Municipal solid waste incineration (MSWI) fly ash could be used as a catalyst for pyrolysis of oil-based drill cuttings from shale gas exploitation industry

Abstract

Oil-based drill cuttings (OBDC) and MSWI fly ash are both hazardous wastes and are produced in huge amounts every year. OBDC are often treated by pyrolysis for recovering hydrocarbons, while municipal solid waste incineration (MSWI) fly ash is solidified and then landfilled. This study found that MSWI fly ash had the porous structure with catalytic metal element loaded on the solid acid catalyst structure. Moreover, the specific surface area and pore size of MSWI fly ash were suitable for cracking and mass transfer of hydrocarbons in OBDC. Control experiment indicated that MSWI fly ash could promote pyrolysis of OBDC by 14.5% compared with that without any catalyst. Orthogonal experiments further confirmed that the catalytic properties of MSWI fly ash were comparable to some commercial catalysts and laboratory catalysts. Thermogravimetric results showed that the pyrolysis of OBDC was divided into three stages, and the activation energy of each stage increased gradually. Kinetic analysis proved that using MSWI fly ash as catalyst could reduce the activation energy of the third stage which needed the maximum activation energy to react, so promoted the cracking of heavy hydrocarbon and enhanced the recycling rate of hydrocarbons in OBDC.