Ni-WC/Al2O3 and Ni-WC/MgWO4/MgAl2O4 catalysts for resource recovery via pyrolysis combined with the dry reforming of plastics (PCDR)

Plastic waste (PW) is currently one of an environmental threat. Despite the increasing share of recycled plastics, their disposal remains high. Therefore, there is a high demand for new PW management systems. Among them, pyrolysis combined with dry reforming (PCDR) is an advantageous solution because it allows for resource re-covery in the form of gas and liquid fuels, with simultaneous utilization of CO2. To date, catalysts based on Ni, Co, and noble metals supported on metal oxides have been examined. However, these catalysts suffer from quick deactivation due to coking and sintering. Therefore, testing other materials for PCDR is of particular importance. In this regard, Ni-WC/Al2O3 and Ni-WC/MgWO4/MgAl2O4 were investigated as potential PCDR catalysts. The catalysts were characterized by BET, BJH, XRD, CO2-TPD, H2-TPR, SEM, TEM, TG and DTG. The catalytic activity was evaluated in a two-step PCDR process using low-density polyethylene (LDPE), polystyrene (PS), polyethylene terephthalate (PET), and simulated waste plastic (SWP). The structure of the polymer strongly determines the yields of gas, liquid, and solid products. The highest yield of synthetic gas generation was observed for Ni-WC/ MgWO4/MgAl2O4 and was 48.20 +/- 2.41 mmol/gp. Different origins of the structural changes including oxidation or coking were observed for different plastics. PCDR of PET led mainly to oxidation, LDPE to the coking deposition. Catalysts after the process with PS were characterized by preservation of crystalline structure. The results indicate a high potential of carbide catalysts in the recovery of gaseous and liquid raw materials.