Conventional and cement-catalyzed co-pyrolysis of rice straw and waste polyethylene into liquid and gaseous fuels by using a fixed bed reactor

Abstract

Rice straw is the main agricultural by-product while polyethylene is among the most widely produced plastics in the world. The bulk of rice straw and discarded polyethylene end up in landfills and pose concerns with waste management. By valorizing these wastes into valuable fuels through a suitable conversion approach, the associated environmental pollution and waste management problems can be reduced. In the reported work, a low-cost cement catalyst was tested for co-pyrolysis of rice straw and waste polyethylene into combustible liquid and gases in a fixed bed pyrolysis reactor. Under optimum conditions, the co-feed rice straw and polyethylene yielded 57.2 wt.% of liquid fuel, 21.3 wt.% of gas, and 21.5 wt.% of bio-char. When compared with rice straw alone, the co-feed feedstock produced 16.60% more liquid fuel and 7.5% less bio-char. The liquid product increased with an increase in plastic content of the blend. The amount of liquid product increased from 57.2 to 74.18 wt.% for rice straw to polyethylene ratio of 1:3. The catalyst showed a noticeable effect on composition of the fuels. With the use of catalyst, the gas yield increased from 21.3 to 28.16 wt.% and hydrogen content of gas increased from 19.33 to 31.18 mL/g.