Porous Nitrogen-Doped Carbon Ni Nanocatalysts for H₂-Free and Solvent-Free Pyrolysis of Real Coal Tar to Light Aromatics (C₆–C₁₀)

Catalytic fast pyrolysis (CFP) for aromatics production is a key strategy to achieve high-value-added utilization of real medium-low temperature coal tar (CT). However, this technology still suffers from low yield of aromatics and low selectivity for light aromatics (C6–C10). Herein, we found that Ni nanocatalysts (Ni/BNC) prepared by activation and N-doping of biochar can catalyze CT pyrolysis to produce light aromatics (C6–C10) without H2 and solvent. Experimental and theoretical evidence suggests that N-doping can subtly improve the defect structure and optimize the electron transfer and charge distribution of Ni0 in Ni/BNC, favoring the adsorption and activation of CT pyrolysis components. Meanwhile, this strategy endows Ni/BNC with a large specific surface area, strong Ni0 metallicity, good dispersion, and suitable acidic sites, thus stabilizing the Ni0 activity center and accelerating the aromatization of aliphatic hydrocarbons and the cracking of polycyclic aromatic hydrocarbons (PAHs). The Ni/BNC catalyst achieves an 83.14% yield of aromatics at 500 °C without H2 and solvent, among which the selectivity of light aromatics (C6–C10) reached 95.06%. Moreover, the N-doped carbon (BNC) achieves a high aromatics yield (70.73%) and light aromatics (C6–C10) selectivity (82.58%) without Ni loading. Additionally, Ni/BNC demonstrates applicability to a variety of coal tars. The experimental results show that this strategy extends to other transition metals (Fe, Co, Cu) with promising potential for application.