Highly Efficient Transformation of Tar Model Compounds into Hydrogen by a Ni–Co Alloy Nanocatalyst During Tar Steam Reforming

Abstract

Hydrogen (H 2 ) production from coal and biomass gasification was considered a long-term and viable way to solve energy crises and global warming. Tar, generated as a hazardous byproduct, limited its large-scale applications by clogging and corroding gasification equipment. Although catalytic steam reforming technology was used to convert tar into H 2 , catalyst deactivation restricted its applicability. A novel nanocatalyst was first synthesized by the modified sol−gel method using activated biochar as the support, nickel (Ni) as the active component, and cobalt (Co) as the promoter for converting tar into H 2 . The results indicated that a high H 2 yield of 263.84 g H 2 / kg TMCs (Tar Model Compounds) and TMC conversion of almost 100% were obtained over 6% Ni−4% Co/char, with more than 30% increase in hydrogen yield compared to traditional catalysts. Moreover, 6% Ni−4% Co/char exhibited excellent resistance to carbon deposition by removing the nucleation sites for graphite formation, forming stable Ni−Co alloy, and promoting the char gasification reaction; resistance to oxidation deactivation due to the high oxygen affinity of Co and reduction of the oxidized nickel by H 2 and CO; resistance to sintering deactivation by strengthened interaction between Ni and Co, high specific surface area (920.61 m 2 /g), and high dispersion (7.3%) of Ni nanoparticles. This work provided a novel nanocatalyst with significant potential for long-term practical applications in the in situ conversion of tar into H 2 during steam reforming.