from the prior reactor being substantially freed of hydrogen prior to entry into a subsequent polymerization reactor operating at low hydrogen pressure to produce a high molecular weight olefin. The economics and operating performance of such a series slurry reactor polyethylene process can be significantly improved through the use of an intermediate slurry transfer system and hydrogen removal apparatus that employs flash drums in series in conjunction with a warm recycle solvent slurry diluent.

Abstract: An aromatic diamino-diol (such as 4,6-diaminoresorcinol) is made by reducing an aromatic halo-dinitro-diol (such as 2-halo-4,6-dinitroresorcinol) with molecular hydrogen in an aqueous mixture containing a noble metal hydrogenation catalyst, an aqueous solvent and about 2 moles of hydrogen halide per mole of aromatic halo-dinitro-diol, plus an additional quantity sufficient to provide a 0.75 to 4 molar solution of the hydrogen halide.