Fabrication of highly dispersed carbon doped Cu-based oxides as superior selective catalytic oxidation of ammonia catalysts via employing citric acid-modified carbon nanotubes doping CuAl-LDHs

Abstract

In this work, the CuAl-LDO/c-CNTs catalyst was fabricated via in situ oriented assembly of layered-double hydroxides (LDHs) and citric acid-modified carbon nanotubes (c-CNTs) followed by annealing treatment, and evaluated in the selective catalytic oxidation (SCO) of NH3 to N2. The CuAl-LDO/c-CNTs catalyst presented better catalytic performance (98% NH3 conversion with nearly 90% N2 selectivity at 513 K) than other catalysts, such as CuAlOx/CNTs, CuAlOx/c-CNTs and CuAl-LDO/CNTs. Multiple characterizations were utilized to analyze the difference of physicochemical properties among four catalysts. XRD, TEM and XPS analyses manifested that CuO and Cu2O nanoparticles dispersed well on the surface of the CuAl-LDO/c-CNTs catalyst. Compared with other catalysts, larger specific surface area and better dispersion of CuAl-LDO/c-CNTs catalyst were conducive to the exposure of more active sites, thus improving the redox capacity of the active site and NH3 adsorption capacity. In-situ DRIFTS results revealed that the internal selective catalytic reduction (iSCR) mechanism was found over CuAl-LDO/c-CNTs catalyst.