화학공학소재연구정보센터
Applied Catalysis A: General, Vol.562, 106-113, 2018
Deposition-precipitation approach for preparing core/shell SiO2@Ni-Rh nanoparticles as an advanced catalyst for the dehydrogenation of 2-methoxycyclohexanol to guaiacol
A novel core/shell nano-bimetallic catalyst SiO2@Ni-Rh was successfully prepared by deposition-precipitation method, using liquid ammonia as a precipitating agent. SEM, TEM, XRD, XPS, H-2-TPR, H-2-TPD and adsorption/desorption of nitrogen were employed to systematically investigate the surface morphology, size, chemical composition, reducibility, Ni dispersion and structure of the as-synthesized nanoparticles. It is found that the nickel and rhodium are uniformly dispersed on the silica surface to form core/shell SiO2@Ni-Rh nanoparticles with Ni atoms and Rh atoms as the outer shell and SiO2 as the core, which possess high dispersion of Ni on the surface and high specific surface area (234.063 m(2)/g) of the catalyst with the mean particle size of ca. 130 nm. The dehydrogenation of 2-methoxycyclohexanol to guaiacol was used as the model reaction for evaluating the catalytic activity of the as-synthesized core/shell various Ni and Rh-containing bimetallic nanoparticles in a tubular stainless steel reactor. SiO2@15Ni-0.4Rh nanoparticles have exhibited remarkable catalytic performance, with 98.3% conversion and 93.6% selectivity of guaiacol, due to high dispersion of metal nanoparticles and synergistic effect of bimetallic Ni-Rh over the special core/shell SiO2@Ni-Rh by the addition of rhodium. Furthermore, turn over frequency value of SiO2@15Ni-0.4Rh nanoparticles achieves 0.47 s(-1), showing high catalytic efficiency. In general, the dehydrogenation of 2-methoxycyclohexanol over the core-shell-like SiO2@ Ni-Rh nanoparticles in a continuous fixed-bed reactor is a more promising, high atom economy, high efficient, easy separation, environmental friendliness, green synthetic pathway of guaiacol.