High-melting wax production from polyolefin, for use e.g. as bitumen additive, involves thermal degradation, first in circulating system of tubular reactors and then at higher temperature in stirred cracking reactor

摘要

Production of high-melting wax from polyolefin involves degradation to an average molecular weight of 15000-10000 in a circulating system of tubular reactors at 340-360 deg C followed by further degradation to a molecular weight of 8000-2000 in a stirred cracking reactor at 360-380 deg C in the absence of oxygen while nitrogen is passed through the melt. A multi-stage thermal degradation process for the production of high-melting wax from polyolefins or waste polyolefins involves melting the chopped plastic in a suitable vessel and then: (1) reducing the molecular weight to 15000-10000 in a circulating system of tubular reactors operating at 340-360 deg C with an average residence time of 4-12 minutes; and (2) reducing the molecular weight further to 8000-2000 in a stirred cracking reactor at 360-380 deg C in the absence of oxygen (with nitrogen passing through the melt at 4-8 Nm3/hour), after which the product is cooled to 150-160 deg C in a separate cooling circuit, taken off through a decanter centrifuge with a separation size of 20-50 microns m and then packaged.