Catalytic production of olefins using natural halloysite nanotubes

Abstract

The production of C2-C4 olefins by deep catalytic cracking and the thermocontact pyrolysis of vacuum gas oil, commercial-grade cottonseed oil, and a vacuum gas oil-cottonseed oil 90: 10 mixture in the temperature range of 600–800°C is studied using natural halloysite extracted from kaolinite fields in the form of aluminosilicate sheets rolled in nanotubes. It is found that in the deep catalytic cracking of vacuum gas oil at 600°C using halloysite as a catalyst, the gain in the yield of ethylene is 6.4–10.1 wt %, compared to yields of this product when using ZSM-5 catalyst. Adding 10% commercial-grade cottonseed oil to the vacuum gas oil further increases the yield of ethylene by 2.2 wt % with a simultaneous 3.3 wt % rise in the yield of propylene. The cracking of pure cottonseed oil under identical conditions yields ethylene and propylene of 16.1 and 9.2 wt %, respectively. The possibility of using halloysite nanotubes as a heating surface for the thermal pyrolysis of the above feedstocks at temperatures of 700–800°C in order to obtain yields of C2-C3 olefins exceeding those of identical products in industry, and of reusing halloysites in the thermoconversion of the studied feedstocks via their complete regeneration, is confirmed.