Green conversion of wood plastic composites: A study on gasification with an activated bio-char catalyst

Abstract

The excessive use of wood plastic composites (WPCs) at construction sites owing to their outstanding properties has caused serious disposal problems recently. Thermochemical conversions, such as pyrolysis and gasification, provide a solution for WPC disposal as a means of biofuel generation in an environmentally friendly manner. In this study, air gasification of WPCs was performed over activated bio-char-based catalysts for green valorization with the aim of achieving higher H2 generation. The KOH activation resulted in a significant increase in the Brunauer-Emmett-Teller surface area (14 times) and total pore volume (∼6.7 times), and KOH activated char was an excellent adsorbent for trapping tar, resulting in higher tar conversion into lighter hydrocarbons and H2. In addition, KOH-activated biochar showed the highest gas yield (69 wt%) and highest H2 selectivity (29.76 vol.%) compared to non-catalytic and non-activated bio-char catalysts. In contrast, an equivalence ratio of 0.20 was considered optimal over KOH-activated biochar for obtaining a higher H2 selectivity (29.76%) and minimum CO2 (17.08%). The increased catalyst/feedstock ratio from 0.1 to 0.2 also enhanced the conversion of WPC toward H2 generation (29.76%–35.93%). Finally, the Ni loading over KOH-activated biochar provided the highest H2 selectivity of 43% owing to the synergy of tar cracking, water gas shift reaction, and steam and dry reforming reactions. The increase in the H2 content of the product gas was significant because it increased the overall heating value and quality of the obtained gas. Largely, this study will be a stepping stone toward sustainable valorization of WPC over activated biochar-based catalysts for higher H2 generation.