Catalytic Pyrolysis of Fischer-Tropsch Wax
Fischer-Tropsch wax is a methylene polymer, an alkane polymer synthesized from hydrocarbon-based syngas or natural gas. It mainly relies on low-cost raw materials of coal chemical industry for iron-based or cobalt-based synthesis, which has obvious advantages over the price of oil wax.
The catalytic cracking performance of Fischer-Tropsch wax over different active catalysts and coke deposition catalysts was investigated in a small fixed fluidized bed reactor using MMC-2 catalyst. The results showed that Fischer-Tropsch wax was easily converted, and the activity of MMC-2 catalyst had little effect on its conversion, but had great influence on product distribution. With the increase of catalyst activity from 52% to 83%, dry gas yield from 4.12% to 10.34%, coke yield from 2.20% to 10.50%, and gasoline yield from 36.10% to 22.99%. The yield of liquefied gas has little change, about 56%, but the mass fraction of propylene and butene in liquefied gas decreases obviously. The lower the activity of MMC-2 catalyst, the lower the acid center density, the more conducive to the production of low-carbon olefins. Fischer-Tropsch wax is suitable for the production of low-carbon olefins on low-activity catalysts. Coke modification can also reduce the acid content of the catalyst and improve the olefin selectivity of the product. Fischer-Tropsch wax is more conducive to the production of low-carbon olefins when the mass fraction of coke deposited on MC-2 catalyst is between 0.6% and 0.8%.